The role of hydroxypropyl methylcellulose in wet-mixed mortar

The role of hydroxypropyl methylcellulose in wet-mixed mortar

The wet-mixed mortar is cement, fine aggregate, additives and water, and various components are determined according to the performance. After measuring and mixing in a certain proportion at the mixing station, the mixture is transported to the place of use in a special container for storage, and the wet mix is ​​used within the specified time.

The use of hydroxypropyl methyl cellulose as a water retention agent and retarder for cement mortar to make mortar can be pumped. In the mortar as a binder, in order to improve the spreadability and extend the operating time, the water retention of hydroxypropyl methylcellulose HPMC will not cause the slurry to crack due to drying too fast after coating, and improve the hardened strength. Water retention is an important property of hydroxypropyl methylcellulose HPMC and the performance of many wet mixed mortar manufacturers in China. The factors that affect the water retention effect of the 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 performance, 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. It depends on the water absorption rate of the base layer, the composition of the mortar, the thickness of the mortar layer, the water demand of the mortar and the setting time of the setting material. The higher the transparency of hydroxypropyl methyl cellulose, the better the water retention.

Factors that affect the water retention of wet mix mortar include cellulose ether viscosity, added amount, particle fineness and use temperature. The greater the viscosity of 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 vary greatly, and some even double the difference. Therefore, when comparing the viscosity, it must be carried out 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 be reduced 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 mortar, but not proportional. The higher the viscosity, the higher the viscosity of the wet mortar, and it will show a sticky knife and high adhesion to the substrate during use. However, increasing the structural strength of the wet mortar itself is not helpful. During the construction, the anti-sag performance is not obvious. On the contrary, some low-viscosity but modified hydroxypropyl methylcellulose improves the structural strength of wet mortar with excellent performance.

The more the amount of cellulose ether HPMC 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 methyl cellulose.

The fineness of hydroxypropyl methylcellulose also has a certain effect on its water retention. In general, for hydroxypropyl methyl cellulose with the same viscosity and different denier, the finer the fineness, the smaller the fineness. Water retention effect is better.

In the wet mixed mortar, the addition 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. Correct selection of hydroxypropyl methylcellulose has a great influence on the performance of wet-mixed mortar.