Concrete in a test cylinder and concrete in a structure seldom cure at exactly the same temperature. During cold weather, the structure may cure more slowly, or it could cure more quickly as cement hydration heats up the concrete in the forms. But since we don’t know the in-place strength, to be safe, we have to wait to be sure the concrete is up to strength before we strip forms, stress post-tensioning cables, or allow traffic onto a road surface. We need a reliable way to determine the actual strength of the concrete in the structure. That’s where the maturity test comes in.