Concrete Strength Acceptance Criteria IS:456-2000

Strength of concrete is commonly considered its most Important property, although in many practical cases, other characteristics, such as durability and permeability, may in fact be more important. However, the strength of concrete is almost invariably a Important element of structural design and is specified for compliance purposes.

Table 1 : Frequency (IS: 456-2000 clause 15.2.2)
The minimum frequency of sampling of concrete of each grade shall be in accordance with the following:

ACCEPTANCE CRITERIA (IS: 456-2000 clause 16)

(A) Compressive strength (Clause 16.1)

The concrete shall be deemed to comply with the strength requirement when both the following conditions are met:

i) The mean strength determined from any group of four non-overlapping consecutive test results, complies with the appropriate limits col. 2 of Table 2.

ii) Any individual test result complies with the appropriate limits in col. 3 Table 2.

(B) Flexural strength (Clause 16.2)
When both the following conditions are met, the concrete complies with the specified flexural strength.
a) The mean strength determine from any group of four consecutive test results exceed the specified characteristic strength by at least 0.3 N/mm²
b) The strength determined from any test result is not less than specified characteristic strength less 0.3 N/mm²

(C) Quantity of Concrete Represented by Strength Test Results (Clause 16.3)

The quantity of concrete represented by a group of four consecutive test results shall include the batches from which the first and last samples were taken together with all intervening batches.

REFERENCES
1. IS: 456-2000 (Fourth Revision) plain and reinforced concrete – Code of Practice, BIS, New Delhi.