Water is a vital ingredient of concrete as it actively participates in the chemical reaction with cement, but people still ignore quality aspect of this ingredient.The quality and quantity of water has much effect on the strength of mortar and cement concrete in construction work.
“Water suitable for drinking purpose is generally considered as satisfactory for construction works.”
For major construction projects and for important elements such as sub structure and super structure, it is advisable that the water is tested through a certified lab. The detail test procedure is described in IS 3025 part 22 & 23 for the testing of water used for construction purpose which is briefly described below.
Simple water testing methods at site lab:
Limit of Acidity:
To neutralize 200 ml sample of water, use phenolphthalein as an indicator. It does not require more than 2 ml 0.1 normal NAOH.
Limit of Alkalinity:
To neutralize 200 ml sample of water, use methyl oil as an indicator, it does not require more than 10 ml 0.1 normal HCL.
Another method to check water quality is to perform following test at site lab.
1. Make 3 cubes of concrete with water to be used for construction purpose at site.
2. Make another sets of cubes with same mix proportion, but with distilled water.
3. Test both sets of cubes after 28 days for compressive strength test.
4. Test results should not be less than 90 % of the result noted with distilled water samples.
Permissible Limit for solids as per IS 456 is given in below table
|SN||Type of solids||IS code refer||Permissible Limit (Max.)|
|i)||organic||IS 3a25 (Part- 18)||200 mg/lit|
|ii)||Inorganic||IS 3025 (Part – 18)||3000 mg/lit|
|iii)||Sulphates (us SO3)||IS302s(Part – 24)||400 mg/lit|
|iv)||Chlorides (as Cl)||IS 3025 (Part – 32)||2000 mg/lit|
|v)||Suspended matter||IS 3025 (Part – 17)||2000 mg/lit|
Due to presence of harmful salts in sea water, Sea Water Mixing or curing of concrete with sea water is not recommended. Under unavoidable circumstances seawater may be used for mixing or curing in plain concrete with no embedded steel after having given due consideration to possible disadvantages and precautions including use of appropriate cement system.