After approximately how many days is the average concrete shrinkage around 60%?

The average concrete shrinkage reaching around 60% typically occurs at approximately 90 days. This timeframe is significant due to the curing process that concrete undergoes. Initially, when concrete is poured, it undergoes hydration, and the volume of the mixture begins to decrease as moisture evaporates and chemical reactions occur.

At about 90 days, concrete has usually reached a substantial part of its strength and the shrinkage effects can be more accurately measured, as the more significant changes have typically taken place within this period. By this time, environmental factors like temperature and humidity have also played critical roles in the drying and curing process, contributing to this level of shrinkage.

This understanding is key in planning for structural integrity, as excessive shrinkage can lead to cracking if not properly managed. Therefore, knowing that approximately 60% of concrete's total shrinkage occurs around this time is crucial for contractors in ensuring quality outcomes in construction projects.