Le rôle des Hydroxy Propyl Méthyl Cellulose in wet-mixed mortar
1. The wet mixed mortar is cement, fine aggregate, additives and water, and various components are determined according to the performance. After measuring the mixing in a certain proportion at the mixing station, the mixture is transported to the place of use with a mixing truck and placed in a special container for storage, and the wet mixture is used within the specified time.
2. Use hydroxypropyl methylcellulose as a water-retaining agent and a retarder for cement mortar to make mortar that can be pumped. In the mortar as a binder, in order to improve the spreadability and prolong the operating time, the water retention of hydroxypropyl methylcellulose HPMC will not cause the slurry to break due to excessive drying after coating, and improve the hardening strength. Water retention is an important property of hydroxypropyl methylcellulose HPMC. 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 methylcellulose HPMC in wet-mixed mortar is mainly manifested in three aspects, one is its excellent water retention performance, the other is its influence on the consistency and thixotropy of wet-mix mortar, and the third is its interaction with cement. effect. Cellulose ether has a good water retention effect. It depends on the water absorption of the base layer, the composition of the mortar, the thickness of the mortar, the water demand of the mortar and the setting time of the solidified material. The higher the transparency of hydroxypropyl methylcellulose, the better the water retention.
4. Factors affecting 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. 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 twice the difference. Therefore, when comparing the viscosity, it must be carried out between the same test methods, including temperature, rotor and so on.
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 solubility 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 of the mortar, but not proportional. The higher the viscosity, the higher the viscosity of the wet mortar, and it will exhibit stickiness and high adhesion to the substrate when applied. However, increasing the structural strength of the wet mortar itself is not helpful. During construction, the anti-sagging performance is not obvious. On the contrary, some low-viscosity but modified Hydroxy Propyl Méthyl Cellulose has excellent properties to improve the structural strength of wet mortar.
6. The more the amount of cellulose ether HPMC added to 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 methylcellulose also has a certain effect on its water retention. Generally speaking, for Hydroxy Propyl Méthyl Cellulose with the same viscosity and different denier, the finer the denier, the smaller the denier, and the better the water retention effect.
