Sorry 25%.
Spent half a lifetime making and testing (as concrete cubes mainly) and analysing cement in cement industry.
10 Newtons at 24 hours
20 Newtons at 3 days
30 Newtons at 7 days
40 newtons at 28 days
Or thereabouts - +- about 5 Newtons at 28 days.
For the standard BS testing mix - A floor will possibly only need about 20 Newton concrete dependent on loadings and cross section.Rapid hardening cement will have higher initial strengths, but the ultimate strength will probably be less than Ordinary Portland Cement NO steam curing here for 7 day strength at 24 hours! - just standard curing at 20 degrees Celsius, moulds covered with plastic sheet for 24 hours then cubes under water.
STEAM curing and accelerators will make a lot of difference. Beams etc need to be de-moulded for a fast turn around of the mould. Floor pads don"t and there is no steam curing here! And concrete won"t even set below about 5 degrees Celsius without accelerators to get it started.
We supplied about 4000 tonnes of Cement to concrete manufacturers each day of the week, every week. that was Ordinary Portland, Rapid Hardening Portland, Sulphate Resisting Portland, White, High alumina, and cement blends with fly ash, blast furnace slag, etc.
RAB
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