Frost Resistance and Meso-deterioration Analysis of Microcapsulated Phase Change Materials Modified Concrete

Abstract

The damage of concrete by freeze–thaw has always been a key issue affecting the safe operation and service of projects in cold regions. In this paper, concrete modified by microcapsulated phase change materials (mPCMs) was evaluated for its frost resistance; the evolution of its internal pore structure and meso-deterioration during freeze–thaw cycles was investigated by industrial computerized tomography; additionally, NanoSiO2 was incorporated for secondary modification to reduce strength loss as the frost resistance of phase change concrete increased. The results show that the incorporation of mPCMs effectively inhibits heat diffusion and temperature change in concrete, conducive to frost resistance, and the freeze–thaw life of phase change concrete increases drastically compared to ordinary concrete. With increasing mPCMs, increment in porosity within concrete decreases and the overall pore distribution tends to be dominated by relatively large pores. When the content of mPCMs exceeds 10%, the pore structure is relatively stable during freeze–thaw. However, the incorporation of mPCMs also reduces the strength of concrete. Under the guarantee of certain strength, the optimal content of mPCMs is initially chosen for 10%; the optimal content of nanomaterials added for reinforcement is 1.5%, with a strength improvement of 11.68%.