碳纳米管增强水泥基复合材料的自收缩及抗裂性能碳纳米管增强水泥基复合材料的自收缩及抗裂性能
Autogenous shrinkage and crack resistance of carbon nanotubes reinforced cement based composites

水泥基材料的收缩开裂已经成为其破坏的一个主要原因，受到国内外关注，碳纳米管（CNTs）作为一种纳米纤维状材料，可能可以抑制水泥基材料收缩。本文将CNTs放入水中，经过超声处理分散后，形成CNTs分散液，设置不同的CNTs掺量将其掺入到水泥基材料中，通过波纹管实验及圆环试验对该种新型复合材料的自收缩及抗裂性能进行研究。结果表明：CNTs的掺入可以很大程度上抑制水泥基材料的自收缩，最高降低率可到40%以上，且明显提高了水泥基材料的抗裂性能。水灰比的增加会提高CNTs对水泥基材料收缩的抑制效果。当CNTs的掺量为0.1wt%时，可以获得最优效果。同时，CNTs的掺入不仅对水泥基材料自收缩有抑制作用，一定程度上也会抑制水泥基材料的干燥收缩。通过将CNTs掺入到建筑结构关键部分的水泥基材料中，可以提高建筑安全系数。 Shrinkage cracking of cement-based materials has become a major cause of its destruction, which has attracted attention at home and abroad. Carbon nanotubes (CNTs), as a nano-fibrous material, may inhibit the shrinkage of cement-based materials. In this paper, CNTs were put into water and dispersed by ultrasonic treatment to form CNTs dispersion liquid. Different CNTs contents was set and added into cement-based materials. The autogenous shrinkage and anti-cracking properties of the new composite were studied through linear shrinkage test and ring test. The results show that the incorporation of CNTs can largely inhibit the self-shrinkage of cement-based materials, with the highest reduction rate reaching more than 40%, and significantly improve the crack resistance of cement-based materials. The increase of water-cement ratio will improve the inhibition effect of CNTs on the shrinkage of cement-based materials. When the content of CNTs is 0.1wt%, the optimal effect can be obtained. Meanwhile, the incorporation of CNTs not only inhibits the self-shrinkage of cement-based materials, but also inhibits the drying shrinkage of cement-based materials to a certain extent. By adding CNTs to cement-based materials in key parts of the building structure, the building safety coefficient can be improved. 国家自然科学基金面上项目（51778582；51879235）；国家重点研发计划子课题（2017YFC0804809