Comparison the properties of carbon fiber-based Portland cement and alkali-activated fly ash/slag conductive cementitious composites

Abstract

This study aims to investigate the essential differences of carbon fiber (CF) on the properties of Portland cement and alkali-activated fly ash/slag (AAFS) pastes. The workability, rheological performance, and electrical properties of CF-based AAFS were investigated and compared with CF-based cement paste. The electrical microstructure of CF composites was analyzed by electrical impedance spectroscopy (EIS). The simplified suspension model and the equivalent circuit model are proposed herein describing the carbon fiber based electrically conductive cementitious composites (ECCC). The results show that the flowability of the suspension (i.e. CF as solid phase, plain paste as fluid phase) depends on the fiber factor (F). When F is in the region (region II) between the critical (Fc) and dense F (Fd), satisfactory workability and electrical conductivity were simultaneously obtained from C-CF and AAFS-CF composite. AAFS system has the advantage of CF dispersion compare to cement due to the higher plastic viscosity and the softening effect of alkaline activator. The equivalent circuit simulation parameters show the bulk resistance of the of AAFS matrix is lower than that of cement matrix. The presence of mobile soluble ions in AAFS enhanced the conductivity of AAFS than cement. Therefore, AAFS-CF composite was considered as a promising material for ECCC.