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In recent years, with the continuous deterioration of the environment, the carbon dioxide content in the air has been increasing. Concrete exposed to the air for a long time reacts with the carbon dioxide in the air, reducing the alkalinity of concrete, leading to accelerated corrosion of steel bars in concrete, cracking, peeling and other phenomena, seriously affecting the durability of concrete and reducing its service life. Therefore, analyzing the impact of carbonation on concrete is particularly important.
1. Water cement ratio
On the one hand, the size of the water cement ratio to a certain extent determines the compactness of concrete. The higher the water cement ratio, the more pores the concrete will have after hardening, and the larger the contact surface with carbon dioxide in the air; On the other hand, as the water cement ratio increases, the ability of carbon dioxide to diffuse in concrete becomes stronger.
2. Cement dosage
The amount of cement used affects the compactness of concrete. The more cement used, the better the compactness of concrete. The fewer pores inside the concrete, the smaller the area in contact with carbon dioxide, and the lower the degree of carbonation of concrete.
3. Admixtures
Adding admixtures such as fly ash, mineral powder, and silica fume to concrete, a large amount of active substances in the admixtures replace some of the cement and participate in the hydration process, reacting with calcium hydroxide in the cement hydration products. This process not only consumes some of the cement dosage, but also greatly reduces the alkalinity of the concrete. The added admixtures are also mixed with the hydration products generated by the secondary hydration reaction of cement, filling the internal pores of the concrete again, and the overall integrity of the concrete is improved.
4. Admixtures
There are various types of admixtures, and the active substances in each type of admixture are also different. When added to different types of cement, the anti carbonization effect produced is also different. The combination of high-quality admixtures and corresponding cement can reduce the water consumption of concrete to a certain extent, increase the overall compactness of concrete, and enable concrete to exert its superior properties and reduce carbonation reactions.
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