Slow Curing Cutback Asphalt
Slow Curing Cutback Asphalt
Asphalt cutback use petroleum solvents for dissolving asphalt cement. The solvents are variously called distillate, diluents or cutter stock. If the solvent used in making the cutback asphalt is highly volatile, it will quickly escape by evaporation. Solvents of lower volatility evaporate more slowly. On the basis of the relative speed of evaporation, cutback asphalts are divided into three types: rapid curing (RC), medium curing (MC) and slow curing (SC).
The invention relates to bitumen cutback, in particular to the use of fatty acid esters as bitumen cutback agents. These bitumen cutback agents may also be described as cutters, cutback additives, bitumen solvents, or bitumen thinners.
agent to bitumen to reduce (or cutback) the viscosity of the bitumen. The mixture obtained may be called cutback bitumen.
The reduction in viscosity of the bitumen aids the construction of seal coats in road pavements as the softened mixture wets the chips more easily. The cutback agent evaporates from the seal coat, the cutback agent becoming a negligible component of the seal coat a few months after application. If significant amounts of the cutback agent remain in the seal coat an unwanted long term softening effect may result.
Slow curing (SC) cutback asphalt cement and oils of low volatility generally in the heavy distillate range (SC-70, 250, 800, 3000). The degree of liquidity developed in each case depends principally on the proportion of solvent to asphalt cement. To a minor degree, the liquidity of the cutback may be affected by the hardness of the base asphalt from which the cutback is made. The degree of fluidity results in several grades of cutback asphalt—some quite fluid at ordinary temperatures and others somewhat more viscous. The more viscous grades may require a small amount of heating to make them fluid enough for construction operations.
Slow curing (SC) cutback asphalt are often called road oils and are used primarily in road-mixing and dust-laying applications. This term originated in earlier days when asphalt residual oil was used to give roads a low-cost, all-weather surface. SC cutback asphalts are also used for stockpile patching mixes, plant-mixed with graded aggregates and occasionally for priming.
