High Strength Concrete
For mix made with normal weight aggregates, high strength concrete (HSC) is considered to be the one having a compressive strength in excess of 40 MPa. To produce concrete above this strength more stringent quality control and more care in selection and proportioning of materials
are needed. The tentative classification of HSC is as given in Table 20.5. The tricalcium aluminate component is kept as low as possible (<8%). Most cements used to produce HSC have fineness in the range of 300-400 m2/kg with an exception of high early strength cement for which fineness should be at least 450 m2/kg. For HSC a smaller maximum size of coarse aggregate leads to higher strength. Fine aggregate should have a F.M >3.
High Performance Concrete
High-performance concrete (HPC) is relatively new technology. HPC originated in France in 1980, followed by Canada in 1990. In 1989, under the direction of paul Zia of North Carolina State University, a major effort in HPC technology began in the United States with the initiation of the Strategic Highway Research Program (SHRP). SHRP
defined HPC in terms of strength, low w/c, and freeze/thaw durability. These early efforts were in response to alarming deterioration rates of the nation's roads and bridges.The concept of HPC has certainly evolved with time. What exactly is 'high-performance?'Various parameters have been attached to HPC, with high strength being a
popular descriptor.While equating HPC with high strength certainly has some merit, it doesn't present a completeor, in some cases, accurate picture. Other properties of the
concrete must also be considered, and may even override the strength issue. Three influences must be considered: the structure in which the concrete will be used, including support; the environment in which the structure will be placed; and the type and number of forces to which the structure will be subjected.These considerations are discussed in detail, before defining HPC.
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