Autogenous shrinkage and crack resistance of carbon nanotubes reinforced cement based composites

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.