Strain sensing of carbon fiber reinforced geopolymer concrete

Health monitoring of concrete structures is performed by assessing the structure's state of stress. One such method involves monitoring electrical resistance variations as an indirect measure of stress variations. Carbon fibers were added to fresh geopolymer mix to enhance its electrical conductivity. AC-impedance spectroscopy analyses were performed on sample specimens to obtain their electrical resistance. Geopolymer concrete specimens entrained with carbon fibers were dynamically loaded in bending and uniaxial compression to observe changes in electrical resistance with respect to variations in their stress state. For beam specimens electrical resistance was found to follow a descending trend with increasing bending stresses. A more complex relationship was noted for cylinder specimens that were loaded axially. Overall experimental results suggest that conductive geopolymer could serve as a smart material in health monitoring applications of concrete structures.