1. Introduction
Cement-based tile adhesive is the most commonly used dry mortar in construction. It consists of cement as the main binder, combined with aggregates, water-retaining agents, latex powders, and other additives. This adhesive is mixed with water before use and offers superior bonding strength compared to ordinary cement mortar. It has excellent anti-slip properties and resistance to water, heat, and freeze-thaw cycles. Tile adhesive is widely used for installing wall and floor tiles, both indoors and outdoors, in areas like kitchens, bathrooms, and floors. When evaluating tile adhesive performance, key factors include workability, anti-slip ability, mechanical strength, and open time.
2. Impact of Cellulose Ether on Tile Adhesive
2.1 Influence on Rheology and Workability
Cellulose ethers, such as HPMC (Hydroxypropyl Methylcellulose), significantly affect the rheological properties of tile adhesive. They influence factors like workability, slip resistance, and the consistency of the adhesive.
2.2 Influence on Open Time
In tile adhesive, both rubber powder and cellulose ether are present in the mortar. While the rubber powder binds with cement hydration products, cellulose ether influences the viscosity and setting time. When water evaporates from the mortar, cellulose ether forms a surface film within 5 minutes, which slows down further evaporation. If the film is too thin, it won’t effectively retain water, reducing adhesive strength. On the other hand, a thick film can make it difficult to apply tiles.
The type of cellulose ether (HPMC, HEMC, MC) and its degree of substitution directly affect the film formation, and in turn, the open time of the tile adhesive.
3. Impact on Adhesion Strength
3.1 Retardation of Cement Hydration
Cellulose ether slows the hydration of cement, mainly by adsorbing onto hydration products like C-S-H and calcium hydroxide. This effect increases the viscosity of the mortar and reduces ion activity in the solution, further delaying hydration. However, studies have shown that cellulose ether viscosity has little impact on hydration kinetics.
3.2 Influence of Substitution Degree
The degree of substitution in cellulose ether significantly affects the mechanical strength of tile adhesive. In particular, modified HPMC enhances water retention, ensuring proper hydration and bonding. Research suggests that the type and combination of substituent groups in cellulose ether are more important than viscosity in controlling cement hydration.
4. Conclusion
To achieve high-performance tile adhesive, both the rheological properties and the mechanical behavior of cellulose ethers must be considered. The degree of substitution and the formulation of the cellulose ether are crucial for ensuring proper workability, open time, and strength of the adhesive.