redispersible latex powder RDP for tile adhesivesDecember 7th 2023
Influence of Cellulose Ether on Mortar Cohesiveness
In addition to the adhesion of mortar and substrates obtained by cement, gypsum, calcium hydroxide and dispersible polymer powders, cellulose ethers also provide adhesion.
Cellulose ethers improve the bond strength of fresh and hardened mortars. The water retention of cellulose ether in the mortar can meet the necessary water amount 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 bond strength of mortar.
Macroscopically, cement-based tile adhesives appear hard and strong. From microscope observation, it can be seen that the addition of MC introduces small pores, and the bonding material is linked by continuous pores. In cement-based tile adhesives on vitrified tiles, it can be clearly seen that the adhesive consists of an open porous structure.
Cellulose has a certain function of water absorption and thickening, and has a stable structure. Cellulose has a flat strip-like structure and has many capillary channels, so it has a good water-conducting function in mortar.
Cellulose fibers have pseudoplastic rheological properties when dispersed in water due to their ability to lock 5-8 times their own weight in liquid.
This characteristic of cellulose gives the mortar good workability. When plastering the mortar with a spatula, it is equivalent to giving a shear force to the mortar system. At this time, the liquid locked by the cellulose fibers in the system is released, which reduces the consistency of the mortar system and improves the workability of the mortar.