Utilization of municipal sewage sludge and waste glass powder in production of lightweight aggregates

This paper presents a study on the feasible utilization of municipal sewage sludge (SS) and waste glass (WG) powder for the production of lightweight aggregates (LWAs). Mixtures with different WG contents (0%, 5%, 10%, 15%, and 20%) were sintered at 1180 °C with heating rate of 10 °C/min and a dwelling time of 20 min to obtain LWAs samples. The thermophysical behavior of the mixtures was examined through TG-DTA and fusibility tests. The physic-mechanical properties of the obtained LWAs including water absorption, particle density, and compressive strength were studied. The phase compositions and microstructure of the LWAs were analyzed by SEM-EDS, XRD, and micro-CT. Results indicated that adding an appropriate amount of WG contributed to the bloating of SS and to the production of LWAs with high porosity and proper mechanical property. LWAs containing 10% WG and sintered at 1180 °C for 20 min showed a particle density of 0.76 g/cm3, water absorption of 0.87%, and compressive strength of 6.48 MPa, thereby meeting standard requirement of GB/T 17431.2–2010. The obtained LWAs also showed uniform pore-volume distribution.