Evaluating the effect of warm mix additive dosage rate on workability of asphalt

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University of New Brunswick


Asphalt concrete construction using hot mix asphalt causes enormous greenhouse gases emissions. Warm mix additives help decrease the production temperatures of asphalt concrete, thus reducing emissions and improving workability at lower temperatures. Generally, the manufacturer recommends the additive dosage rate. This project aimed to study the effect of dosage rate on the viscosity and workability of asphalt. Two asphalt binders, PG 58S-28 and PG 58H-28, with two warm mix additives, Zycotherm and Evotherm, with different dosage rates, were selected. The results of asphalt binder tests showed no significant difference in penetration grade, softening point and rotational viscosity of binder after the incorporation of additives. However, the steady shear flow test did show some reduction in mixing and compaction temperatures in the case of Evotherm. Moreover, densification curves showed additives worked better at an optimum dosage of 0.07% for Zycotherm and 0.4% for Evotherm, achieving a 10°C reduction in compaction temperatures.