Wang Yejia, Wang Chengjin, Luo Aibo, Dong Minqi, Su Qian, Zhou Chenling, Zhang Zongyu, Pei Yanfei
Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, UK.
School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, China.
Materials (Basel). 2023 Jul 27;16(15):5269. doi: 10.3390/ma16155269.
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.
为减少大体积混凝土结构因温度裂缝导致的结构劣化，并降低传统大体积混凝土水化热冷却过程所造成的能源消耗，本文报道了采用轻质高强黑色陶粒和58号全精炼石蜡作为相变材料（PCM），通过真空压实法制备混凝土温控相变骨料（PCA），以及使用超细水泥和环氧树脂对骨料进行封装的技术。此外，通过室内试验，测试了封装后PCA的圆柱体抗压强度、热稳定性和搅拌破损率，并研究了相变骨料混凝土（PCAC）与普通混凝土在抗压强度、抗折强度和劈裂抗拉强度等力学性能方面的差异。设计了一种测试PCA蓄热效果的试验方法，并基于能量守恒定律分析了PCAC的温控效果。研究结论如下：（1）超细水泥和环氧树脂外壳均提高了骨料的强度，环氧树脂的增强效果大于超细水泥。采用超细水泥和环氧树脂封装后，PCA的热稳定性良好。然而，用超细水泥封装的PCA比用环氧树脂封装的更容易破碎。（2）在水浴加热和半保温条件下，当水浴温度达到85℃时，PCA与普通石骨料之间的温差可达6℃。基于能量守恒定律，将试验结果换算为相同体积骨料混合物的大体积混凝土，PCAC与普通混凝土的温差可达10℃，温控效果显著。（3）与普通混凝土相比，骨料替代率为100%的PCAC的力学性能有不同程度的降低，环氧树脂封装的PCA性能下降幅度小于超细水泥封装的；在实际工程中，可提高混凝土等级来弥补这一缺陷。
