Thermal and mechanical performances of cement-based mortars reinforced with vegetable synthetic sponge wastes and silica fume

Abstract Appropriate sand for construction is getting scarce in many countries leading to a growing interest in the use of wastes from several origins in mortar and concrete production. This paper investigates the performances of mortar containing the industrial wastes of vegetable synthetic sponges (VSS) as natural sand replacement. After preparation, different amounts of VSS particles (up to 20 wt% of sand replacement) were incorporated in the cementitious matrix containing 20% of silica fume by weight of cement. The use of silica fume improved the cement-aggregate interface leading to reduce the porosity and to increase consequently the mechanical strength. The replacement of the natural sand with VSS improved the thermal performance of the studied composites by causing a decrease of thermal conductivity up to 63% for 20 wt% of sand replacement by VSS. The thermal diffusivity of composites decreased and the specific heat capacity increased. The combination of VSS and silica fume in cementitious materials can largely improve the post-cracking extension and fracture energy, even if the compression strength is reduced. The study showed that the use of vegetable synthetic sponge wastes provides good potential to answer a major challenge: reducing environmental impact of this material while providing a new use with optimum technical properties, as found with 8 wt% of VSS.