Testing methods ofcement and water content in fresh concretes and estimation of 28 day strength at early age- state of the art in Japan Y.KASAI Nihon University, Narashino, Japan

Abstract The rapid and the early age test methods estimating both the 28 days strength and the mi parameters of fresh concretes and their state-of-the-art in Japan are briefly reviewed. Twenty three test methods for the unit amount of cement, the unit amount of water and the watei cement ratio to estimate indirectly the 28 days strength are given, while ten direct methods base on accelerated curing are presented as well. These thirty three methods are arranged in terms of measuring principles and their characteristics. A comparative study of each test method is given with respect to the hardness, the accuracy, th time required and the expense for the equipments.