High-performance concrete is a term used to describe concrete with special properties not attributed to normal concrete. High-performance means that the concrete has one or more of the following properties: low shrinkage, low permeability, a high modulus of elasticity, or high strength. According to Henry Russell, ACI defines high performance concrete as "concrete that meets special performance and uniformity requirements that cannot always be achieved routinely by using only conventional materials and normal mixing, placing, and curing practices. The requirements may involve enhancements of placement and compaction without segregation, long-term mechanical properties, early-age strength, toughness, volume stability, or service life in severe environments" (Concrete International, p. 63). High-strength concrete is typically recognized as concrete with a 28-day cylinder compressive strength greater than 6000 psi or 42 Mpa. More generally, concrete with a uniaxial compressive strength greater than that typically obtained in a given geographical region is considered high-strength, although the preceding values are widely recognized. Strengths of up to 20,000 psi (140 Mpa) have been used in different applications. Laboratories have produced strengths approaching 60,000 psi (480 Mpa).
High-strength concrete can resist loads that normal-strength concrete cannot. Several distinct advantages and disadvantages can be analyzed. It is important to consider all peripheral results of selecting high-strength concrete since special considerations must be addressed beyond strength properties.
Once it is decided to use high-strength, high-performance concrete, the mix design and production process can begin. The materials used and concepts involved in increasing the strength of concrete must be clearly understood in order to obtain the desired properties. Testing is an integral step in the production process, since quality control studies show that slight changes in mixture proportions can lead to large changes in the compressive strength of concrete. When the design proportioning is complete, mixing can commence with extra consideration for workability and related properties of the mix.
Once the high-strength concrete is placed, the hardened concrete properties can be predicted in addition to its special characteristics. Some of the properties slightly differ from concrete with lower strength while some vary more significantly. In order to examine the performance of high-strength concrete in practice, several case studies can be investigated.
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