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Dosto is video me app logo ko batayunga stripping time of formwork as per is 456 ke bare me.
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The removal of concrete formwork also called as strike-off or stripping of formwork should be carried out only after the time when concrete has gained sufficient strength, at least twice the stress to which the concrete may be subjected to when the formworks are removed.
The rate of hardening of concrete or the concrete strength depends on temperature and affects the formwork removal time.
Structural members are constructed based on designed load. But before a structure is complete and subjected to all loads assumed during structural design, the structural members are subjected to its self weight and construction loads during construction process.
Factors Affecting Concrete Formwork Striking Times
The striking time of concrete formwork depends on the strength of structural member. The strength development of concrete member depends on:
Grade of concrete - higher the grade of concrete, the rate of development of strength is higher and thus concrete achieves the strength in shorter time.
Grade of cement - Higher cement grade makes the concrete achieve higher strength in shorter time.
Type of Cement - Type of cement affects the strength development of concrete. For example, rapid hardening cement have higher strength gain in shorter period than the Ordinary Portland Cement. Low heat cement takes more time to gain sufficient strength than OPC.
Formwork should not be removed until the concrete has developed sufficiently strength to support all loads placed upon it. The time required before formwork removal depends on the structural function of the member and the rate of strength gain of the concrete. The grade of concrete, type of cement, water/cement ratio, temperature during curing etc. influence the rate of strength gain of concrete.
The formwork parts and connections should be arranged in a way that makes formwork removal easy and simple, prevents damage to concrete and formwork panels so that it can be reused without extensive repair.
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