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The materials used to produce high strength concrete (HSC) should be of high quality to achieve designated concrete compressive strength. High-quality materials meet the performance criteria for workability, strength, durability, and other properties. This article presents some tips to help engineers in the process of materials selection for the production of high strength concrete.
Tips for Selection of Materials for High Strength Concrete
- Low C3A cements generally produce concrete with improved rheology.
- Maximum aggregate size ranges from 20 to 28 mm can produce concrete compressive strength of nearly 70MPa.
- Concrete compressive strength of 100MPa is achievable when utilized maximum aggregate size ranges from 10 to 20 mm.
- A maximum aggregate size of 10 to 14mm is used to produce concrete compressive strength greater than 125 MPa.
- Supplementary cementitious materials can reduce the production cost of concrete and tackle the slump loss issues. Examples of supplemental materials are blast-furnace slag, fly ash, and natural pozzolans.
- Silica fume is commonly employed in the production of concrete with a compressive strength greater than 70 MPa.
- Using fine aggregates with higher fineness modulus (around 3.0) is advised because the use of coarser fine aggregates requires less water to obtain the same workability. During the mixing process, the coarser fine aggregates would generate higher shearing stresses that can help prevent flocculation of the cement paste.
- Fine aggregates with a fineness modulus of about 3.0 give the best workability and compressive strength (ACI 363R).
- When well-graded coarse and fine aggregate decreases porosity and increases density, and thus enhances the strength and durability of concrete.
- Well-graded fine aggregate lessens the quantity of paste that is the weak link in a mass of concrete, increase economy, and improve unit weight and the interfacial bond between coarse aggregates and mortar matrix.
- Cement content should be below 500 kg/m3 to avoid excessive increase in brittleness and reduce the material cost of concrete.
- Water that is clean, fresh, and free from contamination should be preferred for mixing the raw materials.
FAQs for selection of materials for high strength concrete
What type of cement is desired to produce high strength concrete?
Low C3A cements are desired since they generally provide concrete with improved rheology.
Why are high-quality materials essential for high strength concrete production?
High-quality materials meet the performance criteria for workability, strength, durability, and other properties.
Why are pozzolanic materials added to the concrete mix?
Supplementary cementitious materials can reduce the production cost of concrete and tackle the slump loss issues.
Why is silica fume added to concrete?
The silica fume increases the strength of concrete.