Microstructure, durability and surface free energy of lightweight aggregate modification of sanitary ceramic wastes and sewage sludge

Abstract

The research on the durability and physical properties of lightweight aggregate (LWA) with addition of sanitary ceramic wastes and sewage sludge was presented in the paper. The following characteristics of LWA were defined: contact angle (CA), absorptivity, roughness, surface free energy (SFE) before and after the UV radiation durability test, thermal conductivity coefficient λ, compressive strength, freezing-thawing, salt resistance and others. Open porosity was examined using computed tomography, it reached 20.987 % for the ceramic waste aggregate, and 7.023 % for the reference aggregate. The aggregate with the largest amount of ceramic waste (20 %) and sewage sludge (10 %) has the highest average roughness (Ra), which is 14 % higher than the Ra of the reference aggregate. The contact angle decreased by almost 4 times and samples had higher absorptivity (19.994 %) when 10 % sewage sludge and 20 % sanitary ceramic were added to the aggregate. The sanitary ceramic waste application may enhance the poor durability characteristics of lightweight aggregate with/without sewage sludge. Replacing natural loess with sanitary ceramic waste material brings benefits both in terms of respect for natural resources and also improves the properties of lightweight aggregates.