The formation of small patches of plaster swelling out beyond the plastered surface is known as________.
blowing of plaster
Understanding Plaster Defects in Construction
In building construction, plastering is a common process used to give walls and ceilings a smooth finish. However, various defects can occur in plasterwork, impacting both the appearance and durability. The question describes a specific type of plaster defect where small patches of the plaster surface swell outwards. Let's analyze the given options to identify this defect.
Analyzing the Plaster Defect Options
- Falling out of plaster: This refers to the complete detachment or crumbling of plaster from the surface. It's a more severe defect than swelling and involves loss of material.
- Blowing of plaster: This defect is characterized by the formation of small, localized swellings or blisters on the plastered surface. These swellings occur due to various reasons, often related to trapped air, moisture, or soluble salts beneath the plaster layer. This description perfectly matches the phenomenon of small patches of plaster swelling out beyond the plastered surface as mentioned in the question.
- Efflorescence: This defect appears as white, powdery deposits on the surface of plaster or masonry. It is caused by soluble salts present in the building materials or water, which are brought to the surface by moisture and left behind as crystals when the water evaporates. While related to moisture and salts, it is a surface deposit, not a physical swelling of the plaster itself.
- Cracking: This involves the formation of fissures or lines in the plaster surface. Cracks can vary in size and pattern and are caused by factors like shrinkage, structural movement, or improper application. Cracking is a break in the surface continuity, not a swelling.
Based on the analysis, the defect described as the formation of small patches of plaster swelling out beyond the plastered surface is known as blowing of plaster.
| Defect Type | Description | Appearance |
|---|---|---|
| Blowing of Plaster | Localised swelling outwards | Small blisters or bulges on the surface |
| Falling out of Plaster | Complete detachment/loss of plaster | Patches where plaster has fallen off |
| Efflorescence | Formation of salt deposits | White powdery patches on the surface |
| Cracking | Formation of fissures | Lines or networks of breaks in the surface |
Therefore, the correct term for the formation of small patches of plaster swelling out beyond the plastered surface is blowing of plaster.
Revision Table: Common Plaster Issues
| Defect | Key Characteristic |
|---|---|
| Blowing | Surface swelling/blisters |
| Falling Out | Loss of material, detachment |
| Efflorescence | White salt crystals |
| Cracking | Lines or breaks in surface |
Additional Information on Plaster Defects
Blowing of plaster can be caused by several factors, including:
- Incomplete slaking of lime, where unhydrated particles expand later.
- Presence of soluble salts in the aggregates, water, or background material.
- Trapped air or moisture during the application process.
- Application over a dusty or poorly prepared surface.
Understanding these causes helps in preventing blowing of plaster during application or addressing the issue during repair. Proper material selection, surface preparation, and correct mixing and application techniques are crucial for achieving a durable and defect-free plaster finish.
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