Modification of in-situ polymerization of acrylamide and synergies with fiber in enhancing cement-based composite

Abstract

Due to its inherent brittleness and heterogeneity, high performance cement-based materials continue to be a challenge. An enhancing cement-based composite is prepared based on polymer-fiber synergies, combining the structure design and toughening strategy of the dual organic networks. Crucially, the modification is performed by in-situ polymerization of acrylamide and synergies with fiber. The mechanical properties of the composite are significantly improved, such as flexural strength and toughness. Incorporating 4 wt% polymers and 1.75 vol% fibers, this approach shows that the remarkable flexural strength is increased by 151.7 %. And the brittle fracture of conventional cement-based materials is transformed into a distinct ductile fracture. The composite has obvious performance advantages over the single reinforcing material. Further, the dual network and synergistic modification mechanisms are revealed by microscopic characterizations. On the one hand, through structural design, in-situ polymers and fibers promote the formation of an interwoven dual network. On the other hand, the bonding interaction between polymers, fibers, and hydration products is confirmed by the experimental results, including hydrogen bonding and carboxyl-metal ion bonding, facilitating the formation of an interwoven and tightly integrated polymer-fiber ductile organic network. In addition, the bonding interaction establishes an efficient energy dissipation mechanism to enhance the bonding properties between fibers and hydration products significantly. Notably, in-situ polymerization can in-situ modify the fiber surface's interfacial structure, improving pore size distribution. The dual network structure and toughening strategy based on in-situ polymerization provide a viable and promising instance for manufacturing high-toughness cement-based composites and in-situ microstructure design.