Views: 0 Author: Site Editor Publish Time: 2017-06-12 Origin: Site
Tile adhesive is a crucial material for construction, but sometimes it fails to provide the expected stickiness even after adding hydroxypropyl methyl cellulose (HPMC). Here’s a breakdown of the possible reasons:
1. Incorrect HPMC Selection or Dosage
- Low Viscosity or Insufficient Quantity: If the HPMC used has too low viscosity (e.g.,<20,000 CPS) or is under-dosed (<0.1%-0.3%), it cannot retain enough water or suspend solid particles, leading to poor adhesion.
- Excessive Viscosity or Overuse: High-viscosity HPMC (>40,000 CPS) may thicken the adhesive too much, reducing workability and preventing proper contact with tiles. Overuse can also cause shrinkage cracks.
2.Formula and Mixing Issues
- Improper Mixing: HPMC is shear-thinning—excessive or high-speed mixing can break its molecular structure, permanently reducing viscosity.
- Unbalanced Ingredients: Lack of redispersible polymer powder (<1%) or incorrect cement-sand ratio weakens cohesion.
3. Environmental Factors
-High Temperature (>35°C) or Dirty Substrate: Accelerates water evaporation before HPMC forms a film; dusty/wet surfaces block adhesion.
- Extended Open Time: If the adhesive dries before tile placement, surface hardening occurs, causing bonding failure.
4. Material Degradation or Contamination
- Expired or Poorly Stored HPMC: Heat/moisture exposure degrades HPMC, reducing viscosity.
- Electrolytes or Microbial Contamination: Excess additives (e.g., accelerators) disrupt HPMC hydration; microbes enzymatically break it down.
