Gasification Char and Used Foundry Sand as Alternative Fillers to Graphene Nanoplatelets for Electrically Conductive Mortars with and without Virgin/Recycled Carbon Fibres

Abstract

Structural health monitoring to assess the safety, durability and performance of structures can be performed by non-destructive methods such as the measurement of impedance in self-sensing cement-based elements. Cement-based materials, like mortars and concretes, generally have high electrical resistivity but the addition of carbon-based fillers and fibres decreases their electrical resistivity and thus enhances their self-sensing capabilities. In this study, two waste carbon-based fillers, namely, used foundry sand and gasification char were compared to commercial graphene nanoplatelets and used to produce self-sensing cement mortars, both with and without recycled or virgin carbon fibres. The mortars were tested in terms of their mechanical and electrical properties as well as their propensity to capillary water absorption. The results demonstrate that gasification char alone is the best carbonaceous waste for decreasing the electrical resistivity (−42%) and water absorption (−17%) of mortars, while their compressive strength remains unaltered. Moreover, although there is a slight reduction in compressive strength and an increase in water suction when gasification char is coupled with fibres, the combination of fillers and fibres has a synergistic effect in decreasing mortars’ electrical resistivity, especially when recycled carbon fibres are used (−80%).

New Materials and Technologies for Durability and Conservation of Building Heritage

“…Comparing steel and carbon fibers [ 38 ], a recently published work has shown the best effectiveness is in recycled carbon fibers (RCF) compared with virgin carbon fibers (VCF) and brass-coated fibers (BSF) in noticeably reducing concrete resistivity even at low fiber dosages [ 39 ]. This result can be ascribed to the high number of carbon micro-particles on the fibers’ surface, which increase the specific conductive surface of RCF [ 40 ].…”

Biochar as construction materials for achieving carbon neutrality

“…5g). The addition of biochar at a dosage of 1% (v/v) to cement significantly reduced the electrical resistivity (− 42%) whilst maintaining good mechanical properties (Mobili et al 2021). Engineered biochar at the dosage of 5% incorporated in self-sensing cement composites, exhibiting a 70% reduction in the water adsorption, a 23% increase in electrical conductivity, and an approximately 45% reduction in embodied carbon footprint (Haque et al 2021).…”

Effect of High-Dispersible Graphene on the Strength and Durability of Cement Mortars

“…Cement mortar samples were demolded and dried after 28 days of standard curing, the aluminum foil tape was used to seal the samples, leaving only the top and bottom surfaces, and the gap between the tape and the underside was filled with paraffin. Then, samples were dried in an oven at 60 ℃ to constant weight to ensure that the water in the sample evaporated completely [34]. The mass of each cement mortar sample was weighed and the mass of each group of samples was averaged as the initial mass.…”