Ratio of Strength of Cement Concrete at 7 Days to 28 Days Curing

The strength of cement concrete increases with time as the hydration process continues. The ratio of strength of cement concrete at 7 days to what at 28 days curing is an important parameter for determining the quality of concrete. It helps in assessing the rate of strength gain of concrete and provides an indication of the long-term durability of the structure.

Approximate Ratio

The approximate ratio of the strength of cement concrete at 7 days to what at 28 days curing is 0.60. This means that the strength of concrete at 28 days is approximately 1.67 times the strength of concrete at 7 days.

Explanation

When concrete is first mixed, it is in a plastic state and has no strength. As the hydration process starts, the concrete gains strength and hardens. The rate of strength gain is not constant and depends on various factors such as cement type, water-cement ratio, temperature, curing method, etc.

In general, the strength of concrete increases rapidly in the first few days and then slows down. At 7 days, the concrete has gained around 70-80% of its ultimate strength, and at 28 days, it has gained around 95-99% of its ultimate strength.

The ratio of strength of cement concrete at 7 days to what at 28 days curing varies based on the above factors. However, the approximate ratio of 0.60 is commonly used in practice.

Conclusion

The ratio of strength of cement concrete at 7 days to what at 28 days curing is an important parameter for assessing the quality of concrete. The approximate ratio of 0.60 is commonly used in practice, indicating that the strength of concrete at 28 days is approximately 1.67 times the strength of concrete at 7 days.

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