High strength concrete - High Strength Concrete...

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Unformatted text preview: High Strength Concrete igh-strength concrete P.K. Mehta and P.J.M. Monteiro, Concrete: Microstructure, Properties, and Materials Definitions The definition of high-performance concrete is more controversial. Mehta and Aitcin used the term, high- performance concrete (HPC) for concrete mixtures possessing high workability, high durability and high ultimate strength. igh-strength concrete P.K. Mehta and P.J.M. Monteiro, Concrete: Microstructure, Properties, and Materials Definitions ACI defined high-performance concrete as a concrete meeting special combinations of performance and uniformity requirements that cannot always be achieved routinely using conventional constituents and normal mixing, placing, and curing practice. igh-strength concrete P.K. Mehta and P.J.M. Monteiro, Concrete: Microstructure, Properties, and Materials Typical Classification High Strength Ultra High Strength Especial Normal Strength 20-50 MPa 50-100 MPa 100-150 MPa > 150 MPa igh-strength concrete P.K. Mehta and P.J.M. Monteiro, Concrete: Microstructure, Properties, and Materials Microstructure From the general principles behind the design of high-strength concrete mixtures, it is apparent that high strengths are made possible by reducing porosity, inhomogeneity, and microcracks in the hydrated cement paste and the transition zone. igh-strength concrete P.K. Mehta and P.J.M. Monteiro, Concrete: Microstructure, Properties, and Materials Microstructure The utilization of fine pozzolanic materials in high-strength concrete leads to a reduction of the size of the crystalline compounds, particularly, calcium hydroxide. Consequently, there is a reduction of the thickness of the interfacial transition zone in high-strength concrete. The densification of the interfacial transition zone allows for efficient load transfer between the cement mortar and the coarse aggregate, contributing to the strength of the concrete. For very high-strength concrete where the matrix is extremely dense, a weak aggregate may become the weak link in concrete strength. igh-strength concrete P.K. Mehta and P.J.M. Monteiro, Concrete: Microstructure, Properties, and Materials Materials - Cement Almost any ASTM portland cement type can be used to obtain concrete with adequate rheology and with compressive strength up to 60 MPa. In order to obtain higher strength mixtures while maintaining good workability, it is necessary to study carefully the cement composition and finenesses and its compatibility with the chemical admixtures. Experience has shown that low-C3A cements generally produce concrete with improved rheology. igh-strength concrete P.K. Mehta and P.J.M. Monteiro, Concrete: Microstructure, Properties, and Materials Materials -- Aggregate In high-strength concrete, the aggregate plays an important role on the strength of concrete....
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High strength concrete - High Strength Concrete...

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