High-quality hydroxypropyl methyl cellulose can be uniformly and effectively dispersed in cement mortar and gypsum-based products, and wrap all solid particles, and form a layer of wetting film. The moisture in the base is gradually released over a long period of time. The hydration reaction occurs with inorganic cementing materials to ensure the bonding strength and compressive strength of the materials.
Therefore, in the high temperature summer construction, in order to achieve the effect of water retention, it is necessary to add high-quality HPMC products in sufficient quantities according to the formula, otherwise, insufficient hydration, reduced strength, cracking, hollowing and falling off will occur due to excessive drying. Problems, but also increase the difficulty of construction workers. As the temperature decreases, the amount of HPMC added can be gradually reduced, and the same water retention effect can be achieved.
How can hydroxypropyl methylcellulose promote water retention? In dry mortar, hydroxypropyl methyl cellulose has a very low addition of cellulose ether, but it can significantly improve the performance of wet mortar and is a major additive that affects the construction performance of mortar. Now, the cellulose ether used in dry mortar of hydroxypropyl methyl cellulose is mainly hydroxypropyl methyl cellulose ether.
In dry mortar, HPMC mainly plays a role in water retention, thickening, and improvement of construction performance. Hydroxypropyl methyl cellulose HPMC does not participate in any chemical reaction, only plays an auxiliary role. The putty powder is added with water and applied to the wall. It is a chemical reaction. Because of the formation of new substances, the putty powder on the wall is removed from the wall and ground into powder. Then it will not work, because a new substance (calcium carbonate) ) Again.
The main components of gray calcium powder are: a mixture of Ca(OH)2, CaO and a small amount of CaCO3, CaO+H2O=Ca(OH)2 —Ca(OH)2+CO2=CaCO3↓+H2O Gray calcium in water and air Under the action of CO2, calcium carbonate is formed, while HPMC only retains water and assists the better reaction of gray calcium, and it does not participate in any reaction.