Effect of styrene-butadiene rubber on the electrical properties of carbon black/cement mortar

Abstract

The piezoresistivity of carbon black/cement mortar (CB/PC) makes it a potential candidate for the development of smart structures with sensing capability. To ensure reliable sensing results in different environments, a hydrophobic styrene-butadiene rubber (SBR) was incorporated to reduce the effect of moisture on the piezoresistivity. The influence of SBR content (0, 5, 10 and 15 wt%) on the electric conductivity and piezoresistivity of SBR/CB/PC mortar with different moisture content was experimentally studied. Results indicate that the electric conductivity and piezoresistivity effect of SBR/CB/PC mortars increase with increasing SBR content. Also, compared to pure CB/PC mortars, the electrical properties of SBR/CB/PC mortars were significantly less sensitive to the variation of moisture. Under cyclic loading, both positive (PP) and negative piezoresistivity (NP) are found to occur in SBR/CB/PC mortars. This behavior can be explained in terms of a mechanism with both the tunneling effect and capacitance effect between CB particles during compression.