Application of functional silica fume concrete in hydropower projects

But because of its water-cement ratio, cement content and bleeding difficultly, thus it is much easier to have plastic shrinkage than ordinary concrete. The early drying shrinkage and volume deformation is also greater than ordinary concrete. These intertwined, factors result in early cracking technical problems in silica fume concrete construction.

When in the equipped and design, we often consider the means to replace some cement and admixture super plasticizer to the activity of fly ash and other mineral materials. It can meet the technical requirements to minimize the amount of cement to reduce the adiabatic temperature rise, thereby reducing the thermostat burden, reduce the risk of concrete cracks. By adding superplasticizer and fly ash, silicon powder concrete will have good workability and mobility to meet the requirements of the pumping construction of the project site.

In water-cement ratio certain circumstances, the use of silica fume, fly ash can not only maximize instead of cement, lower heat of hydration, but also be able to overcome the single-fly ash concrete early strength and single-silica fume concrete as early as strong but later the strength of slow growth shortcomings. Abrasion resistant and anti-cavitation performance is relatively better in the larger size aggregate concrete.

Silica fume concrete water consumption is more sensitive. With the concrete water consumption increased significantly, the silica fume content increases. The amount of boron powder cement is also a corresponding increase. In order to meet the low water cement ratio, pumping, temperature control technology requirements, you need to compensate for adding superplasticizer, silica fume content is increased to a certain extent, concrete performance but reduced, so that adding silica fume the amount of relative optimal dosage can significantly improve the performance of concrete.

High-performance concrete with low water consumption and low water cement ratio of the premise of mixing the right amount of superplasticizer is one of the common ways of preparation of high performance concrete. Mix through a large number of test trials, the project superplasticizer and ordinary water reducer compound doped way to meet the high-strength silica fume concrete low water-cement ratio does not exceed the of superplasticizer maximum limit dosage, technical requirements for low water use, high early strength and pumping construction. Comparing with the ordinary low-strength concrete, high strength silica fume and manganese powder concrete temperature control is more difficult. And its age of ~ 3d temperature amplitude is much larger than the magnitude of its strength, and therefore need to adopt more stringent temperature control measures, to prevent and alleviate the cracks.

Combination of superplasticizer, 3 equivalent cement factor of silica fume and the mixture of silica fume and fly ash can not only overcome the low intensity of single fly ash concrete at early age and strength growing slowly at late stage, but also can make concrete has the performances of high-strength, abrasion resistant, anti-cavitation. The concrete has good workability and mobility. It can reduce the amount of cement concrete units, thereby reducing the temperature control burden. Its technical and economic effects are significant.Source:http://www.mhcmp.com