Application of polymer cement repair mortar in underground engineering: A review

Polymer-modified cementitious repair materials have gained attention as innovative and environmentally friendly construction materials due to their superior water retention, adhesion, freeze-thaw resistance, corrosion resistance, air permeability, and shrinkage resistance compared to ordinary repair materials. Adding a small amount of polymer can alter the concrete microstructure and form a composite material through the interaction between polymer film formation and cement hydration. This review shows that adding a certain percentage of polymers to concrete can improve the physical, fresh properties, durability, mechanical properties and microstructural development of concrete and improve the effectiveness of concrete repair treatment of underground structures. The discovery of different types and amounts of polymer cement from both physical and chemical perspectives can significantly enhance the performance of cement mortar. Various modifications, such as fibers and nanomaterials are explored to improve the properties of polymer cement for optimal treatment results. Finally, this paper summarizes key findings and provides recommendations for future research.