Details about concrete strength gain
Strength is considered as one of the most crucial characteristics of the concrete strength since it provides the details about the quality of concrete on the whole. Strength of concrete is mainly dependent on the cement paste. There are several factors which impact the rate upon which the strength of concrete is raised once the mixing is completed.
Given below, some vital terms which are directly associated with the strength gain of concrete:
Hardening is the method of increasing strength. It should be kept in mind that setting and hardening are not equivalent.
Setting means the hardening of the concrete once it is placed. Hardening may go on for weeks or months as soon as the concrete is mixed and placed.
The strength gain & rate of strength gain of concrete are based on the following factors :-
Concrete porosity: Air or water can be used to fill the voids in concrete. If concrete becomes more porous, the strength of the concrete is reduced. The porosity in concrete mainly occurs due to the ratio of water to cement in the mix, called as the 'water to cement' ratio.
Water/cement ratio: It is called as the mass of water divided by the mass of cement in a mix. The water/cement ratio can be shortened to 'w/c ratio' or just 'w/c'.
In mixes where the w/c is in excess of approximately 0.4, all the cement can respond to water for creating cement hydration products. At greater w/c ratios, it abides by the space engrossed in the additional water over w/c = 0.4 will remain since pore space filled with water, or with air in case the concrete dries out.
As a result, when the w/c ratio is raised, the porosity of the cement paste in the concrete is also raised. With rise in the porosity, the compressive strength of the concrete will reduce.
Strength of aggregate: If the aggregate in concrete is poor, the concrete will become weak. Rocks having low strength, like chalk, are not recommended to be applied as aggregate.
Aggregate paste bond: The solidity of the bond among the paste and the aggregate is complicated. If no bond exists, voids will be formed in the aggregate & consequently the concrete becomes weak.
Cement-related parameters: There are several parameters in respect of the composition of the cement ingredients and their ratios in the cement which can influence the rate of strength gain and the final strength attained. These comprise of the following:
1. Alite content (Tri-Calcium silicates) & Belite contents (Di-calcium silicates)
2. Alite & belite reactivity
3. Sulfate contents