In principle, yes, for structural concrete, it's reached a good proportion of its potential ultimate strength and hardness by then, so 28 days is often considered its design strength. It won't matter for an ordinary house, but it's nice to have a well-hardened slab for the sake of a few minutes work with a hosepipe and some weighted plastic sheet. Curing starts fast and gets slower and stops once it's dried (see graph below)
It will be hard enough to walk on within a week, but time will make it better to drive or drag vehicles or machinery over. Bricklayer's mortar is much weaker and rarely has time to cure thoroughly. Concrete foundations and ground slabs in UK usually don't dry out, except on the top. It can be annoying to have a prematurely cured floor or drive, because its weakness will make it dusty and the surface will wear faster. Dull, cloudy weather and persistent drizzle are good for new concrete. In hot sunny countries premature drying is a serious issue.
surprisingly, concrete cured at 20C is actually not as strong as if cured at 10C; and higher temperatures are significantly worse. This is not usually a problem for UK foundations, but can affect exposed slabs.
It will be hard enough to walk on within a week, but time will make it better to drive or drag vehicles or machinery over. Bricklayer's mortar is much weaker and rarely has time to cure thoroughly. Concrete foundations and ground slabs in UK usually don't dry out, except on the top. It can be annoying to have a prematurely cured floor or drive, because its weakness will make it dusty and the surface will wear faster. Dull, cloudy weather and persistent drizzle are good for new concrete. In hot sunny countries premature drying is a serious issue.
surprisingly, concrete cured at 20C is actually not as strong as if cured at 10C; and higher temperatures are significantly worse. This is not usually a problem for UK foundations, but can affect exposed slabs.
