Effect of phase-change materials on the hydration and mineralogy of cement mortar

The influence of direct incorporation of thermally efficient phase-change materials (PCMs) on the hydration and mineralogical properties of cement mortar was investigated. To assess the viability of bulk addition of PCMs to a cementitious system, tests of the early age, hydration, mechanical, durability and mineralogical properties were carried out. Organic PCMs showed an increase in setting time, while inorganic materials exhibited fast setting characteristics. Surface temperature was also found to be lower for cement paste with incremental dosages of PCM. However, chemical shrinkage was found to be reduced in the presence of PCM except for the inorganic type. It was observed from the results that PCMs negatively influenced the rate of strength development of a cementitious mortar. The slow rate of strength development was found to be attributed to interrupted hydration, which was confirmed through mineralogical studies. Further, from the thermo-gravimetric analysis, it was observed that the presence of PCMs in a cementitious system increased calcium hydroxide content and reduced the content of water related to hydration products.