The relationship between the construction of epoxy floor and concrete is very important. At present, no admixture has been developed which can effectively prevent the moisture content of calcium hydroxide from precipitating to the surface of concrete. Mixed concrete exudes and bleeds: the more water seeps from the surface of the structure at the beginning of setting, the greater the seriousness of whitening. It is mainly manifested in the following aspects: 1. 水灰比过大。水灰比越大，拌合物内的游离水量也越多，混凝土泌水的可能性也就越大，混凝土泛白较多。为此，在满足施工操作的前提下，应尽量减少拌和用水量，降低水灰比。
1. the water cement ratio is too large. The greater the water cement ratio, the more free water in the mixture, the greater the possibility of concrete bleeding, and the more white concrete. Therefore, under the premise of satisfying the construction operation, we should minimize the mixing water consumption and reduce the water cement ratio.
2. The excessive amount of admixture will also cause the bleeding of concrete mixture. In this case, the amount of admixture should be reduced.
3. is related to cement. Influenced by the source of raw materials, production control and technological conditions, the mineral content of cement produced by different manufacturers is also different. In general, cement with high C3A content, because of its fast hydration and large adsorptive capacity to additives, avoids excessive admixture under the same conditions, and is not easy to appear bleeding caused by excessive admixture. For the cement with low C3A content, the amount of admixture should be reduced appropriately.
4. is related to concrete mix proportion and aggregate gradation. The mixture with too small sand or poor gradation is prone to bleeding.
5. In the case of other conditions unchanged, mixing is generally expected to adjust the admixture to adapt to changes in raw materials, to meet the pumping requirements of different grades of concrete. It is beneficial to improve workability of concrete and reduce bleeding and settlement by adding proper water-retaining, plastic-retaining and air-entraining components into admixtures.
The content of soluble salt and alkali in building materials is high.
1. Cement is the main component of concrete. The higher the content of alkali metal oxides in cement itself, the more alkali can be precipitated under certain conditions, and the greater the possibility of whitening concrete surface. The alkali content of cement has a great influence on the addition of additives. Therefore, when selecting cement, low alkali cement should be used as far as possible.
The content of soluble salt in the 2. aggregate is also an important factor affecting the whitening of concrete surface. If conditions permit, the aggregate should be selectively selected and its soluble salt content should be strictly controlled.
3. Naphthalene-based concrete admixtures are widely used at present. Low concentration of NaSO_4 is the most common, and NaSO_4 content is relatively high. Naphthalene-based concrete admixtures increase the soluble substances in concrete, thus increasing the possibility of whitening concrete surface. Reducing the alkali content of the admixture as far as possible is beneficial not only to prevent alkali-aggregate reaction, but also to improve the application effect of the admixture.
4. in the preparation of concrete, appropriate amount of active silicon admixture is added. In the process of cement hydration, SiO2 can react with the Ca (OH) 2 produced by hydration of cement mineral composition C3S and C2S for two times to form C-S-H gel, which is easier to react with the strong alkali NaOH and KOH in cement and reduce the free alkali content in concrete. In this way, after concrete hardening and drying, even if the moisture permeates into the base material, the amount of salts or alkalis that can be precipitated is very small.
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