SECTION 312—SEAL COAT
312.01 Description
This work shall consist of applying asphalt followed by applying cover material in accordance with these Specifications and in conformity with the lines shown on the plans or as established by the Engineer.
312.02 Materials
a.Asphalt may be changed one viscosity grade by the Engineer during construction at no change in the contract unit price. Asphalt shall conform to Section 210 as applicable.
312.03 Equipment
The Engineer will require the Contractor to use the following equipment or its equivalent:
a.equipment for heating and applying asphalt conforming to Section 314.04(b)
b.a rotary power broom
c.at least one pneumatic tire roller. The Engineer may also require additional rollers that are tandem steel wheel or three-wheel rollers weighing at least 8 tons. The pneumatic tire roller shall be self-propelled, and the gross load adjustable to apply 200 to 350 pounds per inch of rolling width as directed. Tires shall be designed for a tire pressure of at least 90 pounds per square inch. Steel wheel rollers shall be operated at a maximum speed of 3 miles per hour, and pneumatic tire rollers at a maximum speed of 5 miles per hour.
d.a mechanical roller-type hopper or a self-propelled aggregate spreader of an approved design.
312.04 Procedures
The rates of application of materials shall be determined in accordance with the method described in Education Series No. 12 of the Asphalt Institute entitled Asphalt Surface Treatments Construction Techniques. The weather limitations specified in Section 314.03 shall apply to seal coat work. The Contractor shall not begin seal coating operations until the surface is thoroughly compacted and cleaned of dust, mud, and foreign matter and the Engineer has approved the section to be sealed. The Contractor shall apply asphalt by means of a pressure distributor in a uniform continuous spread over the section to be treated and within the temperature range given in Table III-1. A strip of building 312.04 paper at least 3 feet in width and having a length equal to that of the spray bar of the distributor plus 1 foot shall be used at the beginning of each spread. If the cutoff of the distributor is not positive, the use of paper may be required at the end of each spread. The Contractor shall remove and dispose of the paper legally after use. The distributor shall be moving forward at the proper application speed at the time the spray bar is opened. The Contractor shall correct skipped areas and deficiencies. Junctions of spreads shall be carefully made to ensure a smooth riding surface. The length of the spread of asphalt shall be governed by the quantity of cover material in loaded trucks on the project to ensure all asphalt is adequately covered. The spread of asphalt shall be not more than 6 inches wider than the width covered by the cover ma - terial from the spreading device. Asphalt shall not be allowed to chill, set up, dry, or otherwise impair retention of the cover material. The Contractor shall exercise care during asphalt application to prevent spattering adjacent items. The Contractor shall not clean or discharge the distributor into ditches or borrow pits, onto shoulders, or along the right of way. When not in use, the Contractor shall ensure equipment is parked so that the spray bar or mechanism will not drip asphalt material on the surface of the traveled way. The Contractor shall apply cover material in full-lane widths up to 12 feet immediately following as - phalt application. Laps shall be made only at lane dividers or at the crown of the roadway. Successive laps at lane dividers and the roadway crown shall be staggered from 3 to 6 inches. Spreading of cover material shall be accomplished in a manner so that the tires of the truck or aggregate spreader do not contact the uncovered and newly applied asphalt. The Contractor shall moisten the cover material with water to eliminate or reduce dust coating of aggregate when directed to do so by the Engineer. Moistening shall be done the day before the use of aggregate. The Contractor shall cover deficiently covered areas with additional material immediately after cover material is spread. Rolling shall begin immediately behind the spreader and shall consist of at least three complete coverages. The Contractor shall lightly broom or otherwise maintain the wearing surface after application of cover material until it has cured as directed. Maintenance of the surface shall include distributing cover material over the surface to absorb free asphalt and cover any area deficient in cover aggregate. The Contractor shall perform maintenance activities so as not to displace embedded material. Excess material shall be swept from the surface by means of rotary brooms as required or as directed by the Engineer.
312.05 Measurement and Payment
Seal coat will be measured in gallons and will be paid for at the contract unit price per gallon for liquid asphalt and per ton for cover material. Liquid asphalt will be measured in gallons. Cover material will be measured in tons, complete-in-place, and will be paid for at the contract unit price per ton. These prices shall include furnishing and applying materials and maintaining the treatment. 312.04
Referenced in this section
Sections that cite this one
Seal Coat in other states
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Source: Road and Bridge Specifications, 2020 Edition. Pages 413–414 of 1,065. View official source ↗