Abstract
Following the previous report (curing temperature : 100℃, rate of temperature : 80℃/hr., surface pressure by spring : 0.01〜1.4kg/cm^2), the relation between curing conditions and compressive strength at the ages of one day to 91 days has been investigated on 246 concrete cylinders. The test conditions are as follows : Aggregate : river sand and gravel. Water cement ratio : 50, 60, and 70%. Slump : 10cm. Duration of steam curing : 6 hours. Rate of temperature : 15-20℃/hr. Surface pressure : 0.01 and 0.1kg/cm^2. Based on the above test results the following conclusions have been obtained : (1) Evaporation of mixing water and volume expansion of concrete during curing have considerable effects on the strength of concrete. (2) The device of covering and pressing concrete surface during steam curing prevents the deterioration of concrete properties. Using the device, it is possible to make the concrete having approximately the same strength as cured by standard curing (20℃, in water), regardless of holding time, and rale of temperature. Considering above conclusions, an optimum curing condition for 20℃ to 100℃ has been proposed.
