coats are too heavy, they leave a surplus of asphalt thatbleeds into the overlying course. A thin tack coat doesno harm to the pavement and properly bonds thecourses.Tack coat materials may be as follows: (1) a roadtar, grade RTCB 5-6, RT-6, 7, 8, 9, 10, or 11; (2) anasphalt cutback, such as RC-250 or -803; (3) a dilutedemulsion; or (4) an asphalt cement, such as an AP-3(85-100 penetration) or AP-1 (120-150 penetration).Bituminous materials for the tack coat should beapplied in quantities not less than 0.05 or more than0.25 gallon per square yard. The exact quantitydepends upon the condition of the surface to betacked. Normally, the construction projectspecification denotes the ROA for the tack coatapplication; however, when the ROA is not includedin the project specifications, the NCF uses an ROA of.15 for planning and estimating purposes.The procedure for estimating the bitumen requiredfor a tack coat is similar to that described for a primecoat except that the tack coat is applied only over theproposed width of the pavement.The formulas for a tack coat estimates are as follows:For computing gallons:For drums, the formulas are as follows:8-29
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