The role of silica fume in concrete is very obvious, can effectively improve the strength of concrete, durability, etc., but in practice, usually mixed with other mineral admixtures at the same time, the composite use of silica fume, so as to better improve the working properties of concrete, mechanical properties and reduce the cost of high-performance concrete, when the requirements for the composite admixture is more stringent, HSA has compiled for you The HSA has compiled a list of the principles of compounding microsilica powder, as well as the relevant reference technical indicators, in the hope that it can help you to better compound the use of microsilica in concrete mixing.

The proportioning principle of composite silica fume

The compound use of silica fume conditions

Compound use of silica fume, not only a certain amount of silica fume products can be mixed, but to consider the various roles between different admixtures and the mechanism of action, the details are as follows:

1. Consider the mutual superposition of active and inert components, low quality and high quality resources;
2. Considering the reasonable gradation distribution of micro-particles, mainly to enhance and improve the overall compactness;
3. Considering the matching of hydration reaction rate and products (such as gel type and crystalline type) to facilitate their durability;
4. Considering the chemical excitation effect to improve the overall performance;
5. Consider different quality of resources to reduce the unit water consumption to reduce the water-gel ratio.

Compound proportioning principle

The variety and amount of mineral admixture should be based on the quality of the mineral admixture itself, combined with other parameters of concrete (workability, transport time, temperature, slump loss), the nature of the project, the structural parts, the environment (construction environment and environmental erosion and other factors, it is appropriate to select the following principles to determine:

1. Mineral admixture admixture larger amount of concrete should be used low water cement ratio, extend the concrete acceptance age;
2. For the following cases can increase the amount of mineral admixture: higher ambient temperature, concrete structure volume, underwater engineering concrete and corrosion-resistant requirements, well-cared for concrete, etc.;
3. For smaller cross-sectional size of the components of concrete, it is appropriate to use a smaller slump, mineral admixtures should be used in smaller amounts to avoid early strength reduction, water evaporation hydration is not sufficient;
4. For the following cases should be used to reduce the amount of mineral admixture: early strength requirements or the average daily ambient temperature is less than 20 ℃ under the conditions of construction of concrete;
5. The preparation of mineral admixture concrete should be mixed with admixtures at the same time to coordinate the matching of cement and admixtures and other components, in order to give full play to their combined effect. Systematic testing, full verification of familiarity with the performance of raw materials to ensure the quality of the project.

The composite use of silica fume reference indicators

As the composite use of silica fume involves a variety of mineral admixture, for the quality control of raw materials (to avoid the problem of indiscriminate admixture), composite admixture testing should focus on fineness, activity index and flow ratio, etc.: 1:

1. The specific surface area can reflect the fineness of the compound admixture, affecting the activity of the compound admixture, the larger the specific surface area, the finer the compound admixture, the higher the activity, according to the different mineral raw materials used in the compound, generally available specific surface area index control fineness, when using fly ash compound admixture, should increase the sieve index control fineness;
2. The activity index is an important technical indicator of the composite admixture, reflecting the strength and impact of the composite admixture on concrete;
3. The flow ratio is a very important technical index for engineering applications, the flow ratio indirectly reflects the composite admixture water demand index, composite admixture with a large amount of carbon or water demand of poor quality materials will directly affect the flow, activity index.

Compound use of silica fume should consider uniformity and stability, avoid the use of adulterated with other impurities. Can be controlled by testing the content of calcium carbonate mixed with other stone powder, test methylene blue value to control the content of soil, avoid the use of mixed with other stone powder or soil containing more limestone powder; can be used to test the vitreous content or burn loss means to avoid the use of slag powder mixed with other impurities; can be judged through the microscope vitreous content or particle morphology to avoid mixing with false fly ash.

The above content is HSA everyone collated the compound use of silica fume proportioning principles and reference technical indicators, in the actual use of high-strength concrete, in addition to pay attention to the doping ratio, but also according to the different ratios to the concrete maintenance, especially after the compound use of silica fume, the early moisturizing maintenance is more important, otherwise it is easy to crack problems. hsa production of various silica fume products All of them meet the national technical standards and can fully meet the requirements of mineral admixture compound for high-strength concrete, if you need, please leave a message on our website or call our customer service for detailed consultation.