In recent years, in-situ polymerization has emerged as a promising technique for enhancing cementitious composites. This review examines the progress and advancements in in-situ polymerization modified cementitious composites (iPMCC), including the in-situ polymerization system, manufacturing, workability, mechanical properties, durability, microstructure, mechanism, application scenarios, and challenges. Incorporating monomers into ordinary cement-based composites (OCC) has significantly improved flexural strength (up to 203 %) while maintaining compressive strength with slight increases or minor decreases. The continuous polymer network forms strong crosslinks with cement hydrates, resulting in a more resilient polymer-cement system that effectively inhibits crack initiation and propagation under external loading conditions. iPMCC also demonstrate reduced porosity, contributing to improved durability. Lastly, this review illuminates the potential applications of iPMCC and identifies future research and challenges. It is essential for cement-based materials to demonstrate improved longevity and mechanical performance while integrating versatile applications. Overall, this review provides valuable insights into in-situ polymerization techniques for developing robust and functional cementitious materials, while also paving the way for future design, development, and utilization of organic/inorganic composite systems.

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