Peanut Shell Biochar as a Conductive Additive for Cement Composites

Abstract

Extensive efforts have been dedicated to developing conductive carbon materials for cementitious composites to impart multifunctional properties to these materials. Due to environmental concerns, there is a growing demand for abundant, sustainable, and eco-friendly resources. In this context, biochars emerge as a promising option for multifunctional material advancement. Their production process is straightforward and cost-effective, making biochar an attractive carbon-based material choice. This study explores the potential of powdered biochar derived from peanut shells as a conductive additive for cement-based composites. Biochar was generated through thermochemical conversion of peanut shells under oxygendeficient (OD) conditions, achieving a low resistivity of 0.01 Ω·m at 1300 ºC. The properties of cement composite pastes incorporating up to 50 wt% biochar were evaluated. The findings reveal a percolation threshold at approximately 25 wt% in the biochar-cement composite. Below this threshold, the electrical conductivity of the composite was influenced by aging time, while samples above the threshold remained unaffected after solid setting. The composites containing 40 wt% biochar exhibited an electrical resistivity of 0.61 Ω·m, although the compressive strength decreased to 80% of the cement paste. These results highlight the potential of biochars derived from environmentally friendly resources as a sustainable platform for developing novel materials. Furthermore, they offer an alternative to substituting fossil-origin carbons commonly used as additives in cement paste to confer electrical conductivity.