Standard Specifications for Road, Bridge, and Municipal Construction 2020 (M 41-10)

Page 6-24

Concrete Structures

Concrete that fails to meet minimum acceptance levels using the coring method will be
evaluated for structural adequacy. If the material is found to be adequate, payment shall
be adjusted in accordance with the following formula:

Pay adjustment =

3.56(.85f’c – f cores)(UP)(Q)

f’c

Where:

f’c

= Specified minimum compressive strength at 28 days.

f cores = Compressive strength of the cores as determined by AASHTO T 22.

= Unit Contract price per cubic yard for the class of concrete involved.

= Quantity of concrete represented by an acceptance test based on the required

frequency of testing.

Where these Specifications designate payment for the concrete on other than a per cubic
yard basis, the unit Contract price of concrete shall be taken as $300 per cubic yard for
concrete Class 4000, 5000, and 6000. For concrete Class 3000, the unit contract price for
Concrete shall be $160 per cubic yard.

6-02.3(6) Placing Concrete

The Contractor shall not place concrete:
1. On frozen or ice-coated ground or Subgrade;
2. Against or on ice-coated forms, reinforcing steel, structural steel, conduits, precast

members, or construction joints;

3. Under rainy conditions; placing of concrete shall be stopped before the quantity of

surface water is sufficient to affect or damage surface mortar quality or cause a flow
or wash the concrete surface;

4. In any foundation until the Engineer has accepted its depth and character;
5. In any form until the Engineer has accepted it and the placement of any reinforcing in

it; or

6. In any Work area when vibrations from nearby Work may harm the concrete’s initial

set or strength.

When a foundation excavation contains water, the Contractor shall pump it dry before
placing concrete. If this is impossible, an underwater concrete seal shall be placed that
complies with

Section 6-02.3(6)B

. This seal shall be thick enough to resist any uplift.

All foundations, forms, and contacting concrete surfaces shall be moistened with water
just before the concrete is placed. Any standing water on the foundation, on the concrete
surface, or in the form shall be removed.

The Contractor shall place concrete in the forms as soon as possible after mixing. The
concrete shall always be plastic and workable. For this reason, the Engineer may reduce
the time to discharge even further. Concrete placement shall be continuous, with no
interruption longer than 30 minutes between adjoining layers unless the Engineer allows
a longer time. The Type 2 Working Drawing submittal shall include justification that the
concrete mix design will remain fluid for interruptions longer than 30 minutes between

Concrete Structures

6-02

placements. Each layer shall be placed and consolidated before the preceding layer takes
initial set. After initial set, the forms shall not be jarred, and projecting ends of reinforcing
bars shall not be disturbed.

In girders or walls, concrete shall be placed in continuous, horizontal layers 1½ to 2½ feet
deep. Compaction shall leave no line of separation between layers. In each part of a form,
the concrete shall be deposited as near its final position as possible.

Any method for placing and consolidating shall not segregate aggregates or displace
reinforcing steel. Any method shall leave a compact, dense, and impervious concrete with
smooth faces on exposed surfaces. Plastering is not permitted. Any section of defective
concrete shall be removed at the Contractor’s expense.

To prevent aggregates from separating, the length of any conveyor belt used to transport
concrete shall not exceed 300 feet. If the mix needs protection from sun or rain, the
Contractor shall cover the belt. When concrete pumps are used for placement, a
Contractor’s representative shall, prior to use on the first placement of each day, visually
inspect the pumps water chamber for water leakage. No pump shall be used that allows
free water to flow past the piston.

If a concrete pump is used as the placing system, the pump priming slurry shall be
discarded before placement. Initial acceptance testing may be delayed until the pump
priming slurry has been eliminated from the concrete being pumped. Eliminating the
priming slurry from the concrete may require that several cubic yards of concrete are
discharged through the pumping system and discarded. Use of a concrete pump requires
a reserve pump (or other backup equipment) at the site.

If the concrete will drop more than 5 feet, it shall be deposited through a sheet metal
(or other accepted) conduit. If the form slopes, the concrete shall be lowered through
accepted conduit to keep it from sliding down one side of the form. No aluminum
conduits or tremies shall be used to pump or place concrete.

Before placing bridge deck concrete on steel spans, the Contractor shall release the
falsework under the bridge and let the span swing free on its supports. Concrete in
flat slab bridges shall be placed in one continuous operation for each span or series of
continuous spans.

Concrete for bridge decks and the stems of T-beams or box-girders shall be placed in
separate operations if the stem of the beam or girder is more than 3 feet deep. First the
beam or girder stem shall be filled to the bottom of the slab fillets. Bridge deck concrete
shall not be placed until enough time has passed to permit the earlier concrete to shrink
(at least 12 hours). If stem depth is 3 feet or less, the Contractor may place concrete in
1 continuous operation if the Engineer concurs.

Between expansion or construction joints, concrete in beams, girders, bridge decks,
piers, columns, walls, and traffic and pedestrian barriers, etc., shall be placed in a
continuous operation.

Page 6-26

Concrete Structures

No traffic or pedestrian barrier shall be placed until after the bridge deck is complete for
the entire Structure. No concrete barriers shall be placed until the falsework has been
released and the span supports itself. The Contractor may choose not to release the deck
overhang falsework prior to the barrier placement. The Contractor shall submit Type 2E
Working Drawings consisting of calculations indicating the loads induced into the girder
webs due to the barrier weight and any live load placed on the Structure do not exceed
the design capacity of the girder component. This analysis is not required for bridges
with concrete Superstructures. No barrier, curb, or sidewalk shall be placed on steel or
prestressed concrete girder bridges until the bridge deck reaches a compressive strength
of at least 3,000 psi.

The Contractor may construct traffic and pedestrian barriers by the slipform method.
However, the barrier may not deviate more than ¼ inch when measured by a 10-foot
straightedge held longitudinally on the front face, back face, and top surface. Electrical
conduit within the barrier shall be constructed in accordance with the requirements of

Section 8-20.3(5)

When placing concrete in arch rings, the Contractor shall ensure that the load on the
falsework remains symmetrical and uniform.

Unless otherwise allowed by the Engineer, arch ribs in open spandrel arches shall be
placed in sections. Small key sections between large sections shall be filled after the large
sections have shrunk.

6-02.3(6)A

Weather and Temperature Limits to Protect Concrete

6-02.3(6)A1

Hot Weather Protection

The Contractor shall provide concrete within the specified temperature limits. Cooling of
the coarse aggregate piles by sprinkling with water is permitted provided the moisture
content is monitored, the mixing water is adjusted for the free water in the aggregate
and the coarse aggregate is removed from at least 1 foot above the bottom of the pile.
Sprinkling of fine aggregate piles with water is not allowed. Refrigerating mixing water, or
replacing all or part of the mixing water with crushed ice is permitted, provided the ice is
completely melted by placing time.

If air temperature exceeds 90°F, the Contractor shall use water spray or other accepted
methods to cool all concrete-contact surfaces to less than 90°F. These surfaces include
forms, reinforcing steel, steel beam flanges, and any others that touch the concrete.

6-02.3(6)A2

Cold Weather Protection

Concrete shall be maintained at or above a temperature of 40°F during the first seven
days of the Cold Weather Protection Period and at or above a temperature of 35°F
during the remainder of the Cold Weather Protection Period. Cold weather protection
requirements do not apply to concrete in shafts and piles placed below the ground line.

Concrete Structures

6-02

Prior to placing concrete in cold weather, the Contractor shall submit a Type 2 Working
Drawing with a written procedure for cold weather concreting. The procedure shall
detail how the Contractor will adequately cure the concrete and prevent the concrete
temperature from falling below the minimum temperature. Extra protection shall be
provided for areas especially vulnerable to freezing (such as exposed top surfaces, corners
and edges, thin sections, and concrete placed into steel forms). Concrete placement will
only be allowed if the Contractor’s cold weather protection plan has been accepted by
the Engineer.

Prior to concrete placement, the Contractor shall review the 7-day temperature
predictions for the job site from the Western Region Headquarters of the National
Weather Service (

www.wrh.noaa.gov

). When temperatures below 35°F are predicted, the

Contractor shall:
1. Install temperature sensors in each concrete placement. One sensor shall be installed

for every 100 cubic yards of concrete placed. Sensors shall be installed at locations
directed by the Engineer, and shall be placed 1.5 inches from the face of concrete.

2. Immediately after concrete placement, temperature sensors shall be installed on the

concrete surface at locations directed by the Engineer. One sensor shall be installed
for every 100 cubic yards of concrete placed.

Temperatures shall be measured and recorded a minimum of every hour for the duration
of the Cold Weather Protection Period. Temperature data shall be submitted to the
Engineer as a Type 1 Working Drawing within three days following the end of the Cold
Weather Protection Period.

For each day that the concrete temperature falls below 40°F during the first seven
days of the Cold Weather Protection Period, no curing time is awarded for that day and
the Cold Weather Protection Period is extended for one additional day. If the concrete
temperature falls below 35°F during the Cold Weather Protection Period, the concrete
may be rejected by the Engineer.

6-02.3(6)B

Placing Concrete in Foundation Seals

If the Plans require a concrete seal, the Contractor shall place the concrete underwater
inside a watertight cofferdam, tube, or caisson. Seal concrete shall be placed in a compact
mass in still water. It shall remain undisturbed and in still water until fully set. While seal
concrete is being deposited, the water elevation inside and outside the cofferdam shall
remain equal to prevent any flow through the seal in either direction. The cofferdam shall
be vented at the vent elevation shown in the Plans. The thickness of the seal is based
upon this vent elevation.

The seal shall be at least 18 inches thick unless the Plans show otherwise. The Engineer
may change the seal thickness during construction which may require redesign of the
footing and the pier shaft or column. Although seal thickness changes may result in the
use of more or less concrete, reinforcing steel, and excavation, payment will remain as
originally defined in unit Contract prices.

Page 6-28

Concrete Structures

To place seal concrete underwater, the Contractor shall use a concrete pump or tremie.
The tremie shall have a hopper at the top that empties into a watertight tube at least
10 inches in diameter. The discharge end of the tube on the tremie or concrete pump
shall include a device to seal out water while the tube is first filled with concrete. Tube
supports shall permit the discharge end to move freely across the entire Work area and to
drop rapidly to slow or stop the flow. One tremie may be used to concrete an area up to
18 feet per side. Each additional area of this size requires one additional tremie.

Throughout the underwater concrete placement operation, the discharge end of the
tube shall remain submerged in the concrete and the tube shall always contain enough
concrete to prevent water from entering. The concrete placement shall be continuous
until the Work is completed, resulting in a seamless, uniform seal. If the concreting
operation is interrupted, the Engineer may require the Contractor to prove by core
drilling or other tests that the seal contains no voids or horizontal joints. If testing reveals
voids or joints, the Contractor shall repair them or replace the seal at no expense to the
Contracting Agency.

Concrete Class 4000W shall be used for seals, and it shall meet the consistency
requirements of

Section 6-02.3(4)C

6-02.3(6)C

Dewatering Concrete Seals and Foundations

After a concrete seal is constructed, the Contractor shall pump the water out of the
cofferdam and place the rest of the concrete in the dry. This pumping shall not begin until
the seal has set enough to withstand the hydrostatic pressure (3 days for gravity seals
and 10 days for seals containing piling or shafts). The Engineer may extend these waiting
periods to ensure structural safety or to meet a condition of the operating permit.

If weighted cribs are used to resist hydrostatic pressure at the bottom of the seal, the
Contractor shall anchor them to the foundation seal. Any method used (such as dowels or
keys) shall transfer the entire weight of the crib to the seal.

No pumping shall be done during or for 24 hours after concrete placement unless done
from a suitable sump separated from the concrete Work by a watertight wall. Pumping
shall be done in a way that rules out any chance of concrete being carried away.

6-02.3(6)D

Protection Against Vibration

Freshly placed concrete shall not be subjected to excessive vibration and shock waves
during the curing period until it has reached a 2,000 psi minimum compressive strength
for structural concrete and lower-strength classes of concrete.

After the first 5 hours from the time the concrete has been placed and consolidated, the
Contractor shall keep all vibration producing operations at a safe horizontal distance from
the freshly placed concrete by following either the prescriptive safe distance method or
the monitoring safe distance method. These requirements for the protection of freshly
placed concrete against vibration shall not apply for plant cast concrete, nor shall they
apply to the vibrations caused by the traveling public.

Concrete Structures

6-02

6-02.3(6)D1 Prescriptive Safe Distance Method

After the concrete has been placed and consolidated, the Contractor shall keep all
vibration producing operations at a safe horizontal distance from the freshly placed
concrete as follows:

Minimum Compressive

Strength, f’c

Safe Horizontal Distance

Equipment Class L

Equipment Class H

< 1,000 psi

75 feet

125 feet

1,000 to < 1,400 psi

30 feet

50 feet

1,400 to 2,000 psi

15 feet

25 feet

The safe horizontal distance shall be reduced to 10 feet for small rubber tire construction equipment like

backhoes under 50,000 pounds, concrete placing equipment, and legal Highway vehicles if such equipment
travels at speeds of:

• ≤ 5 mph on relatively smooth Roadway surfaces or

• ≤ 3 mph on rough Roadway surfaces (i.e., with potholes)

Equipment Class L (Low Vibration) shall include tracked dozers under 85,000 pounds, track vehicles, trucks

(unless excluded above), hand-operated jack hammers, cranes, auger drill rig, caisson drilling, vibratory roller
compactors under 30,000 pounds, and grab-hammers.

Equipment Class H (High Vibration) shall include pile drivers, vibratory hammers, machine-operated impact

tools, pavement breakers, and other large pieces of equipment.

After the concrete has reached a minimum compressive strength specified above, the safe
horizontal distance restrictions would no longer apply.

6-02.3(6)D2 Monitoring Safe Distance Method

The Contractor may monitor the vibration producing operations in order to decrease
the safe horizontal distance requirements of the prescriptive safe distance method.
If this method is chosen, all construction operations that produce vibration or shock
waves in the vicinity of freshly placed concrete shall be monitored by the Contractor
with monitoring equipment sensitive enough to detect a minimum peak particle velocity
(PPV) of 0.10 inches per second. Monitoring devices shall be placed on or adjacent to the
freshly placed concrete when the measurements are taken. During the time subsequent
to the concrete placement, the Contractor shall cease all vibration or shock producing
operations in the vicinity of the newly placed concrete when the monitoring equipment
detects excessive vibration and shock waves defined as exceeding the following PPVs:

Minimum Compressive

Strength, f’c

Maximum PPV

< 1,000 psi

0.10 in/sec

1,000 to < 1,400 psi

1.0 in/sec

1,400 to 2,000 psi

2.0 in/sec

After the concrete has reached a minimum compressive strength specified above, the safe
horizontal distance restrictions would no longer apply.

Page 6-30

Concrete Structures

6-02.3(7)

Tolerances

Unless noted otherwise, concrete construction tolerances shall be in accordance with this
section. Tolerances in this section do not apply to cement concrete pavement.

Horizontal deviation of roadway crown points, cross-slope break points, and curb, barrier
or railing edges from alignment or work line: ±1.0 inch

Deviation from plane: ±0.5 inch in 10 feet

Deviation from plane for roadway surfaces: ±0.25 inch in 10 feet

Deviation from plumb or specified batter: ±0.5 inch in 10 feet, but not to exceed a total of
±1.5 inches

Vertical deviation from profile grade for roadway surfaces: ±1 inch

Vertical deviation of top surfaces (except roadway surfaces): ±0.75 inch

Thickness of bridge decks and other structural slabs not at grade: ±0.25 inch

Length, width and thickness of elements such as columns, beams, crossbeams,
diaphragms, corbels, piers, abutments and walls, including dimensions to construction
joints in initial placements: +0.5 inch, -0.25 inch

Length, width and thickness of spread footing foundations: +2 inches, -0.5 inch

Horizontal location of the as-placed edge of spread footing foundations: The greater
of ±2% of the horizontal dimension of the foundation perpendicular to the edge and
±0.5 inch. However, the tolerance shall not exceed ±2 inches.

Location of opening, insert or embedded item at concrete surface: ±0.5 inch

Cross-sectional dimensions of opening: ±0.5 inch

Bridge deck, bridge approach slab, and bridge traffic barrier expansion joint gaps with a
specified temperature range, measured at a stable temperature: ±0.25 inch

Horizontal deviation of centerline of bearing pad, oak block or other bearing assembly:
±0.125 inch

Horizontal deviation of centerline of supported element from centerline of bearing pad,
oak block or other bearing assembly ±0.25 inch

Vertical deviation of top of bearing pad, oak block or other bearing assembly: ±0.125 inch

6-02.3(8) Vacant

Concrete Structures

6-02

6-02.3(9) Vibration of Concrete

The Contractor shall supply enough vibrators to consolidate the concrete (except that
placed underwater) according to the requirements of this section. Each vibrator shall:
1.  Be designed to operate while submerged in the concrete,
2.  Vibrate at a rate of at least 7,000 pulses per minute, and
3.  Receive the Engineer’s acceptance on its type and method of use.

Immediately after concrete is placed, vibration shall be applied in the fresh batch at the
point of deposit. In doing so, the Contractor shall:
1. Space the vibrators evenly, no farther apart than twice the radius of the visible

effects of the vibration;

2. Ensure that vibration intensity is great enough to visibly affect a weight of 1-inch

slump concrete across a radius of at least 18 inches;

3. Insert the vibrators slowly to a depth that will effectively vibrate the full depth of

each layer, penetrating into the previous layer on multilayer pours;

4. Protect partially hardened concrete (i.e., nonplastic, which prevents vibrator

penetration when only its own weight is applied) by preventing the vibrator from
penetrating it or making direct contact with steel that extends into it;

5. Not allow vibration to continue in one place long enough to form pools of grout;
6. Continue vibration long enough to consolidate the concrete thoroughly, but not so

long as to segregate it;

7. Withdraw the vibrators slowly when the process is complete; and
8. Not use vibrators to move concrete from one point to another in the forms.

When vibrating and finishing top surfaces that will be exposed to weather or wear, the
Contractor shall not draw water or laitance to the surface. In high lifts, the top layer shall
be shallow and made up of a concrete mix as stiff as can be effectively vibrated and
finished.

To produce a smooth, dense finish on outside surfaces, the Contractor shall hand tamp
the concrete.

Vibration of SCC shall only be used as described below or as approved by the Engineer:
1. To prevent the formation of a cold joint in between placement of successive batches

of SCC.

2. Near the end of an SCC placement to aid in leveling the SCC in the forms.

When vibration of SCC is allowed, the magnitude and duration of the applied vibration
shall be kept as minimal as possible.

Page 6-32

Concrete Structures

6-02.3(10) Bridge Decks and Bridge Approach Slabs

6-02.3(10)A

Pre-Deck Pour Meeting

A pre-deck pour meeting shall be held 5 to 10 working days before placing deck concrete
to discuss construction procedures, personnel, equipment to be used, concrete sampling
and testing and deck finishing and curing operations. Those attending shall include, at a
minimum, the superintendent, foremen in charge of placing and finishing concrete, and
representatives from the concrete supplier and the concrete pump truck supplier.

If the project includes more than one bridge deck, and if the Contractor’s key personnel
change between concreting operations, or at request of the Engineer, additional
conferences shall be held before each deck placement.

6-02.3(10)B

Screed Rail Supports

The Contractor shall place screed rails outside the finishing area. When screed rails
cannot be placed outside the finishing area as determined by the Engineer, they shall
rest on adjustable supports that can be removed with the least possible disturbance to
the screeded concrete. The supports shall rest on structural members or on forms rigid
enough to resist deflection. Supports shall be removable to at least 2 inches below the
finished surface. For staged constructed bridge decks, the finishing machine screed
rails shall not be supported on the completed portion of deck and shall deflect with the
portion of structure under construction.

Screed rails (with their supports) shall be strong enough and stiff enough to permit the
finishing machine to operate effectively on them. All screed rails shall be placed and
secured for the full length of the deck/slab before the concreting begins. If the Engineer
concurs in advance, the Contractor may move rails ahead onto previously set supports
while concreting progresses. However, such movable rails and their supports shall not
change the set elevation of the screed.

On steel truss and girder spans, screed rails and bulkheads may be placed directly on
transverse steel floorbeams, with the strike-board moving at right angles to the centerline
of the Roadway.

6-02.3(10)C

Finishing Equipment

The finishing machine shall be self-propelled and be capable of forward and reverse
movement under positive control. The finishing machine shall be equipped with augers
and a rotating cylindrical single or double drum screed. The finishing machine shall have
the necessary adjustments to produce the required cross section, line, and grade. The
finishing machine shall be capable of raising the screeds, augers, and any other parts
of the finishing mechanical operation to clear the screeded surface, and returning to
the specified grade under positive control. Unless otherwise allowed by the Engineer, a
finishing machine manufacturer technical representative shall be on site to assist the first
use of the machine on the Contract.

For bridge deck widening of 20 feet or less, and for bridge approach slabs, or where
jobsite conditions do not allow the use of the conventional configuration finishing

Concrete Structures

6-02

machines, or modified conventional machines as described above, the Contractor may
submit a Type 2 Working Drawing proposing the use of a hand-operated motorized power
screed such as a “Texas” or “Bunyan” screed. This screed shall be capable of finishing the
bridge deck and bridge approach slab to the same standards as the finishing machine.

On bridge decks, the Contractor may use hand-operated strike-boards only when the
Engineer concurs for special conditions where self-propelled or motorized hand-operated
screeds cannot be employed. These boards shall be sturdy and able to strike off the
full placement width without intermediate supports. Strike-boards, screed rails, and
any specially made auxiliary equipment shall receive the Engineer’s concurrence before
use. All finishing requirements in these Specifications apply to hand-operated finishing
equipment.

6-02.3(10)D Concrete Placement, Finishing, and Texturing

6-02.3(10)D1 Test Slab Using Bridge Deck Concrete

After the Contractor receives the Engineer’s acceptance of the Class 4000D concrete mix
design, and a minimum of seven calendar days prior to the first placement of bridge deck
concrete, the Contractor shall construct a test slab using concrete of the accepted mix
design.

The test slab may be constructed on grade, shall have a minimum thickness of 8-inches,
shall have minimum plan dimensions of 10-feet along all four edges, and shall be square
or rectangular.

During construction of the test slab, the Contractor shall demonstrate concrete sampling
and testing, use of the concrete temperature monitoring system, the concrete fogging
system, concrete placement system, and the concrete finishing operation. The Contractor
shall conduct the demonstration using the same type of equipment to be used for the
production bridge decks, except that the Contractor may elect to finish the test slab with
a hand-operated strike-board.

After the construction of the test slab and the demonstration of bridge deck construction
operations is complete, the Contractor shall remove and dispose of the test slab in
accordance with Sections

2-02.3

and

2-03.3(7)C

6-02.3(10)D2 Preparation for Concrete Placement

Before placing bridge approach slab concrete, the subgrade shall be constructed in
accordance with Sections

2-06

and

5-05.3(6)

Before any concrete is placed, the finishing machine shall be operated over the entire
length of the deck/slab to check screed deflection. Concrete placement may begin only if
the Engineer accepts after this test.

Immediately before placing concrete, the Contractor shall check (and adjust if necessary)
all falsework and wedges to minimize settlement and deflection from the added mass
of the concrete deck/slab. The Contractor shall also install devices, such as telltales, by
which the Engineer can readily measure settlement and deflection.

Page 6-34

Concrete Structures

6-02.3(10)D3 Concrete Placement

The placement operation shall cover the full width of the bridge deck or the full width
between construction joints. The Contractor shall locate any construction joint over a
beam or web that can support the deck/slab on either side of the joint. The joint shall
not occur over a pier unless the Plans permit. Each joint shall be formed vertically and
in true alignment. The Contractor shall not release falsework or wedges supporting
bridge deck placement sections on either side of a joint until each side has aged as these
Specifications require.

Placement of concrete for bridge decks and bridge approach slabs shall comply with

Section 6-02.3(6)

. In placing the concrete, the Contractor shall:

1. Place it (without segregation) against concrete placed earlier, as near as possible to

its final position, approximately to grade, and in shallow, closely spaced piles;

2. Consolidate it around reinforcing steel by using vibrators before strike-off by the

finishing machine;

3. Not use vibrators to move concrete;
4. Not revibrate any concrete surface areas where workers have stopped prior to

screeding;

5. Remove any concrete splashed onto reinforcing steel in adjacent segments before

concreting them;

6. Maintain a slight excess of concrete in front of the screed across the entire width of

the placement operation;

7. Operate the finishing machine to create a surface that is true and ready for final

finish without overfinishing or bringing excessive amounts of mortar to the surface;
and

8. Leave a thin, even film of mortar on the concrete surface after the last pass of the

finishing machine pan.

Workers shall complete all post screeding operations without walking on the concrete.
This may require work bridges spanning the full width of the deck/slab.

After removing the screed supports, the Contractor shall fill the voids with concrete (not
mortar).

If the surface left by the finishing machine is porous, rough, or has minor irregularities,
the Contractor shall float the surface of the concrete. Floating shall leave a smooth and
even surface. Float finishing shall be kept to the minimum number of passes necessary
to seal the surface. The floats shall be at least 4-feet long. Each transverse pass of the
float shall overlap the previous pass by at least half the length of the float. The first
floating shall be at right angles to the strike-off. The second floating shall be at right
angles to the centerline of the span. A smooth riding surface shall be maintained across
construction joints.

Concrete Structures

6-02

The edge of completed roadway slabs at expansion joints and compression seals shall

have a ⅜-inch radius.

After floating, but while the concrete remains plastic, the Contractor shall test the entire
deck/slab for flatness (allowing for crown, camber, and vertical curvature). The testing
shall be done with a 10-foot straightedge held on the surface. The straightedge shall be
advanced in successive positions parallel to the centerline, moving not more than one half
the length of the straightedge each time it advances. This procedure shall be repeated
with the straightedge held perpendicular to the centerline. An acceptable surface shall be

one free from deviations of more than ⅛-inch under the 10-foot straightedge.

If the test reveals depressions, the Contractor shall fill them with freshly mixed concrete,
strike off, consolidate, and refinish them. High areas shall be cut down and refinished.
Retesting and refinishing shall continue until a surface conforming to the requirements
specified above is produced.

6-02.3(10)D4 Vacant

6-02.3(10)D5 Bridge Deck Concrete Finishing and Texturing

Except as otherwise specified for portions of bridge decks receiving an overlay or
sidewalk under the same Contract, the Contractor shall texture the surface of the bridge
deck as follows:

The Contractor shall texture the bridge deck using diamond tipped saw blades
mounted on a power driven, self-propelled machine that is designed to texture

concrete surfaces. The grooving equipment shall provide grooves that are ⅛" ± 1/64"
wide, 3/16" ± 1/16" deep, and spaced at ¾" ± ⅛". The bridge deck shall not be textured

with a metal tined comb.

The Contractor shall submit a Type 2 Working Drawing consisting of the type of
grooving equipment to be used. The Contractor shall demonstrate that the method
and equipment for texturing the bridge deck will not chip, spall or otherwise damage
the deck.

Unless otherwise allowed by the Engineer, the Contractor shall texture the concrete
bridge deck surface either in a longitudinal direction, parallel with centerline or in
a transverse direction, perpendicular with centerline. The Contractor shall texture
the bridge deck surface to within 3-inches minimum and 24-inches maximum of the
edge of concrete at expansion joints, within 1-foot minimum and 2-feet maximum of
the curb line, and within 3-inches minimum and 9-inches maximum of the perimeter
of bridge drain assemblies.

The Contractor shall contain and collect all concrete dust and debris generated by
the bridge deck texturing process, and shall dispose of the collected concrete dust
and debris in accordance with

Section 2-03.3(7)C

Page 6-36

Concrete Structures

If the Plans call for placement of a sidewalk or an HMA or concrete overlay on the
bridge deck, the Contractor shall produce the final finish of these areas by dragging a
strip of damp, seamless burlap lengthwise over the bridge deck or by brooming it lightly.
Approximately 3-feet of the drag shall contact the surface, with the least possible bow in
its leading edge. It shall be kept wet and free of hardened lumps of concrete. When the
burlap drag fails to produce the required finish, the Contractor shall replace it. When not
in use, it shall be lifted clear of the bridge deck.

After the bridge deck has cured, the surface shall conform to the surface smoothness
requirements specified in

Section 6-02.3(10)D3

The surface texture on any area repaired to address out-of-tolerance surface smoothness
shall match closely that of the surrounding bridge deck area at the completion of the
repair. Methods used to remove high spots shall cut through the mortar and aggregate
without breaking or dislodging the aggregate or causing spalls.

6-02.3(10)D6 Bridge Approach Slab Finishing and Texturing

Bridge approach slabs that are being built as part of a bridge construction project shall
be textured in accordance with

Section 6-02.3(10)D5

. All other bridge approach slabs

shall be textured using metal tined combs in the transverse direction, except bridge
approach slabs receiving an overlay in the same Contract shall be finished as specified in

Section 6-02.3(10)D5

only.

The comb shall be made of a single row of metal tines. It shall leave striations in the

fresh concrete approximately 3/16-inch deep by ⅛-inch wide and spaced approximately

½-inch apart. The Engineer will decide actual depths at the site. If the comb has not been
accepted, the Contractor shall obtain the Engineer’s acceptance by demonstrating it on
a test section. The Contractor may operate the combs manually or mechanically, either
singly or with several placed end to end. The timing and method used shall produce the
required texture without displacing larger particles of aggregate.

Texturing shall end 2-feet from curb lines. This 2-foot untextured strip shall be hand
finished with a steel trowel.

Surface smoothness, high spots, and low spots shall be addressed as specified in

Section

6-02.3(10)D5

. The surface texture on any area cut down or built up shall match closely

that of the surrounding bridge approach slab area. The entire bridge approach slab shall
provide a smooth riding surface.

6-02.3(10)E Sidewalk

Concrete for sidewalk shall be well compacted, struck off with a strike-board, and floated

with a wooden float to achieve a surface that does not vary more than ⅛ inch under a 10-

foot straightedge. An edging tool shall be used to finish all sidewalk edges and expansion
joints. The final surface shall have a granular texture that will not turn slick when wet.

Concrete Structures

6-02

6-02.3(10)F

Bridge Approach Slab Orientation and Anchors

Bridge approach slabs shall be constructed full bridge deck width from outside usable
Shoulder to outside usable Shoulder at an elevation to match the Structure. Unless
otherwise shown in the Plans, the pavement end of the bridge approach slab shall be
constructed normal to the Roadway centerline. The bridge approach slabs shall be
modified as shown in the Plans to accommodate the grate inlets at the bridge ends if the
grate inlets are required.

Bridge approach slab anchors shall be installed as detailed in the Plans, and the anchor
rods, couplers, and nuts shall conform to

Section 9-06.5(1)

. The steel plates shall conform

to ASTM A36. All metal parts of the approach expansion anchor shall receive one coat
of paint conforming to

Section 9-08.1(2)F

or be galvanized in accordance with AASHTO

M232. The pipe shall be any nonperforated PE or PVC pipe of the diameter specified in
the Plans. Polystyrene shall conform to

Section 9-04.6

. The anchors shall be installed

parallel both to profile grade and centerline of Roadway. The Contractor shall secure
the anchors to ensure that they will not be misaligned during concrete placement. For
Method B anchor installations, the epoxy bonding agent used to install the anchors
shall be Type IV conforming to

Section 9-26.1

. The compression seal shall be as noted

in the Contract documents. Dowel bars shall be installed in the bridge approach slabs in
accordance with the requirements of the

Standard Plans

and

Section 5-05.3(10)

The compression seal shall be a 2½ inch wide gland and shall conform to
Section 9-04.1(4).

6-02.3(11) Curing Concrete

After placement, concrete surfaces shall be cured as follows:
1. Bridge sidewalks, roofs of cut and cover tunnels – curing compound covered by

white, reflective type sheeting or continuous wet curing. Curing by either method
shall be for at least 10 days.

2. Bridge decks — See

Section 6-02.3(11)B

3. Bridge approach slabs (Class 4000A concrete) – Two coats of curing compound and

continuous wet cure for at least 10 days.

4. Concrete barriers and rail bases – See

Section 6-02.3(11)A

5. All other concrete surfaces – Continuous wet cure for at least 3 days.

During the continuous wet cure, the Contractor shall keep all exposed concrete surfaces
saturated with water. Formed concrete surfaces shall be kept in a continuous wet cure by
leaving the forms in place. If forms are removed during the continuous wet cure period,
the Contractor shall treat the concrete as an exposed concrete surface. Runoff water shall
be collected and disposed of in accordance with all applicable regulations. In no case shall
runoff water be allowed to enter any lakes, streams, or other surface waters.

Page 6-38

Concrete Structures

When curing Class 4000A, two coats of curing compound that complies with

Section

9-23.2

shall be applied immediately (not to exceed 15 min.) after tining any portion of

the bridge approach slab. The continuous wet cure shall be established as soon as the
concrete has set enough to allow covering without damaging the finish.

For all other concrete requiring curing compound, the Contractor shall apply two coats
(that complies with

Section 9-23.2

) to the fresh concrete. The compound shall be applied

immediately after finishing. Application of the second coat shall run at right angles to
that of the first. The two coats shall total at least 1 gallon per 150 square feet and shall
obscure the original color of the concrete. If any curing compound spills on construction
joints or reinforcing steel, the Contractor shall clean it off before the next concrete
placement.

If the Plans call for an asphalt overlay on the bridge approach slab, the Contractor shall
use the clear curing compound (Type 1, Class B), applying at least 1 gallon per 150 square
feet to the concrete surface. Otherwise, the Contractor shall use white pigmented
curing compound (Type 2), agitating it thoroughly just before and during application. If
other materials are to be bonded to the surface, the Contractor shall remove the curing
compound by sandblasting or acceptable high pressure water washing.

The Contractor shall have on the site, back-up spray equipment, enough workers, and a
bridge from which they will apply the curing compound. The Engineer may require the
Contractor to demonstrate (at least 1 day before the scheduled concrete placement) that
the crew and equipment can apply the compound acceptably.

The Contractor shall cover the top surfaces with white, reflective sheeting, leaving it in
place for at least 10 days. Throughout this period, the sheeting shall be kept in place by
taping or weighting the edges where they overlap.

When accelerating admixtures are used, the concrete shall be cured in accordance
with these specifications or until the concrete has reached 70 percent of the mix design
28-day strength, but not less than 3 days.

6-02.3(11)A

Curing and Finishing Concrete Traffic and Pedestrian Barrier

The Contractor shall supply enough water and workers to cure and finish concrete barrier
as required in this section. Unit contract prices shall cover all curing and finishing costs.

6-02.3(11)A1 Fixed-Form Barrier

The edge chamfers shall be formed by attaching chamfer strips to the barrier forms.

After troweling and edging a barrier (while the forms remain in place), the Contractor
shall:
1.  Brush the top surface with a fine bristle brush;
2.  Cover the top surface with heavy, quilted blankets; and
3.  Spray water on the blankets and forms at intervals short enough to keep them

thoroughly wet for 3 days.

Concrete Structures

6-02

After removing the forms, the Contractor shall:
1. Remove all lips and edgings with sharp tools or chisels;
2. Fill all holes with mortar conforming to

Section 9-20.4(2)

;

3.  True up corners of openings;
4.  Remove concrete projecting beyond the true surface by stoning or grinding;
5.  Cover the barrier with heavy, quilted blankets (not burlap);
6.  Keep the blankets continuously wet for at least 7 days.

The Contractor may do the finishing Work described in steps 1 through 4 above during
the second (the 7-day) curing period if the entire barrier is kept covered except the
immediate Work area. Otherwise, no finishing Work may be done until at least 10 days
after pouring.

After the 10-day curing period, the Contractor shall remove from the barrier all form-
release agent, mud, dust, and other foreign substances in either of two ways: (1) by light
sandblasting and washing with water, or (2) by spraying with a high-pressure water jet.
The water jet equipment shall use clean fresh water and shall produce (at the nozzle)
at least 1,500 psi with a discharge of at least 3 gpm. The water jet nozzle shall have a
25-degree tip and shall be held no more than 9 inches from the surface being washed.

After cleaning, the Contractor shall use brushes to rub mortar conforming to

Section

9-20.4(2)

at a ratio of 1:1 cement/aggregate ratio into air holes and small crevices on all

surfaces except the brushed top. As soon as the mortar takes its initial set, the Contractor
shall rub it off with a piece of sacking or carpet. The barrier shall then be covered with
wet blankets for at least 48 hours.

No curing compound shall be used on fixed-form concrete barrier. The completed surface
of the concrete shall be even in color and texture.

6-02.3(11)A2 Slip-Form Barrier

The edge radius shall be formed by attaching radius strips to the barrier slip form.

The Contractor shall finish slip-form barrier by: (1) steel troweling to close all surface
pockmarks and holes; and (2) for plain surface barrier, lightly brushing the front and back
face with vertical strokes and the top surface with transverse strokes.

After finishing, the Contractor shall cure the slip-form barrier by using either Method A
(curing compound) or B (wet blankets) described below.

Method A – Under the curing compound method, the Contractor shall:
1. Spray two coats of clear curing compound (Type 1) on the concrete surface after the

free water has disappeared. (Coverage of combined coats shall equal at least 1 gallon
per 150 square feet.)

2. No later than the morning after applying the curing compound, cover the barrier with

white, reflective sheeting for at least 10 days.

Standard Specifications for Road, Bridge, and Municipal Construction 2020 (M 41-10) - page 30