Pavement Preservation Journal, Spring, 2012
M. Bahadir Erten and Umid Azimov
Prime coat is used to penetrate and bond the loose material on the sub-base before subsequent hot mix asphalt or surface treatment is applied.
As Stephen et al. stated, “Low viscosity medium curing (MC) grades of liquid asphalt are generally used for prime coat when dense, hard to penetrate bases are to be primed, typically an MC-30 or MC-70” (Stephen & Shrestha, 2005, p. 28). MC-30 is a type of cutback asphalt which is prepared by blending high viscosity asphalt cement with petroleum solvent to lower the viscosity in order to achieve better penetration.
However, engineers are concerned with the use of cutback asphalt as prime coat for at least three reasons: environmental issues, fire hazards and potential health risks posed to construction workers.