High Performance Concrete

High Performance Concrete (HPC) refers to concrete with a specified compression strength of 6,000 psi (40 MPa) and greater. In fact, Prairie has had great success with HPC mix designs at upwards of 21,000 psi.

HPC can be specified for a number of applications:
The most common use of high-strength concrete is for construction of high-rise buildings. At 969 ft, Chicago's 311 South Wacker Drive uses concrete with compressive strengths up to 12,000 psi (41 MPa) and is the tallest concrete building in the United States.

To put concrete into service earlier, such as opening pavement to traffic in three days.

To reduce the column size and increase usable space in high-rise buildings.

To build the superstructures of long span bridges and the durability of bridge decks.

To satisfy specific needs such as durability, modulus of elasticity, and flexural strength for special applications. These include parking garages, dams, grandstand roofs, etc.

By carrying loads more efficiently than normal-strength concrete, high-strength concrete also reduces the total amount of material placed and lowers the overall cost of the structure.

Manufacture of high-strength concrete involves making optimal use of the basic ingredients that constitute normal-strength concrete. Prairie knows which factors affect compressive strength and knows how to manipulate those factors to achieve the required strength. In addition to selecting a high-quality portland cement, we optimize aggregates, then optimize the combination of materials by varying the proportions of cement, water, aggregates, and admixtures.

When selecting aggregates for high-strength concrete, Prairie considers the strength of the aggregate, the optimum size of the aggregate, the bond between the cement paste and the aggregate, and the surface characteristics of the aggregate. Any of these properties could limit the ultimate strength of high-strength concrete.

Admixtures
Pozzolans, such as fly ash and silica fume, are the most commonly used mineral admixtures in high-strength concrete. These materials create additional strength by reacting with portland cement hydration products to create additional C-S-H gel, the part of the paste responsible for concrete strength.

It would be difficult to produce high-strength concrete mixtures without using chemical admixtures. A common practice is to use a superplasticizer in combination with a water-reducing retarder. The superplasticizer gives the concrete adequate workability at low water-cement ratios, leading to concrete with greater strength. The water-reducing retarder slows the hydration of the cement and allows workers more time to place the concrete.

Information provided by the Portland Cement Association
 
   
 


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