The effect of cellulose ether on performance of self-leveling mortar

The effect of cellulose ether on performance of self-leveling mortar

Self-leveling mortar can form a flat, smooth and strong foundation on the substrate by its own weight, so that other materials can be laid or bonded, and large-area and high-efficiency construction can be carried out. Therefore, high fluidity is very self-leveling mortar.

A significant feature; especially as a backfill or reinforced grout for bulky, reinforced or slits less than 10 mnl. In addition to good fluidity, self-leveling mortar must have certain water retention and bonding strength, no bleeding segregation, and low thermal insulation and low temperature rise. Generally, self-leveling mortar requires better fluidity, but the actual fluidity of the cement slurry is usually only 10 to 12 cm; the self-leveling mortar can be self-compacting, and the initial setting time is long and the final setting time is short. Cellulose ether (CE) is a major additive for ready-mixed mortar. Although it is added in a low amount, it can significantly improve the performance of the mortar. It can improve the consistency, workability, bonding performance and water retention performance of the mortar. It plays a very important role in the field of ready-mixed mortar.

HPMC can effectively improve the water retention of self-leveling mortar and reduce the consistency of mortar; the introduction of HPMC can improve the bonding strength of mortar, but it reduces the compressive strength, flexural strength and fluidity.

Cellulose ether can improve the water retention of self-leveling mortar. With the increase of the amount of cellulose ether, the water retention of the mortar is gradually enhanced, and the fluidity and setting time of the mortar are reduced to some extent. The excessive water retention will make

The porosity in the hardened slurry increases, which may cause a significant loss in the compressive and flexural strength of the hardened mortar. In the production experiment, we found that when the dosage is between 0.02% and 0.04%, the strength is obviously reduced, and the more the cellulose ether is used, the more obvious the retardation effect. Therefore, when using cellulose ether, it is necessary to comprehensively consider the mechanical properties of self-leveling mortar, and reasonably select the amount and synergistic effect with other chemical materials including cement, water reducing agent and redispersible latex powder.

The use of cellulose ether will reduce the compressive strength and flexural strength of the cement paste, which will increase the bonding strength of the mortar. Analysis of the reasons for the change in strength, mainly caused by changes in microscopic products and structures, on the one hand, cellulose ether rubber powder

The particles are first adsorbed on the surface of the cement particles to form a latex film, which delays the hydration of the cement, which causes the loss of early strength of the slurry; on the other hand, it is also beneficial to the cement due to the film forming effect and the water retention effect. Complete hydration is conducive to the improvement of bonding strength. These two changes in intensity mainly exist in the boundary of the condensation period. The advance and post-extension of this boundary may be the critical point for the magnitude of the two intensity ranges, which is more in-depth systematic research.

A critical point will be beneficial to better regulate and analyze the hydration history of the cementitious material in the slurry, which is beneficial to adjust the amount of cellulose ether and curing time according to the mechanical properties of the mortar to improve the performance of the mortar.

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