EFFECT OF REDUCTION IN PRODUCTION TEMPERATURES ON PROPERTIES OF BITUMINOUS MIXES WITH AN ORGANIC WMA ADDITIVE

Warm mix asphalt (WMA) refers to the group of technologies that allow a considerable decrease in production, placement and compaction temperatures of bituminous mixes through the addition of organic additives, chemical additives or foaming processes. The use of modified binders in the bituminous courses has become common practice to sustain the high vehicular traffic, climatic variations, and heavy axle loads. This paper presents properties of bituminous concrete (BC) mixes at different additive contents and production temperatures for two modified binders (polymer modified, PMB, and crumb rubber modified, CRMB). WMA additive selected in the study belongs to an organic family. Statistical analysis is performed to analyse the effects of individual factors and their interactions on the test results. Results show that an increase in the additive content improves bulk density and Marshall stability of WMA mixes at all production temperatures. Warm mixes prepared with both binders (PMB and CRMB) were able to satisfy all the requirements set forth by MoRTH specifications of India up to 40°C reduction in production temperatures. Statistical analysis revealed that binder type, additive content, and reduction in production temperature significantly affect properties of BC mixes.