Multivariate analysis of effects of microencapsulated phase change materials on mechanical behaviors in light-weight aggregate concrete

In this study, a multivariate analysis of light-weight aggregate concrete embedded by microencapsulated phase change material (MPCM-LWAC) was performed by assessing the effect of water-cement ratio (0.5,0.55, and 0.6), MPCM content (0%, 2.5%, 5.0%, 7.5%, and 10%), curing time (3 d, 7 d, 14 d, and 28 d), as well as MPCM state (liquid and solid state) on the compressive strength , splitting tensile strength , and elasticity modulus. In order to understand the mechanism of the strength change, porosity, SEM images and adiabatic temperature rise of MPCM-LWAC were measured. Results shown that porosity of MPCM-LWAC is linearly proportional to the water-cement ratio, while with the increase of MPCM content, the growth rate of porosity of MPCM-LWAC with the larger water-cement ratio grow more slowly than that of MPCM-LWAC with the lower water-cement ratio, which is contrary to the changes of compressive and splitting tensile strength of MPCM-LWAC. The growth rate of compressive and splitting tensile strength at each age reduces with increasing amount of MPCM, which attributes to the delay in the hardening time of the cement. When MPCM-LWAC samples are subjected to temperature greater than the melting temperature of MPCM, the mechanical behaviors of MPCM-LWAC slightly reduced. The addition of MPCM to LWAC resulted in a linear reduction in elastic modulus . In addition, SEM images showed that no phase change material leakage was found in the damaged specimens.