How are concrete strength-test cylinders usually cured?
A. The curing method varies with the purpose for testing the cylinders. Test results may be used as the basis for acceptance of the concrete. Acceptance-test results represent the potential strength of the concrete thats discharged from the truck. The test isnt intended for determining the in-place strength of the concrete because it makes no allowance for the effects of placing, compaction, or curing. When cylinder tests are used to indicate whether or not the producer delivered concrete of the specified strength, standard curing is mandatory. The details for standard curing are given in ASTM C 31, Practice for Making and Curing Test Specimens in the Field. Standard initial curing for test cylinders requires them to be stored immediately after molding, for a period up to 48 h, at a temperature range from 60 and 80 F (16 and 27 C) and in an environment preventing moisture loss. The cylinders must also be shielded from direct sunlight. After this period, the cylinders are cured with fre
