Index Manuals Abu Dhabi, United Arab Emirates. STANDARD CONSTRUCTION SPECIFICATIONS (PART 2 - ROAD STRUCTURES, 2020)

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Abu Dhabi, United Arab Emirates. STANDARD CONSTRUCTION SPECIFICATIONS (PART 2 - ROAD STRUCTURES, 2020) - page 4

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c. The Contractor must demonstrate that the proposed reinforced soil wall system has

previously been used in the UAE.

d. The wall system as a whole shall have a current British Board of Agreement (BBA), passing

the HITEC (Highway Innovative Technology Centre) evaluation protocol, or equivalent
certificate for Roads and Bridges, demonstrating suitability for use in highways walls and
abutments with a minimum 75 year design life.

e. The scope of work shall also include the design and construction of the concrete barrier

above the reinforced fill wall together with its counterbalancing slab all as indicated on the
Contract plans, All exposed faces of the concrete barrier and coping above the reinforced fill
wall shall be precast.

f. A Representative of the reinforced fill retaining wall manufacturer shall be present on site

during the casting and erection phases for a sufficient period to ensure that the quality of the
works performed by the Contractor is in accordance to the Specification. Furthermore the
Engineer/Owner reserves the right to ask for the Manufacturer's Representative whenever
they deem necessary. All expenses relative to his presence on site shall be borne by the
Contractor.

g. The design shall address the climatic and soil conditions existing in UAE and provide a

minimum design life of 75 years. The design must be performed by the supplier of the wall
system, who shall submit proof of professional indemnity insurance coverage. The
specifications as presented to the Engineer shall state any requirements for or limitations on
the reinforced infill to ensure the design life.

20.6.4.4 Submittals

Design Calculations

The following design criteria shall be considered:
1.

The vertical live load to be allowed in the design shall be: 1.5 x [LRFD HL93].

However,  no  vertical  load  shall  be  allowed  when  considering  the  resistance  to
overturning  of  the  concrete  barrier/counterbalance  slab  when  subjected  to  vehicle
impact load. Reference is to be made to Section 11.10 in the above AASHTO (LRFD),
Bridge Design Specifications.

The simplified Coherent Gravity Method should be used (Kr=Ka).

Live load surcharge shall be in accordance with AASHTO LRFD with an additional
magnification factor of 1.5 fill.

Analysis Concept and the Factors of Safety for External and Internal Stability

Design reduction factor, due to temperature effects (in addition to creep,
degradation and Installation damage reduction factors) should not be less than
1.11 times the value reported at 20

ii.

Design Temperature shall be ≥40

iii.

The wall supplier should use a 33

friction angle and a unit weight of 1921kg/m

for the backfill material in their design computations unless otherwise indicated
on the plans.

iv.

The factor of safety for pullout resistance in the select fill should not be less than
1.5, based on the pullout resistance at 13mm (1/2”) deformation.

Design global factor of safety should be 1.5.

vi.

Seismic Stability (Extreme Event Limit State I, with A=0.1 and 0.07):

FOS ≥ 0.75 of static FOS (All failure modes)
Check eccentricity (LRFD; Fig. 11.6.3.2-2 and Cl. 11.6.3.3),
soil bearing capacity (LRFD; Cl. 11.5.7) and
sliding under Extreme Event Limits I & II (LRFD;eq, 10.6.3,3-2).

Safety factors against slope slide at critical sections should be as per Table 20-8

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Table 20-8: Safety factors

Earthquake Acceleration Factor

Safety Factors Against Slide

0.0

1.50

0.07

1.40

≥ 0.10

1.30

(min. as per AASHTO-LFD, Cl. 5.2.2.3).

II.

The design of MSE walls shall be based on the following information provided by the main
Contractor:

1. Basic section geometry
2. Backfill Tests Results, Permeability and grading should be presented to the Engineer

as well. The minimum value for the coefficient of uniformity (Cu=D

≥ 2.0) should

be obtained from the Grading Curve. The Internal angle of friction should be at least
33.0

for the backfill behind the MSE wall.



soil-min should be taken as 18KN/m

and



soil-max = 21KN/m

. These properties shall be regularly monitored by the Contractor

during construction to ensure compliance with the approved property limits and
confirming to ISO 26021; "Statistical Interpretation of Test Results".

3. The difference between the reinforced infill and embankment backfill elevations is not

to be more than 600mm at any time during backfilling.

III.

It is the responsibility of the Designer and Contractor to ensure the MSE panels have:

1.  Height less than or equal to some 15.0m.
2.  Toe pressure less than or equal to 143 kPa.
3.  There are no anticipated bearing and/or settlement problems.
4.  Where  groundwater  is  present,  a  suitable  drainage  blanket  is  detailed  below  and

behind the MSE Wall

5. In off-bridge areas, where MSE panels are used, a counter-balance slab monolithic

with the parapets and above the earth retaining walls should be designed to
counteract for the impact due to vehicle collision.

System Information

The system submission shall be accompanied by:

1. A copy of the current BBA certificate or equivalent certificate, which shall include the

following information, as a minimum: a) Design Temperature of Strap. b) Details of
Production Factories. c) ISO Certificate reference of the Production Factories. d)
Design Calculation of the Strap Capacity.

2. Detailed design calculations for the proposed walls in compliance with AASHTO

LRFD, publications No. FHWA-NHI-10-024 & FHWA-NHI-10-025 or the National
Concrete Masonry Association Design Manual for Segmental Retaining Walls, 2

edition for modular blocks.

3.  Soils test information of the proposed reinforced soil fill.
4.  Method statement for construction.
5.  Confirmation  of  the  Professional  Indemnity  insurance  cover  provided  by  the  Wall

System Supplier.

6. Proven track record that the proposed system and type of reinforcement have been

used previously and successfully In the UAE for similar heights as walls of this project.

7. It is very important that the Geosynthetic Friction Reinforcements that the Contractor

proposes to use in the soli has been successfully used before in the UAE and has all
the necessary certification and test results support It.

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Shop Drawings

The Contractor shall submit details and drawings. Any particular requirements of the approved
detailed specifications for the approved proprietary system shall govern over any conflicting or
incompatible requirement contained within this section of the specification. The Contractor shall also
provide a detailed installation method statement.

20.6.4.5 Materials

The MSE retaining walls should conform to the Supplier's standards as previously approved by the
Engineer and AASHTO·LRFD Specification for MSE walls. The soil reinforcing system, which
includes the soil geosynthetic reinforcement, panel embeds and all connection devices, should be
according to the AASHTO-LRFD Standard.

The  wall  system  shall  comprise  of  precast  concrete  panels  with  geosynthetic  reinforcement  and
connectors  designed  to  ensure  a  high  strength,  positive  connection  between  wall  face  and
reinforcement. The Independent approval certificate shall have assessed this connection efficiently.

Precast Concrete Facing Panels

Concrete Class C40/20 shall be used for precast panels, coping, and for barriers and concrete
balance footing.

All precast panels should be manufactured according to the following requirements:

1.  The minimum panel thickness as required by design but should not be less than 140mm.
2.  Fusion bonded epoxy coated reinforcement bars should be used for panels.
3.  The  minimum  reinforcement  bar  cover  should  be  50mm  to  all  faces  of  the  panels  unless

otherwise approved by the Owner.

4. The panels should have a ship lap or tongue and groove system of overlapping joints

between panels designed to conceal joints and bearing pads.

5.  All dimension deviations should be within 5mm.
6.  Angular distortion with regard to the height of the panel should not exceed 5mm in 1.5m.
7.  Surface defects on formed surfaces measured on a length of 1.5m should not be more than

2.5mm.

8. The panel embed/connection devices should be cast into the facing panels with a tolerance

not to exceed 25mm from the locations specified on the approved shop drawings.

9. The back face of the panel should be roughly screeded to eliminate open pockets of

aggregate and surface distortions in excess of 6mm.

10. To prevent out of plane panel rotations, the soil geosynthetic reinforcement should be

connected to the standard panels In at least two different elevations, vertically spaced no
more than 760mm apart unless evidence is submitted that greater spacing is acceptable.

Modular Block Facing Units

1. The blocks shall be machine manufactured from Portland cement concrete specifically

designed for use in a reinforced soli retaining wall system.

2.  Colour of the facing units shell be as specified by the Engineer/Owner.
3.  The blocks shall have a straight split/textured face finish.
4.  Block height shall be 200mm or less.
5.  Block units shall be solid through the full depth of the unit.
6.  Blocks when Installed shall have gap not greater than 4mm between adjacent units.
7.  Block units shall be sound and free of cracks or other defects that would interfere with the

proper placing of the unit or significantly impair the strength or permanence of the structure.
Cracking or excessive chipping may be grounds for rejection. Units showing cracks longer
than 13mm shall not be used within the wall. Units showing chips visible at a distance of 10
meters from the wall shall not be used within the wall.

8. Concrete used to manufacture block units shall have a minimum 28 days compressive

strength of 30N/mm

and a maximum moisture absorption rate, by weight, of 5% as

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determined In accordance with ASTM C 140. Compressive strength test specimens shall
conform to the saw-cut coupon provisions of Section 5.2.4 of ASTM C140 with the following
exception: Coupon shall be taken from the least dimension of the unit of a size and shape
representing the geometry of the unit as a whole.

9. Block units molded dimensions shall not differ more than ± 3mm from that specified.
10. All modular block facing units will be manufactured by a block manufacturer approved by the

Engineer.

11. Only block systems that provide full face without any "voids" when constructed will be

accepted.  The  blocks  should  be  interlocking  from  one  level  to  the  next  by  means  of  an
integrated  mechanical  key  built  into  their  shape.  Blocks  must  achieve  connectivity  by  a
continuous mechanical connection built into the shape, and/or by a mechanical key formed
as part of the connection device.

12. The shear strength between blocks, and the connection strength between block and

geosynthetic reinforcement must be demonstrated in accordance with the procedures of
NCMA SRWU·1 and SRWU-2 or other recognized test standard.

13. A minimum 300mm drainage layer (with drainage pipe) wrapped in geotextile shall be used

behind the block walls to avoid undue build up of hydrostatic pressure. The drainage
collection pipe shall be a perforated or slotted PVC, or corrugated HDPE pipe. The drainage
pipe shall be manufactured in accordance with ASTM D3034 and/or ASTM D1248. The pipe
shall be a minimum of 100mm in diameter.

14. All units shall be manufactured within the following tolerances:



the height of the blocks are to be ±3mm.



the length of the block to be ±3mm



the squareness of the blocks to be ±2mm

15. Particular care shall be taken during storage to avoid staining the front face of the blocks.
16. Blocks will be subject to rejection because of failure to meet any of the requirements of the

Specifications. In addition, any or all of the following defects shall be sufficient cause for
rejection:



Defects that indicate imperfect molding.



Defects indicating honeycombed or open textured concrete.



A block with a damaged surface finish or staining or is otherwise chipped or cracked

on the front face such that In the opinion of the Engineer is visibly different from other
blocks. Such a block may however be used in positions where it is below final ground
level, subject to the Engineer's approval.

Geosynthetic Friction Reinforcement

The geosynthetic friction reinforcement shall be strips of polymeric high tenacity polyester fibers
concentrated in a series of separated bundles and encased in a durable polyethylene sheath.
Polyester fibers shall have a minimum Number Average Molecular Weight of 27000 as per ASTM
D4603 and GGI-GR8 method, and Maximum of Carboxyl End Group Content of 30 as per GRI-GG7
method. The minimum Weight per Unit Area as per ASTM D5261 shall be 270 gm/m

. All polymeric

components shall contain no recycled materials.

All product specific durability testing reports, documented evidence of third party participating, and
any relevant information shall be provided to the Engineer to examine the short-term and long-term
effects of environmental factors. The reports, documents and information shall include, but shall not
be limited to the following:

1. Short-term Tensile Strength, Elongation Tests results and load/strain characteristics

at different testing temperatures as per ASTM D4595.

2. Real time Long Term and Short Term Creep tests results as per ASTM D5262 and

FHWA-NHI-10-024 and FHWA-NHI-10-025. [the manufacturer should have at least
continuous 10,000hrs of data at different testing temperatures (at least one testing
temperature shall be more than 40

C)].

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3. Hydrolysis Resistance Tests as per ASTM D5322 (or EN ISO 13434) at different

testing temperatures (at least one shall be 65

C or more) and exposing periods. There

should be no appreciable loss of tensile strength at normal working temperature range
(20-65

C).

4. Chemical Resistance Tests (Alkali, Acid, and Oxidized Environment) at different

concentrations and testing temperatures (at least one set of the tests shall be
conducted at PH value more than 12 and at testing temperature more than 65

C) as

per ASTM D5322, (or EN ISO 13434).

5. Low Temperature Resistance Tests as per ASTM D4594 and High Temperature

Resistance Tests as per ASTM D4594 and applied ASTM D5322.

6. Installations Damage Resistance Tests in a soil similar In gradation and texture to the

material that will be used for backfill in the reinforced zone as per ASTM D5818.

7. Biological Resistance Tests (to Manufacturer's Recommended Method), Tests should

show below 3% reduction of tensile strength.

8.  Water Absorption Test should be provided to the Engineer as per ASTM D570.
9.  uV Oxidation Resistance tests as per ASTM D4355.
10. Pull-out  tests  to  establish  the  coefficient  of  friction  between  the  geosynthatic

reinforcement and a soil similar in compaction, moisture content, gradation, and
texture to the material that will be used for backfill in the reinforced zone.

Leveling Pad

Material for levelling pad shall consist of class C30/20mass concrete and shall be a minimum of
150mm in depth and 00mm wide.

Connection

For blocks, connection long term durability and strength shall be obtained in accordance with long
term connection strength test as per appendix A of FHWA NHI-00-043 over extended period of time
not less than 10,000 hours.

For panels, connection strength shall be determined by structural tests as per AASHTO LRFD

Drainage System

If the permeability of the MSE fill is less than 10

-2

m/sec, additional drainage measures shall be

required. The MSE wall shall be protected by an impermeable membrane and surface water shall
be channelled into chimney drain located immediately behind the wall.

The drainage system consists of pervious backfill wrapped with geotextile fabric and drainage pipe.
The geotextile fabric shall be as per the requirements of Section 2.5.2.9 of Chapter 2, Earthworks,
of the

Standard Specifications

1. Pervious backfill shall be angular, clean stone or granular fill meeting the following gradation

as determined in accordance with BS 1377 and as per

Table 20-9

Table 20-9: Pervious Backfill Gradation

Sieve Size

Percent Passing

75 mm

100

53 mm

90 - 100

37.5 mm

35 - 70

25 mm

0 - 15

12.5 mm

0 - 5

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2. The drainage collection pipe shall be a perforated or slotted PVC, or corrugated HDPE pipe,

The drainage pipe shall be manufactured in accordance with ASTM D3034 and/or ASTM
D1248, The pipe shall be a minimum of 100mm in diameter.

Reinforced (Infill) Soil

The reinforced soil material should be well graded crushed and angular not sub-rounded, and should
conform to the following:

1.  Maximum particle size 75mm
2.  Uniformity coefficient greater than or equal to 10
3.  Maximum 10% by mass passing the 75μm sieve
4.  Well graded material not gap graded
5.  Granular, Inorganic and non-plastic material
6.  Minimum angle of friction (Ø) of 36 degree
7.  Minimum permeability coefficient of 10

-4

m/sec

Joint Filler

Filler for horizontal joints between panels to be elastomeric pads with shore A hardness 80±5.

Filler for vertical joints shall be flexible open cell polyethylene foam strips unless otherwise noted on
approved shop drawings.

20.6.4.6 Construction

Excavation

The Contractor shall excavate to the lines and grades shown on the project grading plans. The
Contractor shall take precautions to minimize over excavation. Over-excavation shall be filled with
compacted material, or as directed by the Engineer.

The Contractor shall verify location of existing structures and utilities prior to excavation. The
Contractor shall ensure all surrounding structures are protected from the effects of wall excavation.
Excavation support, if required, is the responsibility of the Contractor.

The Contractor shall report immediately to the Engineer any sub-soil conditions which he encounters
during excavation which are likely to result in the bearing capacity required as shown on the Contract
plans not being achieved. The foundation of the structure shall be graded level for a width equal to
or exceeding the width of the strip footing plus a working space.

Prior to wall construction, except where constructed on rock, the sub-soil shall be compacted with a
smooth wheel vibratory roller.

Foundation Preparation

Following the excavation, the foundation soil shall be examined by the Engineer to assure actual
foundation soil strength meets or exceeds the design bearing strength. Soils not meeting the required
strength shall be removed and replaced with reinforced (infill) soils, as directed by the Engineer.

The foundation soils supporting the structure should be graded for a width equal to or exceeding the
length of the soil geosynthetic reinforcement. Prior to wall construction, the foundation should be
compacted with a smooth wheel vibratory roller to 95% of Modified Proctor density. Any foundation
soils found to be unsuitable should be removed and replaced, as per the wall supplier
recommendations and as accepted by the Engineer/Owner.

The strip footing shall be of class C30/20 concrete, to the dimensions indicated in the Contract plans.

Leveling Pad

Leveling pad shall be placed as shown on the construction drawings with a minimum thickness of
150mm to within a tolerance of



2mm of the top level shown on the drawings.

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The levelling pad should extend laterally at least a distance of 100mm from the toe and heel of the
lower most block unit.

Erection of Panels

During the specified backfill placement to install MSE panels, the Contractor shall keep the backfill
at just above the geosynthetic reinforcement connection to panel, prior to making the connection.
The Contractor shall remove and replace any face panel that does not meet the construction
tolerances.

It is recommended to use the geotextile filter cloth across the panel joints. It should be either a non-
woven needle punch polyester or polypropylene or a woven monofilament polypropylene with a
minimum width of 300mm and a minimum non-sewn lap of 150mm where necessary.

For aesthetic considerations and differential settlement concerns, the panels should be erected in
such a pattern that the horizontal panel joint line is discontinuous at every other panel. This should
be accomplished by alternating standard height and half height panel placement along the leveling
pad. Panels above the lowest level should be standard size except as required to satisfy the top of
exposed panel line shown on the Contract plans.

At locations where the plans specify a change of panel alignment creating an included angle of 150

or less, precast corner joint elements will be required. This element should separate the adjacent
panels by creating a vertical joint secured by means of separate soil geosynthetic reinforcement.

Isolation or slip joints, which are similar to corner joints in design and function, may be required to
assist in differential settlements at locations indicated on the plans or as recommended by the wall
supplier. Wall panels with areas greater than 2.8m' may require additional slip joints to account for
differential settlements. The maximum standard panel area should not exceed 4.6m

As fill material is placed behind a panel, the panel should be maintained in its proper inclined position
according to the supplier specifications and as approved by the Engineer.

Vertical tolerances and horizontal alignment tolerances should not exceed 20mm when measured
along a 3.0m straight edge. The maximum allowable offset in any panel joint should be 20mm. The
overall vertical tolerance of the wall, (plumbness from top to bottom) should not exceed 10mm per
3.0m of wall height. The precast face panels should be erected to insure that they are located within
25mm from the contract plan offset at any location to insure proper wall location at the top of the
wall. Failure to meet this tolerance may cause the Engineer to require the Contractor to disassemble
and re-erect the affected portions of the wall. A 20mm joint separation (± 5mm) should be provided
between all adjacent face panels to prevent direct concrete to concrete contact.

The fill and embankment placement should closely follow the erection of each lift of panels. At each
soil  geosynthetic  reinforcement  level,  the  fill  material  should  be  roughly  levelled  and  compacted
before placing and attaching the soil reinforcing system. The soli geosynthetlc reinforcement and the
maximum  lift  thickness  shouid  be  placed  according  to  the  supplier's  recommended  procedures
except, the lifts should not exceed 250mm loose measurement or as approved by the Engineer.

At the end of each day's operations, the Contractor should shape the last level of select fill to permit
runoff of rainwater away from the wall face. Fill should be compacted according to the requirements
of Chapter 2 of the

Standard Specifications,

Earthworks. Select fill compaction should be

accomplished without disturbance or distortion of soil geosynthetic reinforcing system and panels.
Compaction in a strip 1.5m wide adjacent to the backside of the panels should be achieved using a
light weight mechanical tamper, roller or vibratory system as required to achieve the specified in –
situ density.

Erection of Modular Blocks Facing Units

The modular block facing units shall be erected in successive horizontal lifts in the sequence
recommended in the Supplier’s construction manual, and in conjunction with the placing of the fill.
They shall be placed in the required plane and level.

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Unused voids shall be filled with concrete as determined by the designer of the wall.

No height greater than that equivalent to the distance between successive levels of reinforcement
shall have fill placed behind them until the fill has been inspected and approved in position in the
wall by the Engineer.

Particular care shall be taken to protect the blocks from damage throughout all construction
operations, any blocks damaged during construction shall be removed.

All modular block walls shall be capped with a purpose made precast coping unit.

Construction Tolerances of Modular Blocks Facing Units

The finished wall shall have an alignment such that there is no point which is out of line by more than
25 mm on a 3 metre straight edge and



50mm on the overall height of the wall. The horizontal

alignment of the wall shall be within a tolerance of



50mm. The maximum allowable offset at any

block joint shall be 5mm. Deviation in the position along the length of the wall shall be not more than



50mm for any one block from the true position as determined from the Contract Plans, except when

split face profile blocks are used in which case the datum should be taken from a nominal face line.

Any block or group of blocks which is found to be outside these tolerances shall be removed from
the wall and realigned unless agreed otherwise by the Supplier and the Engineer. The Contractor
shall carry out regular alignment checks on the wall by reference to a fixed datum line and level at
foundation level. Where the alignment is found to be out of tolerance the advice of the Supplier shall
be sought immediately.

Placing of Fill

The placing of the fill shall closely follow the erection of each lift of blocks, where lift is the distance
between successive layers of reinforcement, in compacted layers in accordance with the
requirements of Section 2.5.3.4 of Chapter 2

Earthworks, of the

Standard Specifications

. At each

level of reinforcement the fill shall be graded and compacted.

Filling and compaction shall be carried out in a direction parallel to the wall. The area within the two
metres nearest to the wall shall be compacted with a light, manually controlled machine.

The maximum weight of any equipment within two metres of the wall shall not exceed 1.5 tonnes.
Generally, filling and compaction shall be carried out in level planes unless agreed otherwise with
the Engineer and to the requirements of the Specifications for fill. Where it is necessary to create
slopes, these shall not be greater than a slope of 1:1 or such lesser slope as is agreed with the
Engineer, according to the actual fill material being used.

In the case of soil reinforced structures, unless otherwise directed by the Engineer, each layer of fill
material shall be satisfactorily placed and compacted throughout the reinforcement soil wall extent
and the adjacent embankment prior to commencing the next layer of fill material.

Placing Reinforcement

Reinforcement shall be continuously placed to the alignment shown in the Contract Plans in
horizontal layers on a compacted layer of approved fill. Each level of reinforcement shall be pulled
taut and approved by the Engineer prior to the next layer of fill being placed and shall be complete
to the full extent of the structure to the approval of the Engineer prior to placing the next layer of fill
material.

Every effort must be made by the Contractor to ensure that no damage is caused to the
reinforcement. If these materials are damaged such that the Engineer considers that the structural
integrity or durability will be affected, the damaged elements shall be removed and replaced.

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Drainage System

Pervious backfill wrapped in geotextile shall be installed to the line, grades, and sections shown on
the final plans. Pervious backfill fill shall be placed to the minimum thickness shown on the
construction plans between and behind units.

Construction Adjacent to Completed Wall

The Contractor is responsible for ensuring that construction adjacent to the wall by others does not
disturb the wall or place temporary construction loads on the wall that exceed design loads, including
loads such as water pressure, temporary grades, or equipment loading. Heavy paving or grading
equipment shall be kept a minimum of 1m behind the back of the wall face. Equipment with wheel
loads in excess of 15kN/m² live load shall not be operated within 3m of the face of the retaining wall
during construction adjacent to the wall. Care should be taken by the Contractor to ensure water
runoff is directed away from the wall structure until final grading and surface drainage collection
systems and erosion protection measures are completed.

20.6.4.7 Tests

and Inspection

An independent testing agency shall be retained by the Contractor to visually inspect and certify the
stability of MSE Walls.

20.6.4.8

Letter of Guarantee:

The supplier of the MSE panels shall submit Letters of Guarantee and BBA (or similar) Certificate
showing that both his global system and the cast-in dowels have properly considered the potential
degradative effects of elevated temperature and alkalinity. FBEC applicator qualifications per ASTM
A775/A775M.

20.6.4.9 Quality

Assurance:

Quality Assurance should be as per BS EN ISO 9001/2015; "Quality systems-Model for Quality
Assurance in Production, Design and Development Installation and Servicing".

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NDEX

allowable offset, 20-23, 20-24
bearing capacity, 20-5, 20-12, 20-17, 20-22
cast-in-place, 20-7, 20-12
cellular, 20-4
Chlorides, 20-5
cleanout pipes, 20-6
collector pipes, 20-6
Compaction method, 20-2
Concrete gutters, 20-6
crib, 20-4, 20-14, 20-15
design calculations, 20-2, 20-18
design criteria, 20-17
design parameters, 20-2
Drainage blankets, 20-6
Drainage elements, 20-3
drainage system, 20-2, 20-21
durability testing, 20-20
Earthwork requirements, 20-2
expansion joints, 20-9
exposed face, 20-7
factor of safety, 20-17
filter fabric, 20-6
Filter fabric, 20-3
Formwork, 20-8, 20-9
four-sided cells, 20-14
Geocomposite drainage, 20-4, 20-7
geosynthetic friction reinforcement, 20-20
ground anchors, 20-10, 20-11, 20-13, 20-14
ground elevations, 20-2
horizontal joints, 20-22
independent testing, 20-25
internal friction, 20-4, 20-5
internal friction angle, 20-4
Joints, 20-6
Leveling pad, 20-22
masonry, 20-7

Masonry concrete blocks, 20-3
mechanically stabilised earth, 20-4
minimum compressive strength, 20-3
Modified Proctor density, 20-5, 20-22
Modular Block Facing Units, 20-15, 20-19
monolithic cell walls, 20-14
non-proprietary, 20-2
outlet pipes, 20-6
Pervious backfill, 20-4, 20-21, 20-24
polyethylene foam strips, 20-22
precast concrete, 20-6, 20-7, 20-8, 20-9, 20-

11, 20-12, 20-14, 20-16, 20-18

Premoulded joint, 20-9
proprietary, 20-2, 20-15, 20-16, 20-18
proprietary reinforced soil wall, 20-15
Resistivity, 20-5
secant pile, 20-10
sheet pile, 20-10
Shotcrete, 20-3, 20-6, 20-11
Soil bearing pressure, 20-9
soldier-pile, 20-10, 20-11, 20-12, 20-13
soundness, 20-4, 20-5
Standard Direct Shear Test, 20-5
stretcher members, 20-14, 20-15
structure backfill, 20-5, 20-6, 20-15
Subgrade, 20-6
Sulphates, 20-5
tie-back, 20-10
Timber, 20-3, 20-11, 20-12, 20-14, 20-15
timber headers, 20-14
vertical joints, 20-22
Wales, 20-13
wall-facing elements, 20-3
Weep holes, 20-6
weepholes, 20-10

STANDARD CONSTRUCTION SPECIFICATIONS

PART 2

ROAD STRUCTURES

CHAPTER 21 - CONCRETE STRUCTURES

DOCUMENT NO: TR-

FIRST EDITION

JANUARY 2018

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Chapter 21: Concrete Structures

ABLE OF

ONTENTS

Table of Contents............................................................................................................................. i

List of Figures ................................................................................................................................ vii

List of Tables ................................................................................................................................. vii

Concrete Structures ........................................................................................................ 21-1

21.1

General ........................................................................................................................ 21-1

21.1.1

21.1.2

Construction Methods for Concrete Structures ..................................................... 21-1

21.1.3

Reference Standards and Codes .......................................................................... 21-2

21.2

Classes of Concrete..................................................................................................... 21-9

21.2.1

Normal-weight Concrete ....................................................................................... 21-9

21.2.2

Lightweight Concrete ............................................................................................ 21-9

21.3

Materials Used for Concrete Structures ....................................................................... 21-9

21.3.1

Blended Aggregates ............................................................................................. 21-9

21.3.2

Lightweight Aggregates ...................................................................................... 21-10

21.3.3

Concrete Durability Parameters .......................................................................... 21-10

21.3.4

Precast and Prestressed Concrete ..................................................................... 21-10

21.3.4.1

Cement ........................................................................................................ 21-10

21.3.4.2

Aggregates .................................................................................................. 21-10

21.3.4.3

Admixtures................................................................................................... 21-11

21.3.4.4

Concrete-Bonding Agent .............................................................................. 21-11

21.3.5

Steel ................................................................................................................... 21-11

21.3.5.1

Steel Plates, Studs and Anchor Bars in Precast Concrete ........................... 21-11

21.3.5.2

Metal Accessories in Prestressed Concrete Members ................................. 21-11

21.3.5.3

Pipe Sleeves in Prestressed Concrete Members ......................................... 21-11

21.3.5.4

Threaded Inserts and Lifting Devices in Precast Concrete ........................... 21-11

21.3.5.5

Built-in Materials in Prestressed Concrete Members .................................... 21-12

21.3.5.6

Welding Electrodes ...................................................................................... 21-12

21.4

Proportioning of Concrete .......................................................................................... 21-12

21.4.1

Concrete Mixing .................................................................................................. 21-12

21.4.1.1

Responsibility and Criteria for Concrete Mixing ............................................ 21-12

21.4.1.2

Trial Batch Testing for Concrete Mixing ....................................................... 21-12

21.4.1.3

Approval for Concrete Mixing ....................................................................... 21-14

21.4.2

Concrete Mixing Water Content .......................................................................... 21-14

21.4.3

Cement Control for Concrete Mixing ................................................................... 21-15

21.4.4

Concrete Admixtures .......................................................................................... 21-15

21.4.5

Mineral Admixtures ............................................................................................. 21-15

21.4.6

Chemical Admixtures .......................................................................................... 21-16

21.4.7

Corrosion Inhibitor for Structural Concrete Works ............................................... 21-16

21.5

Manufacture of Concrete ........................................................................................... 21-16

21.5.1

Delivery of Concrete ........................................................................................... 21-16

21.5.2

Concrete Sampling and Testing .......................................................................... 21-16

21.5.2.1

Concrete Sampling ...................................................................................... 21-17

21.5.2.2

Frequency of Testing for Concrete Aggregates ............................................ 21-17

21.5.3

Evaluation of Concrete Strength ......................................................................... 21-18

21.5.3.1

Concrete Strength Tests .............................................................................. 21-18

21.5.3.2

Requirements for Controlling Construction Operations ................................ 21-19

21.5.3.3

Requirements for the Acceptance of Concrete ............................................. 21-19

21.5.3.4

Requirements for the Control of Mix Design ................................................. 21-19

21.6

Protection of Concrete during Placing and Curing ...................................................... 21-20

21.6.1

Rain Protection ................................................................................................... 21-20

21.6.2

Hot-weather Protection ....................................................................................... 21-20

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21.6.3

Special Requirements for Bridge Decks .............................................................. 21-20

21.6.4

Concrete Exposed to Salt Water ......................................................................... 21-21

21.6.5

Concrete Exposed to Sulphate Soils or Sulphate Water ..................................... 21-22

21.7

Handling and Placing Concrete .................................................................................. 21-22

21.7.1

Placement Sequences ........................................................................................ 21-22

21.7.1.1

Vertical Members ......................................................................................... 21-22

21.7.1.2

Superstructures ........................................................................................... 21-23

21.7.1.3

Arches ......................................................................................................... 21-23

21.7.1.4

Box Culverts ................................................................................................ 21-24

21.7.1.5

Tunnels and Underpasses ........................................................................... 21-24

21.7.1.6

Tunnels and Underpasses on Rock Surfaces .............................................. 21-24

21.7.1.7

Precast Elements ......................................................................................... 21-24

21.7.2

Concrete Placing Methods .................................................................................. 21-24

21.7.2.1

Concrete Placing Equipment ....................................................................... 21-24

21.7.3

Consolidation Methods ....................................................................................... 21-25

21.7.4

Underwater Placement ....................................................................................... 21-25

21.7.4.1

Underwater Concrete Placement Equipment ............................................... 21-26

21.7.4.2

Underwater Concrete Placement Cleanup ................................................... 21-26

21.7.5

Reinforced-concrete Bridge Slabs ...................................................................... 21-26

21.7.5.1

Construction of Reinforced-concrete Bridge Slabs ....................................... 21-27

21.7.6

Approach Slabs .................................................................................................. 21-27

21.7.6.1

Approach Slab Construction ........................................................................ 21-27

21.7.7

Blinding Concrete ............................................................................................... 21-27

21.7.7.1

Blinding Concrete Construction .................................................................... 21-28

21.7.8

Screed Concrete ................................................................................................. 21-28

21.7.8.1

Crack Control Additive ................................................................................. 21-28

21.7.9

Mass Concrete - Thermal Control ....................................................................... 21-28

21.7.10

Removal of Falsework and Forms....................................................................... 21-29

21.7.10.1

Time of Removal.......................................................................................... 21-30

21.7.10.2

Extent of Removal ....................................................................................... 21-31

21.8

Construction Joints .................................................................................................... 21-31

21.8.1

Horizontal Joints ................................................................................................. 21-31

21.8.2

Vertical Joints ..................................................................................................... 21-31

21.8.3

Bonding .............................................................................................................. 21-31

21.8.4

Bonding and Dowelling to Existing Structures ..................................................... 21-32

21.8.5

Forms at Construction Joints .............................................................................. 21-32

21.8.6

Waterstops at Construction Joints ...................................................................... 21-32

21.9

Expansion and Contraction Joints .............................................................................. 21-32

21.9.1

Expansion and Contraction Joint Materials ......................................................... 21-32

21.9.1.1

Pre-moulded Expansion Joint Fillers ............................................................ 21-32

21.9.1.2

Polystyrene Board Fillers ............................................................................. 21-33

21.9.1.3

Contraction Joint Material ............................................................................ 21-33

21.9.1.4

Pourable Joint Sealants ............................................................................... 21-33

21.9.1.5

Metal Armour ............................................................................................... 21-33

21.9.1.6

External and Internal Waterstops ................................................................. 21-33

21.9.2

Expansion and Contraction Joint Installation ....................................................... 21-35

21.9.2.1

Open Joints ................................................................................................. 21-35

21.9.2.2

Filled Joints .................................................................................................. 21-35

21.9.2.3

Sealed Joints ............................................................................................... 21-35

21.9.2.4

Waterstops .................................................................................................. 21-35

21.9.2.5

Expansion Joint Armour Assemblies ............................................................ 21-36

21.9.2.6

Sheet Packing, Preformed Pads, and Board Fillers ..................................... 21-36

21.9.3

Injection of Expansion and Construction Joints ................................................... 21-36

21.9.3.1

Construction Joints ...................................................................................... 21-37

21.9.3.2

Expansion Joints.......................................................................................... 21-37

21.9.3.3

Injection of Leaking Joints ............................................................................ 21-37

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21.10

Finishing Plastic Concrete ......................................................................................... 21-37

21.10.1

Roadway Concrete Surface Finish ...................................................................... 21-37

21.10.1.1

Striking off and Floating ............................................................................... 21-37

21.10.1.2

Straight Edging ............................................................................................ 21-40

21.10.1.3

Texturing ..................................................................................................... 21-40

21.10.1.4

Surface Testing and Correction ................................................................... 21-41

21.10.2

Pedestrian Walkway Surface Finish .................................................................... 21-41

21.10.3

Trowelled and Brushed Finish ............................................................................. 21-41

21.10.4

Surfaces under Bearings .................................................................................... 21-41

21.11

Curing Concrete ......................................................................................................... 21-41

21.11.1

Curing Concrete Materials .................................................................................. 21-42

21.11.1.1

Water ........................................................................................................... 21-42

21.11.1.2

Liquid Membranes ....................................................................................... 21-42

21.11.1.3

Waterproof Sheet Materials ......................................................................... 21-42

21.11.2

Curing Concrete Methods ................................................................................... 21-42

21.11.2.1

Forms-in-place Method ................................................................................ 21-42

21.11.2.2

Water Method .............................................................................................. 21-42

21.11.2.3

Liquid-membrane Curing Compound Method .............................................. 21-42

21.11.2.4

Waterproof Cover Method ............................................................................ 21-43

21.11.2.5

Steam or Radiant-heat Curing Method ......................................................... 21-43

21.11.2.6

Insulated Curing Method .............................................................................. 21-44

21.11.3

Bridge Decks ...................................................................................................... 21-44

21.12

Finishing Formed Concrete Surfaces ......................................................................... 21-44

21.12.1

Class 1: Ordinary Surface Finish ........................................................................ 21-45

21.12.2

Class 2: Rubbed Finish ....................................................................................... 21-45

21.12.3

Class 3: Tooled Finish ........................................................................................ 21-45

21.12.4

Class 4: Sandblasted Finish................................................................................ 21-46

21.12.5

Class 5: Wire-brushed or Scrubbed Finish .......................................................... 21-46

21.12.6

Concrete Architectural Rustication ...................................................................... 21-46

21.12.6.1

Materials ...................................................................................................... 21-46

21.12.6.2

Formwork..................................................................................................... 21-46

21.12.6.3

Sample ........................................................................................................ 21-46

21.12.6.4

Construction ................................................................................................ 21-46

21.13

Precast Concrete Structural Members ....................................................................... 21-47

21.13.1

Quality Assurance ............................................................................................... 21-47

21.13.1.1

Reference Codes and Standards ................................................................. 21-47

21.13.1.2

Qualifications of Precast Prestressed Concrete Subcontractor .................... 21-47

21.13.1.3

Welder Qualifications ................................................................................... 21-47

21.13.2

Precast Concrete Submittals............................................................................... 21-47

21.13.2.1

Working Drawings ........................................................................................ 21-47

21.13.2.2

Shop Drawings ............................................................................................ 21-47

21.13.2.3

Samples ...................................................................................................... 21-48

21.13.2.4

Full Size Sample .......................................................................................... 21-48

21.13.3

Precast Concrete Materials and Manufacture ..................................................... 21-48

21.13.3.1

Formwork for Precast Prestressed Members ............................................... 21-49

21.13.3.2

Precast Prestressed Concrete Deck Panels ................................................ 21-50

21.13.4

Sampling and Testing of Precast Concrete Structural Members ......................... 21-51

21.13.5

Curing Precast Concrete ..................................................................................... 21-51

21.13.6

Precast Concrete Storage and Handling ............................................................. 21-52

21.13.7

Precast Concrete Erection .................................................................................. 21-52

21.13.7.1

Precast Prestressed Concrete Girders ......................................................... 21-53

21.13.7.2

Precast Prestressed Concrete Deck Panels ................................................ 21-54

21.13.8

Precast Concrete Finish ...................................................................................... 21-54

21.13.8.1

Concrete Fascia Elements ........................................................................... 21-55

21.13.8.2

Precast Prestressed Concrete Girders ......................................................... 21-55

21.13.8.3

Precast Prestressed Concrete Deck Panels ................................................ 21-55

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21.13.9

Precast Products ................................................................................................ 21-55

21.13.10

Epoxy-bonding Agents for Precast Segmental Box Girders ................................ 21-55

21.13.10.1

Epoxy-bonding Agent Materials ................................................................... 21-55

21.13.10.2

Mixing and Installation of Epoxy ................................................................... 21-59

21.14

Pre-tensioned Concrete Works .................................................................................. 21-59

21.14.1

Placing of Reinforcement Steel and Inserts ........................................................ 21-60

21.14.2

Mixing and Placing Concrete .............................................................................. 21-60

21.14.3

Placing and Compacting ..................................................................................... 21-60

21.14.4

Inspection of Completed Prestressed Members .................................................. 21-61

21.14.4.1

Tolerances ................................................................................................... 21-61

21.14.5

Rejection of Prestressed Members ..................................................................... 21-66

21.15

Post-tensioned Concrete Works ................................................................................ 21-66

21.15.1

Standards and Codes ......................................................................................... 21-66

21.15.2

Submittals ........................................................................................................... 21-66

21.15.2.1

Shop Drawings ............................................................................................ 21-66

21.15.2.2

Certificates................................................................................................... 21-67

21.15.2.3

Test Reports ................................................................................................ 21-67

21.15.3

Scheduling of Post-tensioned Concrete Works ................................................... 21-67

21.15.4

Material ............................................................................................................... 21-67

21.15.4.1

Concrete ...................................................................................................... 21-67

21.15.4.2

Post-tensioning Systems ............................................................................. 21-67

21.15.4.3

Reinforcement Steel .................................................................................... 21-67

21.15.4.4

Built-in Materials .......................................................................................... 21-67

21.15.5

Formwork ............................................................................................................ 21-68

21.15.6

Placing Post-tensioning Systems ........................................................................ 21-68

21.15.7

Mixing and Placing Concrete .............................................................................. 21-69

21.15.8

Stressing Operations .......................................................................................... 21-69

21.15.9

Grouting of Tendons ........................................................................................... 21-70

21.15.10

Protection of End Anchorages ............................................................................ 21-70

21.15.11

Access Doors ..................................................................................................... 21-70

21.15.12

Vent Pipes .......................................................................................................... 21-70

21.15.13

Opening Bridges to Traffic .................................................................................. 21-71

21.16

Precast Concrete Fascia Panels ................................................................................ 21-71

21.16.1

Materials ............................................................................................................. 21-71

21.16.2

Moulds ................................................................................................................ 21-71

21.16.3

Shop Drawings and Method Statement ............................................................... 21-71

21.16.4

Sample Panel ..................................................................................................... 21-71

21.16.5

Fabrication .......................................................................................................... 21-72

21.16.6

Surface Finish ..................................................................................................... 21-72

21.16.7

Installation .......................................................................................................... 21-73

21.17

Cast-in-place Concrete Works for Bridge, Tunnel & Underpass Structures ................ 21-73

21.17.1

Materials ............................................................................................................. 21-73

21.17.2

Shop Drawings ................................................................................................... 21-73

21.17.3

Construction ....................................................................................................... 21-73

21.17.4

Formwork ............................................................................................................ 21-73

21.17.5

Expanded Polystyrene Board .............................................................................. 21-73

21.18

Mortar and Grout ....................................................................................................... 21-74

21.18.1

Mortar and Grout Materials and Mixing ............................................................... 21-74

21.18.2

Placing and Curing of Mortar and Grout .............................................................. 21-74

21.18.3

Grout in Precast Works ....................................................................................... 21-75

21.19

Application of Loads .................................................................................................. 21-75

21.19.1

Earth Loads ........................................................................................................ 21-75

21.19.2

Construction Loads ............................................................................................. 21-75

21.19.3

Traffic Loads ....................................................................................................... 21-76

21.20

Special Requirements for Segmental Bridges ............................................................ 21-76

21.20.1

Geometry Control ............................................................................................... 21-76

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21.20.1.1

Deflection and Camber Data ........................................................................ 21-76

21.20.1.2

Geometry Control ........................................................................................ 21-76

21.20.2

Segmental Bridge Tolerances ............................................................................. 21-76

21.20.3

Shop Drawings and Design Calculation for Construction Procedures ................. 21-77

21.20.3.1

Design Calculation for Construction Procedures .......................................... 21-78

21.20.3.2

Shop Drawings ............................................................................................ 21-78

21.20.4

Forms ................................................................................................................. 21-79

21.20.4.1

Forms for Precast Segmental Construction .................................................. 21-79

21.20.5

Permanent Bearings ........................................................................................... 21-80

21.20.6

Special Provisions for cast-in-place Segmental Construction .............................. 21-80

21.20.6.1

Forming System........................................................................................... 21-80

21.20.6.2

Superstructure Construction ........................................................................ 21-80

21.20.7

Special Provisions for Precast Concrete Segmental Construction ...................... 21-82

21.20.7.1

Fabrication ................................................................................................... 21-83

21.20.7.2

Separation of Match-cast Segments ............................................................ 21-83

21.20.7.3

Handling and Erection of Segments ............................................................. 21-83

21.20.8

Special Provisions for Incremental Launching ..................................................... 21-83

21.20.8.1

Casting of Segments ................................................................................... 21-83

21.20.8.2

Geometric Tolerances ................................................................................. 21-84

21.20.8.3

Launching Force .......................................................................................... 21-84

21.20.8.4

Pier Monitoring ............................................................................................ 21-84

21.20.9

Defects and Breakage ........................................................................................ 21-84

21.21

Architectural Surface Treatment for Tunnel and Underpass Walls ............................. 21-84

21.21.1

Types of Surface Treatment................................................................................ 21-85

21.21.1.1

Ceramic Wall Tiles ....................................................................................... 21-85

21.21.1.2

Textured Concrete Finish ............................................................................. 21-88

21.21.1.3

Painting of Exposed Concrete...................................................................... 21-88

21.21.1.4

Fire Protection Boards ................................................................................. 21-89

21.21.2

Miscellaneous Materials ...................................................................................... 21-90

21.22

Scarifying Concrete Bridge Slabs............................................................................... 21-92

21.22.1

Scarifying Equipment .......................................................................................... 21-92

21.22.2

Concrete Bridge Slab Construction ..................................................................... 21-92

21.23

Extending Concrete Structures .................................................................................. 21-92

21.23.1

Concrete Structure Construction ......................................................................... 21-93

21.23.1.1

Removal of the Existing Structure ................................................................ 21-93

21.23.1.2

Reuse of Removed Portions of the Structure ............................................... 21-93

21.23.1.3

Breaking Back Bridge Slabs ........................................................................ 21-93

21.23.1.4

Splicing Reinforcing Steel ............................................................................ 21-93

21.23.1.5

Concrete Preparation ................................................................................... 21-94

21.24

Raising Existing Structures ........................................................................................ 21-94

21.24.1

Construction While Raising Existing Structures .................................................. 21-94

21.24.1.1

Preparation of Plans .................................................................................... 21-94

21.24.1.2

Raising of Spans.......................................................................................... 21-94

21.25

Spread Footings ........................................................................................................ 21-95

21.25.1

General Requirements for Spread Footings ........................................................ 21-95

21.25.2

Protection of Existing Structures ......................................................................... 21-95

21.25.3

Dewatering ......................................................................................................... 21-96

21.25.4

Excavations ........................................................................................................ 21-96

21.25.4.1

Dry Excavations ........................................................................................... 21-96

21.25.4.2

Dewatered Excavations ............................................................................... 21-96

21.25.4.3

Wet Excavations .......................................................................................... 21-97

21.25.5

Fill or Backfill ...................................................................................................... 21-97

21.25.6

Compaction and Density Requirements .............................................................. 21-97

21.25.7

Forming .............................................................................................................. 21-97

21.25.8

Reinforcing Steel Placement ............................................................................... 21-98

21.25.9

Concrete Placement ........................................................................................... 21-98

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21.25.9.1

Placement.................................................................................................... 21-98

21.25.9.2

Finish ........................................................................................................... 21-98

21.25.9.3

Curing .......................................................................................................... 21-98

21.26

Steps ......................................................................................................................... 21-98

21.26.1

Materials for Steps .............................................................................................. 21-98

21.26.2

Steps Construction ............................................................................................. 21-99

21.27

Concrete for Minor Structures .................................................................................... 21-99

21.27.1

Materials for Minor Structures ............................................................................. 21-99

21.27.2

Composition of Concrete for Minor Structures .................................................... 21-99

21.27.3

Placing of Concrete .......................................................................................... 21-100

21.27.4

Curing of Concrete ............................................................................................ 21-100

21.27.5

Acceptance ....................................................................................................... 21-100

Index ...................................................................................................................................... 21-101

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IST OF

IGURES

Figure 21-1: Evaporation rate nomograph from ACI 308 .......................................................... 21-21

IST OF

ABLES

Table 21-1: Designations and titles for AASHTO and ASTM standards that apply to concrete
structures works ......................................................................................................................... 21-4

Table 21-2: Designations and titles for BS, BS EN, and DIN standards that apply to concrete
structures works ......................................................................................................................... 21-8

Table 21-3: Normal-weight concrete slump test limits at the time of placement ........................ 21-15

Table 21-4: Rates of sampling and testing from same plant ..................................................... 21-17

Table 21-5: Frequency of aggregate testing ............................................................................. 21-17

Table 21-6: Time of removal .................................................................................................... 21-30

Table 21-7: ASTM test method requirements for PVC materials .............................................. 21-34

Table 21-8: Concrete aggregate size for deck panels .............................................................. 21-50

Table 21-9: Maximum dimensional tolerances for deck panels ................................................ 21-51

Table 21-10: Sag flow test for mixed epoxy-bonding agent ...................................................... 21-56

Table 21-11: Gel time test for epoxy-bonding agent ................................................................. 21-56

Table 21-12: Open time test for epoxy-bonding agent .............................................................. 21-57

Table 21-13: Three-point tensile bending test for epoxy-bonding agent ................................... 21-57

Table 21-14: Compression strength test for cured epoxy-bonding agent .................................. 21-58

Table 21-15: Temperature deflection test for epoxy-bonding agent .......................................... 21-58

Table 21-16: Compression and shear strength test for cured epoxy-bonding agent ................. 21-58

Table 21-17: Maximum allowable dimensional tolerances for precast prestressed concrete members
(General) ................................................................................................................................. 21-61

Table 21-18: Maximum dimensional tolerances for AASHTO girders and bulb-tees ................. 21-63

Table 21-19: Maximum dimensional tolerances for double-tees ............................................... 21-64

Table 21-20: Maximum dimensional tolerances for prestressed concrete piling ....................... 21-65

Table 21-21: Maximum dimensional tolerances for prestressed concrete stay-in-place forms.. 21-65

Table 21-22: Tolerances on effective depth and minimum cover .............................................. 21-76

Table 21-23: Completed segment tolerance for segmental box girder bridge construction ....... 21-77

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CONCRETE STRUCTURES

21.1

General

This  work  consists  of  furnishing,  placing,  finishing,  and  curing  concrete  in  bridges,  tunnels,
underpasses,  culverts,  and  miscellaneous  roadway  structures  in  accordance  with  these
specifications  and  conforming  to  the  lines,  grades,  and  dimensions  shown  in  the  Contract
documents. Work includes elements of structures constructed by cast-in-place and precast methods
using either plain, or unreinforced; reinforced; or prestressed concrete

— or any combination thereof.

All  exposed  items  or  surfaces  not  in  contact  with  soil  throughout  concrete  structures,  except  as
otherwise  indicated  on  the  Contract  plans,  shall  be  painted  in  accordance  with  Section  24.7  of
Chapter  24,  Painting,  of  these  standard  specifications.  Surfaces  of  concrete  structures  in  contact
with  soil,  concrete  structures  that  require  water-tightness,  and roadway  surfaces  of bridge  decks,
underpasses, and tunnels shall be protected and waterproofed in accordance with Sections 28.2,
28.3,  and  28.5  of  Chapter  28, Waterproofing,  of  these  standard  specifications,  as  applicable.  All
exposed  surfaces  for  concrete  structures  indicated  on  the  Contract  plans  not  to  be  painted  or
waterproofed shall be sealed as per the requirements of Section 29.6 of Chapter 29, Miscellaneous
Items for Structures, of these standard specifications.

Fabricating, furnishing, and installing tunnels shall conform to the requirements of this chapter and
Chapter 34, Road Tunnels, of these standard specifications.

21.1.1

Work Related to Concrete Structures

Other works involved in the construction of concrete structures shall be as specified in the applicable
chapters of these specifications, especially in the following:

Chapter 1: General Requirements, of these Standard Specifications;

Chapter 4: Concrete Works, of these Standard Specifications;

Chapter 5: Reinforcing Steel, of these Standard Specifications;

Chapter 22: Prestressing Systems, of these Standard Specifications;

Chapter 24: Painting, of these Standard Specifications;

Chapter 28: Waterproofing, of these Standard Specifications;

Chapter 29: Miscellaneous Items for Structures, of these Standard Specifications; and

Chapter 34: Road Tunnels, of these Standard Specifications.

Where there is a conflict in the requirements of Chapter 4 with that of Chapter 21, the requirements
as set forth in Chapter 21 shall take precedence and shall govern for all concrete works in bridges,
tunnels, underpasses, and culverts.

21.1.2

Construction Methods for Concrete Structures

Whenever the Contract documents permit the Contractor to select the method or equipment to be
used for any operation, it shall be the Contractor's responsibility to employ methods and equipment
that will produce satisfactory work under the conditions encountered such that no damage is
imparted on completed or partially completed work.

The Contractor shall construct concrete road tunnels based on one of the construction methods
specified in Chapter 34, Road Tunnels, unless otherwise indicated in the Contract documents.

Falsework and forms shall conform to the requirements of Section 1.20.8 of Chapter 01, General
Requirements, of these standard specifications.

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Generally, all concrete shall be fully supported until the required strength and age has been reached.
However, the slip form method may be permitted for the construction of pier shafts and railing,
providing the Contractor's plan assures the following:

a. Results will be equal in all respect to those obtained by the use of fixed forms.
b. Adequate arrangements will be provided for curing, finishing, and protecting the concrete.

21.1.3

Reference Standards and Codes

Standards and codes shall be as specified in these specifications, in the Contract documents, if any,
and the following, in their latest edition:

AASHTO LRFD

American Association of State Highway and Transportation Officials - Load
and Resistance Factor Design, Bridge Construction Specifications;

AASHTO LRFD

American Association of State Highway and Transportation Officials - Load
and Resistance Factor Design, Bridge Design Specifications;

AASHTO

Standard Specifications for Transportation Materials and Methods of
Sampling and Testing;

ACI

American Concrete Institute;

ACI 207.4R-05

Cooling and Insulating Systems for Mass Concrete;

ACI 207.1R-05

Guide to Mass Concrete;

ACI 207.2R-07

Report on Thermal and Volume Change Effects on Cracking of Mass
Concrete;

ACI 301-10

Specifications for Structural Concrete”;

ACI 305R-10

American Concrete Institute Standard "Guide to Hot Weather Concreting";

ACI 308R-01

Guide to Curing Concrete;

ACI 318-08

Building Code Requirements for Structural Concrete and Commentary;

ADQCC (TR-516)

Road Structures Design Manual;

ANSI

American National Standards Institute;

ANSI A108.1B

Installation of ceramic tile on a cured Portland Cement Mortar setting bed-
1999 with DRY-SET or latex Portland Cement Mortar;

ANSI A108.5

Ceramic tile installed with DRY-SET Portland Cement Mortar or latex

– 1999

Portland Cement Mortar;

ANSI A108.10

Specifications for Installation of Grout in Tilework; -1999

ANSI A108/A118/

Specifications for the Installation of Ceramic Tile; A136.1-2012

ANSI A135.4

American National Standards Institute

– Basic Hardboard Standard;

ANSI A137.1:

American National Standards Specifications for Ceramic Tile;2008

ANSI/AWS D1.1/

American National Standards Institute, Structural welding code

—Steel;

D1.1M:2010

ASTM

American Society for Testing and Materials;

AWS - D1.1/

American Welding Society - Structural Welding Code

– Steel; D1.1M:2010

AWS - D1.4/

American Welding Society - Structural Welding Code

– Reinforcing Steel;

D1.4M:2011

British Standards;

BS EN

European Standards;

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BRS Digest

British Building Research Station; No 35, 1968

CRD-C-566-64

Corps of Engineers - Specifications for Grout Fluidifier - Handbook for
Concrete and Cement, U.S. Army Engineer Waterways Experiment Station,
Vicksburg, MS;

CRD-C 572-74

Corps of Engineers Specifications for Polyvinylchloride Water stop;

CRSI

Concrete Reinforcing Steel Institute 1990;

DIN

German Institute for Standardization;

FS Army MMM-

Federal Specification - Grout, Adhesive, Epoxy Resin, Flexible, Filled; G-650B
CANC

FS TT - S-1543

Federal Specification - Class A- Sealing Compound, Silicone Rubber Base,
(For Caulking, Sealing and Glazing in Buildings and Other Structures);

FS LLL-B-810

Federal Specification - Building board (Hardboard) Hard Pressed Vegetable
Fiber;

FS MMM-G-650A

Federal Specifications - Epoxy Bonding Agent;

FS SS-A-701

Federal Specifications - Bituminous Protective Coating;

FS TT-S-230

Federal Specifications - Sealing Compound, Synthetic-Rubber Base, Single
Component Chemically Curing (For Calking, and Glazing In Building
Construction);

FS-FF-P-395

Federal Specifications - Drive Pins (Power Actuated and Hand Driven);

FS QQ-Z-325

Federal Specifications - Zinc Coating, Electrodeposited

ISO

International Organization for Standardization;

ISO 9000

Quality management;

ISO 9001:2015

Quality management systems

– Requirements;

ISO 14001

Environmental management systems -- Requirements with guidance for use;
NFPA National Fire Protection Association;

NFPA 502

Standard for Road Tunnels, Bridges, and Other Limited Access Highways;

PCI

Precast/ Prestressed Concrete Institute - Architectural Precast Concrete Color
& Texture Selection Guide, 2nd Edition;

PCI MNL-116-99

Precast Concrete Institute - Manual for Quality Control for plants and
production of Structural Precast Concrete Products;

PCI MNL-117-77

Precast Concrete Institute - Manual for Quality Control for Plants and
Production of Architectural Precast Concrete Products (1977);

PCI MNL-120-14

Precast Concrete Institute - PCI Design Handbook

– Precast and prestressed

Concrete, 7th Edition;

PCI MNL 127-99

Precast Concrete Institute -

Erectors’ Manual: Standards and Guidelines for

the Erection of Precast Concrete Products;

PCI Certification

I’s Plant Certification Program;

SAE AMS-QQ-

Society of Automotive Engineers - Steel, Corrosion Resistant, Bars, Wire,

S-763

Shapes, and Forgings;

TCA

Tile Council of America - Installation Guide Handbook.

Table 21-1 and Table 21-2 presents American Association of State Highway and Transportation
Officials (AASHTO), American Society for Testing and Materials (ASTM), British (BS), European (BS

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EN), and German (DIN) Standards that are related to materials for concrete structures works. It also
includes designations and titles.

Table 21-1: Designations and titles for AASHTO and ASTM standards that apply to concrete

structures works

AASHTO
Designation

ASTM
Designation

Title

AASHTO M85-
12

ASTM C150 /
C150M - 12

Standard Specification for Portland Cement

ASTM C845 - 04

Standard Specification for Expansive Hydraulic Cement

AASHTO M6-08

Standard Specification for Fine Aggregate for Hydraulic
Cement Concrete

ASTM

C33

C33M - 11a

Standard Specification for Concrete Aggregates

AASHTO M195-
11

ASTM C330 /
C330M - 09

Standard Specification for Lightweight Aggregates for
Structural Concrete.

AASHTO M
194M/M 194-12

ASTM C494 /
C494M - 12

Standard Specification for Chemical Admixtures for
Concrete

AASHTO T152-
12

ASTM C231 /
C231M - 10

Standard Test Method for Air Content of Freshly Mixed
Concrete by the Pressure Method

ASTM C109 /
C109M - 11b

Standard Test Method for Compressive Strength of
Hydraulic Cement Mortars (Using 2-in. or [50-mm] Cube
Specimens)

AASHTO T126

ASTM C192 /
C192M - 07

Method of Making and Curing Concrete Test Specimens
in the Laboratory

ASTM C457 /
C457M - 11

Standard Test Method for Microscopical Determination of
Parameters of the Air-Void System in Hardened Concrete

AASHTO M157

ASTM

C94

C94M - 12

Standard Specification for Ready-Mixed Concrete

AASHTO R 60-
12

ASTM C172 /
C172M - 10

Standard Practice for Sampling Freshly Mixed Concrete

AASHTO T
121M/T 121-12

ASTM C138 /
C138M - 12

Standard Test Method for Density (Unit Weight), Yield,
and Air Content (Gravimetric) of Concrete

AASHTO T27-11 ASTM C136 - 06

Standard Test Method for Sieve Analysis of Fine and
Coarse Aggregates

AASHTO T
119M/T 119-11

ASTM C143 /
C143M - 10a

Standard Test Method for Slump of Hydraulic-Cement
Concrete

AASHTO T 84-
10

ASTM C128 - 12

Standard Test Method for Density, Relative Density
(Specific Gravity), and Absorption of Fine Aggregate

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AASHTO
Designation

ASTM
Designation

Title

AASHTO T 85-
10

ASTM C127 - 12

Standard Test Method for Density, Relative Density
(Specific Gravity), and Absorption of Coarse Aggregate

ASTM C567 /
C567M - 11

Standard Test Method for Determining Density of
Structural Lightweight Concrete

AASHTO T 23-
08

ASTM

C31

C31M - 12

Standard Practice for Making and Curing Concrete Test
Specimens in the Field

AASHTO T 22-
10 (2011)

ASTM

C39

C39M - 12

Standard Test Method for Compressive Strength of
Cylindrical Concrete Specimens

AASHTO M 213-
01 (2010)

ASTM D1751 -
04(2008)

Standard Specification for Preformed Expansion Joint
Filler for Concrete Paving and Structural Construction
(Nonextruding and Resilient Bituminous Types)

AASHTO M 153-
06 (R2011)

ASTM D1752 -
04a(2008)

Standard Specification for Preformed Sponge Rubber
Cork and Recycled PVC Expansion Joint Fillers for
Concrete Paving and Structural Construction

AASHTO M 33-
99 (2012)

ASTM D994 /
D994M - 11

Standard Specification for Preformed Expansion Joint
Filler for Concrete (Bituminous Type)

ASTM C203 -
05a(2012)

Standard Test Methods for Breaking Load and Flexural
Properties of Block-Type Thermal Insulation

AASHTO M 282-
99 (2012)

ASTM D3406 -
95(2006)

Standard Specification for Joint Sealant, Hot-Applied,
Elastomeric-Type,

for

Portland

Cement

Concrete

Pavements

AASHTO M301-
01

Joint Sealants, Hot Poured, for Concrete and Asphalt
Pavements

ASTM D792 - 08

Standard Test Methods for Density and Specific Gravity
(Relative Density) of Plastics by Displacement

ASTM D2240 -
05(2010)

Standard Test Method for Rubber Property

— Durometer

Hardness

ASTM D638 - 10

Standard Test Method for Tensile Properties of Plastics

ASTM D746 - 07

Standard Test Method for Brittleness Temperature of
Plastics and Elastomers by Impact

ASTM D747 - 10

Standard Test Method for Apparent Bending Modulus of
Plastics by Means of a Cantilever Beam

AASHTO M
138M/M 138-08

ASTM

B152

B152M - 09

Standard Specification for Copper Sheet, Strip, Plate, and
Rolled Bar

AASHTO M 148-
05

ASTM C309 - 11

Standard Specification for Liquid Membrane-Forming
Compounds for Curing Concrete

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AASHTO
Designation

ASTM
Designation

Title

AASHTO M 171-
05

ASTM C171 - 07

Standard Specification for Sheet Materials for Curing
Concrete

AASHTO T
197M/T 197-11

ASTM C403 /
C403M - 08

Standard Test Method for Time of Setting of Concrete
Mixtures by Penetration Resistance

AASHTO
M235M/ M235

Standard Specification for Epoxy Resin Adhesives

ASTM D2471-99

Standard Test Method for Gel Time and Peak Exothermic
Temperature

Reacting

Thermosetting

Resins

(Withdrawn 2008)

AASHTO T 97-
10

ASTM

C78

C78M - 10

Standard Test Method for Flexural Strength of Concrete
(Using Simple Beam with Third-Point Loading)

ASTM D695 - 10

Standard Test Method for Compressive Properties of
Rigid Plastics

ASTM D648 - 07

Standard Test Method for Deflection Temperature of
Plastics under Flexural Load in the Edgewise Position

ASTM G109 - 07

Standard  Test  Method  for  Determining  Effects  of
Chemical  Admixtures  on  Corrosion  of  Embedded  Steel
Reinforcement  in  Concrete  Exposed  to  Chloride
Environments

AASHTO T 277-
07 (2011)

ASTM C1202 - 12

Standard Test Method for Electrical Indication of
Concrete's Ability to Resist Chloride Ion Penetration

ASTM

A36

A36M - 08

Standard Specification for Carbon Structural Steel

ASTM A108 - 07

Standard Specification for Steel Bar, Carbon and Alloy,
Cold-Finished

ASTM

A706

A706M - 09b

Standard Specification for Low-Alloy Steel Deformed and
Plain Bars for Concrete Reinforcement

ASTM

A153

A153M - 09

Standard Specification for Zinc Coating (Hot-Dip) on Iron
and Steel Hardware

ASTM

A123

A123M - 12

Standard Specification for Zinc (Hot-Dip Galvanized)
Coatings on Iron and Steel Products

ASTM A666 - 10

Standard Specification for Annealed or Cold-Worked
Austenitic Stainless Steel Sheet, Strip, Plate, and Flat Bar

ASTM

A453

A453M - 12

Standard Specification for High-Temperature Bolting, with
Expansion

Coefficients

Comparable

Austenitic

Stainless Steels

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AASHTO
Designation

ASTM
Designation

Title

ASTM

A510

A510M - 11

Standard Specification for General Requirements for Wire
Rods and Coarse Round Wire, Carbon Steel

ASTM B633 - 11

Standard Specification for Electrodeposited Coatings of
Zinc on Iron and Steel

ASTM C827 /
C827M - 10

Standard Test Method for Change in Height at Early Ages
of Cylindrical Specimens of Cementitious Mixtures

ASTM C207 -
06(2011)

Standard Specification for Hydrated Lime for Masonry
Purposes

ASTM C778 - 12

Standard Specification for Standard Sand

ASTM C126 - 12

Standard Specification for Ceramic Glazed Structural Clay
Facing Tile, Facing Brick, and Solid Masonry Units

ASTM C499 - 09

Standard Test Method for Facial Dimensions and
Thickness of Flat, Rectangular Ceramic Wall and Floor
Tile

ASTM C627 - 10

Standard Test Method for Evaluating Ceramic Floor Tile
Installation Systems Using the Robinson-Type Floor
Tester

ASTM E136 - 12

Standard Test Method for Behavior of Materials in a
Vertical Tube Furnace at 750°C

ASTM E84 - 12b

Standard Test Method for Surface Burning Characteristics
of Building Materials

ASTM D751 -
06(2011)

Standard Test Methods for Coated Fabrics

ASTM C144 - 11

Standard Specification for Aggregate for Masonry Mortar

ASTM

A421

A421M - 10

Standard Specification for Uncoated Stress-Relieved
Steel Wire for Prestressed Concrete

AASHTO T180

Standard Method of Test for Moisture-Density Relations of
Soils Using a 4.54-kg (10-lb) Rammer and a 457-mm (18-
in.) Drop

ASTM C920 - 11

Standard Specification for Elastomeric Joint Sealants

ASTM D5947 - 11

Standard Test Methods for Physical Dimensions of Solid
Plastics Specimens

ASTM D570 -
98(2010)e1

Standard Test Method for Water Absorption of Plastics

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AASHTO
Designation

ASTM
Designation

Title

ASTM D624 -
00(2012)

Standard Test Method for Tear Strength of Conventional
Vulcanized Rubber and Thermoplastic Elastomers

ASTM D543 - 06

Standard Practices for Evaluating the Resistance of
Plastics to Chemical Reagents

ASTM D1621 - 10

Standard Test Method for Compressive Properties Of
Rigid Cellular Plastics

ASTM D1622 - 08

Standard Test Method for Apparent Density of Rigid
Cellular Plastics

ASTM

E96/

E96M-10

Standard Test Methods for Water Vapor Transmission of
Materials, 2010

ASTM C1116 /
C1116M - 10a

Standard Specification for Fiber-Reinforced Concrete

AASHTO M
241M/M 241-11

ASTM C 685/C
685M-07

Standard Specification for Concrete Made by Volumetric
Batching and Continuous Mixing

AASHTO M 145-
91 (2008)

Standard Specification for Classification of Soils and Soil-
Aggregate Mixtures for Highway Construction Purposes

ASTM C1582 /
C1582M - 11

Standard Specification for Admixtures to Inhibit Chloride-
Induced Corrosion of Reinforcing Steel in Concrete

Table 21-2: Designations and titles for BS, BS EN, and DIN standards that apply to concrete

structures works

BS
Designation

BS EN Designation

DIN
Designation

Title

1881-

122:2011

Testing

concrete.

Method

for

determination of water absorption

BS EN 12390-1:2000

Testing hardened concrete. Shape,
dimensions and other requirements
for specimens and moulds

BS EN 12390-2:2009

Testing hardened concrete. Making
and curing specimens for strength
tests

BS EN ISO 9001:2015

Quality

management

systems.

Requirements

12620:2002+A1:2008

Aggregates for concrete

EN 13501

Fire classification of construction
products and building elements

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BS
Designation

BS EN Designation

DIN
Designation

Title

BS EN 12350-2:2009

Testing Fresh Concrete. Slump-Test

BS EN 12390-3:2009

Testing

hardened

concrete.

Compressive

strength

test

specimens

DIN

1048-

5:1991-06

Testing concrete; testing of hardened
concrete (specimens prepared in
mould)

1881-

208:1996

Testing  concrete.  Recommendations
for  the  determination  of  the  initial
surface absorption of concrete

BS EN 480-2:1997

Admixtures for concrete, mortar and
grout. Test methods. Determination of
setting time

4370-

2:1993

Methods of test for rigid cellular
materials. Methods 7 to 9

21.2

Classes of Concrete

Concrete classes used in each part of the structure shall be as specified herein or as shown in the
Contract documents. If not shown or specified, the Engineer will designate the class of concrete to
be used.

21.2.1

Normal-weight Concrete

Normal-weight concrete used in bridges, tunnels, underpasses, culverts, and miscellaneous
roadway structures shall be defined as per concrete classes provided in Section 4.3.9, Chapter 4,
Concrete Works, of these Standard Specifications.

21.2.2

Lightweight Concrete

Lightweight, or low-density, concrete shall conform to the requirements specified in the Contract
documents. When the Contract documents require the use of natural sand for a portion or all of the
fine aggregate, the natural sand shall conform to the American Association of State Highway and
Transportation Officials (AASHTO) M6-08.

21.3

Materials Used for Concrete Structures

Cementitious materials, water, aggregates, mineral admixtures, and chemical admixtures

— the five

major constituent materials of concrete

— shall conform to the requirements of Section 4.3 of

Chapter 4, Concrete Works, of these Standard Specifications.

Other Materials for concrete structures shall comply with the standards and requirements outlined in
this section.

21.3.1

Blended Aggregates

Where suitable lightweight aggregates are available, a common practice is to blend light- with
normal-weight aggregates to achieve a desired concrete unit weight. This is done to control beam,
or other product, weights to satisfy shipping limitations, and jobsite conditions

— such as crane size,

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reach limits, plant, or erection equipment capacities. Blends of fine and coarse aggregates shall
conform to the requirements of AASHTO T27-11 and approved by the Engineer.

21.3.2

Lightweight Aggregates

Lightweight aggregates for concrete shall conform to the requirements of AASHTO M195-11 (ASTM
C330 / C330M - 09).

21.3.3

Concrete Durability Parameters

For all structural concrete having a required cubical strength of 40MPa or greater the following
durability parameters shall apply:

1. Water absorption

of ≤ 1.5 % (as tested according to BS 1881-122:2011).

Rapid Chloride Penetration value of ≤ 700 coulombs at 28 days (as tested according to
AASHTO T 277-07 (2011) (ASTM C1202

– 12)).

3. Water permeability of the concrete shall be tested in accordance with DIN 1048-5:1991-06

and the maximum penetration at 28 days shall be < 10 mm.

4. Initial surface absorption (ISAT) shall be tested in accordance with BS 1881-208:1996 and

the ISAT value at 28 days shall be < 0.15 ml/m²/s (10 minute test).

5. Shrinkage test at 28 days shall be in compliance with the British Building Research Station

(BRS) Digest No 35, 1968.

Tests shall be conducted at an independent laboratory as approved by the Engineer.

For the above tests, the frequency should be a minimum of one (1) set of specimens (3 cores taken
from test cubes) for every 500m

of each class of concrete, as approved by the Engineer. For every

500m

of each class of concrete cast, a minimum of one (1) set of specimens (3 cores) shall be

taken from the structure(s) or portions of the structure(s), as designated by the Engineer. All test
specimens should comply with the limits stated above. The Engineer may require additional testing,
as deemed necessary, at no extra cost to the Owner. All core holes in the structures should be filled
/ repaired with suitable non-shrink mortar or grout, as approved by the Engineer.

The

Contractors’ proposed mix designs shall be submitted for the Engineer’s testing and approval.

21.3.4

Precast and Prestressed Concrete

All precast and prestressed concrete materials shall be as specified in Section 4.3 of Chapter 4,
Concrete Works, of these Standard Specifications

— and as specified herein.

21.3.4.1

Cement

Cement for typical prestressed members, precast and fascia members shall be ASTM C150 / C150M
- 12 Type II Portland cement or of Cementitious materials as defined in Section 4.3 of Chapter 4,
Concrete Works, of these Standard Specifications, and as approved by the Engineer. All cement
shall be Manufacturer's standard grey cement, unless otherwise indicated on the Contract drawings
or specified in the Contract documents.

21.3.4.2

Aggregates

Aggregates for typical prestressed members, precast and fascia members shall conform to the
requirements of Section 4.3.7 of Chapter 4, Concrete Works, of these Standard Specifications

—

and as follows:

•

Fine Aggregates

. Fine aggregate shall consist of natural sand conforming to the gradations

of ASTM C33 / C33M - 11a, except that not more than 1 percent shall pass a No. 200 sieve.

•

Coarse Aggregates

. Coarse aggregate shall consist of gravel or crushed stone. Nominal

sizes of coarse aggregates shall measure 20 mm to a No. 4 sieve and shall conform to the
grading requirements for size No. 67 aggregates of the ASTM C33 / C33M - 11a.

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21.3.4.3

Admixtures

Admixtures may be used only with written approval of the Engineer and as defined in Section 4.3.6
of Chapter 4, Concrete Works, of these Standard Specifications. Calcium chloride, or admixtures
containing calcium chloride, shall not be permitted.

21.3.4.4

Concrete-Bonding Agent

Concrete-bonding agents shall comply with the Federal Specification Army MMM-G-650B CANC.
The application of the concrete-bonding agent

shall be strictly in accordance with manufacturer’s

recommendations to avoid any de-bonding.

21.3.5

Steel

Materials and installation of reinforcing and prestressing steel shall conform to the requirements of
Chapter 5, Reinforcing Steel; and Chapter 22, Prestressing Systems

— respectively. All steel plates,

metal accessories, sleeves, inserts, and built-in materials in precast and prestresses concrete
members shall conform to the following:

21.3.5.1

Steel Plates, Studs and Anchor Bars in Precast Concrete

All steel shapes and plates embedded or cast in precast concrete shall be structural steel complying
with ASTM A36 / A36M - 08. Welded headed studs shall be in conformance with ASTM A108 - 07
and compatible with ANSI/AWS D1.1/D1.1M:2010 Type B. Deformed bar anchors shall conform to
ASTM A706 / A706M - 09b.

All steel shape and plate assemblies along with the studs and welded bars and anchors shall be hot
dipped galvanized per ASTM A153 / A153M - 09 and ASTM A123 / A123M - 12 and as approved by
the Engineer.

Any embedded items proposed by the Contractor to suit his method of operations, shall be subject
to the approval of the Engineer relative to their effect upon the strength, appearance, or properties
of the concrete, strand, or reinforcement steel.

21.3.5.2

Metal Accessories in Prestressed Concrete Members

Spacers, chairs, ties, hold-down devices, supports, and other devices for properly assembling,
placing, spacing, and supporting the reinforcement steel and the prestressing in place, shall be high-
strength, low-alloy carbon steel as approved by the Engineer. When coated reinforcement is
specified, spacers, chairs, and ties shall be epoxy-coated. Care shall be taken not to have dissimilar
metals in contact with each other in order to prevent galvanic corrosion. Hold-down devices shall be
coated with a suitable elastomeric (polyurethene) barrier coating of at least 125 µ DFT.

Accessories that are exposed on concrete surfaces may be hot-dipped galvanized per ASTM A153
/ A153M - 09 or stainless steel as specified in the Contract documents; otherwise, they shall be
stainless steel. Stainless steel shall be ASTM A666 - 10, Type 304 or 316 as directed and approved
by the Engineer, or as specified herein. Stainless steel bolts, nuts, and washers shall conform to
ASTM A453 / A453M - 12, Grade 651, Class B, 3510 kilograms per square centimetre. All stainless-
steel surfaces in contact with dissimilar metals shall be provided with 1.5 mm thick neoprene gasket
between contact faces or as directed by the Engineer.

21.3.5.3

Pipe Sleeves in Prestressed Concrete Members

Embedded pipe sleeves shall be as hot-dipped, galvanized pipe complying with ASTM A153 / A153M
- 09, Type S, Grade A.

21.3.5.4

Threaded Inserts and Lifting Devices in Precast Concrete

Embedded lifting devices, ferrule inserts and coil inserts, including loop inserts, and the
corresponding threaded and coil bolts and bars shall be manufactured of steel corresponding to the
following:

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For wire:

ASTM A510 / A510M - 11, Grade No. 1017

For rods:

ASTM A108 - 07, Grade No. 1018 or ASTM A36 / A36M - 08

All components shall be galvanized as per ASTM B633 - 11, SC-4.

Anchor bolts, where provided, shall be as per Section 30.3 of Chapter 30, Miscellaneous Metals.

21.3.5.5

Built-in Materials in Prestressed Concrete Members

The Contractor shall furnish and install all built-in materials and items as specified herein, and as
directed by the Engineer.

21.3.5.6

Welding Electrodes

Welding electrodes shall comply with AWS Standards and requirements of Article 23.4.11.1 of
Chapter 23, Steel Structures.

21.4

Proportioning of Concrete

Proportions of constituent materials for all concrete used in bridges, culverts, and miscellaneous
roadway structures shall be established to provide the following:

•

Workability and consistency to permit concrete to be easily worked into forms and around

reinforcement under conditions of placement to be employed, without segregation or
excessive bleeding;

•

Resistance to special exposures;

•

Conformance with strength test requirements;

•

Acceptable colour and texture, including aesthetics.

21.4.1

Concrete Mixing

21.4.1.1

Responsibility and Criteria for Concrete Mixing

Performance of all concrete mixes used in the bridge and culvert structures, and other roadway
structures, shall be designed by

— and be the responsibility of — the Contractor. Selected mix

proportions shall produce concrete that is sufficiently workable and finishable for all uses intended
and shall conform to the requirements of Section 4.3.10 of Chapter 4, Concrete Works, of these
Standard Specifications, and all other requirements of this chapter.

The mix design shall be based on the specified properties. When strength is specified, an average
concrete strength shall be selected sufficiently above the specified strength so that, considering the
expected variability of the concrete and test procedures, no more than one in ten strength tests will
be expected to fall below the specified strength.

21.4.1.2

Trial Batch Testing for Concrete Mixing

Laboratory tests on trial and plant batches shall verify the performance of the proposed mix design
for all classes of concrete; precast concrete; lightweight, or low-density, concrete. Test results shall
be furnished to the Engineer by the Contractor, or the Manufacturer of precast elements, at the time
the proposed mix design is submitted.

The average values obtained from trial batches for the specified properties, such as strength, shall
exceed design values by a certain amount based on variability. For compressive strength, the
required average strength used as a basis for selection of concrete proportions shall be determined
in accordance with AASHTO M 241M/M 241-11 (ASTM C 685/C 685M-07).

Control charts shall be applied by the Manufacturer to monitor product characteristics (e.g. cube
strength, consistence, w/c ratio), constituent materials (aggregate grading, cement strengths etc.) or
production (batching accuracy).

The Manufacturer shall continuously assess the compressive strength results in order to:

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•

check whether target strengths are being achieved;

•

measure the variations from target;

•

identify magnitude of any variation;

•

objectively define action required (e.g. change w/c ratio) to get the process

back on target;

•

identify periods and concretes where the strength was less than specified, so

that investigations can be carried out and corrective action taken.

The use of control charts should not be treated in isolation from the rest of production control. For
example routine checking and maintenance of weigh equipment will minimise the risk of a weigh-
scale failure. All the information available to the Manufacturer should be used to interpret the
information provided by the control charts and make informed decisions. Such information leads to
the cause of the change in quality being identified and appropriate action being taken. For example
a loss of accuracy in the weigh-scales should lead to repair, maintenance and re-calibration and not
a change in mix proportions. Where a change in mix proportions is required, the use of control charts
can lead to objectively defined changes in proportions.

Initial Standard Deviation

The initial standard deviation can be determined through a range of pairs approach where:

Initial standard deviation = 0.886 x mean range of successive pairs of results

The range is the numerical difference between successive results and the difference is always taken
as a positive number. Minimum 40 results are required to calculate the initial standard deviation.

Once the initial population standard deviation has been estimated, two methods will be permitted for
verifying the initial estimate. The first method involves checking that the standard deviation of the
most recent 15 results does not deviate significantly from the adopted value. The second method
involves the use of continuous control systems.

The target mean strength shall be selected by the Manufacturer, but the Manufacturer shall have to
comply with certain minimum values. The target strength should never be lower than:

Target mean

strength ≥ characteristic compressive strength + 1.64 x initial standard deviation

Current Margin

The current margin for a concrete mix shall be determined by the Contractor and shall be taken as
the lesser of:

1. 1.64 times the standard deviation of cube tests on at least 100 separate batches of concrete

of nominally similar proportions and materials and produced over a period not exceeding 12
months by the same plant under similar supervision but not less than one sixth of the
characteristic strength for concretes class up to 15 MPa or 3.75 MPa for concretes of class
20 MPa or above;

2. 1.64 times the standard deviation of cube tests on at least 40 separate batches of concrete

of nominally similar proportions and materials and produced over a period exceeding 5 days
but not exceeding 6 months by the same plant and under similar supervision but not less
than one third of the characteristic strength for concrete class up to 15 MPa or 7.5 MPa for
concretes class of 20 MPa or above.

Where there is insufficient data to satisfy items (1) or (2) above the margin for the initial mix design
it shall be taken as two thirds of the characteristic strength for concrete class up to 15 MPa or 15.0
MPa for concrete class of 20 MPa or above. This margin shall be used as the current margin only
until sufficient data is available to adopt items (1) or (2) above. However, subject to the Engineer's
approval, when the specified characteristic strength approaches the maximum possible strength of
concrete made with a particular aggregate, a smaller margin of not less than one third of the
characteristic strength up to class 15 MPa or 7.5 MPa for concretes of class 20 MPa or above may
be used for the initial mix design.

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Trial Mixes

At least 8 weeks before commencing any concreting in the Works, the Contractor shall propose the
mix proportions to the Engineer and shall make trial mixes using samples of materials typical of those
proposed  for  the Works.  Trial  mixes  shall  be  carried  out  for  cool  weather  (winter)  conditions  and
again  for  hot  weather  (summer)  conditions.  The  personnel,  the  concrete  plant  and  the  means  of
transport to be used in the Works shall be employed to make the trial mixes and to transport them a
representative distance and time.

A clean, dry mixer shall be used and the first concrete batch discarded.

The workability of each batch shall be determined both at the mixer and after the representative
transport distance as described above.

Preliminary  standard test  cubes shall  be  made  and  tested from  each  class  of concrete.  For  non-
prestressed  concrete,  12  cubes  shall  be  made  from  one  sample  from  each  of  three  consecutive
batches, and from each set of 12 cubes 3 shall be tested at an age of 7 days, 3 at an age of 28 days,
3 at an age of 56 days and 3 at an age of 90 days. For prestressed concrete, 12 cubes shall be
made from one sample from each of three consecutive batches and from each set of 12 cubes, 3
shall be tested at an age of 3 days, 3 at an age of 7 days, 3 at an age of 28 days, and 3 at an age
of 90 days. All cubes shall be made, cured, stored, transported and tested in accordance with BS
EN 12390-1:2000 and BS EN 12390-2:2009.

The average strength of the nine cubes tested at 28 days shall not be less than the initial target
mean strength minus 3.5 MPa.

As soon as the preliminary tests have been completed, the Contractor shall submit to the Engineer
full details of all trial mixes and tests made.

Before commencing any concreting of the Works, the Contractor shall submit to the Engineer full
details, including details of the aggregate type and grading and an assessment of the target mean
strength.

Prior to approval of the mixes for concrete above pilecap level, satisfactory trial panels shall have
been constructed as agreed with the Engineer.

When a mix has been approved, no variations shall be made without the consent of the Engineer.
Any such consent will be dependent upon the satisfactory outcome of further trial mixes and tests
carried out fully in accordance with the above requirements. These further requirements may include
new trial panels if deemed necessary by the Engineer.

The Contractor shall give the Engineer a minimum of three days notice of all trial mix operations and
ascertain whether the Engineer wishes to witness each operation. If so, the Contractor shall make
arrangements with him accordingly.

21.4.1.3

Approval for Concrete Mixing

All mix designs and any modifications thereto shall be approved by the Engineer prior to use. Mix
design data provided to the Engineer for each class of concrete required shall include the name,
source, type, and brand of each of the materials proposed for use and the quantity to be used per
cubic metre of concrete.

21.4.2

Concrete Mixing Water Content

Water amounts used shall not exceed the limits provided in Table 4-16 of Chapter 4, Concrete
Works, of these Standard Specifications

for water to cement (W/C) ratios, and shall be as per the

approved mix design as per laboratory or plant trials; and shall be further reduced, as necessary, to
produce concrete of the consistencies listed in

Table 21-3. Water for concrete shall be from an approved source only.

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