504.01 DESCRIPTION. Prepare and treat existing asphalt or portland
cement concrete pavement surfaces with asphalt material in accordance with these specifications and in conformity with the lines and grades shown on the plans or established.
504.02 ASPHALT MATERIALS. Use an undiluted asphalt emulsion
Grade NTSS-1HM, CRS-2P, CSS-1H, SS-1H, SS-1L or PET as required by Section 501, Section 502, and Section 507 and as listed on the Approved Materials List and comply with Section 1002.
504.03 WEATHER LIMITATIONS. Do not apply asphalt tack coat on a
wet surface or when the ambient air temperature is below 40°F. For full depth patching, do not place asphalt tack coat when ambient air temperature is below 35°F.
504.04 EQUIPMENT. Provide equipment for applying asphalt material
and prepare the surface to be tacked. Apply with equipment conforming to
503.13.1 and 503.15.1. A hand-held pressure nozzle may be used for tack
coat application in lieu of the spray bar/tachometer combination for irregular sections or short sections of 1500 feet or less.
504.05 SURFACE PREPARATION. Clean the pavement surface by
sweeping or other approved methods. Satisfactorily clean edges of existing pavements that will form joints with new pavement before tack coat is applied.
504.06 APPLICATION. Uniformly apply asphalt tack coat to a clean
dry surface with no bare areas, streaks or puddles with an asphalt distributor at a rate in accordance with Table 504-1. If bleeding, ponding, or slipping are evident, these rates may be reduced to a minimum of 0.04 gallon/square yard with a minimum 0.02 gal/sq yd residual with approval of the engineer. Table 504-1 Section 502 Asphalt Tack Coats Surface Type Rate1; Gal/Sq yd Existing Surface Treatment2 New Hot Mix Existing Hot Mix Portland Cement Concrete Cold Planed/Milled 0.12 0.06 0.09 0.09 0.08 1Rates are minimum rates of undiluted asphalt emulsion. 2Section 507 Asphalt Surface Treatment Type E Interlayer does not require a tack coat. The minimum application temperature of the emulsified asphalt Grades NTSS-1HM, CRS -2P and Polymer Emulsion Tack (PET) is 160°F and Grades CSS -1H and SS -1H, is 70°F, or as recommended by the manufacturer. Apply tack coat in such manner as to cause the least inconvenience to traffic. Traffic is not permitted on tacked surfaces prior to application of the mixture placement. The contractor will be permitted to apply the tack coat one calendar day prior to the mixture laydown for non -traffic areas. However, when tack coat has been damaged or contaminated by dirt, dust or mud, clean the surface and retack prior to the mixture la ydown at no direct pay. Retack previously tacked surfaces exposed to damage or due to inclement weather at no direct pay.
504.07 MEASUREMENT. Asphalt tack coat will not be measured for
payment and is considered incidental to the 501 item; however, it will be measured by the gallon in-place using a calibrated stick and/or charts on level ground at the application temperature described in 504.06 for specification compliance.
504.08 PAYMENT. Payment of asphalt tack coat will be specified in
501.11, and 502.15.4 subject to the payment adjustment provisions of Section 1002 for specification deviations of the asphalt materials. The Materials and Testing Section will provide the payment adjustment percentage for specification deviations of the asphaltic materials.
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