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为预测混凝土强度,曾建议用下述经验公式: R_28=R_7+B/Ц(R_4-R_1)(1)式中R_28为标准条件养护下混凝土的28天强度计算值;R_1、R_4和R_7分别为经1天、4天和7天标准条件养护后同一批标准试块的强度。根据公式(1)所预测的强度是可靠的,其计算值与实际强度及试验数据都吻合,但获得预测值需7天,这样长的时间限制了现代化生产,特别是在快速施工时。要想提高公式(1)预测混凝强度的可靠性,就要通过计算混凝土的7天强度,代替试验数据。根据已测得的强度,即1天和4天的试验数据,公式(1)可用两种型式表示,其中最好的一种可按下式:
In order to predict concrete strength, the following empirical formula has been suggested: R_28=R_7+B/Ц(R_4-R_1) (1) where R_28 is the standard 28-day strength calculation of concrete under standard conditions; R_1, R_4, and R_7 are It is the strength of the same batch of standard blocks after standard conditions of 1 day, 4 days and 7 days. The predicted strength according to formula (1) is reliable, and its calculated value is consistent with the actual strength and test data, but it takes 7 days to obtain the predicted value. Such a long time limits modern production, especially in the case of rapid construction. To increase the reliability of formula (1) in predicting the strength of coagulation, it is necessary to calculate the 7-day strength of the concrete instead of the test data. Based on the measured intensities, ie test data for 1 and 4 days, equation (1) can be expressed in two types, the best of which is the following: