High-range water-reducing admixtures (H-R admixtures) are being used by an increasing number of North American precast concrete producers. Use of H-R admixtures in concrete mixes permits reduced cement contents, increased workability, and improved strength development. H-R admixtures were originally patented as a concrete admixture as early as 19351 Nevertheless, they did not come into real commercial use until the 1960s. They have been used in Japan for about 15 years and in Western Europe for nearly 10 years. A few other countries such as Australia have also used them commercially (especially in the precast concrete industry) producing apparently favorable results.
