The use of concrete admixtures is not only for reducing costs and improving economic benefits, it has a wide range of uses. Different additives have their own effects.
Points to note:
1. The amount of additives
Each kind of additive has an optimal blending amount, which is determined according to the quality of the additive and the cement and aggregate used. If the blending amount is too small, the admixture will not play its due role and the expected effect will not be achieved; if the blending amount is too high, it will not only fail to achieve the intended purpose, but also play the opposite role. Therefore, before use, the most suitable dosage should be confirmed through experiments. When the expected effect cannot be achieved, the use error should be controlled within ±2%.
2. Mixing evenly, we must try to make the admixture evenly distributed in the whole mixture to make it fully play its role, to avoid the negative consequences of local excessive concentration. If the powder is added together with cement, it should be spread out, and the dry mixing time should be properly extended; the liquid should also be spread evenly to prevent local concentration.
3. The mixing process must not be disordered. For concrete mixed with several admixtures, pay attention to the order of addition. It may be added first, or it may be added later, or it may be added after being shipped to the site. So pay attention to the order of addition of additives.
With the different seasons, (when the ambient temperature is different), the admixture should be replaced in time. Different additives have different characteristics. During the transition from autumn to winter construction, the antifreeze should be replaced in advance.