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What role does HPMC play in the wet-mixed mortar
Hydroxypropyl methylcellulose is playing an important role. Let's take a brief look at it today.
The wet mix mortar is cement, fine aggregate, additives and water, and various components are determined according to the properties. After the mixing is measured at the mixing station according to a certain ratio, the mixture is transported to the place of use by a mixing truck and placed in a special container for storage, and the wet mixture is used within the specified time.
Mortar can be pumped using hydroxypropylmethyl cellulose as a water retention agent and retarder for cement mortar. In the mortar as an adhesive, in order to improve spreadability and prolong operation time, HPMC's water retention will not cause the slurry to crack due to drying too fast after coating, and it will increase the strength after hardening. Water retention is an important property of cellulose HPMC, and is also the performance of many wet-mixed mortar manufacturers in China. Factors affecting the water retention effect of wet-mixed mortar include the amount of HPMC added, the viscosity of HPMC, the fineness of the particles, and the temperature of the use environment.
The important role of hydroxypropyl methylcellulose HPMC in wet-mixed mortar is mainly manifested in three aspects, one is excellent water retention, the other is the effect on the consistency and thixotropy of wet-mixed mortar, and the third is the interaction with cement. Cellulose ether has a good water retention effect. Taking it 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 solidified material. The higher the transparency, the better the water retention.
Factors affecting the water retention of wet-mixed mortar include cellulose ether viscosity, added amount, particle fineness and use temperature. The higher the viscosity of the cellulose ether, the better the water retention. Viscosity is an important parameter for HPMC performance. For the same product, the viscosity results measured by different methods vary widely, and some even double the difference. Therefore, when comparing viscosity, it must be performed between the same test methods, including temperature, rotor, etc.
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 workability of the mortar. The higher the viscosity, the more pronounced the thickening effect of the mortar, but disproportionate. The higher the viscosity, the higher the viscosity of the wet mortar, and when applied it will show sticky knives and high adhesion to the substrate. However, increasing the structural strength of the wet mortar itself does not help. During the construction, the anti-sagging performance is not obvious. In contrast, some low-viscosity but modified celluloses have excellent properties for improving the structural strength of wet mortar.
The more 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 its important performance index.
The fineness of hydroxypropyl methylcellulose also has a certain effect on its water retention. In general, for celluloses having the same viscosity and different finenesses, the finer the fineness, the smaller the fineness. Better water retention.
In the wet mixed mortar, the added amount of cellulose ether HPMC is very low, but it can significantly improve the construction performance of the wet mixed mortar, which is the main additive that affects the construction performance of the mortar. The correct choice of this product has a great influence on the properties of wet-mixed mortar.