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

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AASHTO
Designation

ASTM
Designation

Title

ASTM F714 -
12e1

Standard Specification for Polyethylene (PE) Plastic
Pipe (DR-PR) Based on Outside Diameter

ASTM G14-88
(1996)e1

Standard Test Method for Impact Resistance of
Pipeline Coatings (Falling Weight Test)

ASTM B117 - 11

Standard Practice for Operating Salt Spray (Fog)
Apparatus

ASTM A90/
A90M - 11

Standard Test Method for Weight [Mass] of Coating on
Iron and Steel Articles with Zinc or Zinc-Alloy Coatings

ASTM D2657 -
07

Standard Practice for Heat Fusion Joining of Polyolefin
Pipe and Fittings

AASHTO M 85-12

ASTM C150/
C150M - 12

Standard Specification for Portland Cement

AASHTO T
106M/T 106-12

ASTM C109 /
C109M - 11b

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

ASTM D1505 -
10

Standard Test Method for Density of Plastics by the
Density-Gradient Technique

ASTM D1238 -
10

Standard Test Method for Melt Flow Rates of
Thermoplastics by Extrusion Plastometer

ASTM D790 - 10

Standard Test Methods for Flexural Properties of
Unreinforced and Reinforced Plastics and Electrical
Insulating Materials

ASTM D638 - 10

Standard Test Method for Tensile Properties of Plastics

ASTM D1639 -
90(1996)e1

Standard Test Method for Acid Value of Organic
Coating Materials

ASTM D2837 -
11

Standard Test Method for Obtaining Hydrostatic Design
Basis for Thermoplastic Pipe Materials or Pressure
Design Basis for Thermoplastic Pipe Products

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Table 22-2: Designations and titles for BS and BS EN standards that apply to prestressing

steel works

BS
Designation

BS EN Designation Title

BS 4486:
1980

Specification for hot rolled and hot rolled and processed
high tensile alloy steel bars for the prestressing of
concrete

BS EN 197-
1:2011

Cement. Composition, specifications and conformity
criteria for common cements

BS EN 1008:2002

Mixing water for concrete. Specification for sampling,
testing and assessing the suitability of water, including
water recovered from processes in the concrete industry,
as mixing water for concrete

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
5896:2012

High tensile steel wire and strand for the prestressing of
concrete. Specification

BS EN ISO
9001:2015

Quality management systems. Requirements

BS 5075-
1:1982

Concrete admixtures. Specification for accelerating
admixtures, retarding admixtures and water reducing
admixtures

BS 5075-
3:1985

Concrete admixtures. Specification for superplasticizing
admixtures

EN 10138

Prestressing Steel

BS EN ISO 527-
1:2012

Plastics. Determination of tensile properties. General
principles

BS EN ISO 4892-
2:2006+A1:2009

Plastics. Methods of exposure to laboratory light sources.
Xenon-arc lamps

22.4

Prestressing Quality Assurance

Prestessing work shall comply with the requirements for quality assurance outlined in this section.

22.4.1

Qualifications of Prestressing Subcontractor

The subcontractor who performs prestressing work on the Project shall meet the qualifications
outlined in this section.

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22.4.1.1

Precast Prestressed Girder

Before a precast, prestressed girder subcontract is awarded, the Contractor shall submit the pre-
qualification document of the proposed organisation or subcontractor to the Engineer for approval
for the performance of the prestressing works.

Each proposed organisation to perform the prestressed concrete works under these specifications
shall be certified by the Precast/Prestressed Concrete Institute (PCI), Plant Certification program
prior to start of production of works.

The subcontractor approval by the Engineer for the performance of the prestressing work as
specified in these specifications shall not relieve the Contractor of overall responsibility for such work.

If the subcontractor cannot perform the prestressing work in a manner acceptable to the Engineer,
the Contractor shall replace such subcontractor in accordance with the Contract documents. This
alternate subcontractor and the Contractor shall comply with paragraphs 1, 2, and 3 of this section.

22.4.1.2

Post-tensioned Concrete

If the Contractor proposes to perform the post-tensioned concrete work with its own forces, the
Contractor shall submit all details of its qualifications, as specified herein, and as required by the
Engineer, for approval by the Engineer of the Contractor to perform the work.

If the Contractor cannot provide acceptable and adequate information on its qualifications and is
rejected by the Engineer for the post-tensioned concrete work, the Owner shall require the
Contractor to subcontract such work.

The Owner shall require the Contractor to submit the following information regarding its
qualifications, or those of the proposed subcontractor, to the Engineer for review and approval:

a. For the performance of post-tensioned concrete work, the Contractor shall submit the pre-

qualification document of the proposed organisation or subcontractor, along with a complete
and detailed description of its qualifications and experience.

b. Acceptable evidence shall be submitted by the proposed organisation or subcontractor

proving to the Engineer that the organisation or subcontractor is experienced in the field of
prestressing systems. Further, the Contractor or proposed subcontractor shall submit data
acceptable to the Engineer that it has, within the last five years, performed construction work
comparable to the post-tensioned concrete work as specified in these standard specifications
and indicated in the Contract plans. This experience shall be confirmed by the Contractor by
citing a minimum of two comparable projects that have been successfully accomplished.

c. Approval of the Contract

or’s organisation or the subcontractor by the Engineer for the

performance of the post-tensioned concrete work shall not relieve the Contractor of overall
responsibility for such work.

d. If, after the approval by the Engineer, the Contractor

— or an approved subcontractor —

demonstrates an inability to perform the work as specified in this section, the Engineer
reserves the right to rescind such approval and require the Contractor to submit the name of
another subcontractor to perform the work. All resubmittals shall comply with the
requirements specified herein and in the Contract documents.

22.4.1.3

Supervision of Prestressing Operations

Prestressing  and  grouting  operations  shall  be  under  the  charge  of  a  supervisor  with  appropriate
knowledge, training and experience in carrying out similar operations. That person shall be present
during all procedures and shall be responsible for all safety precautions relating to the operations.
The  Contractor  shall  employ  this  supervisor  and  ensure  that  he  is  aware  of  the  required  tendon
loads,  order of stressing, extensions, allowance for  losses and all other particulars relating to the
operations.

The appointment of the responsible person shall be subject to the approval of the Engineer.

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The supervisor and all operatives shall be certified under a recognized certification scheme as having
the necessary qualifications such as CARES Product Installation Certification.

In addition, for each jacking operation, one technical representative of the approved post-tensioning
system as per Article 22.7.1.1 shall be present through the whole prestressing installation and
operation process. The technical representative shall provide guidance during the installation of the
ducts, anchorages, anchorage reinforcement, and actual post-tensioning operation. The technical
representative shall sign all post-tensioning loading, stressing, and elongation records with the
Contractor’s supervisor and the Engineer.

22.5

Supplementary Drawings

Supplementary drawings including working drawings, shop drawings and composite placement
drawings shall meet the requirements outlined in this section.

22.5.1

Working Drawings

Where the Contract documents do not include complete details of the prestressing system and its
method of installation, or when complete details are provided in the Contract plans and the
Contractor wishes to propose changes, the Contractor shall prepare and submit working drawings
of the prestressing system proposed for use to the Engineer. Fabrication or installation of
prestressing material shall not begin until the Engineer has approved the working drawings.

Working drawings of the prestressing system shall show complete details and substantiating
calculations of the method and materials proposed by the Contractor, including any additions or
rearrangement of reinforcing steel and any revision in concrete dimensions from that shown in the
plans. Such details shall outline the method and sequence of stressing and shall include complete
specifications and details of the prestressing steel and anchoring devices; working and anchoring
stresses; stress-strain curves of the prestressing steel; anticipated gauge pressures; cable profiles;
elongation of prestressing cables; and type of ducts and all other data pertaining to the prestressing
operation, including the proposed arrangement of the prestressing steel in the members.

The working drawing shall include as well erection and handling procedures and sequence for all
precast members.

Designs shall be prepared by a Specialty Engineer who has been approved in advance by the
Engineer.

Working drawings shall be submitted four weeks in advance of the start of the affected work to allow
time for review by the Engineer and correction by the Contractor of the drawings without delaying
the work.

Where required by the Contract plans, or in the Contract documents, the Contractor shall prepare
composite placement drawings for all items embedded in the concrete. If this provision includes a
requirement for additional engineering or design detailing, these requirements shall be clearly stated,
as noted in Section 22.2.

22.5.2

Shop Drawings

The Contractor shall submit shop drawings to the Engineer for approval in accordance with the
requirements of the Contract documents and as specified herein.

The shop drawings shall indicate the complete fabrication, profile, and placement details for all
tendons and strands, including types, locations, anchorages, couplings and methods of support, as
well as, computations for the prestressing of each post-tensioned tendon or all pre-tensioning
strands. The shop drawings shall also show, in addition to the tendons and strands, the placement,
sizes, and details of the reinforcement steel in the prestressed concrete work. Shop drawings shall
be prepared showing formwork and method and types of bracing.

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All shop drawings shall be submitted for review and approval in accordance with the requirements
specified herein. Prints of the final approved shop drawings shall be furnished by the Contractor for
the Engineer's use.

The  shop  drawings  and computations shall  be checked  by the  Contractor  before  submittal  to the
Engineer. All shop drawings, computations and related data shall be accompanied by design data
confirming that the forces indicated on the  Contract plans are obtainable and that all prestressing
hardware  is  adequate  to  transmit  these  forces.  All  shop  drawings  and  computations  shall  be
approved by the Engineer before commencing any fabrication or delivery of material. No deviations
from the approved shop drawings shall be made by the Contractor without written approval of the
Engineer. Any fabrication by the Contractor without such written approval shall be at the Contractor's
risk. Any girders not fabricated in accordance with approved shop drawings will be rejected by the
Engineer.

The Engineer's approval of any proposed methods, materials, or equipment shall not relieve the
Contractor of full responsibility for the successful completion of all work specified in these Standard
Specifications and all related Contract documents.

Shop  drawings  for  post-tensioning  and  other  embedments  and  attachments,  such  as  expansion
joints, bearings, and anchor bolts submitted by suppliers, shall be reviewed for conformance with
the design concept and compliance with the Contract plans and specifications; and then approved
by  the  Engineer.  Where  the  Contract  document  information  on  the  post-tensioning  system  is
modified  by  the  Contractor,  or  where  the  Contract  plans  do  not  provide  detailed  dimensional
information  on  the  post-tensioning  system,  it  is  the  Contractor's  responsibility  to  coordinate  the
placement of the post-tensioning system with other embedments, and to correct any interferences
created  by  the  Contractor-supplied  post-tensioning  system  or  other  substitutions.  Post-tensioning
layouts shall govern the layout of the secondary nonprestressed reinforcement. Where necessary,
location  of  nonprestressed  reinforcement  should  be  adjusted  to  clear  tendons,  subject  to  the
Engineer

’s approval.

22.5.3

Composite Placement Drawings

Where  required  by  the  Contract  documents,  in  addition  to  all  required  working  drawings,  the
Contractor shall prepare composite placement drawings to scale and in sufficient detail to show the
relative  positions  and  depths  of  all  items  embedded  in  the  prestressed  concrete  portions  of  the
structure.  Such  embedded  items  shall  include  the  prestressing  ducts,  vents,  anchorage
reinforcement and hardware, reinforcing steel, anchor bolts, earthquake restrainers, deck joint seal
assemblies, drainage systems, and utility conduits. These drawings shall ensure that the planned
positions of embedded items do not conflict with one another and that concrete cover is adequate.
Working  drawings  shall  be  developed  and  prepared  by  the  Contractor  for  embedded  items  or
proposed  changes  in  the  dimensions  of  the  post-tensioning  systems  work

— as required by the

Contract. This will eliminate conflicts and provide proper cover wherever conflicts arise with or due
to the post-tensioning system. Resolution of the conflicts should follow the provision of Section 22.2.
Before work can begin on any affected item, the Engineer shall approve any revision. All costs
involved with the preparation of drawings and with making necessary modifications to the work
resulting there from shall be borne by the Contractor. This will require composite placement drawings
to be detailed to a scale and sufficient quality to show double-line reinforcement and post-tensioning
tendon details in either 2D or in complete 3D drawings.

22.6

Submittals

The Contractor shall submit the supplementary drawings to the Engineer for approval in accordance
with the requirements of Section 22.5. In addition, submittals shall comply with the requirements
outlined in this section.

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22.6.1

Qualification Details

Experience records and qualification details of the Contractor’s key structural design, fabrication,
installation, and quality control (QC) personnel who will work on the prestressing and concrete
operations shall be submitted by the Contractor. Once approved, the Contractor shall not change or
substitute any of the personnel without the Engineer’s prior approval.

22.6.2

Working Drawings

Working drawings of the proposed prestressing system shall be submitted by the Contractor to the
Engineer for review and approval. For the initial review, six sets of such drawings shall be submitted.
One approved set or one set with corrections and modifications shall be returned by the Engineer.
After modification, six sets of the drawings and their associated calculations, if any, showing any
required corrections shall be submitted for final approval. Working drawings shall be submitted
sufficiently in advance of the start of the affected work to allow time for review and correction without
delaying the approved programmed commencement of the work. Such time shall be proportional to
the complexity of the work but, in no case, shall be less than two months.

Approval of working drawings and other submittals does not absolve the Contractor of the
responsibility for any contractual obligations. No additional payment will be made to the Contractor
for changes required as a result of reviews or approvals. Proper material submittals shall be made
as per Section 1.15, Submittal Procedures, outlined in Chapter 1, General Requirements, of these
standard specifications, for all materials involved.

22.6.3

Certificates

Certificates from the manufacturer, in quantities as directed by the Engineer, shall be furnished to
the Engineer certifying that the materials and equipment to be provided comply with the requirements
of these Standard Specifications, referenced codes and standards and approved shop drawings.

22.6.4

Test Reports

The Contractor shall furnish to the Engineer six (6) copies of test reports and certificates as specified
herein, unless otherwise directed by the Engineer.

22.7

Materials for Prestressing Operations

Materials for prestressing operations shall comply with the requirements outlined in this section.
Samples shall be submitted in the quantities as directed by the Engineer. Sampling and testing shall
be in general compliance with provisions of PCI MNL-117-77. After the Engineer has approved the
shop drawings, a full sized sample shall be prepared for the precast members for final approval of
the Engineer.

22.7.1

Prestressing System Materials

Materials for a prestressing system shall comply with the requirements outlined in this section.

22.7.1.1

Post-tensioning Systems

The post-tensioning system shall comply with latest international standards and the requirements of
these standard specifications, and shall be produced under a permanent system of factory
production control which shall ensure the same level of confidence in the conformity of the finished
product, whatever the manufacturing process.

The post-tensioning system shall subject to an official certification such as BS EN ISO 9001:2015
and CARES certificate relating to factory production control and product conformity.

Except as otherwise specified herein or specifically approved by the Owner, the post-tensioning
system including strands, ducts, anchorages, couplers, installation machines, wedges, stressing

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jacks and pump machine, gauges, grouting equipment, etc. shall be one of the following
manufacturers or systems or equivalent:

1. Bureau BBR Ltd.

2. DYWIDAG System Int.

3. Freyssinet System

4. VSL Corporation

5. Tensacciai System

6. CLL System

7. VLM System

Where a specific item of one of the manufacturers or systems is indicated on the Contract plans or
specified in these standard specifications or the particular specifications, comparable items of other
manufacturers are acceptable, if proven to be of internationally recognized types acceptable to the
Owner/Engineer. The Owner/Engineer shall be the sole judge as to whether or not any proposed
alternative system of post-tensioning is comparable and equal to the specified systems.

22.7.1.2

Prestressing Steel and Anchorage

Prestressing reinforcement shall be high-strength seven-wire strand, high-strength steel wire, or
high-strength alloy bars of the grade and type called for in the Contract plans or in a particular
specification; and, shall conform to the requirements of the following specifications.

Strands

Strands shall be uncoated, seven-wire, high-tensile, cold-drawn, stress-relieved low relaxation steel
conforming to the requirements of AASHTO M 203M/M 203-12 (ASTM A416/ A416M - 12),
Supplement S1 (low relaxation) Grade 1860 MPa, or BS 5896:2012 Grade 1770 MPa. Unless
otherwise specified, the Contractor shall furnish 12.7 mm or 12.5mm diameter strands for all pre-
tensioned members, and 15.24 mm or 15.7 mm diameter strands for all post-tensioned members.
Prestressing strand, however manufactured, shall be in coils of a large enough diameter to ensure
that the strand pays off straight.

Prior to shipment of the strands from the Manufacturer's plant, the Contractor shall submit typical
stress-strain curves obtained from the mill

— or approved independent laboratory — based on test

performance of the strands proposed for use for approval by the Engineer. For each lot of maximum
10-ton, or fractions thereof, of strands produced specifically for this Contract, certified copies of the
Manufacturer's test reports shall be submitted to the Engineer. In addition to the mill certificates, for
every three coils or reels, one set of three specimens, as selected by the Engineer, shall be tested
for tensile strength and elongation at a laboratory approved by the Engineer. Upon building
confidence in the quality of the delivered strength, the Engineer may relax the aforementioned testing
requirement. This testing including samples shall be performed by the Contractor at no cost to the
Owner. Specimens may be cut from the starting end of any length of strand or wire by the Contractor.

All strands accepted and approved shall have affixed to each coil, reel, or reel-less pack a tag
certifying that it has been tested and/or approved by the Engineer.

Wires

Uncoated stress-relieved low relaxation steel wires shall conform to the requirements of AASHTO M
204M/M 204-06 (2010) (ASTM A421/ A421M - 10). Unless otherwise agreed by the Engineer, low
relaxation wires shall be in coils of sufficiently large diameter to ensure that the wire pays off straight.
The quality requirements performed on strands shall be applied on the wires to be used in the
Project.

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Bars

Bars  shall  be  Grade  1035  MPa  uncoated  high-strength  bars  conforming  to  the  requirements  of
AASHTO  M  275M/M  275-08  (ASTM  A722/  A722M  -  12)  or  BS  4486:  1980.  Bars  with  greater
minimum  ultimate  strength,  but  otherwise  produced  and  tested  in  accordance  with  AASHTO  M
275M/M  275-08  (ASTM  A722/  A722M  -  12),  may  be  used  provided  they  have  no  properties  that
make  them  less  satisfactory  than  the  specified  material.  Prestressing  bars  shall  be  straight  upon
delivery. Three randomly selected samples, per size of bar, per heat of steel with a minimum of one
sample per shipment shall be tested for tensile strength and elongation at a laboratory approved by
the Engineer.

Assemblies

Anchorage assemblies, jacks, gauges, grout fittings, and other related equipment and accessories
shall be standard with the system’s Manufacturer and approved by the Engineer. Post-tensioning
ducts shall be as approved by the Engineer.

22.7.1.3

Post-tensioning Anchorage and Couplers

Anchorage assemblies shall be cast units that are standard with the prestressing Manufacturer's
system for the intended purpose (type of anchorages) and to the approval of the Engineer.

All anchorages and couplers shall develop at least 96 percent of the actual ultimate strength of the
prestressing steel, when tested in an unbonded state, without exceeding anticipated set. The
coupling of tendons shall not reduce the elongation at rupture below the requirements of the tendon
itself. Couplers, or coupler components, shall be enclosed in housings long enough to permit
necessary movements. Couplers for tendons shall be used only at locations specifically indicated or
approved by the Engineer. Couplers shall not be used at points of sharp tendon curvature.

Anchorages and couplers shall be handled and used strictly in accordance with the Manufacturer's
instructions and recommendations.

Bonded System

Bond transfer lengths between anchorages and the zone where full prestressing force is required,
under  service  and  ultimate  loads  shall  normally  be  sufficient  to  develop  the  minimum  specified
ultimate  strength  of  the  prestressing  steel.  When  anchorages  or  couplers  are  located  at  critical
sections under ultimate load, the ultimate strength required of the bonded tendons shall not exceed
the  ultimate  capacity  of  the  tendon  assembly,  including  the  anchorage  or  coupler,  tested  in  an
unbonded state.

Housings shall be designed so that complete grouting of all of the coupler components will be
accomplished when grouting the tendons.

Unbonded System

For  unbonded  tendons,  a  dynamic  test  shall  be  performed  on  a  representative  anchorage  and
coupler specimen and the tendon shall withstand, without failure, 500,000 cycles from 60 percent to
66  percent  of  its  minimum  specified  ultimate  strength,  and  also  50  cycles  from  40  percent  to  80
percent of its minimum specified ultimate strength. The period of each cycle involves the change
from the lower stress level to the upper stress level and back to the lower. The specimen used for
the  second  dynamic  test  need  not  be  the  same  used  for  the  first  dynamic  test.  Systems  utilising
multiple strands, wires, or bars may be tested utilising a test tendon of smaller capacity than the full-
sized tendon. The test tendon shall duplicate the behaviour of the full-sized tendon and generally
shall not have less than 10 percent of the capacity of the full-sized tendon. Dynamic tests are not
required on bonded tendons, unless the anchorage is located or used in such manner that repeated
load applications can be expected on the anchorage.

Anchorages for unbonded tendons shall not cause a reduction in the total elongation under ultimate
load of the tendon to less than 2 percent measured in a minimum gauge length of 3 metres.

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All the coupling components shall be completely protected with a coating material prior to final
encasement in concrete.

Special Anchorage Device Acceptance Test

1. Test Block Requirements

Test  blocks  shall  be  a  rectangular  prism  and  shall  contain those  anchorage  components  that  will
also  be  embedded  in  the  structure's  concrete.  Their  arrangement  must  comply  with  the  practical
application  and  the  supplier

’s specifications. Test blocks shall contain an empty duct of an

appropriate size for the maximum tendon size that can be accommodated by the anchorage device.

2. Test Block Dimensions

Dimensions for the test block perpendicular to the tendon in each direction shall be the smaller of
the minimum edge distance or the minimum spacing specified by the anchorage device supplier;
with the stipulation that the cover over any confining reinforcing steel or supplementary skin
reinforcement be appropriate for the particular application and environment. The length of the block
along the axis of the tendon shall be at least two times the larger of the cross section dimensions.

3. Local Zone Reinforcement (Anchorage Zone)

The confining reinforcing steel in the local zone shall be the same as that specified by the anchorage
device supplier for the particular system.

4. Skin Reinforcement

In addition to the anchorage device and its specified confining reinforcement steel, supplementary
skin reinforcement may be provided throughout the specimen. This supplementary skin
reinforcement shall be specified by the anchorage device supplier. Similar reinforcement in the actual
structure shall be furnished to achieve an equivalent action.

5. Concrete Strength

The concrete strength at the time of stressing shall be greater than the concrete strength of the test
specimen at time of testing.

6. Test Procedure

Any of the following three test procedures described below is acceptable:

•

Cyclic loading

•

Sustained loading

•

Monotonic loading

Loads specified for the tests are given in fractions of the ultimate load, or

, of the largest tendon

that the anchorage device is designed to accommodate. Specimens shall be loaded in accordance
with normal usage of the device in post-tensioning applications, except that load can be applied
directly to the wedge plate or equivalent area.

7. Cyclic Loading Test

In a cyclic loading test, the load shall be increased to 0.8

, and then cycled for not less than 10

cycles between 0.1 Fpu and 0.8 Fpu until crack widths stabilize. Crack widths are considered
stabilized if they do not change by more than 0.025 mm over the last three readings. Upon
completion of the cyclic loading the specimen shall be preferably loaded to failure or, if limited by the
capacity of the loading equipment, to at least 1.1

Crack widths and crack patterns shall be recorded at the initial load of 0.8

at least at the last

three consecutive peak loadings before termination of the cyclic loading, and at 0.9

. The

maximum load shall also be reported.

8. Sustained Loading Test

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In a sustained loading test, the load shall be increased to 0.8

and held constant for not less than

48 hours until crack widths stabilize. Crack widths are considered stabilized if they do not change by
more than 0.025 mm over the last three readings. After sustained loading is completed, the specimen
shall be preferably loaded to failure or, if limited by the capacity of the loading equipment, to at least
1.1

Crack widths and crack patterns shall be recorded at the initial load of 0.8

at least three times at

intervals of not less than four hours during the last 12 hours before termination of the sustained
loading, and during loading to failure at 0.9

. Maximum loads shall also be reported.

9. Monotonic Loading Test

In a monotonic loading test, the load shall be increased to 0.9

and held constant for one hour.

Specimen shall then be preferably loaded to failure or, if limited by the capacity of the loading
equipment, to at least 1.2

Crack widths and crack patterns shall be recorded at 0.9

after the one-hour period, and at 1.0

. Maximum loads shall also be reported.

10. Anchorage Zone Requirement

Anchorage zone strengths must exceed the following:

•

Specimens tested under cyclic or sustained loading: 1.1

•

Specimens tested under monotonic loading: 1.2

Maximum crack width criteria, specified below, must be met for moderately aggressive
environments:

•

No cracks greater than 0.25 mm at 0.8

after completion of the cyclic or sustained loading,

or at 0.9

after the one-hour period for monotonic loading

•

No cracks greater than 0.4 mm at 0.9

after completion of the cyclic or sustained loading,

or at 1.0

for monotonic loading

For high-aggressive environments the crack width criteria shall be reduced by at least 50 percent.

11. Test Series Requirement

A test series shall consist of three test specimens. Each specimen must meet the acceptance criteria.
If one of the three specimens fails to pass the test, a supplementary test of three additional
specimens is allowed. The three additional test specimen results must meet all acceptance criteria
of Paragraph 10 of Sub-article c.

For a series of similar special anchorage devices, tests are only required for representative samples,
unless tests for each capacity of the anchorages in the series are required by the Engineer.

12. Records of the Anchorage Device

Records of the anchorage device acceptance test shall include the following:

•

Dimensions of the test specimen

•

Drawings and dimensions of the anchorage device, including all confining reinforcing steel

•

Amount and arrangement of supplementary skin reinforcement

•

Type and yield strength of reinforcing steel

•

Type and compressive strength at time of testing of concrete

•

Type of testing procedure and all measurements required in Paragraphs 7 through 10 of sub-

article c for each specimen

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22.7.2

Grout

The properties of the grout made with the materials and proposed plant and personnel shall be
assessed by the Contractor for suitability for the intended purpose sufficiently in advance of grouting
operations to enable adjustments to be made in use of materials or plant or personnel. All retrials
shall be at the Contractor's expense.

The materials assessment shall consist of the preparation of the grout, made with the materials and
using the plant and personnel proposed for use on site, and the testing of it in accordance with Article
22.8.8.12. The preparation shall be carried out under conditions of temperature expected on site. If
grouting operations are likely to cover different seasons, the assessment shall include the range of
expected temperatures.

The sources of materials and procedures approved as a result of satisfactory trials shall not be
departed from without the written approval of the Engineer.

Unless otherwise instructed or agreed by the Engineer as a result of grouting trials, the grout shall
consist only of Portland cement complying with BS EN 197-1:2011 Class 42.5N, admixtures
complying with Article 22.8.8.13 and water complying with BS EN 1008:2002.

The age, chemical composition, fineness and temperature of the cement shall be subject to close
control.

The materials used shall be such that the chloride ion content of the grout shall not exceed 0.06%
chlorides by mass of the cement.

The post-tensioning grout shall meet the grout physical properties stated in Article 22.7.2.3, Grout
Physical Properties. Grouts may be either a unique design for the Project or supplied in a prebagged
form by the grout Manufacturer. For uniquely designed grouts, the cement and admixtures utilised
in the laboratory trial batches of the proposed grout shall not be changed during construction without
retesting. Cement freshness shall be in accordance with AASHTO M 85-12 (ASTM C150/ C150M -
12), except as specified herein. Daily field testing of the grout for the following properties shall be
required:

•

Fluidity

•

Bleed at three hours

•

Volume change test

Prebagged grout supplied by a grout manufacturer shall be prebagged in plastic-lined or plastic-
coated containers and stamped with date of manufacture, lot number, and mixing instructions. Any
change of materials or material sources shall require retesting and certification of the conformance
of the grout with the physical properties requirements. Grout suppliers shall provide the Contractor
with a copy of the QC data sheet for each lot number and shipment sent to the jobsite; these data
shall also be furnished to the Engineer. Materials with total time from manufacture to usage in excess
of six months shall be removed from the jobsite and replaced.

22.7.2.1

Approval

Manufacturers of post-tensioning grout shall submit certified test reports from an independent
cement and concrete laboratory for approval. These tests shall show that the material meets all the
requirements specified herein.

22.7.2.2

Mixing

Materials shall be mixed in accordance with the manufacturer's recommendations. Water used in
the grout shall be potable, clean, and free of injurious quantities of substances known to be harmful
to Portland cement or prestressing steel.

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22.7.2.3

Grout Physical Properties

Grouts shall achieve a nonbleeding characteristic. Grout shall contain no aluminium powder or gas-
generating  system  that  produces  hydrogen,  carbon  dioxide,  or  oxygen.  Cementitious  grout  shall
meet  or  exceed  the  specified  physical  properties  stated  herein,  as  determined  by  the  following
standard ASTM test methods.

Grout classes shall be taken as specified in Table 22-3, general grout properties

for the Engineer’s

approval in principle shall be as specified in Table 22-4, and field testing of grout for quality control
shall be as per Article 22.8.8.12.

Fluidity

The fluidity of the grout during the injection period shall be high enough for it to be pumped effectively
and adequately to fill the duct, but low enough to expel the air and any water in the sheath. Field
testing of grout fluidity for quality control shall be as per Article 22.8.8.12. The fluidity at the duct
outlets shall not exceed that of the injected grout by more than 10%.

Bleeding

The bleeding of the grout shall be sufficiently low to prevent excessive segregation and settlement
of the grout materials. Field testing of grout bleeding for quality control shall be as per Article
22.8.8.12. The bleeding shall be less than 2% of the initial volume of the grout and the average of
four successive results shall be less than 1%. The water shall be reabsorbed by the grout during the
24 hours after mixing.

Volume Change

The volume change assessed may be either an increase or decrease. Field testing of grout volume
change for quality control shall be as per Article 22.8.8.12. The volume change of the grout shall be
within the range 0% to +5%. For grouts with expanding agents there shall be no decrease in volume.

Strength

The compressive strength of 100mm cubes made of the grout shall exceed 27 MPa at 7 days and
at least 62 MPa after 28 days. Cubes shall be made, cured and tested in accordance with BS EN
12390-1:2000 and BS EN 12390-2:2009 or AASHTO T 106M/T 106-12.

Sieve Test

The grout shall contain no lumps. This shall be verified by checking the sieving medium on the fluidity
test cone.

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Table 22-3: Grout classes

Class

Exposure

Constituent materials

Cement

Fly ash

(type F)

percent
ª

Slag

percent
ª

Silica

fume

(dry)

percentª

Water

cementitious

material ratio

[W/(c+m)]

High-range

water
reducer

(type F or G)
gm/kg

Calcium

nitrite

kg/m

Other

admixtures

Required
testing

Nonaggressive:
Indoor

outdoor

100

0.45 max

Article
22.7.2.3

Aggressive:
Subject wet or
dry

cycles,

marine environ.

100

0 min

25 max

0 min

55 max

0 min

15 max

0.45 max

0 min

29 max

0 min

25 max

per

Manufacturers
recommendation

Article
22.7.2.3

Prepackaged

Aggressive

nonaggressive

0.45 max

Article
22.7.2.3

Special

Determined by the Engineer

Article
22.7.2.3

Notes:

a. Percent of cement substitute.

b. Types D and E admixtures may be permitted with approval of the Engineer.

c. Alternate corrosion inhibitors may be used.

d. Other admixtures, such as anti-bleed admixtures, pumping aids, and air-entraining agents.

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Table 22-4: General grout properties

Property

Test value

Test method

Total chloride ions

Max.0.06 percent by weight of
cementitious material

ASTM C1152/ C1152M -
04e1

Fine aggregate (if utilised)

Max. Size <No. 50 Sieve

ASTM C33 / C33M - 11a

Volume change at 28 days

Min. 0.0 percent at 24 hours
and 28 days

ASTM C1090 - 10

Expansion

≤2.0 percent for up to 3 hours

ASTM C940

– 10a

Initial set of grout

Min. 3 hours

Max. 12 hours

ASTM C953 - 10

Fluidity test

Efflux time from flow cone
immediately after mixing

30 minutes after mixing with
remixing for 30 seconds

At duct outlet time

Min. 11 seconds
Max. 30 seconds

Max. 25 seconds

≥ 10 seconds

ASTM C 939

– 10

Bleeding at 3 hours

Max. 0.0 percent

ASTM C940

– 10a

Rapid chloride permeability at
28 days

Max. 2,500 coulombs at 30
volts for 6 hours

AASHTO T 277-07(2011)
(ASTM C1202 - 12)

22.7.3

Ducts for Prestressing Operations

Ducts used to provide holes or voids in the concrete for the placement of post-tensioned bonded
tendons may be either formed with removable cores or may consist of rigid or semi-rigid ducts that
are cast into the concrete.

Ducts formed with removable cores shall be formed with no constrictions that could block the
passage of grout. All coring materials shall be removed.

Ducts  formed  by  sheaths  left  in  place  shall  be  a  type  that  will  not  permit  the  intrusion  of  cement
paste. They shall transfer bond stresses, as required, and shall retain their shape under the weight
of  the  concrete  while  having  sufficient  strength  to  maintain  their  correct  alignment  without  visible
wobble during concrete placement.

The  system  of  ducts,  duct  connectors  grouting  connections,  vents,  vent  connections,  drains,
transitions  to  anchorage  and  caps  for  anchorages  shall  form  a  complete  air  and  water-tight
encapsulation for the tendons. Ducts shall be of corrosion resistant durable material such as high
density corrugated polyethylene or polypropylene. Galvanized ferrous metal ducts will be permitted.
Ducting which may degrade or corrode during the expected life of the structure in the presence of
contaminants  permeating  the  surrounding  concrete  is  not  permitted.  The  system  shall  be  fully
compatible with the prestressing anchorages, and other details.

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22.7.3.1

Metal Ducts for Prestressing

Sheathing for ducts shall be metal, except as provided herein. Such ducts shall be galvanized ferrous
metal and shall be fabricated with either welded or interlocked seams. Galvanizing of welded seams
will not be required. Rigid ducts shall have smooth inner walls and shall be capable of being curved
to the proper configuration without crimping or flattening. Semi-rigid ducts shall be corrugated and,
when tendons are to be inserted after the concrete has been placed, their minimum wall thickness
shall be as follows:

•

0.45 mm for ducts less than or equal to 66.7 mm in diameter

•

0.60 mm for ducts greater than 66.7 mm in diameter

When bar tendons are preassembled with such ducts, the duct thickness shall not be less than 0.25
mm.

22.7.3.2

Plastic Ducts for Prestressing

For locations in saltwater environment, plastic duct material shall be considered and is
recommended.

Corrugated  plastic  duct  completely  embedded  in  concrete  shall  be  constructed  from  either  high
density  polyethylene  or  polypropylene.  The  minimum  acceptable  radius  of  curvature  shall  be
established by the duct supplier, according to standard test methods. The duct shall have a thickness
as shown in Table 22-5.

Ducts  shall have a  white coating on the outside or  shall be of white material with ultraviolet (UV)
stabilizers  added.  Polyethylene  duct  shall  be  fabricated  from  resins  meeting  or  exceeding  the
requirements of ASTM D3350 - 12, with a cell classification of 345464A.

Polypropylene duct shall be fabricated from resins meeting or exceeding the requirements of ASTM
D4101 - 11, with a cell classification range of PP0340BI4541 to PP0340B67884.

Resin containing antioxidants with a minimum oxidation induction time (OIT) of not less than 20
minutes, in accordance ASTM D3895 - 07, shall be used. OIT tests shall be performed on samples
taken from the finished product.

Rigid, smooth, black polyethylene ducts used where the tendon is not embedded in concrete shall
be rigid pipe manufactured from 100 percent virgin polyethylene resin meeting the requirements of
ASTM D3350 - 12, with a minimum cell class of 344464C. A resin containing antioxidants with a
minimum OIT of not less than 40 minutes shall be used in accordance with ASTM D3895 - 07. OIT
tests shall be performed on samples taken from the finished product. Ducts shall be manufactured
with a dimensional ratio (DR) of 17, as established by either ASTM D 3350 - 12 or ASTM F714

–

12e1, and as appropriate for the manufacturing process used.

Table 22-5: Ducts thickness

Duct shape

Duct diameter (mm)

Duct thickness (mm)

Flat

any size

2.0

Round

2.0

Round

2.0

Round

2.5

Round

2.5

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Duct shape

Duct diameter (mm)

Duct thickness (mm)

Round

100

3.0

Round

115

3.5

Round

130

4.0

Round

145

4.0

22.7.3.3

Duct Area

The provisions of Article 5.4.6.2, Size of Ducts, of the AASHTO LRFD Bridge Design Specifications,
latest edition, shall apply.

22.7.3.4

Duct Fittings

Coupling and transition fittings for ducts formed by sheathing shall be of either ferrous metal
polyolefin (polyethylene or polypropylene), and shall be air- and watertight and of sufficient strength
to prevent distortion or displacement of the ducts during concrete placement and tendon grouting.

All ducts or anchorage assemblies shall be provided with pipes or other suitable connections at each
end of the duct for the injection of grout after prestressing. As specified in Sub-article a, Duct Inlets
and Outlets, of Article 22.8.4.2, ducts shall be provided with ports for venting or grouting at high
points and for draining at intermediate low points.

Vent and drain pipes shall be at least 20 mm in diameter for strand and at least 12 mm in diameter
for single-bar tendons and three- or four-strand flat-duct tendons. Connection to ducts shall be made
with metallic or plastic structural fasteners. Vents and drains shall be mortar tight, taped as
necessary, and constructed with either mechanical or shrink-wrap connections. Vents and drains
shall provide means for injection of grout through the vents and for sealing to prevent leakage of
grout.

22.8

General Prestressing Requirements

A skilled technician supervisor experienced in the prestressing system as required in Article 22.4.1.3
and specified herein shall be employed by the Contractor. This technician supervisor shall be
capable of directing operations and of providing aid and instruction in the use of tensioning and
grouting equipment. This assistance shall be available as long as necessary to assure satisfactory
results in all phases of the tensioning and grouting work.

Prestressing may be accomplished by pre- and post-tensioning, or by combining the two methods
— as specified in the Contract documents, in the approved working drawings, or approved in writing
by the Engineer.

Prestressing steel shall be tensioned by hydraulic jacks so as to produce the forces shown in the
Contract documents or on the approved working drawing with appropriate allowances for all losses.
Losses to be provided for shall be as specified in Article 5.9.5, Loss of Prestress, of the AASHTO
LRFD Bridge Design Specifications, latest edition.

For post-tensioned work, the losses shall also include the anchor set loss appropriate for the
anchorage system employed, and actual wobble and friction losses of ducts.

For pretensioned members, the strand stress prior to seating (jacking stress), shall not exceed 80
percent of the minimum ultimate tensile strength of the prestressing steel (0.8 fs'). This allowable
stress slightly exceeds the values allowed in Article 5.9.3, AASHTO LRFD Bridge Design

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Specifications, and it may be permitted to offset seating losses and to accommodate compensation
for temperature differences specified in Article 22.8.3.1, Pre-tensioning Requirements.

For post-tensioned members, the standard stress prior to seating (jacking stress) and the stress in
the steel immediately after seating shall not exceed the values allowed in AASHTO LRFD Bridge
Design Specifications, Article 5.9.3, and the Road Structures Design Manual (ADQCC TR-516).

The method of tensioning employed shall be one of the following as specified or approved:

1. Pre-tensioning; in which the prestressing strand or tendons are stressed prior to being

embedded in the concrete placed for the member. After the concrete has attained the
required strength, the prestressing force is released from the external anchorages and
transferred, by bond, into the concrete.

2. Post-tensioning; in which the reinforcing tendons are installed in within the concrete and are

stressed and anchored against the concrete after the development of the required concrete
strength. As a final operation under this method, the voids or ducts are pressure-grouted.

3. Combined Method; in which part of the reinforcement is pre-tensioned and part post-

tensioned.

Under this method all applicable requirements for pre-tensioning and for post-tensioning shall apply
to the respective reinforcing elements using these methods.

During strand stressing, individual wire failures may be accepted by the Engineer, provided not more
than one wire in any strand is broken and the area of broken wires does not exceed 2 percent of the
total area of the prestressing steel in the member.

22.8.1

Concrete Strength

Prestressing forces shall not be applied or transferred to the concrete until the concrete has attained
the  strength  specified  for  initial  stressing.  The  Contractor  shall  cast  and  test  sufficient  cubes  to
demonstrate  this  to  the  approval  of  the  Engineer.  Additionally,  for  bridges  not  constructed
segmentally, cast-in-place concrete shall not be post-tensioned until at least 10 days after the last
concrete  has  been  placed  in  the  member  to  be  post-tensioned,  and  the  minimum  required  cube
strength gained for post tensioning.

22.8.2

Prestressing Equipment

Hydraulic jacks used to stress tendons shall provide and sustain the necessary forces and shall be
equipped with either a pressure gauge or a load cell for determining the jacking stress. Jacking
systems shall provide an independent means by which the tendon elongation can be measured. The
pressure gauge shall have an accurately reading dial at least 150 mm in diameter or a digital display,
and each jack and its gage shall be calibrated as a unit with the cylinder extension in the approximate
position that it will be at final jacking force, and shall be accompanied by a certified calibration chart
or curve. The load cell shall be calibrated to an accuracy within ± 2 percent and checked at intervals
to the approval of the Engineer; and shall be provided with an indicator by means of which the
prestressing force in the tendon may be determined. The range of the load cell shall be such that
the lower 10 percent of the manufacturer's rated capacity will not be used in determining the jacking
stress. When approved by the Engineer, calibrated proving rings may be used in lieu of load cells.

Recalibration of gauges shall be repeated at least annually and whenever gauge pressures and
elongations indicate materially different stresses.

22.8.2.1

Cutting

Only oxygen flame or mechanical cutting devices shall be used to cut wire, strands, or bars after
installation in the member or after stressing. All cutting shall be carried out using either of the
following:

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a. A high-speed abrasive cutting wheel or friction saw at not less than 1 diameter from the

anchor, or any other mechanical method approved by the Engineer.

b. An oxy-acetylene cutting flame, using excess oxygen to ensure a cutting rather than a melting

action, not less than 75 mm from the anchor. Temperatures of the tendon adjacent to the
anchor shall not be greater than 200 degrees Celsius. Care shall be taken that neither the
flame nor splashes come into contact with the anchorages or tendons.

Electric arc welders shall not be used.

22.8.2.2

Sequence of Stressing

When the sequence of stressing individual tendons is not specified in the Contract documents, or in
the approved working drawings, the stressing of post-tensioning tendons and the release of
pretensioned tendons shall be done in a sequence that produces a minimum of eccentric force in
the member.

22.8.2.3

Measurement of Stress

A record of gauge pressures and tendon elongations for each tendon shall be provided by the
Contractor for review and approval by the Engineer. Elongations shall be measured to an accuracy
of 1.5 mm. The corresponding wobble and friction coefficients of ducts shall be calculated
accordingly to verify the assumed coefficients used in the design. Stressing tails of post-tensioned
tendons shall not be cut until the stressing records and elongation calculation have been approved.
A facility to measure any movement of the tendon in the gripping devices shall also be provided.

Stresses in the tendons during tensioning shall be determined by the gage or load-cell readings and
shall be verified with the measured elongations. Calculations of anticipated elongations shall utilise
the modulus of elasticity, based on nominal area, as furnished by the manufacturer for the lot of steel
being tensioned, or as determined by a bench test of strands used in the work.

All tendons shall be tensioned to a preliminary force, as necessary, to eliminate any take-up in the
tensioning system before elongation readings are started. This preliminary force shall be between 5
percent and 25 percent of the final jacking force. The initial force shall be measured by a
dynamometer, or by other approved method, so that its amount can be used as a check against
elongation

— as computed and as measured. Each strand shall be marked prior to final stressing to

permit measurement of elongation and to ensure that all anchor wedges set properly.

It is anticipated that there may be discrepancy in indicated stress between jack gage pressure and
elongation. In such event, the load used, as indicated by the gage pressure, shall produce a slight
overstress rather than understress. When a discrepancy between gage pressure and elongation of
more than 5 percent in tendons more than 15 m long or 7 percent in tendons of 15 m or less in length
occurs,  the  entire  operation  shall  be  carefully  checked  and  the  source  of  error  determined  and
corrected  before  proceeding  further.  When  provisional  ducts  are  provided  for  the  addition  of
prestressing  force  in  event  of  an  apparent  force  deficiency  in  tendons  more  than  15  m  long,  the
discrepancy between the force indicated by gage pressure and elongation may be increased to  7
percent before investigation into the source of the error.

22.8.3

Pretensioned Members

Pretensioned members of concrete structures shall comply with the requirements and specifications
outlined in this section.

22.8.3.1

Pre-tensioning Requirements

Stressing shall be accomplished by multiple-strand stressing method subject to approval by the
Engineer. Tensioning of an individual strand is not permitted unless approved by the Engineer. Pre-

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tensioning shall comply with PCI MNL-116 requirements. The amount of stress to be given to the
strands shall be as shown in the Contract documents or in the approved working drawings.

All strands to be stressed in a group (multiple-strand stressing) shall be brought to a uniform initial
tension prior to a full pre-tensioning. The amount of the initial tensioning force shall be within the
range specified in Article 22.8.2.3, Measurement of Stress, and shall be the minimum required to
eliminate all slack and to equalise the stresses in the tendons as determined by the Engineer. The
amount of this force will be influenced by the length of the casting bed and the size and number of
tendons in the group to be tensioned.

When straight tendons are used in the long-line method of pre-tensioning, sufficient locator plates
shall be distributed throughout the length of the bed to ensure that the wires or strands are
maintained in their proper position during concreting. Where a number of units are made in line, they
shall be free to slide in the direction of their length and thus permit transfer of the prestressing force
to the concrete along the whole line.

In the individual mould system, the moulds shall be sufficiently rigid to provide the reaction to the
prestressing force without distortion.

Draped pretension tendons shall either be tensioned partially by jacking at the end of the bed and
partially by uplifting or depressing tendons, or they shall be tensioned entirely by jacking, with the
tendons being held in their draped positions by means of rollers, pins, or other approved methods
during the jacking operation.

Approved low-friction devices shall be used at all points of change in slope of tendon trajectory when
tensioning draped pretension strands, regardless of the tensioning method used. For single tendons
the deflector in contact with the tendon shall have a radius of not less than five times the tendon
diameter for wire or 10 times the tendon diameter for strand, and the total angle of deflection shall
not exceed 15 degrees.

If the load for a draped strand, as determined by elongation measurements, is more than 5 percent
less than that indicated by the jack gages, the strand shall be tensioned from both ends of the bed,
and the load as computed from the sum of elongation at both ends shall agree within 5 percent of
that indicated by the jack gages.

When ordered by the Engineer, prestressing steel strands in pretension members, if tensioned
individually, shall be checked by the Contractor for loss of prestress not more than three hours prior
to placing member concrete. Methods and equipment for checking the loss of prestress shall be
subject to approval by the Engineer. All strands that show a loss of prestress in excess of 3 percent
shall be retensioned to the original computed jacking stress.

Stress on all strands, including hold-down and hold-up forces shall be maintained between
anchorages until the concrete has reached the compressive strength required at the time for the
transfer of stress to concrete, which shall take place slowly to minimize shock.

When  prestressing  steel  in  pretensioned  members  is  tensioned  at  a  temperature  more  than  14
degrees Celsius lower than the estimated temperature of the concrete and the prestressing steel at
the  time  of  initial  set  of  the  concrete,  the  calculated  elongation  of  the  prestressing  steel  shall  be
increased to compensate for the loss in stress due to the change in temperature, but in no case shall
the  jacking  stress  exceed  80  percent  of  the  specified  minimum  ultimate  tensile  strength  of  the
prestressing steel.

Strand splicing methods and devices shall be approved by the Engineer. When single-strand jacking
is used, only one splice per strand will be permitted. When multi-strand jacking is used, either all
strands shall be spliced or no more than 10 percent of the strands shall be spliced. When more than
a strand are spliced, the splice location should be staggered. Spliced strands shall be similar in
physical properties, from the same source, and shall have the same twist or lay. All splices shall be
located outside of the prestressed units.

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Side and flange forms that restrain deflection shall be removed before release of pre-tensioning
reinforcement.

Except when otherwise shown in the Contract documents, all pretensioned prestressing strands shall
be cut flush to the end of the member and the exposed ends of the strand. A 25-mm strip of the
adjoining concrete shall be cleaned and painted. Cleaning shall be by wire brushing or abrasive blast
cleaning to remove all dirt and residue that is not firmly bonded to the metal or concrete surfaces,
which shall be coated with one thick coat of zinc-rich paint conforming to the requirements of U.S.
Military Specification MIL-P-24441/20. Paints shall be thoroughly mixed at the time of application,
and shall be worked into any voids in the strands.

22.8.3.2

Placement of Prestressing Steel

Prestressing steel that resides in a stressing bed shall be protected from corrosion if the stressing
bed is to be exposed to weather for more than 36 hours before encasement in concrete.

Anchor  plates  and  anchorages  shall  be  accurately  located  and  securely fastened to  the forms  or
held in place by approved methods; they shall  be of such nature that strands will not kink, break
down, or be otherwise damaged; and such anchorages shall ensure proper distribution of the load
to  the  concrete-bearing  surfaces  between  anchorages.  Concrete  shall  be  perpendicular  and
concentric with the strands and the line of action of the pre-tensioning. Moulding lengths, as indicated
in the approved shop drawings, shall be verified and recorded for each strand after anchorages are
met. Anchorage devices shall hold the pre-tensioning steel without slip of more than 3 mm at a load
equal to the applied load of the strands at pre-tensioning. If grip type anchorages are used, provisions
shall be made for observation of possible slip. Strands shall be allowed to extend beyond anchorages
at an amount sufficient to permit retensioning before placement of concrete.

Strands shall be carefully handled when removed from storage, uncoiled, placed, and protected from
damage or the intrusion of foreign material.

All strands shall be tensioned according to Article 22.8.3.1. Strands shall not be allowed to unwind
more than one turn. Jacking force records and elongation measurements shall be kept after the
strands are tensioned to 20 percent of final jacking force.

Prestressing steel shall be tensioned to the required stress. Elongation computations shall include
strand anchorage slippage, splice slippage, in place horizontal movement of the structural member
during prestressing operations, and prestressing steel temperature changes between the time of
tensioning and the time when the concrete takes its initial set. All computations must be prepared by
a Professional Engineer.

Prestress bed forms, strands, and reinforcement bar temperatures shall be maintained by the
Contractor within 15 degrees Celsius of the temperature of the concrete to be placed in the forms.
Strands shall be supported with rollers at points of direction change when strands are tensioned in
a draped position. Free-running rollers with minimal friction shall be used. Initially, when strands are
tensioned and then pulled into the draped position, the Contractor shall tension to no more than the
required tension minus the increased tension due to forcing the strand to a draped profile. If the load
in a draped strand at the dead end, as determined by elongation measurements, is less than 95
percent of the jack load, the strand shall be tensioned from both ends of the bed. The load shall be
made, as computed from the sum of elongations produced by jacking at both ends, agree within 5
percent of the jack load.

Within three hours before placing concrete, the tension on the prestressing strands shall be checked.
The method and equipment for checking the loss of prestress shall be subject to approval by the
Engineer. If strands are tensioned individually, each strand shall be checked for loss of prestress.
Strands that show a loss of prestress in excess of 3 percent shall be retensioned by the Contractor
to the original computed jacking stress. If strands are tensioned in a group, the entire group for total
loss of prestress shall be checked. If the total prestress shows a loss in excess of 3 percent, or if any

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individual stand appears significantly different from the rest of the strands in a group, the Contractor
shall release and retension the entire group.

22.8.3.3

Releasing of Prestressing Steel

Transferring of prestressing force from the strands to the concrete shall be performed simultaneously
and in a controlled manner, as approved by the Engineer. Releasing the force by cutting individual
prestressing strands shall not be permitted. No bond stress shall be transferred to the concrete, nor
shall end anchors be released, until the concrete has attained a compressive strength as indicated
by standard cubes made and cured identically with the members, of at least the minimum strength
indicated in the approved shop drawings or in the specifications for such transfer of load. Elements
shall be cut or released in such an order that lateral eccentricity of prestress will be a minimum.

In cases where several beams cast in one continuous line and stressed at one time, elements shall
be cut or released in such an order that lateral eccentricity of prestress will be a minimum.

22.8.4

Post-tensioned Members

Post-tensioned members of concrete structures shall comply with the requirements and
specifications outlined in this section.

22.8.4.1

Post-tensioning Requirements

Prior to post-tensioning any member, the Contractor shall demonstrate to the satisfaction of the
Engineer that the prestressing steel is free and unbonded in the duct.

All strands in each tendon, except for those in flat ducts with not more than four strands, shall be
stressed simultaneously with a multi-strand jack. Tensioning shall be accomplished so as to provide
the forces and elongations specified in Article 22.8.5.1, Pre-tensioning tendons.

Except as provided herein, or when specified in the Contract documents, or in the approved working
drawings, tendons in continuous post-tensioned members shall be tensioned by jacking at each end
of the tendon. For straight tendons, and when one end stressing is shown in the Contract documents,
tensioning may be performed by jacking from one end or both ends of the tendon at the option of the
Contractor.

Deflectors in contact with tendons shall have a radius of not less than 50 times the diameter of the
tendon, and the total angle of deflection shall not exceed 15 degrees unless otherwise agreed by
the Engineer.

Stressing shall continue until the required extension and tendon load are reached or are approved
by the Engineer.

After the tendons have been anchored, the force exerted by the jack shall be decreased gradually
and steadily so as to avoid shock to the tendon or the anchorage. Full records shall be kept of all
tensioning operations, including the measured extensions, pressure gauge, or load-cell readings;
and the amount of anchors set at each anchorage. Copies of these records shall be supplied to the
Engineer within 24 hours of each tensioning operation.

Unless otherwise agreed by the Engineer, tendons shall not be cut less than three days after
grouting.

22.8.4.2

Placement of Ducts

Internal and external surfaces of ducts shall be clean and sound at the time of incorporation in the
work.

Ducts shall be rigidly supported at the proper locations in the forms by ties to reinforcing steel, which
are adequate to prevent displacement during concrete placement. Supplementary support bars

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epoxy coated shall be used, where needed, to maintain proper alignment of the duct. Hold-down ties
shall be used when the buoyancy of the ducts in the fluid concrete will lift the reinforcing steel.

Polyethylene duct and metal duct for longitudinal or transverse post-tensioning in the flanges shall
be supported at intervals not to exceed 600 mm. Polyethylene duct in webs for longitudinal post-
tensioning shall be tied to stirrups at interval not to exceed 600 mm and metal duct for longitudinal
post-tensioning in webs shall be tied to stirrups at interval not to exceed 1.2 metres.

Joints between sections of duct shall be coupled with positive connections that do not result in angle
changes at the joints and will prevent the intrusion of cement paste.

After placing that ducts and reinforcement and forming is complete, an inspection shall be made to
locate possible duct damage.

All unintentional holes or openings in the duct must be repaired prior to concrete placing.

Grout openings and vents must be securely anchored to the duct and to either the forms or to
reinforcing steel to prevent displacement during concrete placing operations.

After installation in the forms, the ends of ducts shall be at all times covered, as necessary, to prevent
the entry of water or debris.

During concrete placement for precast segments, mandrels shall be used as stiffeners in each duct
and shall extend throughout the length of the segment being cast and at least 0.6 m into the
corresponding duct of the previously cast segment. The mandrels shall be of sufficient rigidity to
maintain the duct geometry within the tolerances shown in Table 22-6.

Table 22-6: Duct position tolerances

Tolerances

Vertical position
(mm)

Lateral position
(mm)

Horizontal tendons in slabs or in slab regions of
larger members

±6

±12

Longitudinal draped superstructure tendons in
webs

Tendon over supports or in middle third of span

±6

Tendon in middle-half of web depth

±12

±6

Longitudinal, generally horizontal superstructure

Tendons usually in top or bottom of member

±6

Horizontal tendons in substructures and
foundations

±12

Longitudinal Position
(mm)

Transverse Position
(mm)

Vertical tendons in webs

±6

Vertical tendons in pier shafts

±6

Additionally, the following shall apply:

•

In all other cases, locate tendons within ±6 mm in any direction.

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•

Entrance and exit angles of tendon paths at anchorages or at faces of concrete shall be within

±3 degrees of desired angle measured in any direction and any deviations in the alignment
are accomplished with smooth transitions without any kinks.

•

Angle changes at duct joints shall not be greater than ±3 degrees in any direction and must

be accomplished with smooth transitions without any kinks.

•

Locate anchorages within ±6 mm of desired position laterally and ±25 mm along the tendon

except that minimum cover requirements shall be maintained.

•

Position anchorage confinement reinforcement in the form of spirals, multiple V-shaped bars,

or links, to be properly centred on the duct and to start within 12 mm of the back of the main
anchor plate.

•

If conflicts exist between the reinforcement and post-tensioning duct, position the post-

tensioning duct and adjust the reinforcement locally with the Engineer's approval.

Duct Inlets and Outlets

All ducts for continuous structures shall be supplied with outlets at the high and low points of the
duct profile, except where the profile changes are small, as in continuous slabs, and at additional
locations, as specified the Contract documents. Low-point outlets shall remain open until grouting is
started.

Proving of Post-tensioning Ducts

Upon completion of concrete placement, the Contractor shall prove that post-tensioning ducts are
free and clear of any objections or damage and can accept the intended post-tensioning tendons by
passing a torpedo through the duct. The torpedo shall have the same cross-sectional shape as the
duct, and 6 mm smaller than the clear nominal inside dimensions of the duct. No deductions shall
be made to the torpedo section dimensions for tolerances allowed in the manufacture or fixing of the
ducts. For straight ducts, a torpedo at least 0.6 m long shall be used. For curved ducts, the length
shall be determined so that when both ends touch the outermost wall of the duct, the torpedo is 6
mm clear of the innermost wall. If the torpedo will not travel completely through the duct, the Engineer
shall reject the member, unless through workable repairs the torpedo shall pass through the duct
easily, by hand, and without resorting to excessive effort or mechanical assistance.

Duct Pressure Field Test

Before stressing and grouting internal or external tendons, the Contractor shall install all grout caps,
inlets, and outlets and test the duct with compressed air to determine if duct connections require
repair. In the presence of the Engineer, the duct shall be pressurized to 345 kPa and the outside air
source shall be locked off. Pressure loss shall be recorded for one minute. A pressure loss of 170
kPa is acceptable for ducts that are 45 metres or shorter and a pressure loss of 100 kPa is acceptable
for ducts that are longer than 45 metres. If the pressure losses exceed allowable thresholds, the
Contractor shall repair leaking connections using methods approved by the Engineer and then test
duct pressure again.

22.8.4.3

Placement of Concrete

Where the end of a post-tensioned assembly will not be covered by concrete, the Contractor shall
recess the anchoring devices so that the ends of the prestressing steel and all parts of the anchoring
devices are at least 51 mm inside the end surface of the members.

Before  placing  concrete,  the  Contractor  shall  demonstrate  that  all  ducts  are  unobstructed.
Immediately after concrete placement, the Contractor shall blow out the conduit with compressed,
oil-free  air  to  break-up  and  remove  all  mortar  in  the  conduit  before  it  hardens.  Approximately  24
hours  after  the  concrete  placement,  the  Contractor  shall  flush  the  conduits  with  water  that  may

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contain lime or calcium oxide, or slaked lime or calcium hydroxide, in the amount of 12 gm per liter.
Water shall be blown out with compressed, oil-free air.

For post-tensioned members that are to be steam cured, the Contractor shall not install prestressing
steel until curing is complete.

22.8.4.4

Placement of Post-tensioning Steel

Unless otherwise directed by the Engineer, prestressing steel installed in members prior to placing
and curing of the concrete, is not acceptable.

When accepted by the Engineer, all prestressing steel preassembled in ducts and installed prior to
the placement of concrete shall be accurately placed and held in position during concrete placement.
Locations and support of each tendon shall be within a tolerance of ±6 cm. Tendons shall be securely
tied in place or supported to prevent their dislocation during the concreting operation.

When the prestressing steel is installed after the concrete has been placed, the Contractor shall
demonstrate to the satisfaction of the Engineer that the ducts are free of water and debris
immediately prior to installation of the steel. At this point, the total number of strands in an individual
tendon may be pulled into the duct as a unit, or individual strands may be pulled or pushed through
the duct.

Anchorage devices or block-out templates for anchorages shall be set and held so that their axis
coincides with the axis of the tendon and anchor plates are normal in all directions to the tendon.

Prestressing steel shall be distributed so that the force in each girder stem is equal or as required
by the Contract plans, except as provided herein. For box girders with more than two girder stems,
at the Contractor's option, the prestressing force may vary up to 5 percent from the theoretical
required force per girder stem provided the required total force in the superstructure is obtained and
the force is distributed symmetrically about the centre line of the typical section.

Protection of Steel After Installation

When prestressing steel, used in post-tensioned concrete members, is installed prior to placing and
curing of the concrete and is not grouted within the time limit specified below, a corrosion inhibitor
placed in the ducts or directly applied to the steel may only be used when directed by the Engineer
to continuously protect the prestressing steel against rust or other corrosion until grouted or encased
in concrete. Otherwise, removal, replacement and reinstallation of strands may be required at the
direction of the Engineer.

Prestressing steel installed and tensioned in members after placing and curing of the concrete and
grouted within the time limit specified below will not require a corrosion inhibitor, as described herein.
Rust that may form during the interval between tendon installation and grouting will not be cause for
rejection of the steel.

Permissible intervals between tendon installation and grouting without use of a corrosion inhibitor for
various exposure conditions shall be as follows:

•

Very damp atmosphere or over saltwater (Humidity >70 percent): 7 days

•

Moderate atmosphere (Humidity from 40 percent to 70 percent): 15 days

•

Very dry atmosphere (Humidity <40 percent): 20 days

After tendons are placed in ducts, the openings at the ends of the ducts shall be sealed to prevent
entry of moisture.

When steam curing is used, steel for post-tensioning shall not be installed until the steam curing is
completed.

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Such tendons shall be protected against corrosion by means of a corrosion inhibitor placed in the
ducts or on the steel, or shall be stressed and grouted within seven days after steam curing.

Whenever electric welding is performed on or near members containing prestressing steel, the
welding ground shall be attached directly to the steel being welded. All prestressing steel and
hardware shall be protected from weld spatter or other damage.

Protection of Tendons

Within four hours after stressing and prior to grouting, tendons shall be protected against corrosion
or harmful effects of debris by temporarily plugging or sealing all openings and vents; cleaning rust
and other debris from all metal surfaces that will be covered by the grout cap; and placing the grout
cap, including a seal, over the wedge plate until the tendon is grouted.

22.8.4.5

Placement of Anchorage

Proper  placement  of  all  materials  shall  be  the  responsibility  of  the  Contractor,  according  to  the
Contract documents, and the requirements stipulated by the anchorage device supplier. Due care
and  attention  shall  be  exercised  by  the  Contractor  in  the  placement  of  anchorage  hardware,
reinforcement, concrete, and consolidation of concrete in anchorage zones. Modifications to the local
zone  details,  verified  under  provisions  of  Article  5.10.9.7.3  of  the  AASHTO  LRFD  Bridge  Design
Specifications  and  Sub-article  c,  Special  Anchorage  Device  Acceptance  Test,  of  Article  22.7.1.3,
shall  be  approved  by  both  the

Contractor’s supervisor and the technical representative of the

approved post-tensioning system.

22.8.4.6

Record of Stressing Operation

A record of the following post-tensioning operations shall be kept for each tendon installed:

•

The Project name and number

•

The Contractor and/or subcontractor

•

Tendon location, size, and type

•

Date tendon was first installed in ducts

•

Coil or reel number for strands or wires and heat number for bars and wire

•

Assumed and actual cross-sectional area

•

Assumed and actual modulus of elasticity

•

Date stressed

•

Jack and gage numbers per end of tendon

•

Required jacking force

•

Gage pressures

•

Elongations, anticipated and actual

•

Anchor sets, anticipated and actual

•

Stressing sequence, including tendons before and after this tendon

•

Stressing mode, such as one end, two ends, simultaneous

•

Witnesses to stressing operation, the Contractor and inspector

•

Date grouted, days from stressing to grouting, grouting pressure applied, and injection end

•

Record any other relevant information, including pour back and bitumastic installation dates

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A complete copy of all stressing operations, and the jack calibration forms, shall be provided to the
Engineer.

22.8.5

Identification and Testing

All wire, strand, or bars shipped to the site shall be assigned a lot number and tagged for identification
purposes. Anchorage assemblies shall be likewise identified. Each cable shall be tagged with its
number from which the coil numbers of the steel used can be identified.

Cables shall not be kinked or twisted. Individual wires and strands for which extensions are to be
measured shall be readily identifiable at each end of the member. No strand that has come
unravelled shall be used.

Each lot of wire or bars and each reel of strand reinforcement shall be accompanied by a
manufacturer's certificate of compliance, a mill certificate, and a test report. The mill certificate and
test report shall include the following:

•

Chemical composition, not required for strands

•

Cross-sectional area

•

Yield and ultimate strengths

•

Elongation at rupture

•

Modulus of elasticity

•

Stress strain curve for the actual prestressing steel intended for use

All values certified shall be based on test values and nominal sectional areas of the material being
certified.

Samples described in the following subsections selected from each lot shall be furnished by the
Contractor to the Engineer for verification testing. Selection of samples shall be made at the
manufacturer’s plant by the inspector, if ordered by the Engineer.

All samples submitted to the Engineer shall be accompanied by a certification from the supplier or
subcontractor certifying that the samples were taken from, and are representative of, the lot of reels
to be furnished. In the case of wire or strand, samples shall be taken from the same master roll.

Actual strengths of the prestressing steel shall not be less than specified by the applicable ASTM or
British standard, and shall be determined by tests of representative samples of the tendon material
in conformance with ASTM or British standards.

If it is proposed to use super strand complying with BS 5896: 2012 Table 6 or other than the lowest
strength 3, 4, 5, 6 or 7mm diameter wires complying with BS 5896: 2012 Tables 4 and 5, reels will
only be accepted if both the breaking load and the 0.1% proof load of the sample exceeds the
specified characteristic loads given in the above Tables 4 or 6. In the case of Table 5 this requirement
shall apply to the breaking load and the load at 1% elongation.

The Contractor shall employ the services of an independent testing laboratory to design the concrete
mixes and test the cement and aggregates, concrete, reinforcing steel, pre-stressing steel, and such
other materials as directed by the Engineer. All of the materials specified for testing shall be furnished
free of cost and shall be delivered in time for tests to be made well in advance of anticipated time of
use.

22.8.5.1

Pre-tensioning Strands

For each certificate furnished for pretensioned strands, one sample at least 5 m long near ends of
fittings shall be furnished in accordance with the requirements of paragraph 9.1 of AASHTO M
203M/M 203-12 (ASTM A416/ A416M - 12).

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22.8.5.2

Post-tensioning Tendons

The following lengths shall be furnished for each 10,000 kg, or portion thereof, lot of material used
in the work:

•

For wires not requiring heading-sufficient length to make up one parallel-lay cable, 1.5 m long

consisting of the same number of wires as the cable to be furnished.

•

For strands to be furnished with fittings, 1.5 m between near ends of fittings.

•

For bars to be furnished with threaded ends and nuts, 1.5 m between threads at ends.

22.8.5.3

Anchorage Assemblies and Couplers

One specimen of each size of the prestressing tendon, including couplings, at the selected type, with
end fittings and anchorage assembly attached, shall be furnished by the Contractor for strength tests
only. These specimens shall be 1.5 m in clear length, measured between ends of fittings. If the
results of the test indicate the necessity of check tests, additional specimens shall be furnished
without cost.

When dynamic testing is required, the Contractor shall perform the testing and shall furnish certified
copies of test results that indicate conformance with the specified requirements prior to installation
of anchorages or couplers. Costs of such testing shall be borne by the Contractor.

For prestressing systems previously tested and approved on projects having the same tendon
configuration, the Engineer may not require complete tendon samples, provided there is no change
in the material, design, or details previously approved. Shop drawings or prestressing details shall
identify the Project on which approval was obtained; otherwise testing shall be conducted.

22.8.6

Protection of Prestressing Steel

All prestressing steel shall be protected against physical damage and rust or other results of
corrosion at all times from manufacture to grouting. Prestressing steel shall also be free of
deleterious material, such as grease, oil, wax, or paint. Prestressing steel that has sustained physical
damage at any time shall be rejected. Development of pitting or other results of corrosion, other than
rust stain, shall be cause for rejection.

Prestressing steel shall be stored clear of the ground and be protected from the weather, from
splashes from any other materials, and from splashes from the cutting operation of an oxyacetylene
torch or arc welding activity. In no circumstances shall prestressing steel, after manufacture, be
subjected to any welding operation, or heat treatment or metallic coating, such as galvanising. This
does not preclude cutting as described in Article 22.8.2.1.

Prestressing steel shall be packaged in containers or shipping forms for the protection of the strand
against  physical  damage  and  corrosion  during  shipping  and  storage.  A  corrosion  inhibitor  that
prevents  rust  or  other  results  of  corrosion  shall  be  placed  in  the  package  or  form,  or  shall  be
incorporated  in  a  corrosion  inhibitor  carrier  type  packaging  material.  When  permitted  by  the
Engineer, a corrosion inhibitor  may  also be applied directly to the steel. Corrosion inhibitors shall
have  no  deleterious  effect  on  the  steel,  concrete,  or  bond  strength  of  steel  to  concrete  or  grout.
Packaging  or  forms  damaged  from  any  cause  shall  be  immediately  replaced  or  restored  to  their
original condition.

Shipping packages or forms shall be clearly marked with a statement that the package contains high-
strength prestressing steel, and the type of corrosion inhibitor used, including the date packaged.

All pre- or post-tensioning steel shall be satisfactorily stored and protected from excessive rust or
other corrosion prior to placing. Such steel shall be free from deleterious substances when placed.
Ample protection shall also be provided for all exposed steel at the ends of prestressed concrete
bridge members to prevent deterioration by rust and corrosion.

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All anchorages, end fittings, couplers, and exposed tendons, which will not be encased in concrete
or grout in the completed work, shall be permanently protected against corrosion.

22.8.7

Corrosion Inhibitor

Corrosion inhibitors shall consist of a vapour-phase inhibitor (VPI) powder conforming to the
provision of Federal Specification MIL-P-3420F-87 or as otherwise approved by the Engineer.

Corrosion inhibitors shall only be used at the direction of the Engineer. When approved, water-
soluble oil may be used on prestressing steel as a corrosion inhibitor.

22.8.8

Grouting

The  Contractor  shall  undertake  grout  trials  in  accordance  with  the  details  described  in  Article
22.8.8.11.  The  trials  are  required  to  demonstrate  that  the  grouting  methods  and  procedures
proposed  by  the  Contractor  will  ensure  that  grout  completely  fills  the  ducts  and  surrounds  the
prestressing steel.

The Contractor shall submit at least 4 weeks before on-site trials a detailed method statement or
grouting operation plan covering proposed materials, duct, anchorage and vent arrangements,
personnel, equipment grouting procedures and quality control for the approval of the Engineer.

When the post-tensioning method is used, the prestressing steel shall be provided with permanent
protection and shall be bonded to the concrete by completely filling the void space between the duct
and the tendon with grout. Grout should be injected from low points pumping toward the high-point
vent. For segmental, span-by-span construction, grout shall be injected through a grout inlet at mid-
span.

All grouting operations shall be carried out by experienced superintendents and foremen that have
received instructional training and have at least three years of experience on previous projects
involving grouting of similar type and magnitude.

A grouting operation plan shall be submitted for approval at least 45 days in advance of any
scheduled grouting operations. Written approval of the grouting operation plan by the Engineer shall
be required before any grouting of the permanent tendons in the structure takes place.

Tendons shall be grouted at not less than eight hours to 12 hours, but within the number of days
specified in Article 22.8.4.4 after tendon installation. The tendons shall be protected against
corrosion by a plug at each end to prevent the passage of air, and such plugs shall be left in place
until the tendon is grouted.

At a minimum, the following items shall be provided in the grouting operation plan:

1. Provide names, and proof of training and experience records for the grouting crew and the

crew supervisor in conformance with this specification

2. Type, quantity, and brand of materials used in grouting including all required certifications

3. Type of equipment furnished, including capacity in relation to demand and working condition,

as well as back-up equipment and spare parts

4. General grouting procedure

5. Duct pressure test and repair procedures

6. Method to be used to control the rate of flow within ducts

7. Theoretical grout volume calculations

8. Mixing and pumping procedures

9. Direction of grouting

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10. Sequence of use of the inlets and outlet pipes

11. Procedures for handling blockages

12. Procedures for possible post grouting repair

13. Grout trials

Before grouting operations begin, a joint meeting of the Contractor, grouting crew, and the Engineer
shall be conducted. At the meeting, the grouting operation plan, required testing, corrective
procedures, and any other relevant issues shall be discussed.

22.8.8.1

Preparation of Ducts

Each duct shall be air-pressure tested prior to the installation of the prestressing steel into the ducts.
If leaks are indicated during the test, the duct shall be repaired to eliminate the leakage or minimize
the consequences of the leakage.

All ducts shall be clean and free of deleterious materials that would impair bonding or interfere with
grouting procedures.

Ducts with concrete walls, or cored ducts, shall be flushed to ensure that the concrete is thoroughly
wetted. Metal ducts shall be flushed, if necessary, to remove deleterious material.

Water used for flushing ducts may contain slack lime or calcium hydroxide, or quicklime (or calcium
oxide, in the amount of 0.012 kg/L.

After flushing, all water shall be blown out of the duct with oil-free compressed air.

22.8.8.2

Equipment

Grouting  equipment  shall  include  a  high-speed  shear  mixer  capable  of  continuous  mechanical
mixing,  which  will  produce  a  grout  free  of  lumps  and  undispersed  cement;  a  storage  reservoir;  a
grout pump with all the necessary connection hoses, valves, measuring devices for water, cement
and  admixtures  and  testing  equipment;  and  stand-by  flushing  equipment  with  water  supply.  The
equipment shall pump the mixed grout in a manner that will comply with all requirements.

Accessory equipment that will provide for accurate solid and liquid measures shall be provided to
batch all materials.

The mixing equipment shall be capable of producing a grout of homogeneous consistency and shall
be capable of providing a continuous supply to the injection equipment.

The capacity of the equipment shall be such that the duct can be filled and vented without interruption
and at the required rate of injection.

The injection equipment shall be capable of continuous operation with little variation of pressure and
shall include a system for recirculating the grout while actual grouting is not in progress.

The equipment shall have a constant delivery pressure of less than 1 MPa, it shall be equipped with
a pressure gauge and shall prevent pressures above 2 MPa. The pressure gage shall be placed at
some point in the grout line between the pump outlet and the duct inlet. Pumps shall have seals
adequate to prevent introduction of oil, air, or other foreign substance into the grout, and to prevent
loss of grout or water. All piping to the grout pump shall have a minimum number of bends, valves
and changes in diameter and shall incorporate a sampling Tee with stop cock.

The equipment shall be capable of maintaining pressure on completely grouted ducts and shall be
fitted with a valve that can be locked off without loss of pressure in the duct.

Grouting equipment shall contain a screen having clear openings of 3.35 mm maximum size to filter
the grout prior to its introduction into the grout pump. If a grout with a thixotropic additive is used, a

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screen opening of 4.75 mm is satisfactory. This screen shall be easily accessible for inspection and
cleaning.

Grouting equipment shall utilise gravity feed to the pump inlet from a hopper attached to and directly
over it. Hoppers must be kept at least partially full of grout at all times during the pumping operation
to prevent air from being drawn into the post-tensioning duct.

Under normal conditions, the grouting equipment shall be capable of continuously grouting the
largest tendon on the Project in no more than 20 min.

During the grouting operation, the Contractor shall provide adequate flushing-out plant to facilitate
complete removal of the grout in the event of a breakdown of the grouting equipment or other
disruption before the grouting operation has been completed and shall demonstrate that this
equipment is in full working order.

All equipment shall be kept free from build-up of adhering materials by washing as required.

22.8.8.3

Batching and Mixing of Grout

All materials shall be batched by weight except the mixing water and liquid admixtures which may
be batched by weight or volume. The accuracy of batching shall be:

•

± 2% for cement and admixtures

•

± 1% for mixing water

of the quantities specified. The mixing water shall include the water content of liquid admixtures.

Depending upon environmental or materials influence (e.g. temperature, configuration of the tendon
and properties of the cement used), the water/cement ratio shall be kept as low as possible having
regard to the required plastic properties of the grout.

The maximum w/c ratio shall be 0.40. The material shall be mixed to produce a homogeneous grout
and kept in slow continuous agitation until pumped into the duct. Water shall be added to the mixer
first, followed by the cement and admixtures. The batch quantities of cement and admixture may be
added as a whole or in part in sequence until the total quantities are added. The minimum mixing
time determined from grouting trials shall be adhered to.

The temperature of freshly mixed grout shall be between 5°C and 25°C.

Grout shall be mixed in accordance with the manufacturer's instructions using a colloidal mixer to
obtain homogeneous mixture. A fluidity test shall be performed on the mixed grout prior to beginning
the injection process. Target flow rates, as a function of mixer type used and ambient temperatures,
shall be obtained from the grout manufacturer. The grouting process shall not be started until the
proper grout properties have been obtained.

Mixing shall be of such duration as to obtain a uniform, thoroughly blended grout, without excessive
temperature increase or loss of expansive properties of the admixture. Grout shall be continuously
agitated until it is pumped.

Water shall not be added to increase grout flow, which has been decreased by delayed use of the
grout.

22.8.8.4

Injection of Grout

Grouting operations shall be carried out by operatives with appropriate knowledge, training and
proven experience in carrying out similar operations and certified under an approved scheme.

A check shall be made to ensure the ducts, vents, inlets and outlets are capable of accepting injection
of the grout. This shall be done by blowing through the system with dry, oil-free air and proving each
vent in turn.

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Where there is water in the duct, it shall be removed through outlets at the lowest points. Dry, oil-
free compressed air may be used for this purpose.

Grouting of the ducts shall be carried out as soon as is practicable after the tendons in the ducts
have been stressed and the Engineer's written agreement to commence has been obtained. All grout
vents shall be opened before grouting starts. Injection and ejection vents with positive shut-offs shall
be provided. Grout shall be allowed to flow from the first injection vent until any residual flushing
water or entrapped air has been removed prior to closing that vent. Remaining vents shall be closed
in sequence in the same manner. Injection shall be continuous, and it shall be slow enough to avoid
producing segregation of the grout. Unless otherwise agreed by the Engineer, grout injection shall
be at the rate of between 10 and 15 metres of duct per minute as per CEB-FIP Model Code1990.

Pumping pressure at the injection vent should not exceed 1 MPa. Normal operations shall be
performed at approximately 0.5 MPa. If the actual grouting pressure exceeds the maximum allowed,
the injection vent shall be closed and the grout shall be injected at the next vent that has been, or is
ready to be, closed; as long as a one-way flow is maintained. Grout shall not be injected into a
succeeding vent from which grout has not yet flowed.

The method of injecting grout shall ensure complete filling of the ducts and complete surrounding of
the  steel.  Grout  shall  be  allowed  to  flow  from  each  vent  and  the  free  end  of  the  duct  until  its
consistency is equivalent to that of the grout injected and no visible slugs of water or air are ejected.
Following  this,  a  further  5  litres  at  each  vent  shall  be  vented  into  a  clean  receptacle,  tested  in
accordance with Article 22.8.8.12 and then discarded. The opening shall be firmly closed. All vents
shall  be  closed  in  a  similar  manner  one  after  another  in  the  direction  of  the  flow  except  that  at
intermediate crests the vents 400mm downstream shall be closed before their associated crest vent.

The injection tubes shall then be sealed off under pressure. A pressure of 0.5 MPa shall be
maintained for at least one minute.

Grout vents at high points shall be reopened 10 minutes after completion of grouting and any escape
of air, water or grout recorded and reported immediately to the Engineer. A further pumping of grout
may be required at this stage to expel bleed water and/or entrapped air. This shall be carried out
with only the high points open one at a time sequentially in the direction of grouting.

The filled ducts shall not be subjected to shock or vibration within 24 hours of grouting.

Not less than 48 hours after grouting, the level of grout in the injection and the vent tubes shall be
inspected, all defective grout shall be removed from the vent and the level topped up as necessary
with freshly mixed grout.

Not less than 48 hours after grouting, the end caps at anchorages shall be removed and a
photographic record taken, clearly identified.

If, in the opinion of the Engineer, there is cause for doubt that the ducts are completely filled with
grout, the Engineer may require non-destructive testing to be carried out.

The Contractor shall keep full records of grouting for each duct including the date each duct was
grouted,  the  proportion  of  the  grout  and  any  admixtures  used,  the  pressure,  details  of  any
interruptions  and  topping  up  required,  and  the  records  shall  be  in  accordance  with  the
recommendations  of  the  certification  scheme.  Copies  of  these  records  shall  be  supplied  to  the
Engineer within 24 hours of grouting.

Grout vents shall be positively sealed to be waterproof on completion of grouting so as to maintain
the encapsulation to the tendons by a means separate from the concrete waterproofing.

The fluidity test shall be performed on each tendon in accordance with Article 22.8.8.12, measuring
the grout fluidity from the discharge outlet. Measured grout efflux times shall not be faster than the
efflux time measured at the inlet or the minimum efflux time established in Article 22.7.2.3. If the
grout efflux time is not acceptable, additional grout shall be discharged from the discharge outlet.
Grout efflux time shall be tested. This cycle shall continue until acceptable grout fluidity is achieved.

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To ensure that the tendon remains filled with grout, the ejection and injection vents shall be closed
in sequence, respectively, under pressure when the tendon duct is completely filled with grout. The
positive shut-offs at the injection and ejection vents shall not be removed or vents opened until the
grout has set.

22.8.8.5

Grouting During Adverse Weather

Hot Weather

Grouting in conditions where the shade air temperature exceeds 30

C will only be permitted when

the Contractor's proposals for ensuring that the grout quality will not be impaired have been accepted
by the Engineer.

During  hot  weather,  the  Contractor  shall  ensure  that  the  constituent  materials  of  the  grout  are
sufficiently  cool  to  prevent  the grout from  stiffening  in  the  interval  between  its  discharge from the
mixer  and compaction in its final position. Cement  shall not be allowed to come into contact with
water at a temperature greater than 40°C.

Notwithstanding the above recommendations grouting shall not be carried out when the shade air
temperature exceeds 40° C or during "ghibli" conditions.

Cold Weather

When the ambient temperature may be expected to fall below 5°C, accurate temperature records
shall be kept covering maximum and minimum air temperatures, and temperatures of the structures
adjacent to the ducts to be grouted.

No grout shall be placed when the temperature of the structure adjacent to the ducts is below 5°C,
or is likely to fall below 5°C during the following 48 hours, unless the member is heated so as to
maintain the temperature of the placed grout above 5°C for at least 48 hours. Methods of heating
shall be to the approval of the Engineer.

Ducts shall not be warmed with steam.

22.8.8.6

Vertical Grouting

In lieu of a positive shut-off, vertical or near vertical tendon ducts for grouting shall terminate in
reservoirs at the upper-most point. The reservoir shall have sufficient capacity to store excess grout
and bleed water. Visible grout levels shall be maintained in the reservoirs, which shall be maintained
until the grout has set.

Grout shall be injected at a rate of 5 m of duct per minute.

22.8.8.7

Post-grouting Inspection

Vacuum grouting shall be used to fill any voids that expose strands discovered in the grouting
process.

Where possible, all anchorages and high-point vents shall be drilled and probed 48 hours after
grouting, until the Engineer is assured that no bleed water or subsidence, such as settlement, voids
exist. After the Engineer is assured that voids do not exist, only one or two anchorages per span
shall be drilled and probed to ensure quality grouting. Any voids discovered should be filled
immediately with the approved grout.

22.8.8.8

Finishing

The following requirements apply:

a. Valves, caps, and vent pipes shall not be removed or opened until the grout has set.

Abu Dhabi, United Arab Emirates. STANDARD CONSTRUCTION SPECIFICATIONS (PART 2 - ROAD STRUCTURES, 2020) - page 8