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To reduce the structural deterioration of mass concrete structures from temperature cracks, and lower energy consumption caused by the traditional mass concrete hydration heat cooling process, this paper reports the preparation of concrete temperature-controlled phase change aggregate (PCA) by a vacuum compaction method using light and high-strength black ceramite and No. 58 fully refined paraffin wax as phase change material (PCM), and the encapsulation technology of the aggregate by using superfine cement and epoxy resin. Further, through laboratory tests, the cylinder compressive strength, thermal stability and mixing breakage rate of the encapsulated PCA were tested, and the differences in mechanical properties such as compressive strength, flexural strength and splitting tensile strength between phase change aggregate concrete (PCAC) and ordinary concrete were studied. A test method was designed to test the heat storage effect of PCA, and the temperature control effect of PCAC was analyzed based on the law of conservation of energy. The research conclusions are as follows: (1) Both superfine cement and epoxy resin shells increase the strength of the aggregate, with the epoxy resin increasing it more than the superfine cement. The thermal stabilization of the PCA is good after encapsulation of superfine cement and epoxy resin. However, PCA encapsulated in superfine cement is more easily crushed than that encapsulated in epoxy resin. (2) Under the condition of water bath heating and semi-insulation, when the water bath temperature reaches 85 °C, the temperature difference between the PCA and the common stone aggregate can be up to 6 °C. Based on the law of energy conservation, the test results will be converted to mass concrete with the same volume of aggregate mixture;, the difference of PCAC and ordinary concrete temperature can be up to 10 °C, so the temperature control effect is significant. (3) The mechanical properties of PCAC with 100% aggregate replacement rate compared to ordinary concrete are reduced to varying degrees, and the performance decline of the epoxy-encapsulated PCA is smaller than that encapsulated with superfine cement; in an actual project, it is possible to improve the concrete grade to make up for this defect. [ABSTRACT FROM AUTHOR]

• A composite phase change microcapsule particle with both heat reflection and thermal storage is developed. • An indoor solar simulation system that simulates both solar heat radiation and air heat convection is developed. • The heat reflection and energy storage effect of the developed coating is analyzed. • The cooling effect of the developed coatings is quantitatively simulated and investigated. To solve the problems of interlayer cracking, up-arching and warping of ballastless track slab of high-speed railway under temperature load, a composite phase-change microcapsule (MPCM) was developed, and a series of physical and chemical experiments was conducted. The practicality and functional advantages of composite phase-change microcapsules were investigated by SEM, FTIR, DSC and other material tests. The cooling effects of the coating were evaluated and simulated by indoor tests and numerical simulations. The results show that the developed MPCM exhibits both strong reflectivity of TiO 2 and the phase change energy storage property of paraffin, which can reflect 59%-63% of the near-infrared radiation in solar radiation. Moreover, 1 g MPCM can absorb and store 98.3–112.5 J of heat when the ambient temperature exceeds 40 °C. The MPCM coating can reduce the rate of temperature rise of the test specimen, and also decrease its overall temperature difference to 12–15 °C. Furthermore, it can reduce the longitudinal temperature gradient of the test specimen at least by 50%, and its surface temperature by 18%-28%. The temperature regulation ability of coating is positively correlated with the content of MPCM, and its cooling effect reaches the best when the content of MPCM is 20%. The coating reduces the vertical deformation of track slab by 25%-59.6% and the temperature difference inside the track slab by 12.2 °C under high-temperature condition. [ABSTRACT FROM AUTHOR]