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There are only a few tests to ensure concrete quality before placing in domestic construction site; One is the slump test for workability, the others are the air content test and the chloride content test for durability. The concrete compressive strength which is the one of important factors to influence on concrete quality was tested after 28 days when placed. Methods for early estimation of concrete strength have been introduced for concrete quality control, but such methods are expensive, and required experienced skill and time. Therefore, these have difficulties in situ application for concrete quality control. The subject of this study is the result of 1442 compressive strength tests on 59 different kinds of mix design with specified compressive strength of 180∼270kgf/㎠, water-cement ratio of 0.39∼0.62, Gmax 25㎜, and slump of 12∼15㎝. This study aimed at reviewing application of prediction equation of compressive strength as a means of strength control of ready-mixed concrete, making an regression equation which enables to estimate compressive strength at 28 days by multiple linear regression analysis on the basis of mix proportion of ready-mixed concrete and compressive strength test results of construction site.