Stress-Solid Materials-Voids interaction of foamed concrete in isotropic compression

Solid materials and voids were two significant components for foamed concretes and had the characteristic of coordinated deformation. However, two parts seemed disconnected to date. This research investigated the stress -solid materials-voids interaction by conducting isotropic compression experiments. The stress-strain curves, deformation process, nu-lnp curves, and key mechanical parameters were analyzed in detail. The results indicated that the stress-strain curves in isotropic compression could be divided into three phases: initial elastic stage, voids compression stage, and densification stage. The nu-lnp curves were deduced to describe the reduction in porosity along with the stress. Correspondingly, the isotropic yield strength and structure failure strength were proposed to characterize the strength variation of solid materials in isotropic compression. Based on two strengths, the features of solid materials with elastic deformation and compressing pores were illustrated in detail. Furthermore, a piecewise function was proposed to describe the nu-lnp relationship, and corresponding compression indexes were established to calculate the rate of voids compression. Besides, the isotropic yield strength was related to the mix condition and was on average 25.2% larger than the uniaxial compressive strength. Moreover, the final volume strain was a little smaller than the initial void ratio, signifying that foamed concretes possessed some micro-pores that could not be filled by solid materials.