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Design Mix Concrete Acceptance Criteria:
I. The concrete shall be deemed to comply with the strength requirements if:
a) every sample has a test strength not less than the characteristic value;or
b) The strength of one or more samples though less than the characteristic value, is in each case not less than the greater of :
1) The characteristic strength minus 1.35 times the standard deviation; and
2) 0.80 times the characteristic strength ; and the average strength of all the samples is not less than the characteristic strength plus
times the standard deviation.
II. The concrete shall be deemed not to comply with the strength requirements if:
a) The strength of any sample is less than the greater of :
1) the characteristic strength mix is 1.35 times the standard deviation; and
2) 0.80 times the characteristic strength ; or
b) The average strength of all samples is less than the characteristic strength
plus
times the standard deviation.
III Concrete which does not meet the strength requirements as specified in I, but has a strength greater than that required by II may, at the discretion of the designer, be
accepted as being structurally adequate without further testing.
IV. Concrete of each grade shall be assessed separately.
V Concrete shall be assessed daily for compliance.
VI. Concrete is liable to be rejected if it is porous or honey-combed; its placing has been interrupted without providing a proper construction joint; the reinforcement has been
displaced beyond the tolerances specified; or construction tolerances have not been met. However, the hardened concrete may be accepted after carrying out suitable remedial
measures to the satisfaction.
VIII. Where the value of the average strength of the tests (preferably 30 tests or 15 tests) is less than
shall be rejected.
