Sensing properties of slag-based geopolymer composite with carbon fibers under compressive loading

Application of functional materials has become a new trend in the construction industry. This paper aims to study the electrical and self-sensing properties of slag-based geopolymer composite. In order to improve the electrical conductivity of the basic geopolymer mortar, carbon fibers in the amount of 0.5, 1 and 2% were added. The influence of fiber addition on the electrical properties was determined by impedance spectroscopy and microstructure was analyzed by means of mercury intrusion porosimetry and SEM. The sensing properties were tested under repeated compressive loading in the elastic range and finally under loading till failure. The electrical resistance decreased with the addition of carbon fibers but it caused a deterioration of the mechanical properties. The addition of fibers does not generally improve the sensing performance of the geopolymer composite, but the mixture with 2% of fibers appeared to be unsuitable for this purpose due to the low signal-to-noise ratio.