Factors Affecting the Strength Of Concrete

Strength is described as capability to withstand alteration. Strength is one of the most crucial characteristics of concrete. Strength is the most vital factor as the complete quality of concrete is determined by it. Generally strength of concrete is directly associated with cement paste.

The rate of strength is dependent on various factors at which the strength of concrete expands as soon as the mixing is completed.

The following terms are associated with the strength gain of concrete :-

Hardening belongs to the method of growth of strength. This has quite similarity with 'setting' but setting and hardening are different.

Setting belongs to the hardening of the concrete as soon as it is arranged. Hardening may last for weeks or months once the concrete is mixed and positioned.

The strength gain & rate of strength gain of concrete is dependent on the following factors :-

Concrete porosity: Voids in concrete are loaded with air or with water. If the concrete become more porous, the strength will be reduced. The porosity in concrete is mostly influenced by the ratio of water to cement in the mix, described as the 'water to cement' ratio.

Water/cement ratio: It is described as the mass of water divided with the mass of cement in a mix. The water/cement ratio is shortened as 'w/c ratio' or just 'w/c'. In mixes where the w/c is in excess of approximately 0.4, all the cement reacts with water to develop cement hydration products. At greater w/c ratios, the space absorbed in the extra water above w/c = 0.4 will persist as pore space loaded with water, or with air when the concrete dries out.

Therefore, with the rise of the w/c ratio, the porosity of the cement paste in the concrete also upsurges. With the rise of porosity, the compressive strength of the concrete will be reduced.

Soundness of aggregate: If the aggregate in concrete is poor, the concrete becomes feeble. Rocks containing low strength, like chalk, are inappropriate to be applied as aggregate.

Aggregate paste bond: The solidity of the bond among the paste and the aggregate is dangerous. Without bond, the aggregate efficiently denotes a void & voids cause feebleness in concrete.

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