Construction ceramsite from low-silicon red mud: Design, preparation, and sintering mechanism analysis

Abstract

Low-silicon red mud (LSRM) is limited in its application in the field of light aggregates for construction. Supplementation sintering materials (SSMs) effectively aids LSRM in preparing sintered construction ceramsite. To produce an LSRM-based ceramsite with economical and effective performance, this study investigated the effect of SSMs (silica fume, bentonite, and glass powder) on the performance of the ceramsite and determined the optimum ratio using the response surface method (RSM). The results indicated that the silica fume (SF) significantly influenced the apparent density (AD) and water absorption (WA) of the ceramsite; with an increase in SF, AD increased and WA decreased. SF and glass powder (GP) were negatively correlated with particle strength (PS), whereas bentonite was positively correlated with PS. The optimum doping values for SF, bentonite, and GP were determined as 19.79, 9.28, and 12 wt%, respectively. Ceramsite could achieve the best performance with an AD of 1254 kg/m3, a WA of 3.13%, and a PS of 13.1 MPa. In addition, the formation of aluminosilicate played a positive role in the fixation of heavy metals and the reduction of the pH value of ceramsite, ensuring its good environmental performance.