Nonsintered lightweight aggregates produced from waste sludge and its characteristics affected by additives

摘要

In order to solve the disposal problem of municipal solid waste incineration bottom ash sludge (MSWI-BAS) and decrease the energy consumption and environmental pollution of lightweight aggregates (LWAs) prepared by traditional sintering methods, nonsintered LWA were produced with MSWI-BAS. The effects of different curing time and additives on the performance of LWA were studied. Results showed that the LWA after 28 days of curing has the best physical properties: compressive strength 1.50 MPa, 1 hr water absorption 35%, and particle density 868 kg/m~3. When the MSWI-BAS content is 64%, the granules have the highest particle strength and particle density, reaching 2 MPa and 860 kg/m~3, respectively. Ca~(2+) and SO_4~(2-) disintegrated from CaSO_4·2H_2O interact with the skeleton of LWA to produce silica-alumina gel materials, which are beneficial to strength. The sodium silicate mainly acts as a binder to promote the reaction of Ca~(2+) and Al~(3+) in the reaction system to produce C-S-H gels, which increase the density and strength. This innovative technology using MSWI-BAS to produce high performance and nonsintered LWA is fully compliant with the requirements of clean production and sustainable development.