Application of waste rice straw as fibre or filler in asphalt mixtures: materials characterisation and performance evaluation

Abstract

ABSTRACT This study investigated the application of agricultural waste rice straw as fibre or filler in asphalt mixtures. Initially, the physical, chemical, mineralogical and morphological characterisation of rice straw products were analysed. Subsequently, the performance of stone matrix asphalt (SMA) mixtures containing rice straw fibre was evaluated in terms of rutting, crack resistance and moisture susceptibility, compared to cellulose fibre. Additionally, the properties of asphalt concrete (AC) mixtures incorporating rice straw filler to replace conventional mineral filler partially were examined. The findings revealed that rice straw products exhibited similar characteristics to cellulose fibre or mineral filler, indicating their suitability for use in asphalt mixtures. The appropriate addition of rice straw fibre or filler demonstrated enhancement in the high-temperature performance, low-temperature crack resistance and moisture stability of asphalt mixtures. Through experimental tests, the optimum content of rice straw fibre in SMA-13 mixtures was determined to be 0.4%, while for the rice straw filler in AC-13 mixtures, it was 20%. The mechanisms of rice straw fibre and filler added in asphalt mixtures to strengthen their road performance were binder adsorption and reinforcement effect through scanning electron microscope (SEM) images. Furthermore, rice straw filler also contributed to void filling within asphalt mixtures.