The effect of retarder is as follows:

　　1)降低半水石膏的溶解度;

　　1) Decrease the solubility of hemihydrate gypsum;

　　2)减缓半水化石膏的溶解速度;

　　2) slowing down the dissolution rate of hemihydrated gypsum;

　　3)吸附结晶石膏二水化物晶体表面的离子，并将其结合到晶格中;

　　3) Adsorb the ions on the crystal surface of crystalline gypsum dihydrate and combine them into the lattice.

　　4)形成络合物，限制离子向二水石膏晶体附近扩散。

　　4) Formation of complexes to restrict ion diffusion near dihydrate gypsum crystals.

　　常用缓凝剂主要有:碱性磷酸盐和磷酸铵、有机酸及其可溶性盐(如柠檬酸和柠檬酸盐)、受损蛋白等。

　　Commonly used retarders are alkaline phosphate and ammonium phosphate, organic acid and its soluble salts (such as citric acid and citrate), damaged protein, etc.

　　学者们对几种缓凝剂进行了测试，结果表明，缓凝剂的缓凝效果按如下顺序增加。结果表明，在初始凝固时结晶较粗、较短，硬化强度低于纯水。

　　Scholars have tested several retarders. The results show that the retarding effect of retarders increases in the following order. The results show that the initial solidification crystallization is coarser and shorter, and the hardening strength is lower than that of pure water.

　　学者等研究了蔗糖对巴黎石膏凝固过程的影响，发现当Ca(OH)2同时存在时，蔗糖对巴黎石膏具有明显的缓凝作用，认为这可以用吸附理论来解释。

　　Scholars have studied the effect of sucrose on the solidification process of Paris gypsum, and found that when Ca (OH) 2 exists at the same time, sucrose has obvious retarding effect on Paris gypsum, which can be explained by adsorption theory.

　　关于柠檬酸和柠檬酸钠的延缓作用，专家认为柠檬酸具有延缓作用。加入少量(小于0.1%)，有轻微的缓速效果，强度略有降低。当掺量增加(超过0.2%)时，会严重影响二水石膏晶体的形成习惯，使晶体不能相互生长和连接。石膏浆即使完全水化，也不会凝结。

　　As for the delaying effect of citric acid and sodium citrate, experts believe that citric acid has delaying effect. Adding a small amount (less than 0.1%) has a slight slow-down effect and a slight decrease in strength. When the content increases (more than 0.2%), the formation habit of dihydrate gypsum crystals will be seriously affected, so that the crystals can not grow and connect with each other. Gypsum slurry will not coagulate even if it is completely hydrated.

　　学者们研究了柠檬酸钠对巴黎石膏凝固的影响，发现柠檬酸钠在含量大于0.1%时具有较强的缓凝作用，降低了硬化浆体的强度。但当掺量低于0.05%时，具有促进凝固的作用，硬化强度高于纯水。他们认为这是因为在浓度超过0.1%时，由于冷凝时间长，晶体完全长大，并且它具有促进结晶生长的作用，所以结晶体的形成，硬化强度降低。但在低浓度下，情况正好相反，就像在水中一样，会产生细小的针状晶体。

　　Scholars have studied the effect of sodium citrate on the solidification of Paris gypsum, and found that sodium citrate has a strong retarding effect when the content of sodium citrate is more than 0.1%, which reduces the strength of hardened paste. But when the dosage is less than 0.05%, it can promote the solidification, and the hardening strength is higher than that of pure water. They think that the reason is that when the concentration exceeds 0.1%, because of the long time of condensation, the crystal grows completely, and it has the effect of promoting crystal growth, so the formation of crystals and the hardening strength decrease. At low concentrations, however, the opposite is true, as in water, where fine needle-like crystals are produced.

　　混凝剂温和的凝血机制往往由于各种原因变得非常复杂,有时超出掺合料的佳用量本身会产生相反的效果,有时两个或更多外面的另一个复合混合了反效果,除了进一步的研究在理论上,这些问题取决于积累经验在生产实践的过程中,选择合适的剂量的添加剂品种和选择好的。

　　The mild coagulation mechanism of coagulant often becomes very complicated for various reasons. Sometimes the best dosage of coagulant will produce the opposite effect. Sometimes the compound of two or more outside will mix the opposite effect. In addition to further research, these problems depend on the selection of the most appropriate dosage of additives in the process of production and practice. Choose the best.