When the first issue of Concrete Construction hit the streets in 1956, concrete producers began leveraging the benefits of air-entraining and water-reducing admixtures to improve the buildings and infrastructure where concrete was called on to perform. While the earliest water-reducing admixtures date from the 1930s and 1940s, liquid water-reducing and retarding admixtures were introduced in the 1960s. Increased workability, lower water/cement ratios, higher strengths, and additional control over setting time allowed placement in a wider range of temperatures, further expanding the market and marketability of concrete.
Research and development led to significant advances in admixtures during the last two decades of the 20th century, resulting in dramatic improvements in concrete construction. The first generation of high-range water reducers, used to produce flowing concrete, were introduced in Japan and Europe in the 1960s, and the United States in the early 1970s. New developments in “next generation” high-range water reducers dispersed cement particles in concrete mixes more effectively than naphthalene or melamine-based superplasticizers, improving the placeability and in-place engineering properties of concrete.
In the late 1980s the pace of innovation accelerated. Corrosion-inhibiting admixtures increased the service life of concrete structures, protecting steel embedded in concrete exposed to chloride ions. A new family of admixtures, midrange water reducers, was developed, facilitating production of concrete in the 3- to 8-inch slump range with greatly improved finishing and pumping characteristics. Most recently, the development of polycarboxylate superplasticizers has allowed concrete producers to begin producing self-consolidating concrete.
Read more highlights from 50 Years of Concrete Construction Progress.