- August 10, 2021
- Posted by: admin
- Category: News
The role of hydroxypropyl methyl cellulose in wet-mixed mortar
1. Wet-mixed mortar is composed of cement, fine aggregate, admixtures, water and various components determined according to performance. After being measured and mixed in a certain proportion, the wet-mixed mortar is transported to the place of use by a mixer truck. Store the wet mix in a special container and use it within the specified time.
2. Hydroxypropyl methylcellulose is used as a water-retaining agent and retarder for cement mortar to make the mortar pumpable. When the plaster is used as a binder, it improves the spreadability and prolongs the working time. The water retention property of hydroxypropyl methylcellulose HPMC prevents the slurry from cracking due to drying too fast after application, and enhances the strength after hardening. Water retention is an important performance of hydroxypropyl methylcellulose HPMC, and it is also a performance that many domestic wet-mix mortar manufacturers pay attention to. The factors that affect the water retention effect of wet-mixed mortar include the amount of HPMC added, the viscosity of HPMC, the fineness of particles and the temperature of the environment in which it is used.
3. The important role of hydroxypropyl methyl cellulose HPMC in wet-mixed mortar mainly has three aspects:
1. It has excellent water retention capacity,
2. It is the influence on the consistency and thixotropy of wet-mixed mortar,
3. It is the interaction with cement.
The water retention effect of cellulose ether depends on the water absorption of the base layer, the composition of the mortar, the layer thickness of the mortar, the water demand of the mortar, and the setting time of the coagulating material. The higher the transparency of hydroxypropyl methylcellulose, the better the water retention.
Fourth, the factors that affect the water retention of wet-mixed mortar include cellulose ether viscosity, addition amount, particle fineness and use temperature. The greater the viscosity of the cellulose ether, the better the water retention performance. Viscosity is an important parameter of HPMC performance. For the same product, the viscosity results measured by different methods are very different, and some are even doubled. Therefore, when comparing the viscosity, it must be carried out between the same test methods, including temperature, rotor, etc.
5. Generally speaking, the higher the viscosity, the better the water retention effect. However, the higher the viscosity, the higher the molecular weight of HPMC, and its dissolution performance will decrease accordingly, which has a negative impact on the strength and construction performance of the mortar. The higher the viscosity, the more obvious the thickening effect on the mortar, but it is not directly proportional.
Sixth, the higher the viscosity, the more viscous the wet mortar will be. During construction, it exhibits high adhesion to the scraper and to the substrate. But it does not help much to increase the structural strength of the wet mortar itself. During construction, the performance of anti-sagging performance is not obvious. On the contrary, some modified hydroxypropyl methyl cellulose with medium and low viscosity has excellent performance in improving the structural strength of wet mortar.
7. The greater the amount of hydroxypropyl methylcellulose added in the wet-mixed mortar, the better the water retention performance, and the higher the viscosity, the better the water retention performance. Fineness is also an important performance index of hydroxypropyl methylcellulose. The fineness of hydroxypropyl methyl cellulose also has a certain influence on its water retention. Generally speaking, for hydroxypropyl methyl cellulose with the same viscosity but different fineness, the finer the fineness is at the same amount of addition. The water retention effect is better.
8. In the wet-mixed mortar, the addition amount of hydroxypropyl methylcellulose is very low, but it can significantly improve the construction performance of the wet-mixed mortar, and it is a major additive that affects the construction performance of the mortar. Reasonable selection of the correct hydroxypropyl methyl cellulose has a great influence on the improvement of the performance of wet-mixed mortar.