Specified Testing for Concrete Quality

Tests for checking quality of concrete should be done to detect variation of quality of concrete being supplied for a given specification.

To establish whether the concrete has attained a sufficient strength or concrete has set sufficiently for stripping, stressing, de-propping, opening to traffic and To establish whether the concrete has gained sufficient strength for the intended purpose.

However, the following are the lists of various tests conducted for concrete quality.

Tests on hardened concrete:

• Compressive strength - Tensile strength - Direct tension - Modulus of rupture - Density - Shrinkage - Creep - Absorption - Freeze/thaw resistance

Tests on Fresh concrete:

• Workability Test -Temperature Test - Setting Test - Air Content - Unit Weight - Bleeding

Of these many tests for concrete quality, in practice well over 90% of all routine tests on concrete are concentrated on compression tests and slump tests. It is also desirable to conduct fresh concrete temperature and hardened concrete density determination tests. In practice the most commonly specified tests are the “slump test” and the “cube test”. The reasons for the selection of “Cube Test” (Compressive Strength) and “Slump Test” (Workability Tests) in practice for quality control testing of concrete are:

1. All or most other properties of concrete are related to its compressive strength.
2. Compressive strength test is the easiest, most economical or most accurately determinable test.
3. Compressive strength testing is the best means available to determine the variability of concrete.
4. Slump tests also checks for variation of construction materials in mix, mainly water-cement ratio
5. Slump test is easy and fast to determine quality of concrete before placement based on recommended slump values for the type of construction.