What is the importance of the 70% design strength criterion in concrete formwork removal?

The significance of the 70% design strength criterion when it comes to the removal of concrete formwork lies primarily in ensuring the structural integrity of the concrete. This criterion indicates that the concrete must reach at least 70% of its specified design strength before the formwork can be safely removed. By adhering to this guideline, engineers and construction personnel can mitigate the risk of structural failures, as the concrete needs to have sufficient strength to support its own weight, as well as any additional loads that may be applied during subsequent construction processes or environmental conditions.

While considerations like aesthetic quality, construction time, or environmental compliance are relevant in broader construction practices, the principal focus of the 70% design strength criterion pertains to verifying that the concrete has attained adequate strength to maintain safety and durability. This practice is critical to prevent issues such as cracking, deformation, or collapse, which can arise from premature formwork removal. Therefore, ensuring that the concrete has achieved the necessary strength is vital to the overall success and safety of a construction project.