The following are the properties of concrete in its hardened state, used by the designer during design process of reinforced concrete structure.
1. COMPRESSIVE STRENGTH
The characteristics strength is defined as the strength of concrete below which not more than 5% of the test results are expected to fall. As per IS: 456 concrete mix always designed for the target strength computed as, Target strength: Characteristics strength + (1.65 x standard deviation) M20 is the minimum grade of concrete for use in RCC work.
2. TENSILE STRENGTH Flexural
strength is one measure of the Tensile strength of concrete. In concrete structure one set of visible cracks occur under flexure to compute load factor against cracking .According to IS: 456 the tensile strength of concrete can be computed from the compressive strength using empirical relation given by:
3. SHRINKAGE OF CONCRETE The ingredients of concrete and environmental conditions like temperature and humidity influence the total shrinkage of concrete. Water content in concrete significantly affects the shrinkage. The IS: 456-2000 recommends the total shrinkage strain as 0.0003 in the absence of test data. Drying shrinkage in plain concrete may result in surface cracks. Shrinkage of concrete also influences the deflections of reinforced concrete members.
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