High-Strength Concrete: Past, Present, Future

Abstract : This paper summarizes the current status of high-strength concrete, the research needed, and the information and experience required for high-strength concrete to become universally accepted. Discussion involves examination of three levels of high-strength concrete: (1) the present range of 5,000 to 10,000 psi (34.4 to 68.9 MPa), (2) the available range of 10,000 to 15,000 psi (68.9 to 103.4 MPa), and (3) the exotic area of 15,000 psi (103.4 MPa). Present practices include use of low W/C, high cement factor, mixtures with fly ash, high-quality crushed aggregates, high-range water-reducing admixtures, and more coordination and quality control efforts. the second range is attainable with available materials and equipment such as slurry mixing, no-slump concrete, closer control, compaction by pressure, new admixtures, longer curing, and polymer material. research in the areas of vibration and compaction, use of artificial aggregates, polymers, discontinuous reinforcement, interaction with the energy situation, and design considerations will be needed before the 15,000-psi (103.4-MPa) range can be successfully entered. the exotic area may include heretofore impractical techniques such as combining pressure and vibration and development of the silica-lime bond. A prediction is offered of the technique to be used for the manufacture, placement, and consolidation of high-strength concrete in the year 2000. (Author)