Dynamic properties of alkali residue-based foamed concrete under dry-wet cycles

Alkali residue-based foamed concrete (A-FC) is a lightweight and sustainable building material made from cement, alkali residue, blast furnace slag and foam. The dynamic properties under drywet cycles and confining pressure are essential considerations for the engineering application of A-FC. Dynamic triaxial tests were used in this study to explore the influence of dry-wet cycles and confining pressure on the backbone curves, damping ratio, and dynamic elastic modulus of A-FC. A calculation model was established to illustrate the combined effects of confining pressure and dry-wet cycles on the maximum dynamic elastic modulus. Test results indicate that during drywet cycles, the coupling effects of temperature, expansion force, and osmotic pressure cause vulnerable pore walls to rupture, pores to become rougher, and microcracks to develop. The backbone curves demonstrate elastoplastic deformation, with no significant change in shape caused by the dry-wet cycles. As the number of dry-wet cycles increases, internal damage accumulates, resulting in a weakening of dynamic deformation ability and a decline in the dynamic elastic modulus. The damping ratio rises with the number of dry-wet cycles once the axial dynamic strain surpasses the transitional strain. Increasing confining pressure can mitigate the adverse impacts of dry-wet cycles on dynamic performance. A-FC demonstrates remarkable durability and favorable dynamic performance, supporting its widespread application in diverse environments.