In concrete compression test, normally 150mmx150mmx150mm concrete cube samples is used for testing
Instrument And Material.
- Concrete cube mould of size 150mm or 100mm. It is used for aggregate size of not greater than 40mm and 25mm. Cube mould for test must be made from steel or cast iron with smooth inner surface. Every mould must have steel plate to support and to prevent leakage.
- Compacting steel rod with 16mm diameter and 600mm long.
- Compression test machine.
- Mould and base plate must be clean and applied with oil to prevent concrete from sticking to the side of the cube.
Baseplate is attached to the mouldby using bolt and nut.
- Fill the cube with concrete in three layers.
- Every layer must be compacted for 25 times. This process is carried out systematically and compaction is done uniformly to all surfaces of the concrete. Compaction can also be conducted using machine.
- The surface of concrete must
be smoothenso it will hasthe same level with the upper side of the mould.
- Cubes which are made at
constructionsite must be covered with plasticcover for a period of 24 hours before the mouldscan be dismantled.
remoulded, the concrete cubes are submerged in water for curing.
- Compression strength test must be carried out for concrete at age 7, 14, and 28 days by using
The Strength value of each cube must be recorded and compared with the targeted strength value. The purpose of carrying out concrete test on 7 th day and the 14 th day is to predict whether the concrete could archive the targeted 28 th day strength.In general, concrete would have acquired 70% strength on the 7 th day.