Deformation and mechanical properties of foamed concrete under various components and pore structure

Based on macroscopic experimentation and microcosmic testing techniques, the effects of water-binder ratio, water reducer, fly ash and rubber particle content on the settlement, compressive and folding strength, dried shrinkage rate and microstructure of foamed concrete were investigated. The sample's porosity and average pore diameter were measured and combined with the sample's settlement, mechanical properties and dry shrinkage to analyze the difference of the microstructure and its influence on the macro properties in order to provide a basis for the control of the settlement and dry shrinkage of foamed concrete. The results demonstrated that the optimal water-to-binder ratio enhanced the ability of the froth and cementitious material to disperse, as well as the cementitious material's capacity to uniformly envelop the bubbles. It is evident that the water-reducing agent can enhance the pore structure of foamed concrete because the pore wall structure is more complete. By re-hydration of fly ash with the calcium hydroxide produced by cement hydration, internal cavities can be filled to a greater extent. Rubber powder can reduce the strength and increase the settlement deformation of foamed concrete, but it can effectively limit the concrete's dry shrinkage deformation. The settlement of the earlier slurry will alter the pore structure of the later material, and the pressure will fracture and fuse the internal pores, resulting in smaller porosity and larger mean aperture.