Abstract
At present, the water-cement ratio that we use in the execution of the concrete building is 50-70 per-cent. The compressive strength of the concrete in this water-cement ratio is not so high, and generally, it is about 150kg/cm2 at 28 days. Therefore, the proportion, or water-cement ratio that is generally used can not be applied in the P. S. concrete which needs very high compressive strength.
This is the experiment of the high quality concrete, whose strength is over 500kg/cm2 at 28 days, especially on the materials, the proportions, the curings, and the time of the vibration at concreting, to which the compressive strength of the concrete is subjected.
