The paper deals with a new composite material for waterproofing the underground parts of buildings and structures. The composite consists of Portland cement, fine aggregate, a complex additive, and chemical additives. Based on experimental data, the main physical and mechanical properties of the material have been determined. The results show that the resulting composite material has high physical and mechanical characteristics and can be used to protect concrete underground structures from groundwater damage.

Keywords: underground structures, durability, protection, waterproofing, composite material, complex additive, strength, crack resistance, adhesion, elasticity