These are hydraulic binders (referred to as anti-cracking double-fast cement) with crack resistance fast setting and rapid hardening properties. They have micro expansion to compensate the dry shrinkage and the gap in expansion. Shrinkage is small. Especially the free dry shrinkage is just the 1/10-1/8 of the Portland cement. 28d Free Expansion Rate :In Water ≤0.08%;In Air ≥-0.05%. The 2h compressive strength of products made by this cement can reach 10Mpa, a satisfactory anti-corrosion property.
Performance Characteristics：
The main cause of concrete cracking is the large shrinkage and high volume change rate of cement. For cement with expansion properties, the free expansion rate index is generally used in standards to directly reflect the cement's volume change rate, which is closely related to the crack resistance of concrete.
This cement has micro-expansion performance, using expansion to compensate for shrinkage, so the difference between the two is small. Especially, the shrinkage value in the free state is only about 1/10 to 1/8 of that of sulfoaluminate cement. This is a significant improvement in the crack resistance of cement.
It sets and hardens quickly: the compressive strength reaches ≥15MPa within 4 hours; currently, the 2-hour compressive strength of the produced product has reached about 10MPa.
Sulfoaluminate cement has high requirements for curing; a little carelessness can easily lead to surface sanding of concrete, which increases the water absorption rate of concrete and reduces its impermeability and durability. Crack-resistant fast-setting cement solves this problem well.
This cement uses rapid-setting and hardening high-belite sulfoaluminate cement clinker. Its main mineral is dicalcium silicate; the content of calcium sulfoaluminate is low, and there is no tricalcium silicate mineral. Therefore, the total heat of hydration is low.
It has micro-expansion performance. Compared with Portland reference cement, its penetration height under the same pressure is only half that of Portland reference cement, so its impermeability is much higher than that of Portland cement.
At the 180-day age, the corrosion resistance coefficient in 3% sodium sulfate solution is 1.46, in 3% sodium carbonate solution is 1.41, and in 3% sodium chloride solution is 1.51. It has excellent corrosion resistance against the above corrosive media.
