Use of agricultural waste ashes in asphalt binder and mixture: A sustainable solution to waste management

Abstract

Annually, tonnes of agriculture waste ash from crop residues (husks, bagasse, and straws) are generated as a result of energy production activities. The land-fill disposal and open dumping of generated ash have serious environmental and health problems, primarily due to groundwater contamination. Further, non-availability of land for further dumping is another major problem associated with it. Considering the problems associated with agriculture waste ash, three types of nano agriculture waste ash were used in this study to modify asphalt binder and mixture. Rice husk ash, Sugar cane bagasse ash and Wheat straw ash were first reduced to Nanoscale using a ball mill. The size and chemical properties of these samples were studied using particle size analyser, X-ray fluorescence and X-ray diffraction. Then these samples were mixed with asphalt binder at 2%, 4% and 6% by weight of asphalt binder. All modified binder samples were then tested for storage stability, Fourier transform infrared spectroscopy, penetration, softening point, ductility, performance grading and frequency sweep. All asphalt mixtures prepared using modified binder samples were tested for bitumen-bond strength, rolling bottle, dynamic modulus, cooper wheel tracker and four point beam fatigue. The results confirmed Nano size of each type of agriculture waste ash and amorphous SiO2 as their major chemical component. Further, asphalt binder and mixture samples modified with 6% nano rice husk ash, 6% nano sugar cane bagasse ash and 4% nano wheat straw ash performed better against moisture damage, rutting with the negligible negative effect on fatigue resistance. From the results it can be concluded that incorporation of each nano agriculture waste ash in asphalt binder and mixture is a sustainable and environmental friendly way of its disposal.