Effect of cellulose ether on self-leveling mortar

Self-leveling mortar relies on its own weight to form a flat, smooth, and solid foundation on the substrate, allowing other materials to be laid or bonded, while achieving large-area and high-efficiency construction. Therefore, high fluidity is a very important feature of mortar self-leveling mortar; in addition, it must have a certain water retention and bonding strength, there will be no segregation of water, and it has the characteristics of insulation and low temperature.

Generally, self-leveling mortar requires good fluidity, but the actual flow of cement mortar is usually only 10-12cm; cellulose ether is the main premixed mortar additive. Although the amount of addition is very low, it can significantly improve the performance of the mortar and can improve the mortar. Consistency, working performance, adhesion performance and water retention performance. It plays a very important role in the field of ready-mixed mortar.

1 Liquidity

Cellulose ether has a significant influence on the water retention, consistency and construction performance of self-leveling mortar. Especially as a self-leveling mortar, fluidity is one of the main indicators for evaluating self-leveling performance. Under the premise of ensuring the normal composition of the mortar, the fluidity of the mortar is adjusted by changing the amount of cellulose ether. But too high content will reduce the fluidity of the mortar, therefore, the amount of cellulose ether should be controlled within a reasonable range.

2 Water retention

Water-retaining mortar is an important indicator of the stability of the internal components of fresh cement mortar. In order to make the gel material fully hydrated, a reasonable amount of cellulose ether can be used for a long period of time to maintain the moisture in the mortar. Generally speaking, as the amount of cellulose ether increases, the water retention rate of the slurry also increases. The water-retaining effect of cellulose ether can prevent the matrix from quickly absorbing too much water and hinder the evaporation of water, thereby ensuring that the slurry environment provides sufficient water for cement hydration. In addition, the viscosity of cellulose ether has a great influence on the water retention of mortar. The higher the viscosity, the better the water retention. The general viscosity of 400mpa.S cellulose ether used in self-leveling mortar can improve the leveling of mortar and mortar to increase the density.

3 Set the time

Cellulose ether has a retarding effect on mortar. As the content of cellulose ether increases, the setting time of the mortar will be extended. The flame retardant effect of cellulose ether on cement paste mainly depends on the degree of substitution of alkyl groups and has nothing to do with molecular weight. The smaller the degree of alkyl substitution and the greater the hydroxyl content, the more obvious the blocking effect. Moreover, the cellulose ether content is high, the early composite hydration lag effect of cement is more obvious, therefore, the more obvious delay effect.

4 Flexural strength and compressive strength

In general, strength is one of the important evaluation criteria for cementitious cement material curing mixtures. As the content of cellulose ether increases, the compressive strength and flexural strength of the mortar will decrease.

5 Binding force

Cellulose ether has a great influence on the adhesion properties of mortar. The function of cellulose ether to form a closed polymer film between the liquid system and the cement hydration particles promotes the polymer particles outside the cement film to generate more water, which is conducive to the complete hydration of the cement, thereby increasing the viscosity of the cement slurry hardening Knot strength. At the same time, the appropriate amount of cellulose ether enhances the plasticity and flexibility of the mortar, reduces the rigidity of the transition zone between the mortar and the matrix, and reduces the slippage between the interfaces. To a certain extent, the bonding force between mortar and matrix is ​​enhanced. In addition, due to the presence of cellulose ether in the cement slurry, a special interface transition zone and interface layer are formed between the mortar particles and the hydration product. The interface layer makes the interface transition zone more flexible and less rigid, so that the mortar has a stronger bonding strength.