Calcium addition synergistic ball milling of municipal solid waste incineration bottom ash improves performance of controlled low-strength material

This study aims to synergistically enhance properties of controlled low-strength material (CLSM) by incorporating ground granulated blast-furnace slag (GGBS) for calcium addition and ball milling municipal solid waste incineration bottom ash (MSWI-BA), enabling its application in road base construction. The engineering performance, microstructure, and environmental impact of CLSM were investigated. The results revealed that with 15% GGBS and ball milling MSWI-BA for 15 min, the flowability remained above 220 mm and drying shrinkage was dramatically reduced. The 7-day unconfined compressive strength reached 4.19 MPa, meeting the strength requirements for road base materials. Through physical refinement and reactive activation, the synergistic effects of ball-milled MSWI-BA and GGBS promoted the formation of C-(A)-S-H and reduced the total porosity. After 12 dry-wet cycles, the strength decreased by only 3.1%. In addition, the leaching of Pb, As, and Cd was effectively diminished, and carbon emissions were reduced by 57.7%.