▎ 摘　　要

NOVELTY - Preparation of an environmentally-friendly nanostructured biocomposite sealant involves (a) preparing graphene or reduced graphene oxide (rGO) or its derivatives via partial exfoliation of graphite in presence of a fuel/fuels and an oxidizer through low-temperature combustion or chemical exfoliation, (b) mixing equal volume of the prepared graphene or reduced graphene oxide to a biopolymer, under continuous stirring at room temperature, to obtain graphene oxide (GO)-biopolymer nanocomposite, (c) mixing calcium/magnesium precursors to the prepared GO-biopolymer nanocomposite, and (d) adding an anti-corrosive and porosity control agent to the GO-biopolymer nanocomposite anchored with the calcium/magnesium precursors. The biocomposite sealant forms calcium carbonate/magnesium hydroxide nanoparticles of size less than 100 nm in-situ when exposed to the concrete environment at ambient temperature during the formation sealant plug. USE - Preparation of environmentally-friendly nanostructured biocomposite sealant used for healing of micro-cracks in concrete, repairing, retrofitting and manufacturing of structural concrete, cement mortar, gypsum and cement-based boards, fiber reinforced composite structural elements and water tight admixtures, and coating on surfaces of steel rebars. ADVANTAGE - The environmentally-friendly and film-forming nanostructured biocomposite sealant is highly stable in the concrete environment and effective in healing the cracks in a short period, has tunable viscosity at ambient conditions and excellent post compressive strength with respect to the concrete specimen, reduces the cost and environmental impact of a building during its life cycle, and is derived from waste-derived material with less embodied energy and enhanced properties. DETAILED DESCRIPTION - Preparation of an environmentally-friendly nanostructured biocomposite sealant involves (a) preparing graphene or reduced graphene oxide (rGO) or its derivatives via partial exfoliation of graphite in presence of a fuel/fuels and an oxidizer through low-temperature combustion or chemical exfoliation, (b) mixing equal volume of the prepared graphene or reduced graphene oxide to a biopolymer, under continuous stirring at room temperature, to obtain graphene oxide (GO)-biopolymer nanocomposite, (c) mixing calcium/magnesium precursors to the prepared GO-biopolymer nanocomposite, and (d) adding an anti-corrosive and porosity control agent to the GO-biopolymer nanocomposite anchored with the calcium/magnesium precursors. The biocomposite sealant forms calcium carbonate/magnesium hydroxide nanoparticles of size less than 100 nm in-situ when exposed to the concrete environment at ambient temperature during the formation sealant plug, and due to the nanosize of the fibers of 20-100 nm and tunable viscosity of 20-1000 cps, the biocomposite sealant penetrates deep inside the cracks on application and chemically binds with the concrete forming a strong and watertight plug at ambient temperature and atmospheric pressure and solidifies in the concrete in a short period to form a strong network with the concrete.