The excellent properties of cellulose ethers are suitable for use as retarders, water-retaining agents, thickeners and binders in building materials. They have been used in gypsum, cement, lime, organic mortar, tiles, mortar, etc. A large number of applications. For example, hydroxyethyl methyl cellulose (HEMC) can significantly improve the water retention of fresh mortar, reduce the volume density of fresh mortar and hardened mortar, and improve the water absorption, compressive strength, flexural strength and elasticity of hardened mortar Modulus improves its performance. In addition, adding various cellulose ethers to cement can have a delayed effect on the hydration of cement, thereby improving the performance of cement. People have found through a lot of research that the type and content of cellulose ether substituents are the most important factors affecting hydration, while other molecular parameters such as molecular weight have little effect. For HEMC and HPMC, the content of methoxy group is a key parameter of the hydration delay mechanism, and the content of hydroxypropyl and hydroxyethyl has little effect.