Water-reducing admixtures are used to increase the strength and workability of concrete and to reduce cost. They consist of organic compounds or mixtures of organic and inorganic compounds to reduce the water requirement of the mixture for a given slump. Reduction in water demand may result in a reduction in the w/cm for a given slump and cement content, an increased slump for the same w/cm and cement content, or a lower cement content Water-reducing admixtures also reduce segregation and improve the flowability of the concrete. Therefore, they are commonly used for concrete pumping applications as well. Water-reducing admixtures typically fall into three groups: low-, medium- and high-range. Water-reducing admixtures essentially neutralize surface charges on solid particles and cause all surfaces to carry like charges. Since particles with like charges repel each other, they reduce flocculation of the cement particles and allow for better dispersion. They also reduce the viscosity of the paste, resulting in a greater slump.
