503 CHIP SEAL SURFACE TREATMENT

From MDOT Policy Manual
Jump to: navigation, search
503.01 DESCRIPTION.
Apply one or two seal coats or a prime coat followed by one or two seal coats as specified. The seal coat consists of emulsified asphalt followed by an application of aggregate. The prime coat, when required, consists of preparing and treating an existing surface with emulsified asphalt.
503.02 MATERIALS.
MATERIAL SECTION APPLICATION SIZE OR GRADE SPREAD RATE

lb/yd2

SPRAY TEMP

F

SPRAY RATE SINGLE COAT OR FIRST COAT

gal/yd2

SPRAY RATE FOR SECOND COAT (Double)

gal/yd2

Aggregate 901 Single or First Coat No. 7 25-50
Second (Double Coat) No. 8 20-35
Emulsified Asphalts 904.03 Seal CoatAn application of asphalt material followed by an application of cover coat aggregate. CRS-1 70-140 0.3-0.5 0.2-0.4
CRS-2 140-160 0.3-0.5 0.2-0.4
RS-1 70-140 0.3-0.5 0.2-0.4
RS-2 140-160 0.3-0.5 0.2-0.4
503.03 CONSTRUCTION.
At least 30 days prior to the start of placement of the chip seal surface treatment, submit a proposed plan, including equipment and material sources, for approval.
Protect the treated pavement against damage from all causes. Repair or replace damaged areas as directed.
503.03.01 EquipmentAll machinery, tools, and apparatus necessary for the proper construction and acceptable completion of the work, together with the necessary supplies for upkeep and maintenance.. All equipment is subject to approval.
(a) Asphalt Distributing EquipmentAll machinery, tools, and apparatus necessary for the proper construction and acceptable completion of the work, together with the necessary supplies for upkeep and maintenance.. This equipment shall be inspected and calibrated by the AdministrationShall mean any one of the Administrations within the Maryland Department of Transportation, as listed in GP 1.02. prior to use and shall bear a current AdministrationShall mean any one of the Administrations within the Maryland Department of Transportation, as listed in GP 1.02. inspection and calibration tag. A calibration chart showing the total capacity in gallons of the distributor tank, and the fractional capacity for each 1/4 in. of tank depth, shall be carried in the unit. The unit shall be capable of uniformly applying the specified material on variable widths of surface at the rates specified in 503.02. In addition, the equipment shall include the following:
(1) A fifth wheel tachometer for maintaining uniform speed.
(2) A thermometer graduated in 2 F increments to determine the specified temperature ranges.
(3) Heaters for uniformly heating the materials to the proper temperatures.
(4) Full circulation spray bars that are laterally and vertically adjustable, plus a hand spray.
(5) A calibrated tank to determine the quantity of asphalt in each load and the amount used.
(6) A valve or petcock built into the equipment for sampling the asphalt.
(7) A motor driven pump with pressure gauges to deliver the material to the spray bars. When a variable speed pump and metering system is used, provide charts prepared by the manufacturer for selecting the proper pump speed for each application.
(b) Aggregate Spreader. Use equipment that is either self-propelled or attached to a truck tailgate.
(c) Rollers. Refer to 504.03.01(c).
503.03.02 Weather Restrictions. Place when the ambient air and surface temperatures are at least 50 F and rising and the pavement is clean and dry. When weather conditions differ from these limits, placement of material en route from the plant to the job site shall be at the ContractorAny person having a Contract with a procurement agency. Contractor does not include an employee with an employment Contract, or an employee organization with a collective bargaining agreement.’s risk. When the EngineerAny person designated by the Administrator or the procurement officer, acting directly or through his duly authorized representative, such representative acting within the scope of the particular duties assigned to him or of the authority given him. stops placement of the material, dispose of all material en route at no additional cost to the AdministrationShall mean any one of the Administrations within the Maryland Department of Transportation, as listed in GP 1.02..
503.03.03 Foundation Preparation. Construct the foundation as specified. When paving over existing pavement, repair ruts and potholes to provide a smooth surface for the application of the chip seal surface treatment.
503.03.04 Prime Coat. Prior to the application, clean the surface of all loose and foreign materials. Uniformly apply the prime coat to the surface at the application rate specified in 503.02. Remove pooled material before applying the next coat.
503.03.05 First Seal CoatAn application of asphalt material followed by an application of cover coat aggregate..
(a) No sooner than 24 hours after the application of the prime coat, spray emulsified asphalt on the surface at the application rate specified in 503.02.
(b) Immediately following this asphalt application, spread a dry, dust free aggregate on the surface at the application rate specified in 503.02. Remove excess aggregate, and correct all areas containing insufficient aggregate.
503.03.06 Rolling. Immediately following the aggregate application, roll the surface until the aggregate is uniformly embedded into the asphalt. Discontinue rolling if the aggregate begins to crush.
503.03.07 Second Seal CoatAn application of asphalt material followed by an application of cover coat aggregate.. When specified, after the first seal coat has cured at least 24 hours, apply a second seal coat to the surface, omitting the prime coat. Apply emulsified asphalt and aggregate at the application rate specified in 503.02. Remove excess aggregate and correct all areas containing insufficient aggregate. Roll the surface as specified in 503.03.06.
503.03.08 Traffic. Close completed sections to traffic until the final seal coat has completely cured. Maintain the treated surface after it has been opened to traffic until final acceptance.
503.04 MEASUREMENT AND PAYMENT.
The payment will be full compensation for the foundation preparation, and for all material, labor, equipment, tools, and incidentals necessary to complete the work.
Chip Seal Surface Treatment will be measured and paid for at the Contract unit price for one or more of the items listed below.
503.04.01  No. 7 Aggregate for Single Coat Chip Seal Surface Treatment per ton.
503.04.02  No. 8 Aggregate for Second Coat Chip Seal Surface Treatment per ton.
503.04.03  Emulsified Asphalt for Seal CoatAn application of asphalt material followed by an application of cover coat aggregate. per gallon.
The actual number of gallons of emulsified asphalt distributed will be corrected to the corresponding volume at 60 F as determined by use of conversion tables furnished by the AdministrationShall mean any one of the Administrations within the Maryland Department of Transportation, as listed in GP 1.02..