The annual high temperature season has raised many new issues for admixture manufacturers, which deserve everyone’s attention. As a new generation of water-reducing admixture, water-reducing admixture is widely used in concrete projects, but there are still some problems during use that are complex and difficult to solve at the moment. Issues that manufacturers of admixtures need to pay attention to when using them
Based on the domestic production status, the author puts forward several precautions:
1. Storage issues of raw materials, large monomers are stored at high temperatures During transportation and production and storage, you are faced with high temperatures, ultraviolet rays, heat accumulation, and radiation. All these external conditions will trigger the polymerization of macromonomers. C4 macromonomers have greater self-polymerization activity, and harsh external conditions will degrade the product. The retention rate of double bonds causes the phenomenon of polymerization of chemical materials. Domestic large monomer companies have technical solutions for controlling chemical materials, but most of them have not been implemented. The stability of C5 large monomer is better than that of C4, and there are not many chemical phenomena. Acrylic suffers from the same self-polymerization problem. It is recommended to transport and store at low temperature, ventilation and shade. The heat dissipation of the liquid monomer may be better, which will reduce the tendency of self-aggregation.
2. For product storage of admixtures, many companies add sugar and other small ingredients in the compound, which will induce the growth rate of microorganisms at high temperatures. If the finished product is stored for a long time, an appropriate amount of preservatives must be added.
3. Concrete strength problem. The high temperature in summer significantly accelerates the hydration rate of cement. The amount of concrete admixture should be increased appropriately. Concrete is faced with the problem of bleeding and segregation. Using air entrainment and defoaming for water reducing agents and adding a small amount of tackifier can improve fresh concrete. of workability. The addition of air-entraining agents can improve the workability of concrete and improve the slump loss of concrete. Air in hardened concrete will significantly reduce the 28-day concrete strength. Experience shows that for every 1% increase in air content, the concrete strength will decrease by 5MPa. Some admixture companies will find that the concrete 28-day strength is unqualified. This is due to the failure to control the fresh concrete. The gas content has a great relationship.
4. The quality risk of synthetic small materials. Rising temperature provides external conditions for the quality fluctuation of all synthetic small materials. Hydrogen peroxide automatically decomposes at high temperatures, the concentration decreases, and the validity period is shortened. Thioglycolic acid, etc. self-polymerize at high temperatures. Acceleration, shortened storage period, and quality fluctuations of all these synthetic small materials will affect the quality of synthetic admixture products to fluctuate significantly.
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