Views: 0 Author: Site Editor Publish Time: 2017-05-11 Origin: Site
Plastering mortar is widely used in construction, but improper application can lead to various problems such as hollowing, cracking, and tile detachment. Understanding these issues and their solutions is crucial for ensuring construction quality.
1. Hollowing and Cracking
The primary causes of hollowing and cracking include improper water addition, poor interface treatment, lack of curing, and unauthorized mix adjustments (e.g., adding mortar plasticizers, sand, or cement). Following national construction standards and avoiding arbitrary changes to the mortar mix can prevent these defects.
2. Tile Detachment on Interior Walls
Low-strength mortar (M5-M10) used for interior plastering may fail to support tiles, leading to hollowing and detachment. For tiled walls, it’s advisable to use M15-strength mortar, apply proper surface roughening (e.g., scratching or using bonding agents), and ensure adequate curing before tiling.
3. Balancing Compressive and Tensile Strength
Some regions replace fly ash with stone powder, reducing the binder content. While compressive strength may meet standards, insufficient tensile strength can cause localized hollowing. A safe ratio is for binders to constitute at least two-thirds of the total powder content.
4. Avoiding Extreme Performance Targets
Over-pursuing high strength, rapid hardening, low density, or excessive water retention can disrupt mortar balance. A moderate approach ensures all performance indicators remain within acceptable ranges without causing secondary issues.
5. Surface Finish vs. Breathability
Excessive pursuit of a smooth surface can reduce breathability, increasing hollowing risks. A balance between finish quality and breathability is essential for long-term durability.
6. Consistency Loss Control
The two-hour consistency loss rate should not exceed 30%. Factors like sand gradation, binder quality, and additives influence this, affecting workability and final quality.
7. Proper Mixing Techniques
High stone powder content in manufactured sand requires extended mixing for homogeneity. However, overmixing can weaken the mortar. Optimal mixing time ensures proper mortar performance.
8. Weather Considerations
In extreme heat (>35°C), accelerated cement hydration may cause cracking; mix adjustments are necessary. In freezing temperatures (<-5°C), antifreeze agents and protective measures (e.g., sealing windows) must be applied to prevent mortar damage.
By addressing these factors, plastering mortar can achieve better performance and durability, reducing construction defects.
