SECTION 310—TACK COAT
310.01 Description
This work shall consist of preparing and treating an existing asphalt or concrete surface with asphalt in accordance with these specifications and in conformity with the lines shown on the plans or as established by the Engineer.
310.02 Materials
b.Non-Tracking Tack Coat liquefied asphalt shall be selected from the Department’ s Approved List 50.1A and conforming to Section 210.
310.03 Procedures
The existing surface shall be patched, cleaned, and rendered free from irregularities to the extent neces- sary to provide a reasonably smooth and uniform surface. The Contractor shall remove unstable corru - gated areas, and replace with suitable patching materials when required by the Contract. The Contractor shall clean the edges of existing pavements that are to be adjacent to new pavement to permit adhesion of tack. The Contractor shall uniformly apply tack coat or non-tracking tack coat material with a pressure distrib- utor conforming to Section 314.04(b). Hand spray equipment shall not be used except in areas inacces - sible by a pressure distributor. The distributor shall be calibrated by the Contractor in the presence of the Engineer prior to initial asphalt plant mix placement to demonstrate an even and accurate spray application. Calibration will be consid - ered acceptable when the spray rate is uniform and within 0.02 gal/yd² of the design application rate. 309.06 All tack coat and non-tracking tact coat materials stored longer than 30 days from the shipping date on the Bill of Lading shall be retested in accordance with Section 210.06 to verify the material still meets product specifications. Tack at joints, adjacent to curbs, gutters, or other appurtenances shall be applied with a hand wand or with a spray bar at the rate of 0.2 gal/yd². At joints, the tack applied by the hand wand or a spray bar shall be 2 feet in width with 4 to 6 inches protruding beyond the joint for the first pass. Tack for the adjacent pass shall completely cover the vertical face of the pavement mat edge so that slight puddling of asphalt occurs at the joint, and extend a minimum of 1 foot into the lane to be paved. Care shall be taken to prevent spattering adjacent items during the application of tack coat. The distributor shall not be cleaned or discharged 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 on the surface of the traveled way. The tack coat or non-tracking tack coat shall be applied to the pavement surface in such a manner that it will bond the overlay and the underlying surfaces together. The Contractor shall apply tack coat and non-tracking tack coat in accordance with the weather limita - tions that apply to the course being placed as well as the manufacturer’ s recommendations. The Engineer will verify, and reserves the right to alter, the quantity, rate of application, temperature, and areas to be treated prior to application. The tack coat or non-tracking tack coat shall be applied in a manner to offer the least inconvenience to traf- fic and to permit one-way traffic without pick up or tracking of the asphalt onto adjacent non-treated areas. All traffic, including construction traffic, shall be excluded from tacked sections until the tack has cured. Tack will not be required atop asphalt stabilized open-graded material drainage layers. The Contractor shall measure and report the rate of tack material applied on a daily basis in accordance with VTM-137 Method B (Tack Yield Method), on forms provided by the Engineer. On a daily basis, the Contractor shall provide the Engineer readings taken from the calibrated distributor establishing the quantity of gallons placed for that day. The Engineer will verify the desired tack application rate is achieved in accordance with VTM-137 Method A (Tack Plate Method). This test shall be performed , at a minimum frequency of once per each roadway, within the first 500 tons of asphalt mix placed, unless otherwise approved by the Engineer. The Engineer reserves the right to perform the tack plate method testing at a higher frequency, as deter- mined necessary, to ensure adherence to specifications.
a.Tack Coat Equipment for heating and applying asphalt shall conform to Section 314.04(b). The maximum application temperature of liquid asphalt shall conform to Table III-1. The Contractor shall apply tack at the rate of 0.05 to 0.10 gal/yd². The Contractor shall allow the tack coat to properly cure and break before placement of the hot mix asphalt course. 310.03
b.Non-Tracking Tack Coat The Contractor shall apply nontracking tack coat between May 1 and October 1. The Contractor may use tack coat as specified herein at other times. Equipment for heating and applying asphalt shall conform to Section 314.04(b) or the non-tracking tack coat material’ s manufacturer’ s recommendations. The maximum application temperature of liquefied asphalt shall conform to the manufacturer’ s requirements. The Contractor shall apply tack material at the rate recommended by the manufacturer. This rate is typically between 0.05 to 0.10 gal/yd². Adjacent concrete or asphalt concrete surfaces shall show minimal visible evidence and white or yellow pavement markings shall show no visible evidence of the asphalt tack material tracking at the end of the production shift. Tracking of the tack material on pavement markings will require the Contractor to immediately restore the marking to their original pre-tack condition. The Contractor shall remove build-up of the tack material on existing pavement surfaces.
c.Referee System When a new asphalt course is placed on a milled or non-milled surface, the Contractor shall take steps to ensure an adequate bond is made between the new material and the existing surface. If the Engineer suspects the Contractor is failing to apply good bond promoting procedures or adequately tacking the existing surface per the manufacturer’ s recommendations, the Engineer may core a min- imum of five core locations to determine the shear strength of the interface. 310.03 TABLE III-1 Liquid Asphalt Application Temperature Grade Max. Temperature (°F) RC-70 180 RC-250 220 RC-800 225 RC-3000 290 MC-70 180 MC-250 220 MC-800 255 MC-3000 290 AC-5 300 AC-10 300 AC-20 300 AC-40 300 RS-2 175 SS-1h 180 AE-4 150 CRS-2 175 CSS-1h 180 CMS-2 200 CRS-1h 175 CRS-1 175 CQS-1h 180
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Tack Coat in other states
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Source: Road and Bridge Specifications, 2020 Edition. Pages 408–410 of 1,065. View official source ↗