What Are The Effects Of Micro Silica Powder (Silica Fume) On The Performance Of Cement Mortar?

The effects of Ewende micro silica powder (silica fume) on the performance of cement mortar mainly include the following aspects:

Improvement of strength:

Significantly improve the compressive and flexural strength of cement mortar. Some studies have shown that when replacing cement with 15% silica fume, it can increase the denseness of cement products and improve their strength on a microscopic scale. This is because the silica fume fills the pores of the cement paste and the voids of the cement particles, reducing the number of pores and improving homogeneity.

Increase the compactness:

observed under the electron microscope, there is crystal growth in the cement stone voids of cement mortar cementite mixed with silica fume. Silica fume particles are very small, uniformly filling the cement mortar micropores, microaggregate filling effect is obvious.

Improvement of waterproof and moisture-proof performance:

It can reduce the water secretion phenomenon of cement mortar and prevent water from gathering under the aggregate, thus improving the compactness and waterproof performance.

Improvement of segregation and water seepage performance:

It can make the cement mortar more difficult to segregate and seepage. When more silica fume is mixed in, even if the concrete slump is larger, it hardly produces segregation and water secretion, and it is not easy to produce segregation even if it is put into water directly. This makes the cement mortar mixed with silica fume can be used in harbor, tunnel and other underwater projects.

Improve impermeability, chemical corrosion resistance and specific resistance:

Fill around the cement particles, make the slurry more dense; and cement hydration generated by the combination of calcium hydroxide to generate hydrated calcium silicate gel, these gels blocked in the capillary, so that the capillary pores become smaller and discontinuous, greatly improving the densification, effectively preventing the intrusion of acid ions, etc., to enhance the resistance to corrosion performance. When the replacement rate of silica powder is 10% to 20%, it can significantly improve the impermeability and chemical corrosion resistance, and the corrosion resistance of steel reinforcement is also improved. At the same time, due to the high specific resistance of silica fume, it can improve the specific resistance of cement mortar by more than 1 times.

Enhance frost resistance:

After many rapid freeze-thaw cycles, the relative modulus of elasticity decreases to a lesser extent.

Improvement of resistance to impact and abrasion and cavitation:

Silica fume concrete is 0.5-2.5 times more resistant to impact and abrasion and 3-16 times more resistant to cavitation than ordinary concrete.

Optimize the interface between cement paste and aggregate:

It can reduce the water secretion phenomenon in the interface transition zone between cement paste and aggregate, and make the interface transition zone of aggregate similar to the microstructure of the net cement paste, thus improving the denseness of the interface filtration zone and effectively reducing the thickness of the interface transition zone.

With early strength:

Silica fume concrete makes the induction period shorter and has the characteristic of early strength.

Reducing the amount of cement and lowering the cost:

Since it can significantly improve the strength of cement mortar, the amount of cement used can be reduced moderately in the production process, thus lowering the cost.

However, when using micro silica powder, it is necessary to pay attention to the reasonable control of its dosage to avoid too much affecting the construction performance. At the same time, it is necessary to choose reliable quality micro silica powder products and operate in strict accordance with the construction specifications to ensure the quality and performance of construction projects.