... mixes)Value of α at water-cement ratio Cement content, kg/m 3 0 .3 0.4 0.5 0.6 0.7 0.8 250 – – – 1.26 1 .32 1 .38 30 0 – – 1 .3 1 .36 1.42 – 35 0 – 1 .32 1 .38 1.44 – – 400 1 .31 1.4 1.45 – – – 500 ... 10, 15, 20, 30 , 40, 60, 80 и 150 mm) Slump, cm Amount of water, kg/m 3 1 43 7.4. Correction of design concrete compositionsInevitable deviations of actual indexes of properties of concrete mixes ... decision of system of two equations of material balance. The first equation expresses equality of volume of the concrete mix to the sum of absolute volumes of the initial components of concrete, ...