This research was planned to study the effect of water-reducing admixtures on the properties of cement paste and concrete. These properties included setting time of cement paste, consistency of fresh concrete and compressive strength of hardened concrete. The main veritables taken into consideration in this study were cement content, water/cement ratio and admixture/cement ratio. A comparison was made between the properties of concrete according to the usage of the optimum dose of the admixture as a result of the experimental test results and the properties of concrete when the dose recommended by the producer was used.
Great improvement was achieved in both the workability of fresh concrete and the compressive strength of hardened concrete when optimum dose of the water-reducing admixture was used which depends on many factors among which are the cement content and water content. The initial and the final setting time of cement increase with the increase of the water-reducing admixture in the cement poste.
However, the limits of the setting time recommended by the specifications have to be taken into consideration when determining the optimum dose of the admixture.