407Tack Coat

Tack Coat

407.1DESCRIPTION

1 This section describes preparing and coating an existing bituminous or concrete surface with emulsified asphalt.

407.2MATERIALS

1 Use emulsions SS-1, CSS-1, SS-1h, or CSS-1h. Provide materials in accordance with the following:

Materials Subsection Emulsified Asphalt 804.3 Water 814

407.3EQUIPMENT

1 Equip tank trucks delivering emulsified asphalt to the project and on-site storage tanks with a sampling valve similar in design to those shown in AASHTO T 40. Mount the valve on the truck or tank’s discharge line. Consult the Materials Testing Manual for drawings of suggested mountings.

2 Provide an asphalt distributor that is equipped, maintained, and operated to apply bituminous material uniformly at variable widths. Equip with a tachometer , pressure gauges, accurate volume measuring devices or a calibrated tank, a thermometer for measuring temperatures of tank contents, a power unit for the pump, full circulation spray bars capable of being adjusted laterally and vertically, and a positive cut-off for the spray bars.

407.4CONSTRUCTION

407.4.1 Surface Preparation

1 Clean the surface of extraneous material including vegetation, dirt, mud, and loose material. Clean edges of existing pavements that will border new pavement to allow adhesion of tack coat. Obtain the engineer’s approval before applying the tack coat.

407.4.2 Sampling Procedures

1 Notify the supplier that undiluted emulsified asphalt samples are required for each conveyance of 5 tons [5 t] or more at the time of loading. The department requires the supplier to collect 1 qt [1 L] samples in wide -mouth high-density polyethylene (HDP E) plastic containers (3 ⅝ in [90 mm] outside diameter with 3 in [75 mm] inside diameter

Tack Coat SECTION 407

opening by 6½ in [162 mm] total height including screw on lid) in accordance with ASTM D2911. Ship the samples directly to the Materials Program in Cheyenne, ensure ar rival no later than seven calendar days after sampling, and accompany each sample with a clearly identified copy of a certificate of compliance that shows the following:

asphalt. The department defines a production run as the quantity of emulsified asphalt produced during one cycle from startup to shutdown of the producer's equipment.

2 Ensure that the supplier of the emulsified asphalt submits each sample with quality control test results for the applicable tests specified in Subsection 804.3, Emulsified Asphalt, and that the test results submitted are for a production sample taken from the same production run and sales tank.

3 Give the certification documents (including the invoice, certificate of compliance, weigh ticket, quality control tests results, etc.) to the engineer at the time of each tank delivery.

407.4.3 Application

1 A pply tack coat in accordance with Subsection 401.4.2, W eather and Seasonal Limitations, and at the rate specified or approved. The specified application rate is for specification material before additional dilution for field application.

2 Emulsified asphalt used for tack coat may be diluted in the field at a ratio of 1 part emulsified asphalt to 1 part water (1:1). Before mixing, heat the dilution water and emulsified asphalt to a minimum temperature specified by the supplier. Dilute by introducing the water into the emulsified asphalt.

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3 Apply the tack coat at a uniform temperature in accordance with Table 407.4.3-1, Emulsion Application Temperatures for Tack Coat

Table 407.4.3-1 Emulsion Application Temperatures for Tack Coat Emulsified Asphalt Temperature Non-polymer modified emulsions 70 to 160 °F [20 to 70 °C]

4 Maintain pressure so that the application rate varies no more than 0.02 gal/yd² [0.10 L/m²]. Apply the emulsified asphalt so that there is uniform, complete coverage at the rate specified. Correct deficiencies and areas not covered.

5 Before placing tack coat, place a section in the presence of the engineer to verify the application rates and the uniformity and completeness of coverage; make available the distributor manufacturer’s instructions for calibrating an accurate spray pattern.

6 Limit application to the area that can be covered by that day’s production equal in width to a single paving ribbon of plant mix pavement.

7 When traffic is present in construction areas, apply tack coat on one half of the application surface at a time. Do not allow traffic on the tack coat until it has cured sufficiently to prevent picking up or tracking.

407.4.4 Acceptance

1 The engineer will accept emulsified asphalt in accordance with Subsection 113.2, Acceptance of Asphalt Materials.

407.5MEASUREMENT and PAYMENT

407.5.1 General

1 The engineer will measure Tack Coat by the short ton [metric ton] in accordance with Subsection 109.1.3, Measurement Methods. Quantities in excess of those specified or approved will not be measured directly for payment. Quantities of water to dilute the emulsified asphalt for application will not be measured and paid for as Emulsified Asphalt.

2 The department will pay as follows:

Pay Item Pay Unit Measure to the Nearest Pay to the Nearest Tack Coat TON [t} 0.01 ton [0.01 t] 0.01 TON [0.1 t]

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407.5.2 Price Adjustment

1 If the samples for a truckload are not received by the Materials Program with proper documentation within seven calendar days of sampling, in accordance with Subsection 407.4.2, Sampling Procedures, the engineer will reduce the payment by as much as 25 percent for that load.

2 The engineer may reduce payment for emulsified asphalt that does not meet specifications but is accepted in accordance with Subsection 113.2, Acceptance of Asphalt Materials.