The influence of cellulose ether on the adhesion of mortar
July 31, 2020
In addition to cement, gypsum, calcium hydroxide and dispersible latex powder, the adhesion between mortar and substrate is obtained, and cellulose ether also provides adhesion. Cellulose ether can improve the bonding strength of fresh mortar and hardened mortar. The water retention of cellulose ether in the mortar can meet the amount of water necessary for the hydration reaction of cement and gypsum, thereby improving the tensile bonding strength of the hardened mortar.
Different types and viscosities of cellulose ethers have very different contributions to the tensile bonding strength of mortar.
Macroscopically, cement-based tile adhesives look hard and strong. Observed from the microscope, it can be seen that the addition of HPMC introduces small pores, and the bonding material is linked by continuous pores. In the cement-based tile adhesive on vitrified tiles, it can be clearly seen that the adhesive consists of an open porous structure. Cellulose has a certain water absorption and thickening function, and has a stable structure. Cellulose has a flat strip structure with many capillary channels, so it has a good water-conducting function in the mortar.
Because the cellulose fiber has the function of locking 5-8 times its own weight in liquid, the cellulose fiber has pseudoplastic rheological properties when dispersed in water.
This characteristic of cellulose gives the mortar good workability. When wiping the mortar with a spatula, it is equivalent to giving a shearing force to the mortar system. At this time, the liquid locked in the cellulose fiber in the system is released, reducing the consistency of the mortar system and improving the workability of the mortar.