防止水泥结合浇注料硬化 满足施工性能要求的关键Preventing cement-bonded castables from hardening is key to meeting workability requirements.

水泥结合浇注料的早期强度主要由水泥水化提供，水泥的硬化速度直接决定着浇注料的拆模时间。

The early strength of cement-bonded castables is mainly provided by cement hydration, and the hardening rate of cement directly determines the demolding time of the castable.

　　众所周知，水泥熟料的矿物组成是影响水泥凝结的关键因素。熟料中硅酸三钙和铝酸三钙的含量越高，水泥的硬化时间就越短。这是因为这些矿物与水发生水化反应后，会形成相互联结的水泥石结构。不同的矿物组成比例会导致不同的水化反应速率。此外，水泥熟料的粒度也是影响水泥水化的重要因素，粒度越细，水化反应和硬化速度就越快。

As is well known, the mineral composition of cement clinker is a key factor affecting cement setting. The higher the content of tricalcium silicate and tricalcium aluminate in the clinker, the shorter the cement hardening time. This is because these minerals, after undergoing a hydration reaction with water, form an interconnected cement stone structure. Different mineral composition ratios lead to different hydration reaction rates. Furthermore, the particle size of cement clinker is also an important factor affecting cement hydration; the finer the particle size, the faster the hydration reaction and hardening rate.

　　除了水泥熟料的组成矿物本身，还有诸多外部因素同样影响水泥浇注料硬化。

Besides the constituent minerals of cement clinker themselves, many external factors also affect the hardening of cement castables.

　　其中，最直观的影响因素当属温度。一般而言，冬季施工时，我们需要采取对浇注料进行保温、添加促凝剂等措施来促进其硬化；夏季则需加入缓凝剂来减缓其硬化速度。这是因为温度升高时，水泥的水化反应和凝结速率会加快；反之，温度降低时，水泥的水化速度也会减慢。

Among these factors, temperature is the most direct influencing factor. Generally speaking, during winter construction, we need to take measures such as heat preservation of the castable and adding accelerators to promote its hardening; while in summer, we need to add retarders to slow down its hardening speed. This is because when the temperature rises, the hydration reaction and setting rate of cement will accelerate; conversely, when the temperature drops, the hydration rate of cement will also slow down.

　　水作为水泥水化的参与者之一，也起着至关重要的作用。为保证浇注料的施工性能，我们会加入适量的水，既要确保浇注料具有良好的流动性，又要保证其强度不受影响。然而，如果加水量过多，在水泥水化过程中，多余的水会在水泥石内形成毛细空隙，从而降低水泥石的强度，进而影响浇注料的硬化时间。

Water, as one of the participants in cement hydration, plays a crucial role. To ensure the workability of the castable, we add an appropriate amount of water, ensuring both good fluidity and maintaining its strength. However, if too much water is added, excess water will form capillary voids within the cement paste during the cement hydration process, thereby reducing the strength of the cement paste and affecting the hardening time of the castable.

　　前面提到，在季节变化时，施工人员在浇注料中添加外加剂来调节硬化时间。这些外加剂主要分为缓凝剂和促凝剂。

As mentioned earlier, construction workers add admixtures to the castable to adjust the hardening time during seasonal changes. These admixtures are mainly divided into retarders and accelerators.

　　缓凝剂包括柠檬酸、柠檬酸钠、葡萄糖酸等有机物。这类缓凝剂大多具有表面活性，它们要么吸附在固 - 液界面上，改变固体粒子的表面性质；要么通过分子中的亲水基吸附大量水分子形成水膜保护层，阻碍晶体接触，抑制水化进程。有些缓凝剂则是通过与游离的 Ca2+ 生成难溶性钙盐并吸附于矿物表面，抑制水化过程，从而达到缓凝效果。另外，像磷酸盐等无机物，在水中电离形成双电层，延缓水化反应，进而延缓浇注料的硬化。

Retarder retarder includes organic compounds such as citric acid, sodium citrate, and gluconic acid. Most of these retarder retarder are surface-active; they either adsorb onto the solid-liquid interface, altering the surface properties of solid particles, or adsorb a large number of water molecules through their hydrophilic groups to form a protective water film, hindering crystal contact and inhibiting the hydration process. Some retarder retarder achieve their retardation effect by reacting with free Ca2+ to form insoluble calcium salts, which are then adsorbed onto the mineral surface, inhibiting the hydration process. Additionally, inorganic compounds such as phosphates ionize in water to form an electrical double layer, slowing down the hydration reaction and thus delaying the hardening of the castable.

上图为缓凝剂

　　促凝剂，如 Ca（OH）2、氟化钠、Li（OH）等，能与水泥熟料中的石膏反应，中和石膏对水泥的缓凝作用，从而加速水泥水化。

Accelerators, such as Ca(OH)2, sodium fluoride, and Li(OH), can react with gypsum in cement clinker, neutralize the retarding effect of gypsum on cement, and thus accelerate cement hydration.

上图为氟化钠

　　此外，浇注料中添加的微粉，如硅微粉，活性较高，与水混合时会形成带负电的胶粒，能够吸附水解过程中析出的 Al3+ 和 Ca2+ 离子。当胶粒不带电时，就会发生凝聚，从而产生结合。

　　浇注料硬化是一个较为复杂的过程，影响因素众多。需要根据不同的现场环境进行调整，以实现合理的硬化速度，满足施工性能和强度要求。

Furthermore, the micro-powders added to the castable, such as silica powder, have high activity and form negatively charged colloidal particles when mixed with water. These particles can adsorb Al3+ and Ca2+ ions released during hydrolysis. When the colloidal particles are uncharged, they aggregate, thus forming bonds.

The hardening of castables is a relatively complex process influenced by numerous factors. Adjustments need to be made according to different site environments to achieve a reasonable hardening rate and meet the requirements for workability and strength.