Effect of hydroxypropyl methyl cellulose in wet mixed mortar

The wet mixed mortar consists of cement, fine aggregate, additives and water, and various components are determined according to the performance. After the mixture is measured in a certain proportion in the mixing station, the mixture is transported to the place of use with a mixer and stored in a special container, and the wet mixture is used within the specified time.

Hydroxypropyl methyl cellulose is used as a water retaining agent and a retarder of cement mortar to make mortar that can be pumped. In the mortar as adhesive, in order to improve the spreadability and prolong the operation time, the water retention of HPMC will not cause the slurry to crack due to the rapid drying after coating, and the strength after hardening is improved. Water retention is an important property of HPMC, and it is also the performance of many wet mixed mortar manufacturers in China. The factors that affect the water retention effect of wet mixed mortar include the amount of HPMC, the viscosity of HPMC, the fineness of particles and the temperature of the environment.

The important role of HPMC in wet mixed mortar is mainly manifested in three aspects: the first is excellent water retention performance, the second is the influence on the consistency and thixotropy of wet mixed mortar, and the third is the interaction with cement. Cellulose ether has good water retention effect. Taking it depends on the water absorption of the base, the composition of the mortar, the thickness of the mortar layer, the water demand of the mortar and the setting time of the solidified material. The higher the transparency of hydroxypropyl methyl cellulose, the better the water retention.

The factors that affect the water retention of wet mixed mortar include the viscosity of cellulose ether, the addition amount, particle fineness and service temperature. The higher 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 are even twice the difference. Therefore, when comparing 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 workability of mortar. The higher the viscosity, the more obvious the thickening effect of mortar, but it is not proportional. The higher the viscosity is, the higher the viscosity of the wet mortar is, and it will show high adhesion to the substrate when applied. However, increasing the structural strength of wet mortar itself is not helpful. During construction, the anti sagging performance is not obvious. On the contrary, some low viscosity but modified hydroxypropyl methyl cellulose has excellent performance in improving the structural strength of wet mortar.

The more cellulose ether HPMC is added to the wet mixed mortar, the better the water retention performance is, and the higher the viscosity is, the better the water retention performance is. Fineness is also an important performance index of hydroxypropyl methyl cellulose.

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 and different sizes, the finer the size, the smaller the size. Water retention effect is better.

In wet mixed mortar, the addition of cellulose ether HPMC is very low, but it can significantly improve the workability of wet mixed mortar, which is the main additive affecting the workability of mortar. The correct selection of hydroxypropyl methyl cellulose has a great influence on the properties of wet mixed mortar.