Green utilization of modified biomass by-product rice husk ash: A novel eco-friendly binder for stabilizing waste clay as road material

The use of traditional binders such as cement or lime has induced critical resource consumption, carbon emission, and environmental issues. Recycling biomass/industrial solid wastes as a novel eco-friendly binder is a promising alternative. This paper explores the critical problems of effectively stimulating the activity of waste RHA and the environmental compatibility of the developed waste-based binder. A series of unconfined compression, chemical, and leaching toxicity tests were conducted to evaluate the feasibility of the waste-based binder for waste clay stabilization in road engineering. The results show that the pozzolanic activity of waste RHA was strongly activated by CS with strong alkalinity. The most significant performance improvement for stabilizing waste clay was achieved at 6% RHA with adding 6% CS as an alkalinity activator and 3% MK as a supplement of aluminum phase composition. The 7d soaked compressive strength qiu of stabilizing waste clay reached 1.4 MPa, which met the requirements of the road base for freeway/first-class highway. There was a positive promotion for the reuse and elimination of massive waste RHA and CS. Moreover, many hazardous elements existing in raw materials RHA, CS, and clay were rarely detected in leaching solutions and satisfied groundwater safety. The utilization of RHA, CS, clay wastes in road engineering did not cause marked environmental risks. Finally, abundant newly generated hydration products can be observed due to the carbonization reaction and pozzolanic reaction, thus exhibiting excellent mechanical properties and environmental compatibility. This study presents a promising recycling and reuse way of biomass/industrial solid wastes as an alternative to cement/lime for soil stabilization in road engineering, contributing to carbon neutralization/carbon peak and sustaining economics.