The role of zeolite in concrete
Keywords
Zeolite, concrete waterproofing agent, impermeable concrete, waterproof concrete, crack-resistant concrete
Zeolite is a water-containing alkali metal or alkaline earth metal aluminosilicate mineral formed by volcanic eruptions over hundreds of millions of years.
Its interior is full of tiny pores and channels, which is much more complex than a honeycomb. There are 1 million nanoscale pores in 1 cubic micron! Zeolite has a huge specific surface area. The surface area of one gram of modified zeolite powder is equivalent to the area of a football field.
Zeolite powder is a volcanic ash material formed by grinding natural zeolite rock. It has a huge internal and external specific surface area and contains a large amount of active SiO2 and Al2O3. Used as a concrete admixture, it can react with Ca(OH)2 released by cement hydration to generate more C-S-H gel and hydrated aluminate, thereby well improving the properties of hardened cement paste. micro structure.
Enhance concrete durability and stability
Zeolite powder can increase the viscosity of concrete, eliminate segregation and bleeding in concrete, and through the filling effect and pozzolanic reaction of zeolite powder, it can greatly reduce the total void ratio of concrete and improve the interface transition between cement slurry and aggregates. area, improve the mechanical properties of concrete, and ensure the stability, durability, and seismic performance of the building.
Improve the impermeability and waterproofness of concrete
After zeolite powder is added to cement concrete, in the early stage of mixing, due to zeolite's super moisture absorption and release properties, part of the free water is absorbed by the zeolite powder. However, during the hardening process of concrete, when the cement is further hydrated, the zeolite powder discharges the water it originally absorbed and expands in volume, which increases the viscosity of the mixture and increases the amount of slurry in the coarse bone. Therefore, the interface between the coarse bone and cement is improved. , the mixture is more uniform, has good workability, and reduces bleeding, thus increasing the impermeability of concrete.
Enhance the crack resistance of concrete
In high-strength concrete, due to the higher cement content, the heat of hydration in the concrete is also more concentrated; in large-volume concrete, the heat of hydration of cement is higher. After adding zeolite powder, due to the reduction of cement consumption, the hydration heat value of cement also decreases accordingly. Although the peak of hydration heat is earlier, the hydration heat value of cement is much lower than that of pure cement concrete, and as the zeolite content increases, the decrease in the hydration heat of concrete also increases. The reduction of hydration heat in high-strength concrete and large-volume concrete is beneficial to inhibit the expansion of concrete.
