Recent studies have shown that concrete containing Phase Change Materials (PCM) with low transition temperatures may reduce the number of freeze/thaw cycles suffered by the cementitious composite in temperate climates. Nevertheless, the positive influence of such admixtures on the frost resistance of cement-based materials has not been directly shown, nor the negative. In this study, mortars with different contents of microencapsulated PCM by volume of cement paste were studied with regard to the progression of their internal and salt scaling damages during freeze/thaw cycles. X-ray micro tomography was used to monitor damage development and spatial distribution in the mortars. Furthermore, the pore system and microstructure of the PCM-modified mortars were characterized to unveil the causes of the observed macroscopic behavior during frost weathering. The results show that limited amounts of PCM in mortar, namely $10\text{\%}$ by volume of cement paste, results beneficial for the frost and scaling resistance of the composite. Whereas, for larger PCM additions, like $30\text{\%}$ by volume of paste, the changes in microstructure, porosity and mechanical strength brought in by these admixtures resulted in worsened performance against freeze/thawing cycles.

最近的研究表明，包含具有低转变温度的相变材料（PCM）的混凝土可以减少在温带气候下水泥复合材料遭受的冻融循环次数。然而，这种掺合料对水泥基材料的抗冻性的正面影响尚未得到直接显示，也没有负面影响。在这项研究中，研究了不同含量的微囊化PCM（按水泥浆体积计）的砂浆，涉及其在冻融循环中内部和盐垢破坏的进展。X射线显微断层摄影术用于监测砂浆中损伤的发展和空间分布。此外，PCM改性砂浆的孔隙系统和微观结构的特征揭示了霜冻风化期间观察到的宏观行为的原因。结果表明，砂浆中PCM含量有限，即$10\text{％}$按水泥浆的体积计，结果有利于复合材料的防霜性和抗结垢性。而对于较大的PCM添加，例如$30\text{％}$ 按糊剂的体积计，这些混合物带来的微观结构，孔隙率和机械强度的变化导致抗冻/融化循环性能变差。