Interfacial interactions and reinforcing mechanisms of cellulose and chitin nanomaterials and starch derivatives for cement and concrete strength and durability enhancement: A review

Nanomaterials have been widely researched for use in construction materials. Numerous studies demonstrate that nanomaterials in small quantities can significantly improve the macroscopic properties of cement paste, mortar, or concrete through various mechanisms. Nanomaterials retrieved from biomass sources have recently gained particular research interest due to remarkable structural properties and the source material’s abundance and renewability. Cellulose and chitin are the most abundant polysaccharides in nature; thus, they are candidates for nanomaterials extraction as multifunctional additives in cementitious systems. In recent years, cellulose nanomaterials in cementitious composites have been extensively investigated, but chitin nanomaterials and starch derivatives for cement and concrete are still emerging research areas. This review article starts with an overview of polysaccharide nanomaterials’ (PNMs) physicochemical properties as a result of different chemical and mechanical extraction processes. Next a brief overview of cement hydration chemistry and microstructure and the interfacial interactions between the cement and the various surface chemical functionalities of PNMs are discussed. Then, the key mechanisms governing the cement strength enhancement by PNMs, such as bridging, nucleating and filling effect, and internal curing, are described. Finally, the impacts of PNMs on other properties of the cement are discussed.