A.General Provide controls to limit dust. Perform concrete work in accordance with Section 509, “Structural Concrete.” Protect traffic under the bridge and adjacent to the work zone while removing bridge deck concrete.
B.Work Plan Before work begins, submit a work plan to the Engineer. Allow 14 days for the Engineer’s review. Include the following in the work plan: Planned work schedule including the following: Traffic control, Project phasing, Surface preparation, Production rate, Patching cure times, and Estimated time for overlay placement; Forming details; A list of project specific equipment to remove concrete, including hand tools; If using hydrodemolition, a plan for treating water used to remove concrete; For Concrete Overlays: A list of project specific equipment and back -up equipment for the following concrete procedures: Mixing, Placing, Consoli dating, Finishing, and Curing; A list of on -site equipment and material quantities for protection from rainy, cold, and hot weather; Concrete mix designs, and the expected travel time for delivery and placement; An outline of the process used for concrete, including the following rework areas: Removal, Surface preparation, Delivery, OVERLAY OF CONCRETE BRIDGE DECKS 505.04 339 Placement, Consolidation, Finishing, and Curing; and A list of checks that will ensure the overlay meets the dimensions shown on the Plans and the quality required by the Contract. For polymer concrete overlays, include the following additional items in the work plan: The compatibility of patching materials with the polymer concrete overlay material, The minimum air and deck surface temperatures, The manufacturer approval o f the work plan and the number of courses and minimum cure times for each course, The manufacturer’s written support of approval for any deviations from these specifications, and Necessary test reports, documentation, explanations, and justification to sup port the proposal. For asphalt membrane overlays, include the following additional items in the work plan: Type of membrane and tack that will be used, Limitations of pavement/deck temperature and moisture content, How the pavement/deck temperature and moi sture content will be measured, Length of time the membrane can be exposed before placing the asphalt overlay, Maximum temperature for the asphalt concrete overlay material, and How the curb line and deck drains will be sealed. Obtain authorization from th e Engineer to proceed before starting work.
C.Surface Preparation
1.Surface Preparation for Polymer Concrete Overlays Patch decks in accordance with subsection 513.04.C , “Deck Repairs and Patching .” Ensure patches obt ain required 28 day strength before placing overlay. Remove and dispose of existing overlays, asphalt, unsound concrete, and foreign material from the surface. Clean the deck surface by shot -blasting or water -blasting in accordance with Subsection 505.03.D, “Shot Blast Cleaning Equipment.” Shot -blast in accordance with International Concrete Repair Institute (ICRI) level 6 -7 after sand -blasting. Before placing the overlay, ensure the deck has no visible moisture. Test for moisture by taping a plastic sheet to the deck for at least 2 hr in accordance with ASTM D 4263 or other Engineer approved methods. Place overlay on hydraulic cement concrete of the Contract required strength. 505.0 4 OVERLAY OF CONCRETE BRIDGE DECKS 340 Shot Blast in accordance with the following: Protect metal deck drains and areas of the curb or railing above the proposed surface from the shot blast. Shot blast the surfaces specified in the plans and follow with an air blast using dry, oil free air or vacuum. Brooming is not acceptable. Remove all pavement marking, loose disintegrated concrete, dirt, paint, oil, asphalt laitance carbonation and curing materials from patches and other foreign material from the surface of the deck. Produce a surface reli ef equal to the International Concrete Repair Institute (ICRI) Surface Preparation Level 6 to 7 or ASTM E 965 Pavement Macrotexture Depth of 0.04 to 0.08 inch. Place the first coat of the polymer concrete overlay within 24 hours of preparing the deck surfa ce. Prepared surfaces exposed for more than 24 ours must be lightly sand blasted prior to application of the overlay.
2.Surface Preparation for Concrete Overlays Use a shot -blast or water -blast to prepare the surface for new decks. For existing decks, prepare deck surfaces using hydrodemolition, vacuuming, shielding, and water control. Scarify (mill) in conjunction with hydrodemolition. Provide controls to limit dust. Use jack hammering and other Engineer -approved methods to place the new concrete ov erlay where hydrodemolition cannot be used. Remove and dispose of existing overlays, asphalt, unsound concrete, and foreign material from the surface in accordance with Subsection 104.09 “Removal and Disposal of Salvag ed Materials Structures and Obstructions, ” and Subsection 107.01 “Laws Rules and Regulations To Be Observed.” Provide a rough, bondable surface at the depth shown on the Plans. Use the Contract required overlay materi al for deck patching. Monolithically place this material for the partial depth repairs. Make full depth repairs before placing the overlay in accordance with Section 513, “Repair of Concrete Bridge Decks.” Place expansion join ts as required by the Contract.
a.Decks with Overlays Remove the overlay with scarification before hydrodemolition for decks with overlays. For decks without overlays, scarify before hydrodemolition. Unless reinforcing steel is encountered, scarify dec k surface leaving last 1/2 in [12 mm] to be done by hydrodemolition.
b.Damage of Reinforcing Steel Immediately stop and adjust the removal depth if the mechanical scarifying equipment snags the top mat of deck reinforcing steel. Repair or replace damage d and dislodged reinforcing at no additional cost to the Department. Remove additional concrete to position the new reinforcing steel at the height shown on the Plans and Contract required lap splice lengths using a 15 lb [7 kg] chipping hammer at an angl e of no more than 45° from horizontal.
c.Hydrodemolition Perform the following if using hydrodemolition for surface preparation: Shield traveling public from debris. Block drains, expansion joints, and areas where water can drain from the deck. OVERLAY OF CONCRETE BRIDGE DECKS 505.04 341 Provide s ediment basins to strain water before releasing it. Adjust drainage treatment until the released water runs clear. Provide a technical field representative on the project site during calibration and hydrodemolition surface preparation operations. Calibrat e the hydrodemolition equipment on an area of sound concrete, and verify that every square inch of the deck is uniformly blasted. Establish the rate of travel and water pressure to selectively remove the deteriorated concrete. Selectively remove deteriora ted concrete using pressures in the range of 13,000 to 20,000 psi [90 to 140 Mpa]. Calibrate the equipment by moving it to an area with unsound concrete to verify that the proposed settings are adequate to remove the unsound concrete after calibration. Modify these settings, if necessary, to remove concrete to the minimum depth shown on the Plans. Hydrodemolish the top surface of the reinforced concrete bridge deck to make a rough and bondable surface. Wash the deck surface with pressurized water to dislo dge debris and slurry. Before the debris and slurry dry, use a high powered vacuum cleaner to clean the deck in one pass. Remove dried material at no additional cost to the Department. Sound the dry deck and mark unsound areas. Repeat the process if the hydrodemolition surface preparation does not leave a bondable surface, remove unsound concrete, rust, oil, asphalt, or other foreign matter, and leave a clean etched concrete surface free of laitance. Splice exposed reinforcing steel if more than 20 percen t of the reinforcing steel section bar area is lost. Where more than one half the reinforcing steel is exposed, handwork areas with 15 lb [7 kg] chipping hammers at 45° angles from horizontal to provide at least ¾ in [20 mm] of clearance around the bar. M inimize the amount of reinforcing steel exposed during hydrodemolition. Use hand -held blast cleaning equipment or 15 lb [7 kg] chipping hammers to clean and provide a bondable surface of the portion of the curb, the parapet wall, or both at the edge of the new overlay.
d.Grouting for High Density Concrete Scrub a thin, even coating of bonding grout into the dry, prepared surface before placing high density concrete. Prevent grout from collecting in pockets. Limit the application rate to ensure the grout does not dry before concrete placement. Since grout will dry on a vertical surface more rapidly than on the flat deck surface, carefully maintain the grout according to the surface condition.
e.Surface Wetting for Latex Modified Concrete or Early Stren gth Concrete Before placing latex modified concrete, clean the repair areas with air blast, then flush them with water. Keep the surfaces wet for at least 1 hr, and remove puddles before placing latex modified concrete.