Effects of Hydrated Lime on Consistency Properties of Asphalt Binders

Abstract

Although the addition of hydrated lime to mineral aggregates at asphalt production plants has become mandatory for use in all asphalt concrete mixtures, the consequences of such additives at asphalt binder- mineral aggregate contact in the hot bin have shown a great effect on the consistency properties of the resulting asphalt mastics as compared to that of a neat asphalt binder. Considering that many highway agencies in developing countries still use asphalt binders consistency properties to verify material specifications for acceptance and construction practices control to build sustainable highways, it is eminent that asphalt mastic other than neat asphalt binder should provide pertinent information for consistency characterization of the neat asphalt binder in question. Fundamental consistency properties of asphalt binder containing hydrated lime to a conventional No. 70 asphalt binder (Penetration Grade) designed to meet the JTG F40-2004 specification of China were investigated. Hydrated lime was dry mixed with neat asphalt binder at hydrated lime to binder ratio’s ranging from 0.0 to 1.5 in ratio increments of 0.3% by weight of asphalt. Analyses of test results show that asphalt mastic consistency properties are well-defined linear functions of hydrated lime content. Penetration and ductility shows a linear reduction at increased hydrated lime content estimated at 14 (0.1mm) and 15cm per 0.1% of hydrated lime increment respectively while softening point and apparent viscosity increases at the rate of 6oC and 0.1 centipoises per 0.1% of hydrated lime increment respectively.