SECTION 403 — ASPHALT EMULSION TACK COAT 400-21 — ASPHALT EMULSION TACK COAT
403.01 Description.
This work includes furnishing, delivering, and placing a liquid asphalt tack coat on asphalt concrete or Portland cement concrete before the placement of an asphalt concrete overlay.
403.02 Materials.
For the asphalt emulsion, use RS-1, RS-1h, SS-1, or SS-1h.
403.03 Construction Methods.
Equipment. For application of the asphalt emulsion tack coat, use a pressure distributor that can produce a uniform continuous fine spray, through multiple nozzles, resulting in a uniform, continuous coat of asphalt emulsion over the entire section to be treated. Squeegee or broom out any puddles of tack coat, or correct by any method that will achieve the required surface treatment. Correct any areas not receiving the specified coverage of tack coat. Application of Asphalt Material.
a.Application Rates. Ensure that the asphalt emulsion is uniformly applied at the following rates over the entire existing surface to be overlaid: ● Old Pavement. Use an application rate of 0.08 gal/sq yd, ±0.02 gal/sq yd. ● New Pavement. The following applies: ○ For new pavements less than seven days old that have not been opened to traffic or construction equipment, a tack coat is not required. ○ For new pavements at least seven days old or that have been opened to traffic, use an application rate of 0.06 gal/sq yd, ±0.02 gal/sq yd. ● Joints. Apply tack coat to all joints. Ensure the faces are completely covered with tack coat at transverse joints and joints at intersections. Tack all longitudinal joints with a distribution truck. Place tack at twice the specified rate when using a distribution truck.
b.Nozzle Settings. Apply tack coat using the proper nozzle settings and the double coverage or triple coverage techniques as outlined in Chapter 5 of Asphalt Institute Publication MS-22, “Construction of Hot Mix Asphalt Pavements.”
c.W eather Limitations . Apply tack coat to a dry surface.
d.Additional Requirements. Allow the tack coat to cure (break) as determined by the Engineer before paving. If the tack coat has not fully cured (break and set) after one hour, paving may proceed over the tacked area. Ensure that any material picked up by equipment is removed before it falls onto or
Part 400 — Asphalt Pavements August 2025
400-22 SECTION 403 — ASPHALT EMULSION TACK COAT affects the newly placed pavement layer. Eliminate or minimize equipment passage over tacked surfaces so as not to hinder or negate the tack’s effectiveness in the pavement bonding process. Correct sections not approved by the Engineer and receive the Engineer’s approval before paving. The Engineer may suspend paving and require the Contractor to provide a detailed action plan outlining the steps to be taken to ensure the proper application of tack coat before the commencement of further paving operations.
403.04 Method of Measurement.
Asphalt Emulsion Tack Coat will not be measured or paid for separately.
403.05 Basis of Payment.
There is no payment for Asphalt Emulsion Tack Coat, which is considered incidental.
Part 400 — Asphalt Pavements August 2025
SECTION 404 400-23 This Section has been Reserved for Future Use.
Part 400 — Asphalt Pavements August 2025
400-24 SECTION 405 This Section has been Reserved for Future Use.
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Source: Standard Specifications for Road and Bridge Construction (Blue Book), 2022 (Aug 2025 compilation) Edition. Pages 240–243 of 951. View official source ↗