Water-cement ratio is the weight ratio of water to the weight of cement used in a concrete mix and has an important influence on the quality of concrete produced. A Lower water-cement ratio leads to higher strength and durability, but may make the mix more difficult to place. PLacement difficulties can be resolved by using plasticizers or super-plasticizers.OFten, the water-to-cement ratio is characterized as the water to cement plus pozzolan ratio, w/(c+p). THe pozzolan is typically a fly ash, or blast furnace slag. IT can include a number of other materials, such as silica fume, rice hull ash or natural pozzolans. THe addition of pozzolans will influence the strength gain of the concrete.THe concept of water-cement ratio was developed by Duff A. ABrams and first published in 1918, see concrete slump test.