Typical Strength Development of Concrete

Age at test	Average crushing strength
	Ordinary Portland cement
	Storage in air 18°C 65%, R H N/mm2	Storage in water N/mm2
1 day	5.5	-
3 days	15.0	15.2
7 days	22.0	22.7
28 days	31.0	34.5
3 months	37.2	44.1

(1 cement - 6 aggregate, by weight, 0.60 water - cement ratio).

In some literature the required grade of concrete is noted by the proportions of cement - sand - stone, so called nominal mixes rather than the compressive strength. Therefore some common nominal mixes have been included in Table 3.12. Note, however, that the amount of water added to such a mix will have a great influence on the compressive strength of the cured concrete.

The leaner of the nominal mixes listed opposite the C7 and C10 grades are only workable with very well-graded aggregates ranging up to quite large sizes.

Ingredients