Permissible limit for chlorides in water for mixing concrete

As per IS 456 : 2000, the permissible limit for chlorides in water used for mixing concrete for reinforced concrete work is 500 mg/l.

Explanation:

- The presence of chlorides in concrete can be detrimental to the reinforcement steel, as it can cause corrosion of the steel, leading to reduced durability and strength of the structure.
- Chloride ions can penetrate into concrete through various sources such as water used for mixing, curing, or exposure to seawater or de-icing salts.
- To prevent the corrosion of reinforcement steel, it is essential to limit the amount of chlorides in water used for mixing the concrete.
- As per IS 456 : 2000, the permissible limit for chlorides in water used for mixing concrete for reinforced concrete work is 500 mg/l.
- This limit is based on the chloride ion content in the mixing water, and not the total dissolved solids (TDS) or the electrical conductivity (EC) of the water.
- The water used for mixing concrete should be tested for its chloride content before use, and if the chloride content exceeds the permissible limit, alternative sources of water should be used.
- In case alternative sources of water are not available, suitable measures such as the addition of corrosion inhibitors or the use of corrosion-resistant reinforcement steel may be adopted to ensure the durability and strength of the structure.

Conclusion:

- The permissible limit for chlorides in water used for mixing concrete for reinforced concrete work is 500 mg/l as per IS 456 : 2000.
- Compliance with this limit is essential to prevent the corrosion of reinforcement steel and ensure the durability and strength of the structure.