Rapid preparation of a composite insulating block comprising waste expanded polystyrene (EPS) foam and rice straw

Abstract

Due to the world’s decreasing energy supply, reducing the energy consumption of building envelopes has become an urgent issue with economic benefits. Rice straw is a generally available agricultural residue. The purpose of this study was to estimate the effects of rapid pretreatment methods and slaked lime on the molding of rice straw insulation blocks and to evaluate the effectiveness of integrating expanded polystyrene (EPS) particle waste with rice straw as building materials to reduce the energy loss in buildings. The pretreatment time was shortened from 6 h to 3 h by mechanical stirring combined with lye soaking. The molding of the insulation block could be improved by the hardening of slaked lime through contrast experiments and electron microscope scanning. Moreover, the influences of the mass ratio of slaked lime to rice straw (RSR) and the dosage of the EPS particles (ωEPS) on the dry apparent density and the thermal conductivity of the insulation blocks were studied. The results showed that the slaked lime would increase the dry apparent density and weight of the insulation block, but the EPS can effectively reduce this negative effect and keep the thermal conductivity of the insulation block below 0.049 W·m-1·K-1. Ultimately, the rapid pretreatment technology was determined to include lye soaking for 3 h and mechanical stirring for 5 min. The material matching ratio scheme was determined to have a ωEPS value of less than 3% and an RSR value equal to 1/7.5.