ITEM 407 TACK COAT
407.01 Description. This work consists of preparing and treating a paved surface with asphalt
material, and cover aggregate if required.
407.02 Materials. Conform to the applicable requirements of 702 for the asphalt material and
use one of the following types: 702.04 RS-1, SS-1, SS-1h, CRS-1, CSS-1, or CSS -1h; 702.12 Non- Tracking Asphalt Emulsion or 702.13 SBR Asphalt Emulsion. Supply 702.12 Non-Tracking Asphalt Emulsion any time Item 407 Non-Tracking Tack Coat is specified. Conform to 703.06 for cover aggregate.
407.03 Equipment. Provide adequate cleaning equipment, spreader boxes, and distributors.
Use distributors designed, equipped, maintained, and operated to apply asphalt material at the specified rate per square yard (square meter) with uniform pressure over the required width of application. Ensure that the distributor includes a tachometer, pressure gauges, and an accurate volume measuring device or a calibrated tank. Mount an accurate thermometer with a range covering the specified application temperature for asphalt material at approximately center height of the tank with the stem extending i nto the asphalt material. Ensure that the distributor has a full -circulating system with a spray bar that is adjustable laterally and vertically. Ensure that the spray bar will maintain a constant height above the pavement under variable load conditions. S upply each distributor with suitable charts showing truck and pump speeds and other pertinent application data necessary to obtain the required results. Do not use equipment that cannot obtain the correct tack application.
407.04 Weather Limitations. Do not apply the asphalt material if the surface temperature is
below the minimum placement temperature for the pavement course to be placed, as specified in 401.05.
407.05 Preparation of Surface. Ensure that the surface is thoroughly clean and dry when the
asphalt material is applied. Remove material cleaned from the surface and dispose of it as the Engineer directs.
407.06 Application of Asphalt Material. Uniformly apply the asphalt material with a distributor
having clean nozzles functioning properly. For irregular areas such as driveways and intersections, apply the asphalt material using a method the Engineer approves. If paving asphalt concrete directly onto Portland cement concrete or brick pavement, tack the pavement with SBR asphalt emulsion conforming to 702.13. Apply the asphalt material in a manner that offers the least inconvenience to traffic. Only apply the asphalt material to areas that will be covered by a pavement course during the same day. Ensure the tack breaks before releasing to construction traffic unless the paver is equipped with a spray bar system to apply tack just prior to mat placement. Apply asphalt material to obtain uniform coverage within the range specified in Table 407.06-1, as directed by the Engineer . Obtain the Engineer's approval for the quantity, rate of application, temperature, and areas to be treated before application of the asphalt material. The Engineer will determine the actual application in gallons per square yard (liters per square meter) by a check on the project. TABLE 407.06-1, TYPICAL TACK COAT APPLICATION RATES Existing Pavement Application Rate gal/yd2 (L/m2) New Asphalt 0.05 to 0.06 (0.23 to 0.27) Oxidized Asphalt 0.08 to 0.09 (0.36 to 0.41) Milled Asphalt Surface 0.08 to 0.09 (0.36 to 0.41) Milled PCC Surface 0.06 to 0.08 (0.27 to 0.36) PCC Surface 0.06 to 0.08 (0.27 to 0.36) The application is considered satisfactory when the actual rate is within ±10 percent of the required rate and the material is applied uniformly with no visible evidence of streaking, ridging or pickup by construction traffic. The Engineer will require proper correction when ridging, streaking, pickup or other non -uniform coverage is observed. Correct non -uniform tack only in areas of non -uniform coverage. Do not reapply tack in areas where the tack meets uniformity and application requirements. If the coverage is not uniform and not corrected the total square yardage of non-uniform application will be considered non -specification material. The Engineer will determine the number of gallons (liters) for non-payment by using the approved rate of application times the total square yards (square meters) of non-uniform application.
407.07 Method of Measurement. The Department will measure Tack Coat and Non -Tracking
Tack Coat by the number of gallons (liters) of undiluted asphalt material applied for each according to Item 109. Provide weight tickets (including weigh back tickets) for every load, or partial load used, according to Supplement 1060 based on weight tickets from an Ohio Permitted Device according to provisions of Ohio Revised Code Section 1327, and Ohio Administrative Code Chapter 901:6.
407.08 Basis of Payment. The cost of cover aggregate is incidental to Tack Coat.
The Department will not pay for non-uniformly applied materials as defined in 407.06. The Department will pay for accepted quantities at the contract prices as follows: Item Unit Description 407 Gallon (Liter) Tack Coat 407 Gallon (Liter) Non-Tracking Tack Coat 407 Gallon (Liter) Tack Coat, 702.13
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