Normal consistency of gypsum powder

　　也称为标准水或标准混合水。为100份半水石膏粉获得标准流动性(试样直径:200±5mm)所需要的加水量，以百分数表示。半水石膏粉性能是描述半水石膏粉性能的重要指标，是比较石膏粉质量和描述半水石膏粉其他性能指标的基础(半水石膏粉性能应在相同浓度下进行比较)。然而，这一指标并不是我们在大规模生产中模拟的混合水量，而是实际情况大于它。半水石膏的标准稠度较小，一般在45% ~ 55%之间，而半水石膏的标准稠度较大，一般在70% ~ 80%之间。通过对半水石膏粉标准稠度的测试，可以初步判别石膏粉的结晶型(型)，判断石膏粉的质量。

　　Also known as standard water or standard mixed water. The amount of water needed to obtain the standard fluidity (sample diameter: 200 + 5mm) for 100 parts of semi-aqueous gypsum powder is expressed in percentage. The performance of hemihydrate gypsum powder is an important index for describing the performance of hemihydrate gypsum powder. It is the basis for comparing the quality of hemihydrate gypsum powder and other performance indexes of hemihydrate gypsum powder (the performance of hemihydrate gypsum powder should be compared at the same concentration). However, this indicator is not the amount of mixed water we simulate in large-scale production, but the actual situation is larger than it. The standard consistency of hemihydrate gypsum is relatively low, generally between 45% and 55%, while that of hemihydrate gypsum is relatively high, generally between 70% and 80%. By testing the standard consistency of hemihydrate gypsum powder, the crystalline type and quality of gypsum powder can be judged preliminarily.

　　石膏细度

　　Gypsum fineness

　　半水石膏粉是表征石膏粉性能的重要指标。它与半水石膏在水中的凝结速率、模型的强度、表面硬度和光洁度有关。测定细度的方法包括筛数(筛渣百分比)、颗粒级配和比表面积。一般来说，石膏粉的细度越细，其颗粒的比表面积越大，与水的接触面积越大，在水中的溶解速度越快。与水结合后反应充分，石膏浆凝结速度越快，形成网状结构，模型强度较高，但吸水率相应降低。石膏粉细度粗，一般在80 ~ 90目，模型强度低;Alpha石膏细度较好，一般在120 - 180目之间，模型强度较高。目前，国内陶瓷生产中使用的石膏粉一般为100 ~ 120目，高不超过180目。国外采用的石膏粉细度为180 ~ 250目。

　　Hemihydrate gypsum powder is an important index to characterize the performance of gypsum powder. It is related to the coagulation rate of hemihydrate gypsum in water, the strength of the model, the surface hardness and the smoothness of the model. The methods for determining fineness include sieve number (percentage of sieve residue), particle size distribution and specific surface area. Generally speaking, the finer the gypsum powder is, the larger the specific surface area of its particles, the larger the contact area with water, and the faster the dissolution rate in water. When combined with water, gypsum slurry reacts sufficiently. The faster the setting speed of gypsum slurry is, the network structure is formed. The strength of the model is higher, but the water absorption decreases accordingly. The fineness of gypsum powder is coarse, generally in 80 - 90 mesh, and the strength of model is low. Alpha gypsum has better fineness, generally in 120 - 180 mesh, and the strength of model is high. At present, gypsum powder used in domestic ceramic production is generally 100 - 120 meshes, up to 180 meshes. The fineness of gypsum powder used abroad is 180 - 250 meshes.