Building Materials, Third Edition

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Chlorides

for RC work 500 mg/l

for plain concrete 2,000 mg/l

Sulphates 400 mg/l

Inorganic matter 3,000 mg/l

Organic matter 200 mg/l

Suspended matter 2,000 mg/l

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Based on the properties admixture imparts to the concrete, a selection can be done and the
manufacture’s instructions followed for its method of use. The Bureau of Indian Standards has
also brought out a standard for admixtures, IS: 9103.

IIR eggi€„exgi2g‚s„i‚se

The acceptance criteria for concrete in accordance with IS: 456–2000 are as follows.

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Every sample shall have a test strength not less than the characteristic strength, fck or if the test
strength of one or more samples is less than the characteristic strength, each case should not be
less than the greater of

(i) fck–1.35
, and

(ii) 0.8 fck

and the average strength fav of all samples should not be less than

fck + 
†



1.65

1.65

n

where,

= standard deviation
n = cumulative number of samples tested till date.

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Concrete is taken as not complying with strength requirements if: the strength of any sample is
less than the greater of

(i) fck –1.35
, and

(ii) 0.8fck

and the average strength of all samples, fav is less than

fck + 
†



3

1.65

n