Preparation and piezoresistive properties of carbon fiber-reinforced alkali-activated fly ash/slag mortar

In this study, a novel type of conductive mortar was proposed and prepared by alkali-activated fly ash/slag (AAFS) combined with carbon fibers. The workability, mechanical properties, electrical resistivity and piezoresistive properties of carbon fiber-reinforced AAFS (CF-AAFS) mortar were investigated and compared with carbon fiber-reinforced cement mortar (CF-CM). It was found that CF-AAFS exhibited much better workability and significantly higher compressive strength (>66 MPa at 28 days) than CF-CM with the same carbon fiber content. With 0.2 vol% carbon fibers, the electrical resistivity of CF-AAFS mortar decreased from 3313 Omega.cm to 165 Omega.cm at 28 days, reaching the percolation threshold. AAFS mortar with only 0.1 vol% carbon fiber content exhibited good piezoresistivity under both monotonic and cyclic compression. Therefore, CF-AAFS was regarded as a promising material in the use of self-sensing structure in construction. (C) 2019 Elsevier Ltd. All rights reserved.