The basic use of hydroxypropyl methylcellulose in the construction field
- By:Italian B2b
Hydroxypropyl methylcellulose HPMC is used as a dispersant, thickener and binder in construction treatment, and is mainly used in the molding of cement mortar and gypsum products. It is used in cement mortar to increase its cohesion, reduce flocculation, improve viscosity and shrinkage, and have water retention. Reduce moisture loss on the concrete surface, strength, prevent cracks and weathering of water-soluble salts, etc.; hydroxypropyl methylcellulose HPMC has thixotropy, and can be formulated with low fluidity and thickly applied to vertical walls at one time. Mortar stucco paint; HPMC has improved adhesion and construction performance, so it is suitable for the preparation of easy-flowing spray mortar for thin-layer painting.
The amount of hydroxypropyl methylcellulose HPMC in building materials is very small, only 0.1%~1%, but it has a great effect, and can be used as a plasticizer, viscosifier, and water-retaining agent for paint, plaster, mortar, and cement products. Agents, air-entraining agents and retarders to increase its workability, water retention or adhesion to the base. In addition, it is also in response to environmental protection requirements. When dry-mixing mortar, it avoids unstable performance caused by on-site mixing, pollution to the surrounding environment, poor construction environment, and low flow efficiency. In the past, 107 adhesive was used more as adhesive for ceramic tiles and putty for interior and exterior walls. From the perspective of environmental protection, it is ideal to apply cellulose ether, such as HEC and HPMC.
Cement has good bonding performance, but the bonding performance of cement slurry and cement mortar is obviously different due to the performance difference and condition of the bonding layer and the bonded surface during the construction process. When the water absorption performance of the bonding surface is large, it will The dehydration of the bonding surface is caused, the plasticity of the cement mortar is greatly reduced, the adhesion is reduced, and the bonding strength is greatly reduced. In the past, gypsum or 107 glue was added to the cement mortar, but there were still defects such as inaccurate measurement and cumbersome construction techniques. The viscosifying effect of cellulose ether in water and weak alkali.
The effects of adding cellulose ether include:
1. Improve the initial and final setting time of cement;
2. Improve the overcoming stress of cement mortar;
3. Improve the water retention capacity of cement and gypsum;
4. The compressive and shear strength of cement mortar is reduced;
5. Improve the bonding performance of mortar.