Carbon black based self-sensing cement composite for structural health monitoring – A review on strength and conductive characteristics

Abstract

Even though concrete buildings have high strength and durability, they are susceptible to damage from hazards, aging, etc. In concrete structures, carbon-based conductive compounds with the potential to increase the electrical conductivity of concrete are preferred. However, it was extremely difficult to handle the high cost that prevented the widespread use of conductive materials in concrete. Carbon black, a low-cost carbon-based conductive substance supports the development of self-sensing cement composite, which has significant applications in Structural Health Monitoring (SHM). This review concentrates on the alteration of compressive strength, split tensile strength, flexural strength and conductive characteristics of concrete properties using carbon black. Utilizing a scanning electron microscope (SEM), the volume and shape of porosities inside the carbon-black embedded cement composite were analyzed. The review revealed that self-sensing cement composite based on carbon black has high durability, cheap cost, and sensitivity. The analysis found that the carbon content, size, and conductivity of the carbon black utilized significantly impact the piezoresistivity of cement composites. Nevertheless, with an increase in carbon black concentration and under conventional curing, cement composites' compressive strength and flexural strength are significantly diminished. The conductivity of the cement composite is directly proportional to the concentration of carbon black; however, the piezoresistivity of the cement composite is not considerably attained beyond the percolation threshold. The review concludes that, despite the inclusion of carbon black with acceptable strength and good sensing characteristics, the carbon-black embedded self-sensing cementitious composite is an appropriate material for structural health monitoring of various concrete infrastructures under various environmental conditions.