In this study, reinforcement effect of 12 types of multiwalled carbon nanotubes (MWCNTs) on mechanical properties of cementitious composites was investigated Research results showed that among pristine MWCNTs with different diameters and lengths, the short MWCNTs with large diameter present the best reinforcing effect on strength of composites. Functionalization of MWCNTs is beneficial for enhancing strength of composites. Moreover, hydroxyl-functionalized MWCNTs feature a better reinforcement effect compared to carboxyl-functionalized MWCNTs. The best relative/absolute enhancements of 79%/74 MPa and 64.4%/5.6 MPa in compressive and flexural strength of composites are achieved by incorporating 0.5% of nickel-coated MWCNTs. XRD analyses revealed that the incorporation of MWCNTs decreases the orientation of CH in matrix, which is consistent with SEM observations. TG analyses showed that MWCNTs inhibit hydration of composites due to their absorption effect. However, extensive MWCNT networks improve microstructure of matrix and hinder the crack development under loading through fiber bridging and pull-out.

本研究研究了12种类型的多壁碳纳米管对水泥基复合材料力学性能的增强作用。研究结果表明，在不同直径和长度的原始MWCNT中，大直径的短MWCNT对强度的增强效果最好。复合材料。MWCNT的功能化对于增强复合材料的强度是有益的。而且，与羧基官能化的MWCNT相比，羟基官能化的MWCNT具有更好的增强效果。通过掺入0.5％的镍包覆的MWCNT，可以使复合材料的抗压强度和抗弯强度分别达到79％/ 74 MPa和64.4％/ 5.6 MPa的最佳相对/绝对增强。XRD分析表明，MWCNT的结合降低了CH在基质中的取向，这与SEM观察结果一致。TG分析表明，由于其吸收作用，MWCNTs抑制了复合材料的水合作用。然而，广泛的MWCNT网络改善了基体的微观结构，并阻碍了在负载下通过纤维桥接和拉拔产生的裂纹。