IMPORTANCE & THEORY:
Cement is usually subjected to compressive stresses when used in the form of concrete or mortar.
Mortar is a mixture of cement and sand in a specified ratio on which the strength of the mortar depends. If the mortar is weak then also its compressive strength is very low but if the mortar is a strong one then its compressive strength is also very high.
The mixture of sand and cement in water is generally weak in tension and is strong in compression that is why when the concrete is subjected to tensile forces then it is provided with steel rods in area of tension that is why it is then called as reinforced concrete. Therefore it is obvious the mortar will be strong in compression as compared to tension.
Mortar is generally used for brick masonry and plastering. In first case the mortar is subjected to very high compressive loads such as the load of the wall above it, therefore it is very much necessary to test the mortar for its compressive strength. For this purpose required cement-sand mixture is prepared before its use and after certain period of curing it is tested. The strength of the mortar depends upon the fineness of cement, the gradation of sand and the most important factor which water-cement ratio.
If any one of the above factors be not according to the ASTM-Standard then the strength of mortar is badly affected.
The standards of ASTM are provided for different ratios of mixture with which the test results are compared and then decided for its use. These values are taken when the mortar is just removed from curing.
For Download Click Here: Compressive Strenght of Mortar Using Mortar Cubes
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