Morphological, mechanical and durability properties of cement mortar reinforced with multi-walled carbon nanotubes

In this research, multi-walled carbon nanotubes (MWCNTs) were applied as a reinforcement to improve the mechanical and durability properties (mechanical, dry shrinkage and chloride ion resistance properties) of cement mortar composites. For a better dispersibility effect of MWCNTs in matrix, a common surfactant (Sodium dodecyl benzene sulfate (SDBS)) was used at the first step of dispersing in aqueous solution. In the second step, cement, sand, dispersed MWCNTs suspension and defoamer were mixed to prepare homo-dispersed MWCNTs cement mortar composites. The proportion of added MWCNTs was 0, 0.2%, 0.5%, 1.0% and 2.0%. Mechanical, dry shrinkage and chloride ion resistance properties were analyzed in this study. Moreover, the dispersibility effect of MWCNTs in aqueous solution and the microstructure were discerned by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results showed that the added MWCNTs improved the mechanical, autogenous shrinkage and chloride ion resistance properties of MWCNTs/cement mortar composites. The optimum proportion of MWCNTs in matrix was 0.5%. With the addition of 0.5% MWCNTs, the optimum mechanical, autogenous shrinkage and chloride ion resistance properties were obtained. Compared to the plain sample, the maximum improving of 53.3%, 10.4%, 42.8% and 33.3% in flexural strength, compressive strength, autogenous shrinkage and chloride ion resistance properties was obtained. The embedded MWCNTs act as bridges and networks across the voids and cracks in matrix, which guarantees the load-transfer in tension. Copyright © 2015 American Scientific Publishers.