Concrete cube and cylinder tests

To maintain quality control of concrete, representative test samples should be taken, cured under controlled conditions and tested for compressive strength after the appropriate 3-, 7- or 28-day period. Steel cylinder and cube moulds (Fig. 3.10) are filled in layers with either hand or mechanical vibration. For hand tamping, a 100 mm cube would be filled in two equal layers, each tamped 25 times with a 25 mm square-end standard compacting bar; mechanical vibration would normally be with a vibrating table or pneumatic vibrator. The mix is then trowelled off level with the mould. Cubes and cylinders are cured under controlled moisture and temperature conditions for 24 hours, then stripped and cured under water at 18-20°C until required for testing.

The European standard concrete tests use cylinders 150 mm in diameter and 300 mm high rather than cubes, as they tend to give more uniform results for nominally similar concrete specimens. For a particular concrete, the characteristic compressive strength as determined by the cylinder test is lower

0 0

Post a comment