Experimental and numerical investigations on the inhibition of freeze–thaw damage of cement-based materials by a methyl laurate/diatomite microcapsule phase change material

The freeze–thaw damage of cement-based materials is a widely considered durability problem, which can be effectively inhibited by keeping its temperature over freezing point. In this paper, a methyl laurate/diatomite microcapsule phase change material (CPCM) was fabricated by porous adsorption and microencapsulation. It is found that an ethyl cellulose film is suitable as a packaging film of CPCM, and it can effectively prevent the leakage of methyl laurate during the phase change process. Based on the BET, XRD, FT-IR and TG-DSC tests, it was proven that the methyl laurate/diatomite CPCM has good chemical stability and thermal stability. The phase change temperature of the CPCM ranges from −1.75 °C to −5.51 °C, and the latent heat value is 65.70 J/g. The methyl laurate/diatomite CPCM was incorporated into cement paste at 10 %, 15 % and 20 % mass fractions, and the mass loss of the cement paste in freeze–thaw cycles can be reduced by up to 57 %; however, the mechanical properties of the cement paste decrease with increasing mass fraction of CPCM. Finally, a thermal transfer numerical model of the cement-based material with CPCM was established, based on which the simulation results agree well with the experimental values. The results show that the existence of CPCM could maintain the temperature of the specimen above zero for 4 h at an ambient temperature of −10 °C. The CPCM prepared in this study can significantly enhance the frost resistance of cement paste.