The effects of a range of carbon nanotube (CNT) additions (0.1 to 0.5% by weight of cement) on the early hydration processes (0-24h) of cementitious composites were investigated by isothermal calorimetry, Fourier transform infrared spectroscopy (FTIR), X-Ray powder diffraction (XRD) analysis and scanning electron microscope (SEM) observation. The addition of CNT can improve the rate of hydration heat of cementitious composites. However, 0.1 wt.% CNT obviously decreased the total cumulative hydration heat of cementitious composites. Additionally, the peaks corresponding to${}_{V_4}{}^{}Si{O}_4^{4-}$ vibrations were shifted from 496 cm^-1 to higher frequencies (534 cm^-1, 534 cm^-1 and 546 cm^-1) at 24h due to the inclusion of CNT (0.1%, 0.3% and 0.5%). It is hypothesized that CNT with high surface energy can improve the energy of cementitious composites and increase the polymerization of C-S-H. According to the XRD test, CNT didn’t affect the types of cement hydration products, but can reduce the orientation index of calcium hydroxide crystal. The microstructure observations demonstrated that CNT can also change the morphologies of hydration products and modify the microstructure of cementitious composites. Such behaviors could be associated with the case that CNT can increase the polymerization degree of C-S-H which was verified by the isothermal calorimetry and FTIR test.

通过等温量热法，傅立叶变换红外光谱（FTIR），X研究了一系列碳纳米管（CNT）添加量（水泥的0.1至0.5％（重量））对胶凝复合材料早期水合过程（0-24h）的影响。 -射线粉末衍射（XRD）分析和扫描电子显微镜（SEM）观察。CNT的添加可以提高水泥基复合材料的水合热速率。然而，0.1重量％的CNT明显降低了水泥复合材料的总累积水合热。此外，对应于${}_{V_4}{}^{}\mathrm{小号}\mathrm{一世}{Ø}_4^{4-}$振动从496厘米偏移^-1到更高的频率（534厘米^-1，534厘米^-1和546厘米^-1）由于加入了CNT（0.1％，0.3％和0.5％）而在24小时内）。假设具有高表面能的CNT可以改善水泥基复合材料的能量并增加CSH的聚合。根据XRD测试，CNT不会影响水泥水合产物的类型，但可以降低氢氧化钙晶体的取向指数。微观结构观察表明，CNT还可以改变水合产物的形态并改变胶结复合材料的微观结构。这种行为可能与碳纳米管可以提高CSH聚合度的情况有关，这已通过等温量热法和FTIR测试得到证实。