6-21Modified Concrete Overlay - Microsilica or Fly Ash

6-21 Modified Concrete Overlay - Microsilica or Fly Ash

6-21.1 Description

This Section 6-21 is for Contracts with the bid item “Modified Concrete Overlay” when the Contractor elects to use microsilica modified concrete or fly ash modified concrete for the overlay. If the Contractor elects to use latex modified concrete for the overlay, use Section 6-22, Modified Concrete Overlay - Latex. This Work consists of surveying, Scarifying the existing concrete bridge deck, removing and replacing unsound concrete below the Scarification Depth, and placing, finishing, curing, and texturing a modified concrete overlay using microsilica modified concrete or fly ash modified concrete.

6-21.1(1) Definitions

Existing Bridge Deck Surface – The surface of the existing bridge deck upon which traffic rides prior to any Work by the Contractor. It includes wheel ruts and other anomalies, if any. Existing Bridge Deck Surface Model – The three-dimensional model of the Existing Bridge Deck Surface, described by station, offset, and elevation, as required in Section 6-21.3(4), Surveying for Scarification and Modified Concrete Overlay. The Existing Bridge Deck Surface Model is created by the Contractor. Idealized Existing Bridge Deck Surface Model – This is the surface from which the Contractor shall measure the Scarification Depth. The Engineer will create the Idealized Existing Bridge Deck Surface Model by making Engineer-desired adjustments to the profile and transverse slopes of the Contractor’s Existing Bridge Deck Surface Model. These Engineer desired adjustments may include eliminating wheel ruts, eliminating bird baths, or improving the ride across and off the bridge. The Idealized Existing Bridge Deck Surface Model is composed of centerline station, elevation, and superelevation, and for crown and grade breaks will additionally include offset, elevation, and superelevation. These will be provided for the same centerline and stations supplied by the Contractor in the Existing Bridge Deck Surface Model. Top of Overlay Model – The three-dimensional model of the required top of finished modified concrete overlay surface, created by the Engineer and provided for the Contractor’s use in setting the finish grades of the concrete finishing machine. The Top of Overlay Model will usually be parallel to the Idealized Existing Bridge Deck Surface Model in order to provide an overlay of uniform thickness. It is composed of centerline station, elevation, and superelevation, and for crown and grade breaks will additionally include offset, elevation, and superelevation. These will be provided for the same centerline and stations provided by the Contractor in the Existing Bridge Deck Surface Model. Process Wastewater means all non-stormwater which, during manufacturing or processing, comes into direct contact with or results from the production or use of raw material, intermediate product, finished product, byproduct, or waste product. If stormwater commingles with Process Wastewater, the commingled water is considered Process Wastewater. Process Wastewater includes water used by the Contractor, which includes but is not limited to:

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M 41-10 Page 6-313 Scarification Depth – The depth identified as such in the plans. It is measured from (a) the Idealized Existing Bridge Deck Surface to (b) the mean depth between peaks and valleys of the deck surface after hydro demolition.

6-21.2(1) Modified Concrete

The decision of whether to use microsilica modified concrete or fly ash modified concrete for the modified concrete overlay belongs to the Contractor. However, the Contractor shall not use both on any one bridge.

6-21.2(1)A Microsilica Modified Concrete

Microsilica modified concrete shall be a workable mix, uniform in composition and consistency. Mix proportions per cubic yard of microsilica modified concrete shall be as follows: Portland Cement Type 1 or Type 2, or Blended Hydraulic Cement Type IL(X) 658 pounds Microsilica Fume 52 pounds Fine Aggregate 1,515 pounds Coarse Aggregate 1,515 pounds Water/Cementitious Ratio 0.33 maximum Air (± 1½ percent) 6 percent Slump 7 inches maximum Fly ash, ground granulated blast furnace slag, and Type 3 portland cement shall not be used in microsilica modified concrete. Fine aggregate shall be Class 1. Coarse aggregate shall be AASHTO grading No. 7 or No. 8. Microsilica admixture shall be either a dry powder or a slurry admixture. Microsilica will be accepted based on submittal of a Manufacturer’s Certificate of Compliance in accordance with Section 1-06.3. If the microsilica is a slurry admixture, the microsilica content of the slurry shall be certified as a percent by mass. The Contractor shall adjust the slump to accommodate the gradient of the bridge deck, subject to the maximum slump specified. The maximum allowable and actual water/cementitious ratio shall be calculated using all of the available mix water, including water added at the plant, water added in transit and at the job site, water in all admixtures, water in the microsilica slurry if a slurry is used, and the free water in the aggregates but not the water absorbed by the aggregates. The following are considered cementitious materials: portland cement, blended hydraulic cement, and microsilica fume. All water-reducing and air entraining admixtures, and superplasticizers, shall be used in accordance with the admixture manufacturer’s recommendations. Mixing of microsilica modified concrete shall be in accordance with Section 6-02, with the following exceptions:

6-21.2(1)B Fly Ash Modified Concrete

Fly ash modified concrete shall be a workable mix, uniform in composition and con- sistency. Mix proportions per cubic yard of fly ash modified concrete shall be as follows: Modified Concrete Overlay - Microsilica or Fly Ash 6-21 Page 6-314 M 41-10 Portland Cement Type 1 or Type 2, or Blended Hydraulic Cement Type IL(X) 611 pounds Fly Ash 275 pounds Fine Aggregate 38 percent of total aggregate Coarse Aggregate 62 percent of total aggregate Water/Cementitious Ratio 0.30 maximum Air (± 1½ percent) 6 percent Slump 7 inches maximum Fly ash shall be Class F only. The Contractor may substitute 886 pounds of blended hydraulic cement Type IP(X)MS for the following: 611 pounds of portland cement Type 1 or 2 and 275 pounds of fly ash. Only Type IP(X)MS that is blended with Class F fly ash is permitted for use. Type IP(X)MS that is blended with natural pozzolans, granulated blast furnace slag, or Type 3 portland cement are not allowed. Ground granulated blast furnace slag and Type 3 portland cement shall not be used in fly ash modified concrete. Fly ash shall not be used in blended hydraulic cement Type IL(X). Fine aggregate shall be Class 1. Coarse aggregate shall be AASHTO grading No. 7 or No. 8. The Contractor shall adjust the slump to accommodate the gradient of the bridge deck, subject to the maximum slump specified. The maximum allowable and actual water/cementitious ratios shall be calculated using all the available mix water, including water added at the plant, water added in transit and at the job site, water in all admixtures, and the free water in the aggregates but not the water absorbed by the aggregates. The following are considered cementitious materials: portland cement, blended hydraulic cement, and fly ash. All water-reducing and air entraining admixtures, and superplasticizers, shall be used in accordance with the admixture manufacturer’s recommendations. Mixing fly ash modified concrete shall be in accordance with Section 6-02, with the following exceptions:

6-21.2(2) Concrete Class M

Concrete Class M shall be proportioned in accordance with the following mix design: Portland Cement Type 1 or Type 2, or Blended Hydraulic Cement Type IL(X) 705 pounds Fine Aggregate 1,280 pounds Coarse Aggregate 1,650 pounds Water/Cement Ratio 0.37 maximum Air (± 1½ percent) 6 percent Slump (± 1 inch) 5 inches The following shall not be used in concrete Class M or in blended hydraulic cement Type IL(X): fly ash, ground granulated blast furnace slag, and Type 3 portland cement. Fine aggregate shall be Class 1. Coarse aggregate shall be AASHTO grading No. 7 or No. 8.

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M 41-10 Page 6-315 The use of a water-reducing admixture conforming to AASHTO M 194 Type A will be required to produce Concrete Class M with the desired slump, Air entraining admixtures shall conform to AASHTO M 154. The use of accelerating admixtures or other types of admixtures is not allowed. Concrete Class M shall be mixed in batch-plants and delivered in ready-mix trucks conforming to Section 6-02.3(4)A. The maximum allowable and actual water/cementitious ratios shall be calculated using all the available mix water, including water added at the plant, water added in transit and at the job site, water in all admixtures, and the free water in the aggregates but not the water absorbed by the aggregates. The following are considered cementitious materials: portland cement and blended hydraulic cement.

6-21.2(3) Material for Sealing Cracks and Cold Joints

High Molecular Weight Methacrylate (HMWM) resin for crack and cold joint sealing shall conform to the following: Viscosity <25 cps (Brookfield RVT with UL adaptor, 50 rpm at 77°F) … California Test 434 Density 8.5 to 8.8 pounds per gallon at 77°F… ASTM D2849 Flash Point >200°F, PMCC (Pinsky-Martens CC) Vapor Pressure <0.04 inches Hg at 77°F, ASTM D323 Tg (DSC) >136°F, ASTM D3418 Gel Time 60 minutes minimum The promoter/initiator system for the methacrylate resin shall consist of a metal drier and peroxide. Sand for abrasive finish of the sealed cracks and cold joints shall be crushed sand, oven dried, and stored in moisture proof bags. The sand shall conform to the following gradation: Sieve SizePercent Passing Minimum Maximum No. 10 98 100 No. 16 55 75 No. 20 30 50 No. 30 8 25 No. 50 0 5 No. 100 0 3 All percentages are by weight. 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.

6-21.3 Construction Requirements

6-21.3(1) Sequence of Work

The general sequence of the Work shall be as follows:

6-21.3(2) Equipment

6-21.3(2)A Rotary Milling Machines

Rotary milling machines shall conform to the following:

6-21.3(2)B Hydro-Demolition Machines

6-21.3(2)B1 Hydro-Demolition Machine Requirements

Hydro-demolition machines shall conform to the following:

6-21.3(2)B2 Hydro-Demolition Trial Area Test

Prior to being approved for production use, the Contractor shall prepare a trial area in the bridge deck to be overlaid to demonstrate that the hydro-demolition equipment and methods of operation are capable of producing results satisfactory to the Engineer. The trial area shall consist of a patch of approximately 30 square feet in sound concrete as

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M 41-10 Page 6-317 determined by the Engineer. Satisfactory results include, but are not limited to, concrete removal within a tolerance of ±¼ inch of the Scarification Depth in sound concrete. The equipment shall be programmed to remove concrete to the 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.

6-21.3(2)C Power Driven Hand Tools

Power driven hand tools are limited to the following:

6-21.3(2)D Air Compressor

Air compressors shall be equipped with oil traps to eliminate oil from being blown onto the bridge deck.

6-21.3(2)E Vacuum Machine

Vacuum machines shall be capable of collecting all dust, concrete chips, freestanding water and other debris encountered while cleaning after Scarifying and after Type 1 and Type 2 Deck Repair. The machines shall be equipped with collection systems that allow the machines to be operated in air pollution sensitive areas and shall be equipped to not contaminate the deck during final preparation for concrete placement.

6-21.3(2)F Water Delivery System

The Contractor shall apply water at the pressures and volumes required for flushing, misting, saturating, and water-blasting. All water applied to the deck for these purposes shall be potable water and shall not be re-used. The water delivery system shall include a portable high-pressure sprayer. The sprayer shall be readily available to all parts of the deck being overlaid and shall be able to discharge water in a fine mist to prevent accumulation of free water on the deck, and for water-blasting concrete to remove laitance, rust, stains, dust, and loose paste. Sufficient water shall be available to thoroughly soak the deck being overlaid and to keep the deck wet prior to concrete placement. The Contractor shall certify that the units used meet the requirements in the table below: Minimum Requirements for Water Delivery Activity Water Pressure Flushing none specified Misting 2,500 psi Water Blasting 7,500 psi Saturating none specified

6-21.3(2)G Flushing Machine

The finishing machine shall meet the following requirements:

6-21.3(3) Submittals

The Contractor shall submit the following Working Drawings in accordance with Section 1-05.3:

6-21.3(4) and a Type 1 Working Drawing of each day’s survey record.

6-21.3(4) Surveying for Scarification and Modified Concrete Overlay

Prior to beginning Scarifying or otherwise removing materials from the Existing Bridge Deck Surface, the Contractor shall complete a survey of the Existing Bridge Deck Surface to establish the Existing Bridge Deck Surface Model (station, offset, and elevation) to form the basis for the Engineer to create the Idealized Existing Bridge Deck Surface Model

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M 41-10 Page 6-319 (station, offset, elevation) and, from that, the Top of Overlay Model (station, offset, and elevation). The Engineer 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 Engineer will also provide horizontal coordinates for the beginning and ending points and for 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 the Contractor’s scheduled surveying work to allow the Engineer time to provide the primary survey control information. The Contractor shall verify the primary survey control information furnished by the Engineer 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 Engineer (Excel spreadsheet format is preferred). Survey information collected by the Contractor to create the Existing Bridge Deck Surface Model shall include the station, offset, and elevation of every point of intersection on a grid created as follows:

6-21.3(5) Operations on the Bridge Deck

The following apply to all Contractor operations on the bridge deck, including but not limited to Scarification, cleaning concrete surfaces, Type 1 and Type 2 Deck Repair, sandblasting, water-blasting, placing, consolidating, finishing, curing, sawing, and sealing concrete:

6-21 3(3).

6-21 3(3).

6-21.3(3) The Contractor shall comply with applicable regulations concerning such

water disposal. Process Wastewater shall not be in-filtrated.

6-21.3(6) Scarifying Concrete Surface

6-21.3(6)A Prerequisites to Scarification

Scarifying shall not begin until after the Contractor has completed all the following:

6-21.3(1) can and will be completed in one and only one construction season.

6-21.3(6)B Restrictions on Scarification Methods

The method used to Scarify the bridge deck from the Existing Bridge Deck Surface down to ½ inch above the Scarification Depth shall be one of the following:

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M 41-10 Page 6-321

6-21.3(6)C Scarification Requirements

Prior to Scarification with a rotary milling machine, the Contractor shall verify the depth of the rebar. The Contractor shall conduct rotary milling in such a manner as to avoid snagging rebar. The Contractor shall Scarify the Existing Bridge Deck to the Scarification Depth and horizontal limits shown in the Plans. Determination of the elevation of the bottom of the Scarification Depth shall be in accordance with the definition of Scarification Depth in Dense, sound areas of existing bridge deck concrete that are difficult to remove with hydro-demolition or rotary milling equipment may, with the concurrence of the Engineer, be left in place provided the concrete is Scarified to a depth sufficient to provide a minimum thickness of Modified Concrete Overlay of 1.0 inch when measured from the peaks of the Scarified surface to the Top of Overlay Model.

6-21.3(6)D Requirements for Rotary Milling

The requirements of this section are in addition to the requirements for rotary milling equipment in Section 6-21.3(2)A. Rotary milling machines shall be operated to Scarify no deeper than the criteria in (1) and

6-21.3(6)E Requirements for Hydro-Demolishing

The requirements of this section are in addition to the requirements for hydro- demolishing equipment in Section 6-21.3(2)B. All hydro-demolition that is intended to remove concrete within a ½ inch immediately above the Scarification Depth shall be performed with rotary heads. The depth of concrete removal with the hydro-demolition machine shall not exceed 2.0 inches in sound concrete in one pass. If the Scarification Depth is less than or equal to 2.0 inches, the hydro-demolition machine shall remove sound concrete to the Scarification Depth in one pass of the machine, within a tolerance of ±¼ inch. Because this pass includes removal of the ½ inch immediately above the Scarification Depth, the full depth of removal shall be performed with rotary heads. If the Scarification Depth is greater than 2.0 inches, multiple passes shall be required, with no pass removing greater than 2 inches of sound concrete. Once the operating parameters of the Hydro-Demolition machine are defined by programming and calibration as specified in Section 6-21.3(2)B, they shall be monitored every 20 feet as the machine progresses across the bridge deck and adjusted as needed to prevent the unnecessary removal of sound concrete below the required Scarification Depth. Modified Concrete Overlay - Microsilica or Fly Ash 6-21 Page 6-322 M 41-10 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.

6-21.3(6)F Scarification Cleanup

After Scarifying is complete to the Scarification Depth and all concrete debris and rubble have been removed - over the entire lane or strip to be overlaid in one operation – the Contractor shall thoroughly vacuum and wash with high-pressure water the entire surface of all dust, freestanding water, and loose particles, to clean it in preparation for ASTM D4580 Method B inspection.

6-21.3(7) Deck Repair

6-21.3(7)A Classification

Deck repair will be classified as Type 1 Deck Repair or Type 2 Deck Repair. The determination of whether an area will be classified as Type 1 or Type 2 will not be made until after completion of deck repair excavation, repair of steel reinforcing bars, and removal of concrete debris.

6-21.3(7)B Chain Drag

After the entire lane or strip to be overlaid has been Scarified and cleaned as required in Section 6-21.3(6), the entire surface shall be inspected by the Contractor, in the presence of the Engineer, in accordance with ASTM D4580, Method B. Based on that inspection, the Contractor shall mark those areas, meeting any of the following criteria, for removal:

6-21.3(7)C Deck Repair Excavation

The areas marked for removal in Section 6-21.3(7)B shall be excavated with equipment as described in Section 6-21.3(2)C, or hydro-demolishing equipment. Excavation shall be to the depth necessary to remove all loose and unsound material, without damaging reinforcing steel or sound concrete. Care shall be taken in removing the deteriorated material to not damage the existing sound concrete 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. Bridge deck areas 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.

6-21 Modified Concrete Overlay - Microsilica or Fly Ash

M 41-10 Page 6-323

6-21.3(7)D Repair of Steel Reinforcing Bars

Where existing steel reinforcing bars inside deck repair areas show natural 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. All reinforcing steel damaged due to the Contractor’s operations shall be repaired by the Contractor. Damage to rebar shall be understood to include damage to epoxy coating. The repair shall be as follows or as directed by the Engineer:

6-21.3(7)E Type 1 Deck Repair

An area will be classified as a Type 1 Deck Repair when the completed concrete excavation complies with both of the following:

6-21.3(7)F Type 2 Deck Repair

An area will be classified as a Type 2 Deck Repair when the completed concrete excavation complies with both of the following:

6-21.3(7)G Filling and Curing Deck Repair Areas

Type 1 Deck Repairs shall be filled with Modified Concrete as part of and during placement of the Modified Concrete Overlay. See Section 6-21.3(8). Type 2 Deck Repairs shall be patched with either concrete Class M or modified concrete. The top of these patches shall be at the bottom elevation of the Scarification Depth. Regardless of whether the Contractor uses concrete Class M or modified concrete for the patching material, all Type 2 deck repair patching shall be performed well enough in advance of the modified concrete overlay to allow all patches to cure as required below. Before placing Concrete Class M or modified concrete in the Type 2 deck repairs, the Contractor shall clean the surfaces to which the concrete will be applied (including rebar) by (1) water-blasting, or (2) sandblasting and flushing with water. The Contractor shall make sure the existing concrete is well saturated at the time of placing concrete in the Type 2 deck repairs but shall remove all freestanding water prior to placing the concrete. The Contractor shall place concrete in the Type 2 deck repair areas while the existing concrete is wet. It shall be consolidated in accordance with Section 6-02.3(8) and wet cured for a minimum of 42 hours in accordance with the same requirements as the Modified Concrete Overlay in Section 6-21.3(10), but separately and prior to placing the Modified Concrete Overlay. During the curing period of concrete placed in Type 2 deck repairs, all vehicular and foot traffic shall be prohibited in the repair area.

6-21.3(8) Modified Concrete Overlay

6-21.3(8)A Surface Preparation

When modified 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

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M 41-10 Page 6-325 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. Following the completion of all Type 1 and Type 2 Deck Repairs (including placement and curing of patching Type 2 Deck Repair areas), the entire lane or strip being overlaid shall undergo final cleaning. Final cleaning shall be accomplished in one shift and consists of the following, in the sequence shown:

6-21.3(8)B Restrictions on Other Work

Hand tool chipping, sandblasting, water-blasting, and cleaning in areas adjacent to a lane or strip being cleaned in final preparation for placing modified 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 debris removal 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 debris 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 debris removal impedes or interferes in any way with the final cleaning or overlay placement as determined by the Engineer, the Scarification and debris removal Work shall be terminated immediately and the Scarification and debris 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 debris removal operation will flow into the area being prepared or overlaid, the Scarification and debris removal operation shall be terminated and shall remain suspended for the first 24 hours of curing time after the completion of concrete placement. 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. Modified Concrete Overlay - Microsilica or Fly Ash 6-21 Page 6-326 M 41-10

6-21.3(8)C Finishing Machine Setup

Screed rails upon which the finishing machine travels shall be placed outside the area to be overlaid. 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. A dry-run of the screed shall demonstrate a finished surface that is + ¼ inch/- ⅛ inch from the Engineer’s Top of Overlay Model. The finishing machine shall be passed over the entire surface to be overlaid and the final screed rail adjustments shall be made to comply with these tolerance limits. After adjustments are made to demonstrate compliance with these tolerance limits, changes in the finishing machine elevation controls will not be allowed. The Contractor shall be responsible for setting screed control to obtain the specified Top of Overlay Model as well as the finished surface smoothness requirements specified in Section 6-02.3(10)D3.

6-21.3(8)D Placing Modified Concrete Overlay

6-21.3(8)D1 Pre-Overlay Conference

Five to ten working days prior to modified concrete overlay placement, a pre-overlay 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, finishing, and curing 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.

6-21.3(8)D2 Placement of Modified Concrete Overlay

The Contractor shall not begin placing the modified concrete overlay until the Engineer agrees that:

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M 41-10 Page 6-327 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.

6-21.3(8)E Acceptance Testing Modified Concrete

When the Contractor has released the Concrete for acceptance testing, the Engineer will perform slump, temperature, and entrained air tests in accordance with Section 6-02.3(5) D and as specified in this section. 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 on the deck 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 Modified Concrete Overlay - Microsilica or Fly Ash 6-21 Page 6-328 M 41-10 requirements. Except for the first load of concrete, up to ½ cubic yard may be placed on the deck 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 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.

6-21.3(9) Finishing Modified Concrete Overlay

Finishing shall be accomplished in accordance with the applicable portions of Section

6-02 3(10), Section 6-21.3(2)G, 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. 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. Deck finishing machine screed rails may be removed at any time after the modified concrete overlay 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.

6-21.3(10) Curing Modified 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 burlap shall be kept wet continuously and the wet curing regimen as described shall remain in place for a minimum of 42-hours.

6-21.3(11) 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.

6-21.3(11)A Repairing Unbonded Concrete

All Work in this Section, 6-21.3(11)A, shall be performed at no additional expense to the Contracting Agency.

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M 41-10 Page 6-329 Concrete in unbonded areas shall be removed and replaced in accordance with the following:

6-21.3(12) Sealing and Texturing Concrete Overlay

After the requirements for checking for bond have been met, all cold joints (transverse and longitudinal, and around repair areas) 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 and cold joints 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.

6-21.4 Measurement

Scarifying concrete surface will be measured by the square yard of surface Scarified. Type 1 Deck Repair and Type 2 Deck Repair will be measured by the square foot of surface area, below the Scarification Depth, of deck concrete removed in accordance with Section 6-21.3(7) . Determination of whether a deck repair is Type 1 or Type 2 shall be in accordance with Section 6-21.3(7) . Modified concrete overlay will be measured by the cubic foot of material placed. 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:

6-21.5 Payment

Payment will be made for each of the following Bid items that are included in the Proposal: “Surveying for Modified Conc. Overlay”, lump sum. The lump sum contract price for “Surveying for Modified Conc. Overlay” shall be full pay to perform the work as specified, including establishing secondary survey control points, performing survey quality control, creating the Existing Bridge Deck Surface Model, and recording, compiling, and submitting the survey records to the Engineer. “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; Scarifying to the Scarification Depth; excavation of unsound concrete below the Scarification Depth when such unsound concrete is removed during the pass of the hydro-demolition machine intended to stop at the Scarification Depth; disposal of all debris generated; scarification cleanup. “Type 1 Deck Repair”, per square foot. The unit contract price per square foot for Type 1 Deck Repair shall be full pay for performing the work as specified, including excavating and disposing concrete, and repair of concrete or rebar damaged by the Contractor’s operations. “Type 2 Deck Repair”, per square foot. The unit contract price per square foot for Type 2 Deck Repair shall be full pay for performing the work as specified, including: excavating and disposing concrete; sandblasting and water-blasting; placing, consolidating, finishing, and curing concrete patches in Type 2 deck repairs; repair of concrete or rebar damaged by the Contractor’s operations. “Modified Conc. Overlay”, per cubic foot. The unit contract price per cubic foot for “Modified Conc. Overlay” shall be full pay for furnishing and placing the modified concrete overlay, including the overlay material placed into Type 1 Deck Repairs in accordance with Section 6-21.3(7)G, and preparing the surface for the overlay including cleaning, sandblasting, and water-blasting. “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 all work required under Sections 6-21.3(9),

6-21 3(10), 6-21.3(11), and 6-21.3(12) including finishing the modified concrete

overlay, curing the modified concrete overlay, checking for bond, repairing unbonded areas, sealing all cracks and cold joints, sanding, and providing longitudinally sawn texture. Payment for the following shall be considered incidental to and included in the unit contract items included in the contract:

6-21 Modified Concrete Overlay - Microsilica or Fly Ash