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    影响环氧地坪因素之一(混凝土表面泛白原因及预防措施)

    2018-10-24 07:15:12 无锡盛发地坪科技有限公司 阅读

    环氧地坪的施工与混凝土的关系很重要,目前国内尚未研制出能真正有效阻止混凝土内含氢氧化钙的水分向表面析出的外加剂,只能针对泛白形成的原因采取相应的预防措施。拌制的混凝土出同泌水:初凝时渗出结构表面的水分越多,出现泛白的严重性就越大。主要表现在以下几个方面:

    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. 外加剂掺量过大也会造成混凝土拌合物泌水,在此情况下应减少外加剂掺量。

    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. 与水泥有关。受原材料来源、生产控制及工艺条件的影响,不同厂家生产的水泥的矿物成分含量也不同。一般情况下,对C3A含量高的水泥,因其水化快,对外加剂的吸附量又大,在同等条件下避免了外加剂的过掺,不易出现因外加剂掺量过大造成的泌水。对C3A含量低的水泥,则应适当减少外加剂掺量。

    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. 与混凝土的配合比及集料级配有关。砂率过小或级配不良的拌合物容易出现泌水。

    4. is related to concrete mix proportion and aggregate gradation. The mixture with too small sand or poor gradation is prone to bleeding.

    5. 在其他条件不变的情况下,搅拌一般希望通过外加剂的调整来适应原材料变化,满足不同标号混凝土的泵送要求。在外加剂中加入适量的保水、保塑及引气组份,对提高混凝土的和易性、减少泌水和沉降有利。

    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.

    建筑材料内容可溶性盐和碱的含量偏高

    The content of soluble salt and alkali in building materials is high.

    1. 水泥是混凝土的主要组成部分,水泥本身的碱金属氧化物含量越高,在一定条件下可供析出的碱量越多,拌制混凝土表面泛白的可能性也就越大。水泥的含碱量同时对外加剂的作用产生很大影响。因此,在选用水泥时,应尽量用低碱水泥。

    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.

    2. 集料中可溶性盐含量的高低也是影响混凝土表面泛白的一个重要因素。如果条件允许,应该对集料有一定的选择性,严格控制其可溶性盐含量。

    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. 萘系混凝土外加剂,目前应用最为广泛,低浓度的居多,NaSO4含量相对较高,增加了混凝土中的可溶性物质,因而增大了混凝土表面泛白的可能性。尽量降低外加剂的含碱量不但对防止碱—集料反应有益,还可以提高外剂的使用效果。

    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. 在配制混凝土时,适量掺加一些活性硅质掺合料。在水泥水化过程中SiO2可以与水泥矿物成分C3S、C2S水化产生的Ca(OH)2发生二次反应形成C-S-H凝胶,更容易与水泥中强碱NaOH、KOH发生反应,降低混凝土中的游离碱含量。这样,混凝土硬化、干燥后,即使水分渗透到基材料内部,可供析出的盐或碱量也很少.优质的矿物掺合料对预防混凝土表面泛白具有良好效果。

    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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