Compressive Strength Test of Concrete.

 

Apparatus Required

•Cube Moulds of dimension 150mm.

•Weighing Machine for Batching

•GI Sheet

•Vibrator

•Compressive Strength Testing Machine

Procedure 

•First of all, batch the materials (Cement, Sand and Aggregate) using the weighing machine. Use proportion as 1:1.5:3 .

•Mix the materials and add water thoroughly to make concrete of uniform colour. Use water cement ratio as 0.6.

•Place the concrete in the mould. Compact the concrete properly using the vibrator to ensure there is no air voids in the cubes.

•The cubes are kept inside the moulds for 24 hrs. After 24 hrs the specimens are removed from the mould.

•The specimens are then kept in clean and fresh water for 1 days to 28 days. The water in which the specimens are submerged should be renewed after every 7 days.

•The cubes are taken out from the water half of an hour prior to the test. The surface of the cubes are cleaned and dried using a cloth.

•The cubes are then placed in the CSTM for compressive strength test and stress of uniform rate is applied (140kg/cm²/min) till the cube breaks.

•The max force at which the each specimen fails is noted.

•Now, the compressive strength of the concrete is calculated as:

`Compressive\ Streng th: (Max\  Compressive\ Fo rce)/(Cross\ Section\ Area)`

Note:

If the specimen is submerged in water for 1 day then the specimen should gain 16% strength. Similarly for 3 days: 40%, for 7 days: 65%,  for 14 days: 90% and for 28 days: 99%.