Volcanic Mud Incorporating Paper Sludge as Raw Materials for Lightweight Aggregates

This study assessed the use of volcanic mud collected from southern Taiwan and the incorporation of paper sludge for manufacturing lightweight aggregate (LWA). The firing process of the raw materials and related sintering mechanisms, including sintering temperature and time, were investigated. LWA was manufactured at sintering temperatures ranging from 950 to 1275 °C with soaking times from 2 to 15 min, and preheating temperatures ranged between 500 and 700 °C with soaking times from 5 to 15 min. Using volcanic mud and mixed sludge (volcanic mud with added paper sludge) resulted in the successful manufacture of various qualified LWAs with particle density ranging from 973 to 1950 g/cm³, water absorption from 6.2 to 20.0%, and crushing strength from 2.2 to 15.8 MPa.