The Effect Of Admixtures On Properties Of Co`ncrete
[CASE STUDIES OF SUGAR, COW BONE ASH, GROUDNUT SHELL ASH, AND LIME STONE POWDER]

3.9    COMPRESSIVE STRENGTH TEST ON CONCRETE CUBES  
    Gopel (2009),out of many test applied to the concrete , this is the most important which gives idea about all the characteristic of concrete. By this single test one can judge whether concreting has been done properly or not. To carryout cube test minimum of two specimens either cubes 150mmx150mmx150mm or 100mmx100mmx100mm depending upon the size of aggregate to be used. For most of work cubical mould of 150mmx150mmx150mm are commonly used.
    The concrete is poured in the mould and tampered properly with tamping rod so as not to have any voids. After 24 hours these mould are removed and test specimens are put in water for curing. The top surface of these specimens should be made even and smooth. This is done by putting cement paste and spreading smoothly on the whole area of the specimen.
    The specimens are tested by compression testing machine after 14 days or 28 days curing. Load should apply gradually at the rate of 140kg/cm2 the failure divided by area of specimen gives the compressive strength off concrete.
Using the mathematical expression,
Compressive strength =     Failure Load
Area of the cubes (N/mm^2)
    Compressive strength test was carried out after adequate curing procedure was fulfilled. This was done in a manually operated hydraulic crushing machine. It consists of various parts like;
1    The base on which the specimen would be placed.
2    Handle for adjusting the steel plate of the machine and
3    The scale which indicates the readings corresponding to the failure load of the specimen.