Concrete as a construction material, in order to meet the needs of the project, will be added to the preparation of different materials to improve its performance, microsilica is one of the mineral admixture often used, it can improve the denseness of concrete, increase the strength of concrete and use of performance, but the amount of admixture and maintenance temperature is not correct, but will make the concrete early cracks, Today HSA will introduce the effect of microsilica on early cracks in concrete.

The effect of microsilica on the early cracks in concrete

Concrete mixed with 10% or less of microsilica will increase its own shrinkage, while increasing the tensile strength, and the sensitivity of concrete to cracks, its own shrinkage and tensile strength are very important performance parameters. When the concrete high temperature curing temperature is higher than 60 ℃, the amount of microsilica admixture increases, its own shrinkage will further expand, at this time, the ratio of tensile stress and tensile strength at any time in the concrete will also increase, and the crack risk index increases, if the amount of microsilica admixture reaches 15%, the possibility of cracks in the concrete early to significantly higher than other concrete. When the concrete high temperature curing temperature does not exceed 40 ℃, the amount of microsilica ≤ 10%, there is no significant impact on the early cracks in concrete.

Microsilica concrete early crack prevention methods

The test learned that when the high temperature curing temperature exceeds 60 ℃, microsilica doping 0% and 5%, the concrete crack resistance restraint degree of 64%, and can maintain the crack risk index is less than 0.8; microsilica doping 10% and 15%, the concrete crack resistance restraint degree of 52% and 42%, respectively. When the high temperature curing temperature does not exceed 40℃ and the initial temperature of concrete does not exceed 20℃, the degree of crack resistance restraint of concrete in the hardening stage is 100% when the amount of microsilica is 10%.

Therefore, to make the concrete mixed with microsilica avoid early cracking, it is necessary to control the initial temperature of concrete, high temperature curing temperature, and the amount of microsilica powder. Therefore, when the initial temperature of concrete does not exceed 20℃, the high temperature curing temperature does not exceed 40℃, and the amount of microsilica does not exceed 10%, and the water-cement ratio is not less than 0.4, the concrete has excellent resistance to cracking, and at the same time, if the amount of microsilica is controlled below 5%, the effect of microsilica on early cracking of concrete will be almost absent.

Through the above microsilica on the impact of concrete re-cracking and treatment methods can be seen, in the microsilica mixed into the concrete, there is a strong interaction between its various performance parameters, such as curing temperature, water-cement ratio, and even the degree of drying will affect the concrete’s own shrinkage, so it is necessary to prepare the concrete before the exact ratio of experiments, so as to better apply microsilica to improve the performance of concrete.

HSA Microsilica

HSA has been a global supplier of high-quality silica fume since 2001. We have established long-term and stable cooperation with many concrete construction companies around the world to provide our customers with high-quality silica fume with different contents and different uses, fully satisfying all kinds of concrete project needs.

If you have any needs for concrete, please feel free to contact us!

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