In designing mixes how much strength increase can we figure for each additional hundred pounds of cement?
An old rule of thumb says that for non-air-entrained concrete in the common range of 2000 to 5000 psi the addition of one 94-pound bag of cement will increase the strength 900 psi or about 950 psi per hundred pounds of cement. The increase is not quite so predictable for air-entrained concretes; for these a value must be obtained by plotting a strength curve for each set of materials.