Sustainable utilization of biomass waste-rice husk ash as a new solidified material of soil in geotechnical engineering: A review

Nearly 150 million tons per year of waste rice husks are produced worldwide and get accumulated due to underutilization. These waste rice husks have caused serious environmental problems. Transforming rice husks into rice husk ash (RHA) and applying into engineering practice contributes to the sustainable recycling of biomass waste. This paper summarized the basic characteristics of RHA and its application in chemical industry, building materials, environmental protection, especially in geotechnical engineering. A comprehensive review of literature available on RHA-soil mixture was performed to identify the gaps in understanding the behavior of the mixture in terms of mechanical properties, durability, environmental impact and internal mechanism. The results showed that the addition of RHA can effectively improve the performance of soil related to shrinkage cracking, and significantly enhance the compressive strength, shear strength and CBR value of the soil, indicating economic and environmental benefits. Overall, the comprehensive utilization of RHA in geotechnical engineering as a partial alternative of cement/lime is promising as it can contribute to energy savings, low-carbon emissions and sustainable development. However, the acquisition of higher active RHA, micro mechanism of RHA-soil, and in complex environment, the durability, deterioration mechanism and environmental impact of RHA treatment on soil mixtures still need to be studied further. Nearly 150 million tons per year of waste rice husks are produced worldwide and get accumulated due to underutilization. These waste rice husks have caused serious environmental problems. Transforming rice husks into rice husk ash (RHA) and applying into engineering practice contributes to the sustainable recycling of biomass waste. This paper summarized the basic characteristics of RHA and its application in chemical industry, building materials, environmental protection, especially in geotechnical engineering. A comprehensive review of literature available on RHA-soil mixture was performed to identify the gaps in understanding the behavior of the mixture in terms of mechanical properties, durability, environmental impact and internal mechanism. The results showed that the addition of RHA can effectively improve the performance of soil related to shrinkage cracking, and significantly enhance the compressive strength, shear strength and CBR value of the soil, indicating economic and environmental benefits. Overall, the comprehensive utilization of RHA in geotechnical engineering as a partial alternative of cement/lime is promising as it can contribute to energy savings, low-carbon emissions and sustainable development. However, the acquisition of higher active RHA, micro mechanism of RHA-soil, and in complex environment, the durability, deterioration mechanism and environmental impact of RHA treatment on soil mixtures still need to be studied further. (c) 2021 Elsevier Ltd. All rights reserved.