1 AEコンクリート製造時におこるAEコンクリート強度の変動理論とその理論的算定値 : 現場打コンクリート強度の変動に関する研究

Abstract

A theoretical analysis of variation in plain concrete strength and of calculated variationsins plain concrete strength with four degrees of control in making concrete were described in the Transaction of the Architectural Institute of Japan, No. 58. This paper describes the various factors which cause variation in air-entrained concrete strength in making concrete, and presents statistical methods which are useful in interpreting these variations. The paper presents the calculated values of the standard deviations and the coefficient of variations in air-entrained concrete strength with four degrees of control, in using the mix proportions of air-entrained concrete and procedure for designing mixes, which has been recommended by Japanese Architectural Standard Specification, number five, at present. The proportion for air-entrained concrete, in containing 4 percent of air, is designed in accordance with such the method as equal to the concrete strength and slump for plain concrete containing 1 percent of air. The paper presents the effects of entrained air on variation in concrete strength, when the mean value of air content is about 4 percent and the standard deviation of entrained air varies from 0.5 to 1.5 percent of air. It is indicated from these values that the standard deviation of air-entrained concrete strength according to a given control is approximately the same as the value of plain concrete.