Dispersion of High Concentrations of Carbon Nanofibers in Portland Cement Mortars

Figure 8

SEM images of hybrid cement powders. (a) OPC with 1 wt% CNFs. (b) Microfine cement with 1 wt% CNFs. (c) OPC with 2 wt% CNF showing some CNF clumping. (d) Microfine cement with 2 wt% CNFs showing no CNF clumps. (e) OPC with 3 wt% CNFs showing severe CNF clumping between the larger cement grains; the regions between the large OPC cement grains are filled with CNF clumps mixed with the smaller cement grains. (f) Microfine cement with 5 wt% showing no CNF clumping. The cement grain size difference between OPC and microfine is clear. As the concentration of CNFs increases in OPC, the CNF clumping between the larger cement grains becomes more obvious, whereas increasing the concentration of CNFs in the microfine cement does not necessarily lead to CNF clumping.