复合胶凝材料水化过程中Ca(OH)_2量的变化

Alteration of Ca(OH)_2 Content during Hydration Process of Composite Binders

采用热分析(TG/DTG)方法对不同水胶比、不同矿物掺和料种类和掺量的复合胶凝材料硬化浆体中Ca(OH)2量的变化情况进行了分析.结果表明:复合胶凝材料浆体中的Ca(OH)2量有所降低,但不与矿物掺和料的掺量成正比,矿物掺和料的稀释作用可促进硅酸盐水泥的水化程度提高;所有试样的Ca(OH)2含量在1 a龄期时均远远高于形成饱和Ca(OH)2溶液所需量,不必担心贫钙现象发生;大掺量矿物掺和料胶凝材料在较低水胶比时,其Ca(OH)2量基本不随水化龄期延长而波动,但在较高水胶比时,其Ca(OH)2量随水化龄期延长而降低.在较大水胶比条件下,矿物掺和料的允许掺量需要从严控制.

The alteration of Ca（OH）2 content in composite binder pastes containing different kinds and replacing proportions of mineral admixture was determinded by thermogravimetric method（TG/DTG） at different curing ages and water-binder ratios. The Ca（OH）2 content in composite binder pastes decreases by adding mineral admixture. However, the decreasing rate is not proportional to the use level of mineral admixture. The diluting effect of mineral admixture enhances the hydration degree of Portland cement clinker. The Ca（OH）2 content in all samples hydrated for 1 a is much higher than that needed to form; the Ca （OH）2 saturated solution in capillary pore. It is not necessary to worry about the calcium deficient in composite binder containing high volume of mineral admixture. Ca（OH）2 content in composite binder pastes undulates little with the prolongation of hydration age under the condition of low water-binder ratio but decreases under the condition of high water-binder ratio. Therefore, the use level of mineral admixture should be limited under the condition of high water-binder ratio.