Concrete for water retention structureAuthor: Aritra Pal; Item no. 2013CEC83141.0 Introduction: The purpose of this study is to select a better choice of watertight concrete for waterproof construction of water retention structures such as tanks, reservoirs, swimming pools, etc. This document includes the study of early age and later aging properties of concretes with chemical admixtures and additional cementitious materials, from the aspect of water impermeability and durability.2.0 Principle of water impermeability: • Concrete shall be dense and durable• Concrete must have the capacity to resist hydrostatic pressure without water infiltration.• Concrete generally contains voids and cracking may occur due to external loading or internal thermal and shrinkage stresses, structural movements etc. These voids and cracks can become the path for water seepage.• For cracks due to external loading nothing can be done with the concrete properties, but for internal shrinkage deformation good mix design with limited content is required of concrete, adequate positioning and curing. • Dense and durable concrete can be obtained with a low water/cement ratio and for proper placement and curing workability of the concrete mix is ​​one of the important factors. • For high strength, low permeability, high durability and workability, the use of an additive is recommended. 3.0 Some properties to take into account: • Permeability: concrete is a mixture of cement and aggregate. Aggregates are generally dense materials, so the permeability of the cement paste determines the waterproofness of the concrete. The gel pores in the cement paste are very small, generally do not affect the density, but the capillary pores with the micro and macro cracks can form the passage for water. Heads...... at the center of the paper...... voids and microcracks can therefore reduce permeability and increase water tightness.• The pozollanic reaction will convert high-density CSH with large cavities into a relatively low density CSH with smaller voids • These properties can increase the strength and durability of concrete. Permeability: • Due to the filling effect of SCM, the permeability of concrete will be reduced effectively. Durability: • Corrosion of steel: the low permeability of concrete prevents the penetration of chloride and therefore reduces the possibility of corrosion in the reinforcing steel. Due to the impermeability of concrete, carbon dioxide gas cannot penetrate into the concrete and the risk of carbonation will be minimized, so the attack in steel by carbonation will be reduced.• Acidic environment: due to the presence of large quantities of calcium hydroxide