Water for concrete
Water
Water used for mixing and curing shall be clean and free from injurious amounts of oils, acids, alkalis, salts, sugar, organic materials or other substances that may be deleterious to concrete or steel.
Potable water is generally considered satisfactory for mixing concrete. As a guide the following concentrations represent the maximum permissible values:
a) To neutralize 100 ml sample of water, using phenolphthalein as an indicator, it should not require more than 5 ml of 0.02 normal NaOH. The details of test are given in 8.1 of Indian Standard 3025 (Part 22).
b) To neutralize 100 ml sample of water, using mixed indicator, it should not require more than 25 ml of 0.02 normal H2SO4. The details of test shall be as given in 8 of Indian Standard 3025 (Part 23).
c) Permissible limits for solids shall be as given in Table 1.
Water used for mixing and curing shall be clean and free from injurious amounts of oils, acids, alkalis, salts, sugar, organic materials or other substances that may be deleterious to concrete or steel.
Potable water is generally considered satisfactory for mixing concrete. As a guide the following concentrations represent the maximum permissible values:
a) To neutralize 100 ml sample of water, using phenolphthalein as an indicator, it should not require more than 5 ml of 0.02 normal NaOH. The details of test are given in 8.1 of Indian Standard 3025 (Part 22).
b) To neutralize 100 ml sample of water, using mixed indicator, it should not require more than 25 ml of 0.02 normal H2SO4. The details of test shall be as given in 8 of Indian Standard 3025 (Part 23).
c) Permissible limits for solids shall be as given in Table 1.
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S.No.
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Particular
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Tested as per
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Permissible Limit Max
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1.
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Organic
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IS 3025 (Part 18)
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200 mg/l
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2.
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Inorganic
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IS 3025 (Part 18)
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3000 mg/l
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3.
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Sulphates (as SO3 )
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IS 3025 (Part 24)
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400 mg/l
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4.
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Chlorides (as Cl)
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IS 3025 (Part 32)
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2000 mg/l
( for concrete not containing embedded steel and 500
mg/l for reinforced concrete work)
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5.
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Suspended matter
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IS 3025 (Part 17)
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2000 mg/l
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A) The sample of water taken for testing shall represent the water proposed to be used for concreting, due account being paid to seasonal variation. The sample shall not receive any treatment before testing other than that envisaged in the regular supply of water proposed for use in concrete. The sample shall be stored in a clean container previously rinsed out with similar water.
B). Average 28 days compressive strength of at least three 150 mm concrete cubes prepared with water proposed to be used shall not be less than 90 % of the average of strength of three similar concrete cubes prepared with distilled water. The cubes shall be prepared. cured and tested in accordance with the requirements of Indian Standard 516
C). The initial setting time of test block made with the appropriate cement and the water proposed to be used shall not be less than 30 min and shall not differ by ± 30 minute from the initial setting time of control test block prepared with the same cement,and distilled water. The test blocks shall be prepared and tested In accordance with the requirements of Indian Standard 4031 (Part 5).
2. The pH value of water shall be not less than 6.
3. Sea Water
Mixing or curing of concrete with sea water is not recommended because of presence of harmful salts in sea water. Under unavoidable Circumstances sea water 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.
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