Allowance for admixtures, air and other factors on water demand and strength of concrete

Admixtures may exert a major influence on the water and/or air void content of concrete by either physical or chemical means. Some may be employed deliberately for their water reducing or air entraining effects, while others may introduce such effects incidentally. The magnitudes of the effects may vary not only with the admixture dosage but also with such parameters as the cement properties, fine aggregate properties, the level of cement content and the workability of the concrete.