Section 412 — Asphalt Tack Coat

Description

412.01This work consists of applying an emulsified asphalt tack coat on a prepared surface.

Material

412.02Conform to the following Subsections: Emulsified asphalt 702.02 Water for construction 725.01(c)

Construction Requirements

412.03General. Use equipment conforming to Subsection 407.05. Current state approved tack coat material may be used if approved. Submit proof of compliance with state specifications.

412.04Surface Preparation. Clean the existing surface of loose material, dirt, or other deleterious material by approved methods. If the surface is concrete, remove excess joint and crack filler material. Remove all pavement markings except waterborne or solvent borne traffic paint by approved methods. Protect manholes, valve covers, curb and gutter, and other adjacent facilities from damage or overspray.

412.05Weather Limitations. Apply asphalt tack only when the following apply:

(a)Surface is dry and unfrozen;

(b)Ambient air temperature is above 35 °F and rising;

(c)Precipitation is not anticipated before the emulsified asphalt breaks; and

(d)Weather is not foggy.

412.06Application. If using slow-setting emulsified asphalt, dilute by adding an equal quantity of water to the emulsified asphalt. Apply the asphalt tack coat according to Subsection 407.09. Use AASHTO R 112 to determine application rates. Provide the CO with the target application rate for approval. Set distributor spray bar height to ensure uniform coverage and at least a double overlap, but no more than triple overlap coverage. Set nozzle angle settings between 15 and 30 degrees from the center of the spray bar axis. Use the same size nozzles with all set at the same angle and open. Apply the asphalt tack coat uniformly and completely by fogging with a hand spray attachment or by other approved methods if application with a distributor spray bar is not practical. Squeegee the excess emulsified asphalt from the surface and dispose of according to Subsection 203.07. Allow the tacked surfaces to completely break before placing the covering course. Place the covering course within 4 hours of placing the asphalt tack coat.

412.07Acceptance. See Table 412-1 for sampling, testing, and acceptance requirements. Emulsified asphalt will be eva luated under Subsections 106.02 and 106.03. Construction of the tack coat will be evaluated under Subsections 106.02 and 106.04.

Measurement

412.08Measure the Section 412 pay items listed in the bid schedule according to Subsection 109.02 and the following as applicable: Measure asphalt tack coat including water added for dilution. Indicate a breakdown of total emulsion and water added on the load invoices provided to the CO. Do not measure asphalt tack coat used for asphalt concrete pavement patching.

Payment

412.09The accepted quantities will be paid at the contract price per unit of measurement for the Section 412 pay items listed in the bid schedule. Payment will be full compensation for the work prescribed in this Section. See Subsection 109.05 . Table 412-1 Sampling, Testing, and Acceptance Requirements

Material or

Product

(Subsection) Type of

Acceptance

(Subsection) Characteristic Category Test Methods

Specifications Sampling

Frequency Point of

Sampling Split

Sample Reporting

Time Remarks

Production

Emulsified

asphalt (702.02 ) Process control (153.03 ) Placement temperature − − 1 per distributor truck minimum Distributor truck No Before incorporating into work −

Tack coat

(412.06) " Application rate & daily yield − − 1 per day minimum Contractor determined No End of shift −