Influence of rice husk ash on moisture susceptibility of warm mix asphalt using chemical based additive

Abstract

Warm mix Asphalt (WMA) is produced at lower temperatures as compared to hot mix asphalt (HMA). It uses several techniques that influence the viscosity property of the bitumen binder, enhances the workability and is beneficial to produce mixes at lower mixing temperatures. In the present study, the chemical-based additive namely Zycotherm used to produce WMA. The effect of rice husk ash (RHA) which is an agricultural waste was varied from 0 to 100% for the replacements of the filler material. A huge amount of RHA is produced every year in the country and disposal is a big issue. Further, hydrated lime was added to check the ability for moisture resistance as an antistripping agent. The viscosity grade (VG 30) was used as the primary binding agent to the mix. The siliceous type of aggregate was used in the warm mix preparation. Dense Bituminous Macadam (DBM) of grade 2 was adopted as an aggregate gradation from the Ministry of Road Transport and Highways (MoRTH, 2013). The Marshall Stability (MS), Retained Marshall Stability (RMS), volumetric properties such as (air voids, voids in mineral aggregates and voids filled with bitumen), Marshall Quotient (MQ) and Indirect Tensile Strength (ITS) test were used to check the strength performance. The durability was assessed by evaluating refusal density and the tensile strength ratio value as per AASHTO T 283. The results reported that the usage of RHA has shown significant improvement as compared to the control mix. The optimum content of RHA was found to be at 50% replacement of natural stone dust. Further increase in RHA content leads to a decrease in stability value. This might be due to the excess content of RHA absorbing more bitumen and insufficient bitumen has remained for coating the aggregate particles.