Physically simulating the dispersion of chopped carbon fibres in mortar

Abstract

Carbon fibre dispersion exerts a critical influence on the characteristics of carbon fibre-reinforced cement mortars (CFRCMs). This study accordingly investigated the dispersion of chopped carbon fibres (CCFs) in mortar using physical experiments with a transparent simulated mortar system comprising colloidal silica and silica sand as replacements for cement and aggregate, respectively, and evaluated the microstructures and conductive performances of corresponding CFRCM specimens. In the simulated solutions, bundled CCFs in order were more prone to disperse into single fibres than clustered ones in disorder due to no physical fixation, colloidal silica prevented the formation of CCF clusters during stirring, and the shear force of moving sand dispersed but also broke CCFs. In the CFRCMs, sand aggregates reaggregated dispersed CCFs while larger sand particles increased CCF dispersion and improved specimen conductivity. Thus, decreasing the amount of CCFs clusters before dispersion, and a short stirring time in a single direction should be provided to prepare CFRCMs with well-dispersed CCFs. Meanwhile, a more dispersible aggregate and less formation of void should be also essential.