563.01 Description
This work consists of placing a bridge deck overlay of either a latex modified concrete or silica fume modified concrete. Select a single type of modified concrete overlay and use it for all locations shown in the contract.
563.02 Materials
563.02.1 Cement
Furnish cement in accordance with Subsection 551.02.1. Use only one brand of cement in each overlay. Do not use Type III cement.
563.02.2 Aggregate
1.Use aggregate in accordance with Subsection 701.01.
2.Furnish aggregate in accordance with Table 551-2.
3.Use aggregate in a saturated surface dry (SSD) condition at the time of mixing concrete.
4.Test the moisture content using AASHTO T 255.
5.Document and submit the results for both total moisture content and for surface moisture content.
563.02.3 Latex Admixture
Use a latex admixture containing a polymer of 66% ± 5% styrene and 34% ± 5% butadiene, with the polymer comprising between 46% - 49% of the total emulsion. The emulsion must have a sodium alkyl sulfate stabilizer acting as an anionic surfactant, polymer average particle size between 1,900 and 2,500 angstroms, a weight of 8.43 to 8.52 lb./gal at 75 °F (mass of 1.01 - 1.02 kg/l at 25 °C), and a pH between 9.5 and 11.0. Always protect the latex admixture from temperatures below 32 °F (0 °C) and above 85 °F (29 °C). Provide a thermometer capable of storing minimum and maximum temperatures and place it with any admixture stored on site. Replace admixture subjected to temperatures outside the range above at Contractor expense to the Department.
563.03 Construction Requirements
563.03.1 Submittals
Submit for approval the following:
1.The method and materials used to contain, collect, and dispose of all debris generated by the removal, cleaning, and surface preparation process.
2.Details of the screed rail support system, including details of anchoring the rails and providing rail continuity, and of other equipment used to apply the overlay.
3.The methods that will be used to prepare the surface to ensure bonding of the overlay to the existing deck concrete.
563.03.2 Pre-placement Conference
Hold a pre-placement conference with a technical representative from the modified concrete supplier and the Project Manager at least 15 calendar days before the planned concrete placement. Present the mix design and methods of accomplishing all phases of the concrete overlay work. 563 – MODIFIED CONCRETE OVERLAY 2020 EDITION V5.1 563-2
563.03.3 Surface Preparation
Prepare the surface to ensure bonding between the surface and the overlay. Blow standing water out of depressions, holes, or areas of concrete removal with oil filtered compressed air. Protect the prepared surface from contamination using plastic sheeting or other means. Deck preparation work may be performed in areas adjacent to newly placed overlay concrete. If this work begins less than 72 hours after overlay placement, perform the work with the following restrictions:
1.Wait a minimum of 1 day after placing the concrete to begin the adjacent surface preparation.
2.Always minimize the disturbance of burlap and plastic sheeting and maintain uncured concrete in a wet condition. Restore disturbed burlap and plastic sheeting as soon as possible. • Use no power tools heavier than 15 pound chipping hammers. • Operate air compressors on the deck only directly over piers or bents. • Prior to placement and completed cure of new concrete, allow no loads other than approved construction equipment on any part of the deck that has undergone surface preparation.
563.03.4 Mobile Mixing Equipment
Use mobile mixing equipment for batching Class Overlay-LM concrete. Do not use mobile mixing equipment to batch Class Overlay-SF concrete unless approved by the Project Manager. Demonstrate that mobile mixing equipment meets the following requirements:
1.Mixing Equipment. Use self-contained, mobile, continuous-mixing equipment in accordance with the following requirements:
a.A capacity to mix a batch of at least 8 cubic yards (6 m 3). The machine capacity must allow finishing operations to proceed at a steady pace, with final finishing completed before formation of the plastic surface film.
b.A positive means of controlling cement content entering the mix, complete with a recording meter visible at all times and a continuous printout of the accurately measured quantity.
c.Positive control of the water, and the latex emulsion (if applicable), flow into the mixing chamber. Positive means to adjust the water flow for variations in aggregate moisture and a flow meter indicating the water quantity. The Project Manager will approve each mobile mixer used on the project based on a demonstration of its ability to produce concrete in accordance with the contract. Calibrate each mobile mixer in the presence of the Project Manager, using the following tests. Record all test results and required calculations and provide the Project Manager with a copy of those data. Inform the Project Manager what moisture content (percentage) the fine and coarse aggregates will have on entering the mix. Dry or wet the stockpiles to within 0.5% of this percentage at the beginning of each work day. Take moisture readings on the stockpiles before calibrating the mixer trucks and before each day’s placement of latex modified concrete. Record and submit the readings to the Project Manager. Perform yield, slump, and air content tests on concrete from each mixer in the Project Manager’s presence.
2.Cement Meter. Obtain the operating speed (in revolutions per minute) and the approximate number of counts required on the cement meter to deliver one 94 pound (43 kg) bag of cement from the truck manufacturer’s mix setting chart. Place at least 40 bags 2020 EDITION V5.1 MODIFIED CONCRETE OVERLAY – 563 563-3 of cement in the cement bin. Place the mixer on a level surface and provide an electrical ground. Adjust the engine throttle to obtain the specified revolutions per minute (rpm). Discharge cement until the belt has made 1 complete revolution. Stop the belt and reset the cement meter to zero. Discharge approximately 1 bag of cement into a container while timing the discharge with a stopwatch. Record the number of counts on the cement meter and determine the mass of cement discharged on the Field Calibration form included in this specification. Repeat the process of discharging 1 bag at a time for a total of 6 runs. Reset the cement meter to zero each time. At the end of the 6 runs, total the number of cement counts, the mass of cement discharged, and the times of each of the runs, in seconds. Perform the following calculations:
a.Mass of cement per cement meter count. Divide the total mass of cement discharged in the 6 runs by the total number of counts on the meter for the 6 runs.
b.Counts per bag of cement. Divide 94 pounds (43 kg) by the mass of cement per cement meter count.
c.Cement discharge rate. Divide the total mass of cement for the 6 runs by the total of the times for each of the 6 discharges.
d.Discharge time for 1 bag. Divide 94 pounds (43 kg) by the cement discharge rate.
3.Latex Throttling Valve. Clear the latex strainer of any obstructions. Adjust the latex throttling valve to deliver 3.5 gallons (13.2 L) of latex, or 30 pounds (13.3 kg) for each bag, or 94 pounds (43 kg) of cement, using the calculation results from Subsection
563.03 4(2)
, where necessary. With the unit operating at the specified rpm, discharge latex into a container for the discharge time for 1 bag calculated above and determine the weight of the latex discharged. Adjust the valve until the machine discharges 30 lbs. (13.6 kg) in the discharge time for 1 bag. Verify the accuracy of this setting by repeating the latex discharge 3 more times.
4.Water Flow Meter. Set the water flow meter to flow at the rate of 0.5 gallons (1.9 L) per minute. Collect and weigh the water discharged during 1 minute with the equipment operating at the specified rpm to verify the discharge rate. Repeat the process with the flow meter adjusted to 1.5 gallons (5.7 L) per minute.
5.Aggregate Bin Gates. Set the gate openings to provide aggregate at a rate matching the specified concrete mix proportions.
563.03.5 Concrete Placement
Place concrete in accordance with Section 551 . Install necessary bulkheads to the required grade and profile before placing any concrete. Alternatively, over-pour the end of the overlay by a minimum of 6 inches (150 mm). Saw cut and remove the over-pour from the rest of the overlay. Dispose of materials that dry out, set, or show evidence of loss of cement paste. Stop overlay placement on discovering those conditions and do the surface preparation again. Strike off the modified concrete at a level ¼-inch (6.0 mm) above final grade. Complete hand finishing and texturing within 15 feet (4.5 m) of the finishing machine. Float and vibrate the concrete as needed to provide a tight finished surface. Vibrate concrete more than 3 inches (75 mm) thick internally, in addition to the vibration of the surface screed. After finishing the concrete, check for surface irregularities with a 563 – MODIFIED CONCRETE OVERLAY 2020 EDITION V5.1 563-4 10 foot (3 m) straight edge. Correct surface areas that vary more than ⅛-inch (3 mm) in that distance.
563.03.6 Curing
Cure the overlay per Subsection 551.03.7.
563.03.7 Phased Construction
If the overlay is placed in phases, apply a bridge deck crack sealant to the phase line joint(s) after the overlay has cured. Furnish a bridge deck crack sealant in accordance with Subsection
717.02 2.
563.03.8 Acceptance
1.Cast at least 1 latex modified concrete cylinder for each day’s overlay placement. Cure the cylinders with their matching deck segments. Break the cylinders at the end of the dry curing process to demonstrate the strength the overlay concrete has attained.
2.Correct areas identified by the Project Manager. Correct variations that prevent drainage from any part of the bridge deck. Do not start the process of saw cutting the transverse deck grooves until the Project Manager has approved all the finished repair work.
3.A drag-chain survey will be conducted to determine the soundness of bond between the repair and the deck, placing emphasis on areas of visible cracking. Remove and replace areas that have debonded. The Project Manager may core the repair to determine depth of cracking. When directed by the Project Manager, seal cracks in repair concrete with a bridge deck crack sealant listed on the QPL . Apply the product in accordance with the manufacturer’s recommendations. In cases of excessive cracking, the Project Manager may require removal and replacement of part of or all of a repair. All corrective actions required for acceptance are at Contractor expense.
563.04 Method of Measurement
Bridge deck overlay is measured by the cubic yard (m3) of modified concrete overlay placed. Include the cost of trial batches in the unit cost of modified concrete overlay. Transverse deck grooving is measured by the square yard (m2) in accordance with Subsection 552.04. Bridge deck crack sealant applied to phase line joint(s) is not measured for payment. Include all costs associated with bridge deck crack sealant applied to phase line joint(s) in the modified concrete overlay item.
563.05 Basis of Payment
Payment for the completed and accepted work is made under the following: Pay Item Pay Unit Concrete - Class Overlay Cubic Yard (m3)
Referenced in this section
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Source: Standard Specifications for Road and Bridge Construction, 2020 (v5.1) Edition. Pages 389–392 of 611. View official source ↗