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

Modified Concrete Overlays

6-09

6-09.3(3)C

Fly Ash Modified Concrete

Fly ash modified concrete shall be a workable mix, uniform in composition and
consistency. Mix proportions per cubic yard shall be as follows:

Portland Cement

611 pounds

Fly

Ash

275

pounds

Fine Aggregate

38 percent of total aggregate

Coarse Aggregate

62 percent of total aggregate

Water/Cement Ratio

0.30 maximum

Air (± 1½ percent)

6 percent

Slump

inches

maximum

6-09.3(3)D

Microsilica Modified Concrete

Microsilica modified concrete shall be a workable mix, uniform in composition and
consistency. Mix proportions per cubic yard shall be as follows:

Portland Cement

658 pounds

Microsilica Fume

52 pounds

Fine

Aggregate

1,515

pounds

Coarse

Aggregate 1,515

pounds

Water/Cement Ratio

0.33 maximum

Air (± 1½ percent)

6 percent

Slump

inches

maximum

6-09.3(3)E

Latex Modified Concrete

Latex modified concrete shall be a workable mix, uniform in composition and consistency.
Mix proportions per cubic yard shall be as follows:

Portland Cement

1.00 parts by weight

Fine Aggregate

2.40 to 2.75 parts by weight

Coarse Aggregate

1.75 to 2.00 parts by weight

Latex Admixture

3.50-gallons per bag of cement

Water/Cement Ratio

0.33 maximum

Air Content of Plastic Mix

6 percent maximum

Slump

inches

maximum

The aggregates shall be proportioned such that the amount of aggregate passing the No.
4 sieve is 65 ± 5 percent of the total aggregate (fine plus coarse). All calculations shall be
based on dry weights.

The moisture content of the fine aggregate and coarse aggregate shall be no more than
3.0 and 1.0 percent, respectively, above the saturated surface dry condition.

The water limit for calculating the water/cement ratio shall include the added water, the
free water in the aggregates, and 52 percent of the latex admixture.

Page 6-246

Modified Concrete Overlays

6-09.3(4) Storing and Handling

6-09.3(4)A

Vacant

6-09.3(4)B

Latex Admixture

The admixture shall be kept in suitable containers that will protect it from freezing and
from exposure to temperatures in excess of 85ºF. Containers of the admixture shall not be
stored in direct sunlight for periods in excess of 10 days. When stored in direct sunlight
the top and sides of the containers shall be covered with insulating blanket material.

Storage of the admixture may extend over a period greater than 10 days as long as the
conditions specified above are maintained and the latex admixture is agitated or stirred
once every 10 days. Stirring or agitation of the admixture shall be done mechanically
in accordance with the manufacturer’s recommendation. If the ambient temperature is
higher than 85ºF at any time during the storage period, the admixture shall be covered
by insulated blankets or other means that will maintain the admixture temperature
below 85ºF.

The admixture shall be strained through a Number 10 strainer at the time it is introduced
into the mixing tank from the storage containers.

6-09.3(4)C

High Molecular Weight Methacrylate Resin (HMWM)

The HMWM resin shall be stored in a cool dry place and protected from freezing and
exposure to temperature in excess of 100ºF. The promoter and initiator, if supplied
separate from the resin, shall not contact each other directly. Containers of promoters
and initiators shall not be stored together in a manner that will allow leakage or spillage
from one to contact the containers or material of the other.

6-09.3(5) Scarifying Concrete Surface

6-09.3(5)A General

The Contractor shall not begin scarifying a concrete bridge deck surface unless
completion of the scarification and concrete overlay can be accomplished within the
current construction season.

The Contractor shall protect adjacent traffic from flying debris generated by the
scarification process in accordance with item 4 of

Section 6-09.3(2)

The Contractor shall collect, contain, and dispose of all concrete debris generated by the
scarification process in accordance with item 4 of

Section 6-09.3(2)

All areas of the deck that are inaccessible to the selected scarifying machine shall be
scarified to remove the concrete surface matrix by a method acceptable to the Engineer.
The maximum scarified depth shall be equal to the nominal scarification depth shown in
the Plans or as otherwise allowed in areas of existing dense, sound bridge deck concrete
repair material. If these areas are hand-chipped then the equipment shall meet the
requirements as specified in

Section 6-09.3(1)A

Modified Concrete Overlays

6-09

Dense, sound areas of existing bridge deck concrete repair material shall be sufficiently
scarified to provide 1-inch minimum clearance to the top of the fresh modified
concrete overlay.

Concrete process water generated by scarifying concrete surface and removing existing
concrete overlay operations shall be contained, collected, and disposed of in accordance
with Sections

Runoff Water

Disposal Plan.

6-09.3(5)B

Testing of Hydro-Demolition Machines

A trial area shall be performed to demonstrate that the equipment and methods of
operation are capable of producing results satisfactory to the Engineer. The trial area
shall consist of a patch approximately 30 square feet in sound concrete as determined by
the Engineer.

The equipment shall be programmed to remove concrete to the nominal scarification
depth shown in the Plans, but no more than 2 inches, with a single pass of the machine.
The Engineer will grant acceptance of the equipment based on successful results from the
trial area test.

6-09.3(5)C Hydro-Demolishing

Once the operating parameters of the Hydro-Demolition machine are defined by
programming and calibration as specified in

Section 6-09.3(5)B

, they shall be monitored

every 20 feet as the machine progresses across the bridge deck, in order to prevent the
unnecessary removal of sound concrete below the required nominal removal depth. The
Contractor shall maintain a minimum production rate of 250-square feet per hour during
the deck scarifying process.

All water used in the Hydro-Demolition process shall be potable. Stream or lake water will
not be permitted.

All bridge drains and other outlets within 100 feet of the Hydro-Demolition machine shall
be temporarily plugged during the Hydro-Demolition operation. When scarifying a bridge
deck passing over traffic lanes, the Contractor shall protect the traffic below by restricting
and containing scarifying operations, and implementing traffic control measures.

The Contractor shall provide for the collection, filtering and disposal of all runoff water
generated by the Hydro-Demolition process, in accordance with the Runoff Water
Disposal Plan in accordance with item 3 of

Section 6-09.3(2)

. The Contractor shall comply

with applicable regulations concerning such water disposal.

6-09.3(5)D Vacant

Page 6-248

Modified Concrete Overlays

6-09.3(5)E

Removing Existing Concrete Overlay Layer by Rotomilling

When the Contractor elects to remove the upper layer of existing concrete overlay, when
present, by rotomilling prior to final scarifying, the entire concrete surface of the bridge
deck shall be milled to remove the surface matrix to the depth specified in the Plans
with a tolerance as specified in

Section 6-08.3(5)B

. The operating parameters of the

rotary milling machine shall be monitored in order to prevent the unnecessary removal of
concrete below the specified removal depth.

6-09.3(5)F

Repair of Steel Reinforcing Bars Damaged by Scarifying

Operations

All reinforcing steel damaged due to the Contractor’s operations shall be repaired by the
Contractor. For bridge decks not constructed under the same Contract as the concrete
overlay, damage to existing reinforcing steel shall be repaired and paid for in accordance
with

Section 1-09.6

if the existing concrete cover is ½ inch or less. All other reinforcing

steel damaged due to the Contractor’s operations shall be repaired by the Contractor at
no additional expense to the Contracting Agency.

The repair shall be as follows or as directed by the Engineer:
1. Damage to epoxy coating, when present on existing steel reinforcing bars, shall be

repaired in accordance with

Section 6-02.3(24)H

2. Damage to bars resulting in a section loss of 20 percent or more of the bar area shall

be repaired by chipping out the adjacent concrete and splicing a new bar of the same
size. Concrete shall be removed to provide a ¾-inch minimum clearance around the
bars. The splice bars shall extend a minimum of 40 bar diameters beyond each end of
the damage.

3. Any bars partially or completely removed from the deck shall have the damaged

portions removed and spliced with new bars as outlined in item 2 above.

6-09.3(5)G

Cleanup Following Scarification

After scarifying is completed, the entire lane or strip being overlaid shall be thoroughly
cleaned of all dust, freestanding water and loose particles.

6-09.3(6) Further Deck Preparation

Once the lane or strip being overlaid has been cleaned of debris from scarifying, the
entire scarified surface shall be inspected by the Contractor, in the presence of the
Engineer, in accordance with ASTM D4580, Method B. The Contractor shall mark those
areas of the existing bridge deck requiring further deck preparation.

Further deck preparation will be required when any one of the following conditions is
present:
1.  Unsound concrete in accordance with ASTM D4580, Method B.
2.  Lack of bond between existing concrete and reinforcing steel.
3.  All existing nonconcrete patches.

Modified Concrete Overlays

6-09

Dense, sound areas of existing bridge deck material shall be sufficiently scarified to the
limits shown in the plans in accordance with 6-09.3(5)A and is not considered further
deck preparation.

If the concrete overlay is placed on a bridge deck as part of the same Contract as the
bridge deck construction, then all Work associated with the further deck preparation shall
be performed at no additional expense to the Contracting Agency.

6-09.3(6)A

Equipment for Further Deck Preparation

Further deck preparation shall be performed using either power driven hand tools
conforming to

Section 6-09.3(1)A

, or hydro-demolition machines conforming to

Section 6-09.3(1)C

6-09.3(6)B

Deck Repair Preparation

All material in the repair area shall be removed by chipping, hydro demolishing, or
other approved mechanical means to a depth necessary to remove all loose and
unsound material.

Care shall be taken in removing the deteriorated material to not damage any of the
existing deck or steel reinforcing bars that are to remain in place. All removal shall
be accomplished by making vertical edges at the boundaries of the repair area. In no
case shall the depth of a sawn vertical cut exceed ¾ inch or to the top of the top steel
reinforcing bars, whichever is less.

The exposed steel reinforcing bars and concrete in the repair area shall be sandblasted or
hydro-blasted and blown clean just prior to placing concrete.

Where existing steel reinforcing bars inside deck repair areas show deterioration greater
than 20-percent section loss, the Contractor shall furnish and place steel reinforcing bars
alongside the deteriorated bars in accordance with the details shown in the Standard
Plans. Payment for such extra Work will be by force account as provided in

Section

1-09.6

Bridge deck areas outside the repair area or steel reinforcing bar inside or outside the
repair area damaged by the Contractor’s operations, shall be repaired by the Contractor at
no additional expense to the Contracting Agency, and to the satisfaction of the Engineer.

6-09.3(6)C

Placing Deck Repair Concrete

Deck repair concrete for modified concrete overlays shall be either modified concrete or
concrete Class M as specified below.

Before placing any deck repair concrete, the Contractor shall flush the existing concrete in
the repair area with water and make sure that the existing concrete is well saturated. The
Contractor shall remove any freestanding water prior to placing the deck repair concrete.
The Contractor shall place the deck repair concrete onto the existing concrete while it
is wet.

Page 6-250

Modified Concrete Overlays

Type 1 deck repairs, defined as deck repair areas with a maximum depth of one-half the
periphery of the bottom bar of the top layer of steel reinforcement or, where depths are
greater, the exposed bar length does not exceed 12-continuous inches along the length
of the bar, may be filled during the placement of the concrete overlay. The Work of Type
1 further deck preparation shall consist of removing and disposing of the concrete within
the repair area.

Type 2 deck repairs, defined as deck repair areas not conforming to the definition of Type
1 deck repairs, shall be repaired with concrete Class M to the scarification depth shown
in the plans and wet cured for 42 hours in accordance with

Section 6-09.3(13)

, prior to

placing the concrete overlay. The Work of Type 2 further deck preparation shall consist
of removing and disposing of concrete within the repair area, and furnishing, placing,
finishing, and curing the repair concrete. During the curing period, all vehicular and foot
traffic shall be prohibited on the repair area.

6-09.3(7) Surface Preparation for Concrete Overlay

Following the completion of any required further deck preparation the entire lane or
strip being overlaid shall be cleaned to be free from oil and grease, rust and other foreign
material that may still be present. These materials shall be removed by detergent-cleaning
or other method accepted by the Engineer followed by sandblasting.

After detergent cleaning and sandblasting is completed, the entire lane or strip being
overlaid shall be cleaned in final preparation for placing concrete.

Hand tool chipping, sandblasting and cleaning in areas adjacent to a lane or strip being
cleaned in final preparation for placing concrete shall be discontinued when final
preparation is begun. Scarifying and hand tool chipping shall remain suspended until
the concrete has been placed and the requirement for curing time has been satisfied.
Sandblasting and cleaning shall remain suspended for the first 24 hours of curing time
after the completion of concrete placing.

Scarification, and removal of the upper layer of concrete overlay when present, may
proceed during the final cleaning and overlay placement phases of the Work on adjacent
portions of the Structure so long as the scarification and concrete overlay removal
operations are confined to areas which are a minimum of 100 feet away from the
defined limits of the final cleaning or overlay placement in progress. If the scarification
and concrete overlay removal impedes or interferes in any way with the final cleaning
or overlay placement as determined by the Engineer, the scarification and concrete
overlay removal Work shall be terminated immediately and the scarification and concrete
overlay removal equipment removed sufficiently away from the area being prepared or
overlaid to eliminate the conflict. If the grade is such that water and contaminants from
the scarification and concrete overlay removal operation will flow into the area being
prepared or overlaid, the scarification and concrete overlay removal operation shall be
terminated and shall remain suspended for the first 24 hours of curing time after the
completion of concrete placement.

Modified Concrete Overlays

6-09

If, after final cleaning, the lane or strip being overlaid becomes wet, the Contractor
shall flush the surface with high-pressure water, prior to placement of the overlay. All
freestanding water shall be removed prior to concrete placement. Concrete placement
shall begin within 24 hours of the completion of deck preparation for the portion of the
deck to be overlaid. If concrete placement has not begun within 24 hours, the lane or strip
being overlaid shall be cleaned by a light sand blasting followed by washing with the high-
pressure water spray or by cleaning with the high-pressure spray.

Traffic other than required construction equipment will not be permitted on any portion
of the lane or strip being overlaid that has undergone final preparation for placing
concrete unless allowed by the Engineer. To prevent contamination, all equipment allowed
on the deck after final cleaning shall be equipped with drip guards.

6-09.3(8) Quality Assurance

6-09.3(8)A

Quality Assurance for Microsilica Modified and Fly Ash Modified

Concrete Overlays

The Engineer will perform slump, temperature, and entrained air tests for acceptance in
accordance with

Section 6-02.3(5)D

and as specified in this section after the Contractor

has turned over the concrete for acceptance testing. Concrete samples for testing shall
be supplied to the Engineer in accordance with

Section 6-02.3(5)E

. Concrete from the

first truckload shall not be placed until tests for acceptance have been completed by the
Engineer and the results indicate that the concrete is within acceptable limits. Sampling
and testing will continue for each load until two successive loads meet all applicable
acceptance test requirements. Except for the first load of concrete, up to ½ cubic yard
may be placed prior to testing for acceptance. After two successive tests indicate that the
concrete is within specified limits, the sampling and testing frequency may decrease to
one for every three truckloads. Loads to be sampled will be selected in accordance with
the random selection process outlined in FOP for WAQTC TM2.

When the results of any subsequent acceptance test indicates that the concrete does not
conform to the specified limits, the sampling and testing frequency will be resumed for
each truckload. Whenever two successive subsequent tests indicate that the concrete is
within the specified limits, the random sampling and testing frequency of one for every
three truck loads may resume.

6-09.3(8)B

Quality Assurance for Latex Modified Concrete Overlays

The Engineer will perform slump, temperature, and entrained air tests for acceptance in
accordance with

Section 6-02.3(5)D

and as specified in this section after the Contractor

has turned over the concrete for acceptance testing. The Engineer will perform testing
as the concrete is being placed. Samples shall be taken on the first charge through each
mobile mixer and every other charge thereafter. The sample shall be taken after the first 2
minutes of continuous mixer operation. Concrete samples for testing shall be supplied to
the Engineer in accordance with

Section 6-02.3(5)E

Page 6-252

Modified Concrete Overlays

During the initial proportioning, mixing, placing, and finishing operations, the Engineer
may require the presence of a technical representative from the latex admixture
manufacturer. The technical representative shall be capable of performing, demonstrating,
inspecting, and testing all of the functions required for placement of the latex modified
concrete as specified in

Section 6-09.3(11)

. This technical representative shall aid in

the proper installation of the latex modified concrete. Recommendations made by the
technical representative on or off the jobsite shall be adhered to by the Contractor. The
Engineer will advise the Contractor in writing a minimum of 5 working days before such
services are required.

6-09.3(9) Mixing Concrete For Concrete Overlay

6-09.3(9)A

Mixing Microsilica Modified or Fly Ash Modified Concrete

Mixing of concrete shall be in accordance with

Section 6-02

, with the following

exceptions:
1. The mixing shall be done at a batch plant.
2. The volume of concrete transported by truck shall not exceed 6-cubic yards per

truck.

6-09.3(9)B

Mixing Latex Modified Concrete

The equipment used for mixing the concrete shall be operated with strict adherence to
the procedures set forth by its manufacturer.

A minimum of two mixers will be required at the overlay site for each concrete placement
when the total volume of concrete to be placed during the concrete placement exceeds
the material storage capacity of a single mixer. Additional mixers may be required if
conditions require that material be stockpiled away from the jobsite. The Contractor
shall have sufficient mixers on hand to ensure a consistent and continuous delivery and
placement of concrete throughout the concrete placement.

Charging the mobile mixer shall be done in the presence of the Engineer. Mixing
capabilities shall be such that the finishing operation can proceed at a steady pace.

6-09.3(10) Overlay Profile and Screed Rails

6-09.3(10)A

Survey of Existing Bridge Deck Prior to Scarification

Prior to beginning the scarifying concrete surface finish work specified under

Section

6-09.3(5)

, the Contractor shall complete a survey of the existing bridge deck(s) specified

to receive modified concrete overlay for use in establishing the existing cross section and
grade profile elevations.

The Contracting Agency will provide the Contractor with primary survey control
information consisting of descriptions of two primary control points used for the
horizontal and vertical control. Primary control points will be described by reference to
the bridge or project-specific stationing and elevation datum. The Contracting Agency
will also provide horizontal coordinates for the beginning and ending points and for

Modified Concrete Overlays

6-09

each Point of Intersection (PI) on each centerline alignment included in the project. The
Contractor shall provide the Engineer 21 calendar days notice in advance of scheduled
concrete surface scarification work to allow the Contracting Agency time to provide the
primary survey control information.

The Contractor shall verify the primary survey control information furnished by the
Contracting Agency and shall expand the survey control information to include secondary
horizontal and vertical control points as needed for the project. The Contractor’s survey
records shall include descriptions of all survey control points, including coordinates and
elevations of all secondary control points.

The Contractor shall maintain detailed survey records, including a description of the work
performed on each shift, the methods utilized to conduct the survey, and the control
points used. The record shall be of sufficient detail to allow the survey to be reproduced.
A Type 1 Working Drawing of each day’s survey record shall be provided to the Engineer
within 3 working days after the end of the shift. The Contractor shall compile the survey
information in an electronic file format acceptable to the Contracting Agency (Excel
spreadsheet format is preferred).

Survey information collected shall include station, offset, and elevation for each lane
line and curb line. Survey information shall be collected at even 20-foot station intervals
and also at the centerline of each bridge expansion joint. The Contractor shall ensure a
surveying accuracy to within ± 0.01 feet for vertical control and ± 0.2 feet for horizontal
control. The survey shall extend 100 feet beyond the bridge back of pavement seat.

Except for the primary survey control information furnished by the Contracting Agency,
the Contractor shall be responsible for all calculations, surveying, and measuring required
for setting, maintaining, and resetting equipment and materials necessary for the
construction of the overlay to the final grade profile. The Contracting Agency may post-
check the Contractor’s surveying, but these post-checks shall not relieve the Contractor
of responsibility for internal survey quality control.

The Contracting Agency will establish the final grade profile based on the Contractor’s
survey, and will provide the final grade profile to the Contractor within three working days
after receiving the Contractor’s survey information.

The Contractor shall not begin scarifying concrete surface work specified under

Section

6-09.3(5)

until receiving the final grade profile from the Engineer.

6-09.3(10)B

Establishing Finish Overlay Profile

The finish grade profile shall be + ¼ inch/- ⅛ inch from the Engineer’s final grade profile.

The final grade profile shall be verified prior to the placement of modified concrete
overlay with the screed rails in place. The finishing machine shall be passed over the
entire surface to be overlaid and the final screed rail adjustments shall be made. If the
resultant overlay thickness is not compatible with the finish grade profile generated
by the Contractor’s screed rail setup, the Contractor shall make profile adjustments as
specified by the Engineer. After the finish overlay profile has been verified, changes in
the finishing machine elevation controls will not be allowed. The Contractor shall be

Page 6-254

Modified Concrete Overlays

responsible for setting screed control to obtain the specified finish grade overlay profile
as well as the finished surface smoothness requirements specified in

Section 6-02.3(10)

Screed rails upon which the finishing machine travels shall be placed outside the area to
be overlaid, in accordance with item 7 of

Section 6-09.3(2)

. Interlocking rail sections or

other approved methods of providing rail continuity are required.

Hold-down devices shot into the concrete are not permitted unless the concrete is to be
subsequently overlaid. Hold-down devices of other types leaving holes in the exposed
area will be allowed provided the holes are subsequently filled with mortar conforming
to

Section 9-20.4(2)

mixed at a 1:2 cement/aggregate ratio. Hold-down devices shall not

penetrate the existing deck by more than ¾ inch.

Screed rails may be removed at any time after the concrete has taken an initial set.
Adequate precautions shall be taken during the removal of the finishing machine and rails
to protect the edges of the new surfaces.

6-09.3(11) Placing Concrete Overlay

Five to ten working days prior to modified concrete overlay placement, a preoverlay
conference shall be held to discuss equipment, construction procedures, personnel, and
previous results. Inspection procedures shall also be reviewed to ensure coordination.
Those attending representing the Contractor shall include the superintendent and all
foremen in charge of placing and finishing the modified concrete overlay.

If the project includes more than one bridge deck, an additional conference shall be held
just before placing modified concrete overlay for each subsequent bridge deck.

The Contractor shall not place modified concrete overlay until the Engineer agrees that:
1. Modified concrete overlay producing and placement rates will be high enough to

meet placing and finishing deadlines,

2. Finishers with enough experience have been employed, and
3. Adequate finishing tools and equipment are at the site.

Concrete placement shall be made in accordance with

Section 6-02

and the following

requirements:
1. After the lane or strip to be overlaid has been prepared and immediately before

placing the concrete, it shall be thoroughly soaked and kept continuously wet with
water for a minimum period of 6 hours prior to placement of the concrete. All
freestanding water shall be removed prior to concrete placement. During concrete
placement, the lane or strip shall be kept moist.

The concrete shall then be promptly and continuously delivered and deposited on
the placement side of the finishing machine.

Modified Concrete Overlays

6-09

If latex modified concrete is used, the concrete shall be thoroughly brushed into the
surface and then brought up to final grade. If either microsilica modified concrete
or fly ash modified concrete are used, a slurry of the concrete, excluding aggregate,
shall be thoroughly brushed into the surface prior to the overlay placement.

Care shall be exercised to ensure that the surface receives a thorough, even coating
and that the rate of progress is limited so that the brushed concrete does not
become dry before it is covered with additional concrete as required for the final
grade. All aggregate which is segregated from the mix during the brushing operation
shall be removed from the deck and disposed of by the Contractor.

If either microsilica modified concrete or fly ash modified concrete are used, the
Contractor shall ensure that a sufficient number of trucks are used for concrete
delivery to obtain a consistent and continuous delivery and placement of concrete
throughout the concrete placement operation.

When concrete is to be placed against the concrete in a previously placed transverse
joint, lane, or strip, the previously placed concrete shall be sawed back 6 inches to
straight and vertical edges and shall be sandblasted or water blasted before new
concrete is placed. The Engineer may decrease the 6 inch saw back requirement to
2 inches minimum, if a bulkhead was used during previous concrete placement and
the concrete was hand vibrated along the bulkhead.

2. Concrete placement shall not begin if rain is expected. Adequate precautions shall

be taken to protect freshly placed concrete in the event that rain begins during
placement. Concrete that is damaged by rain shall be removed and replaced by
the Contractor at no additional expense to the Contracting Agency, and to the
satisfaction of the Engineer.

3. Concrete shall not be placed when the temperature of the concrete surface is

less than 45ºF or greater than 75ºF, and wind velocityone foot above the bridge
deck is in excess of 10 mph. If the Contractor elects to Work at night to meet
these criteria, adequate lighting shall be provided at no additional expense to the
Contracting Agency.

4. If concrete placement is stopped for a period of ½ hour or more, the Contractor

shall install a bulkhead transverse to the direction of placement at a position where
the overlay can be finished full width up to the bulkhead. The bulkhead shall be full
depth of the overlay and shall be installed to grade. The concrete shall be finished
and cured in accordance with these Specifications.

Further placement is permitted only after a period of 12 hours unless a gap is left
in the lane or strip. The gap shall be of sufficient width for the finishing machine
to clear the transverse bulkhead installed where concrete placement was stopped.
The previously placed concrete shall be sawed back from the bulkhead, to a point
designated by the Engineer, to straight and vertical edges and shall be sandblasted or
water blasted before new concrete is placed.

5. Concrete shall not be placed against the edge of an adjacent lane or strip that is less

than 36 hours old.

Page 6-256

Modified Concrete Overlays

6-09.3(12) Finishing Concrete Overlay

Finishing shall be accomplished in accordance with the applicable portions of

Section 6-02.3(10)

and as follows. Concrete shall be placed and struck-off approximately

½ inch above final grade and then consolidated and finished to final grade with a single
pass (the Engineer may require additional passes) of the finishing machine. Hand finishing
may be necessary to close up or seal off the surface. The final product shall be a dense
uniform surface.

Latex shall not be sprayed on a freshly placed latex modified concrete surface; however,
a light fog spray of water is permitted if required for finishing, as determined by
the Engineer.

Construction dams shall be separated from the newly placed concrete by passing a
pointing trowel along the inside surfaces of the dams. Care shall be exercised to ensure
that this trowel cut is made for the entire depth and length of the dams after the concrete
has stiffened sufficiently that it does not flow back.

6-09.3(13) Curing Concrete Overlay

As the finishing operation progresses, the concrete shall be immediately covered with
a single layer of clean, new or used, wet burlap. The burlap shall have a maximum width
of 6 feet. The Engineer will determine the suitability of the burlap for reuse, based on the
cleanliness and absorption ability of the burlap. Care shall be exercised to ensure that the
burlap is well drained and laid flat with no wrinkles on the deck surface. Adjacent strips of
burlap shall have a minimum overlap of 6 inches.

Once in place the burlap shall be lightly fog sprayed with water. A separate layer of white,
reflective type polyethylene sheeting shall immediately be placed over the wet burlap.

As an alternative to the application of burlap and fog spraying described above, the
Contractor may propose a curing system using proprietary curing blankets specifically
manufactured for bridge deck curing. The Contractor shall submit a Type 2 Working
Drawing consisting of details of the proprietary curing blanket system, including product
literature and details of how the system is to be installed and maintained.

The wet curing regimen as described shall remain in place for a minimum of 42-hours.

6-09.3(14) Checking for Bond

After the requirements for curing have been met, the entire overlaid surface shall be
sounded by the Contractor in accordance with ASTM D4580, in a manner accepted by
and in the presence of the Engineer, to ensure total bond of the concrete to the bridge
deck. Concrete in unbonded areas shall be removed and replaced by the Contractor at
no additional expense to the Contracting Agency, in accordance with

Section 6-09.3(6)

except as modified here.

Saw cut the edges around the repair area with an edge perpendicular to the concrete
surface. The depth of the saw cut shall be ¾ inch, but shall be reduced if necessary
to avoid damaging any reinforcement. The geometry of the repair perimeter shall be

Modified Concrete Overlays

6-09

rectangular, avoiding reentrant corners. All concrete in the removal area shall be removed
by chipping, or other approved mechanical means to the depth necessary to remove all
loose or unsound concrete. All removal shall maintain square edges at the boundaries
of the repair area. Concrete for patching shall be

the same modified concrete as used in

the overlay.

The repair area shall be wet cured for 42 hours in accordance with Section 6-09.3(13).
After curing requirements have been met, all repaired areas shall be sounded by the
Contractor in accordance with this section.

6-09.3(15) Sealing and Texturing Concrete Overlay

After the requirements for checking for bond have been met, all joints and visible cracks
shall be filled and sealed with a high molecular weight methacrylate resin (HMWM).

Cracks 1/16 inch and

greater in width shall receive two applications of HMWM.

Immediately following the application of HMWM, the wetted surface shall be coated with
sand for abrasive finish.

After all cracks have been filled and sealed and the HMWM resin has cured, the
concrete overlay surface shall receive a longitudinally sawn texture in accordance with
Section 6-02.3(10)D5.

Traffic shall not be permitted on the finished concrete until it has reached a minimum
compressive strength of 3,000 psi as verified by rebound number determined in
accordance with ASTM C805 and the longitudinally sawn texture is completed.

6-09.4 Measurement

Scarifying concrete surface will be measured by the square yard of surface actually
scarified.

Modified concrete overlay will be measured by the cubic foot of material placed. For
latex modified concrete overlay, the volume will be determined by the theoretical yield of
the design mix and documented by the counts of the cement meter less waste. For both
microsilica modified concrete overlay and fly ash modified concrete overlay, the volume
will be determined from the concrete supplier’s Certificate of Compliance for each batch
delivered less waste. Waste is defined as the following:
1. Material not placed.
2. Material placed in excess of 6 inches outside a longitudinal joint or transverse joint.

Finishing and curing modified concrete overlay will be measured by the square yard of
overlay surface actually finished and cured.

Further deck preparation for Type 1 deck repair and for Type 2 deck repair will be
measured by the square foot of surface area of deck concrete removed in accordance
with

Section 6-09.3(6)

Page 6-258

Modified Concrete Overlays

6-09.5 Payment

Payment will be made for each of the following Bid items that are included in the Bid
Proposal:

“Scarifying Conc. Surface”, per square yard.
The unit Contract price per square yard for “Scarifying Conc. Surface” shall be full
pay for performing the Work as specified, including testing and calibration of the
machines and tools used, containment, collection, and disposal of all water and
abrasives used and debris created by the scarifying operation, measures taken to
protect adjacent traffic from flying debris, and final cleanup following the scarifying
operation.
“Modified Conc. Overlay”, per cubic foot.
The unit contract price per cubic foot for “Modified Conc. Overlay” shall be full pay
for furnishing the modified concrete overlay, including the overlay material placed
into Type 1 deck repairs in accordance with

Section 6-09.3(6)C

“Finishing and Curing Modified Conc. Overlay”, per square yard.
The unit Contract price per square yard for “Finishing and Curing Modified Conc.
Overlay” shall be full pay for performing the Work as specified, including placing,
finishing, and curing the modified concrete overlay, checking for bond, and sealing all
cracks.
“Further Deck Preparation for Type 1 Deck Repair”, per square foot.
“Further Deck Preparation for Type 2 Deck Repair”, per square foot.
“Structure Surveying”, lump sum.
The lump sum contract price for “Structure Surveying” shall be full pay to perform
the work as specified, including establishing secondary survey control points,
performing survey quality control, and recording, compiling, and submitting the
survey records to the Engineer.

Concrete Barrier

6-10

Concrete Barrier

6-10.1 Description

This section applies to building precast or cast-in-place cement concrete barriers as
required by the Plans, these Specifications, or the Engineer.

This Work may also include the removal, storage and resetting of permanent barrier at the
locations shown in the Plans or as specified by the Engineer.

6-10.2 Materials

Materials shall meet the requirements of the following sections:
Cement

9-01

Aggregates

9-03

Premolded Joint Fillers

9-04.1

Reinforcing Steel

9-07

Grout

9-20.3

Wire rope shall be Class 6 × 19, made of improved plow steel that has been galvanized
and preformed. Galvanizing shall meet ASTM A603. The wire rope shall have right regular

lay and a fiber core. It shall be ⅝ inch in diameter and have a minimum breaking strength

of 15 tons.

All hardware (connecting pins, drift pins, nuts, washers, etc.) shall be galvanized in keeping
with AASHTO M 232.

Connecting pins, drift pins and steel pins for type 3 anchors shall conform to

Section

9-06.5(4)

and be galvanized in accordance with AASHTO M232. All other hardware shall

conform to

Section 9-06.5(1)

and be galvanized in accordance with AASHTO M232.

Grout for permanent installations of precast single slope barrier shall conform to

Section

9-20.3(3)

and shall be placed in accordance with

Section 6-02.3(20)

6-10.3

Construction Requirements

Single slope barrier shall be cast-in-place or slipformed, except when precast single slope
barrier is specified in the Plans or specified by the Engineer. Concrete barrier installed in
conjunction with light standard foundations and sign bridge foundations, regardless of the
barrier shape, shall be cast-in-place using stationary forms.

Concrete barrier transition Type 2 to bridge f-shape shall be precast.

Steel welded wire reinforcement deformed, conforming to

Section 9-07.7

, may

be substituted in concrete barrier in place of deformed steel bars conforming to

Section 9-07.2

, subject to the following conditions:

1. Steel welded wire reinforcement spacing shall be the same as the deformed steel bar

spacing shown in the

Standard Plans

Page 6-260

Concrete Barrier

2. The minimum cross sectional area for steel welded wire reinforcement shall be no

less than 86 percent of the cross sectional area for the deformed steel bars being
substituted.

3. Development lengths and splice lengths shall conform to requirements specified in

the AASHTO LRFD Bridge Design Specifications, current edition.

6-10.3(1) Precast Concrete Barrier

The fabrication plant for precast concrete barriers shall be approved by Contracting
Agency prior to the use of barrier and the plant shall perform quality control testing and
inspection on all barrier used by the Contracting Agency. The Contractor shall advise the
Engineer of the production schedule for the fabrication of barrier.

Test results from the fabricators QC testing shall demonstrate compliance with Sections

6-02.3(4)C

consistency,

6-02.3(4)D

temperature and time of placement,

6-02.3(2)A

air content, and compressive strength. All tests will be conducted in accordance with

Section 6-02.3(5)D

The fabricators QC tester conducting the sampling and testing shall be qualified by ACI,
Grade I to perform this Work. The equipment used shall be calibrated/certified annually.

All test results and certifications shall be kept at the fabricator’s facility for review by the
Contracting Agency.

The Contracting Agency intends to perform Quality Assurance Inspection. This inspection
is for the qualification of the plant QC process. This inspection shall not relieve the
Contractor of any responsibility for identifying and replacing defective material
and workmanship.

The concrete in precast barrier shall be Class 5000 for Type F and Class 4000 for all other
precast barriers, and comply with the provisions of

Section 6-02.3

. If Self-Consolidating

Concrete is used, the concrete shall conform to Sections

6-02.3(27)B

and

6-02.3(27)C

No concrete barrier shall be shipped until test cylinders made of the same concrete and
cured under the same conditions show the concrete has reached the specified 28 day
compressive strength.

The Contractor may use Type III portland cement, but shall bear any added cost.

Precast barrier shall be cast in steel forms. After release, the barrier shall be finished to
an even, smooth, dense surface, free from any rock pockets or holes larger than ¼ inch
across. Troweling shall remove all projecting concrete from the bearing surface.

If heat curing methods are used, precast concrete barrier shall be cured in accordance
with

Section 6-02.3(25)D

except that the barrier shall be cured in the forms until a

rebound number test, or test cylinders which have been cured under the same conditions
as the barrier, indicate the concrete has reached a compressive strength of a least 70%
of the specified 28 day compressive strength. No additional curing is required once the
barrier is removed from the forms.

Standard Specifications for Road, Bridge, and Municipal Construction 2020 (M 41-10) - page 37