Enhanced effects of carbon-based conductive materials on the piezoresistive characteristics of cementitious composites

Abstract

In the present study, an enhanced effects of carbon-based conductive materials on the piezoresistive characteristics of cementitious composites were investigated. A polycarboxylate-based superplasticizer and silica fume were used to disperse conductive mateirals effectively into cement pastes. The dispersion of the conductive materials in the cement pastes was evaluated through electrical resistance measurement, zeta-potential test, and sedimentation test. In this study, carbon nanotube (CNT) and carbonyl iron powder (CIP) were used as conductive materials. The piezoresistive characteristics of the cementitious composites under cyclic loading conditions were explored. The effects of the incorporation of CNT and CIP on the piezoresistive performance were evaluated through the electrical resistance change and the relationship between the electrical resistance change and loads. The test results indicated that the incorporation of CIP into cementitious composites with CNT improved the piezoresistive sensing performance of the composites. The maximum electrical resistance changes of the composites with CIP were 67.49% when the CNT content was 0.5 wt%. Furthermore, the effects of various temperature conditions on the piezoresistive characteristics of cementitious composites were studied. Changes in piezoresistive characteristics of the composites exposed to elevated temperature and subjected to freeze-thaw cycles were analyzed. The electrical resistance change of the conductive network significantly changes at 200 °C.