Throughout the construction industry, the common belief is that concrete takes 28 days to cure and reach 100% of its strength.
This evolved from a misunderstanding of what curing actually means. Some regulators characterize concrete as “green” if it has not cured for a certain time frame, not realizing this leads to unnecessary delays and higher project costs. An evaluation of the concepts of measured compressive strength and curing is in order to shed light on the mystery that surrounds the 28-day myth.
The 28-Day Myth – National Precast Concrete Association.