How many days are required to remove the supports provided for casting a roof slab of a house?

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Let me explain you some basic things before answering this question for a better understanding.

Why we provide support to roof?

Actually we are providing support to the slab for 2 reason.

1. One is to support the Form work to cast the concrete
2. To Hold the Concrete until it attains the required strength.

How many days required to remove support?

Support is provided for both the reason and hence we need to keep the support until the concrete attains its strength. As we all know that the maximum strength of the concrete will be attained at 28th day after the concrete is casted. But if we wait that much longer we can’t able to deliver the project on time. Hence we consider a sweet spot based on the compressive strength attaining ability of the concrete. So the Strength attaining capacity of the concrete is as follows,

• At 1st day of casting - 16% of compressive Strength
• At 3rd day of casting - 40% of Compressive Strength
• At 7th day of casting - 65% of Compressive Strength
• At 14th day of casting - 90% of Compressive Strength
• At 28th day of casting - 99% to 100% of Compressive Strength.

Hence, it is ideal to provide at least minimum 14 days the support need to be there after casting of concrete, after that we can remove the support since the concrete will attain nearly 90% of strength at the 14th day of casting.

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