29/12/2025
SO ,WHY ARE IRREGULAR QUARRY STONES NOT GOOD FOR SUPERSTRUCTURE?
Irregular quarry stones are not recommended for superstructure (walling above ground level) mainly because they affect strength, stability, construction quality, and finishing. Here’s a clear technical breakdown:
1. Poor Load Distribution
Superstructures carry vertical loads from slabs, beams, and roofs.
Irregular stones:
Do not seat evenly on each other
Create point loading instead of uniform load transfer
Lead to stress concentration → cracks and eventual failure
2. Excessive Mortar Use
Because the stones are uneven:
Thick mortar joints are required to level courses
Thick mortar shrinks and cracks
Mortar becomes the weak link instead of the stone itself
👉 In masonry, stones should carry load, not mortar.
3. Weak Bonding & Interlocking
Irregular shapes:
Reduce proper interlocking
Make it difficult to achieve good bond patterns
Lower resistance to shear forces and lateral loads (wind, seismic)
4. Difficulty in Achieving Plumb and Level Walls
Superstructure walls must be:
Plumb (vertical)
Level (horizontal)
Irregular quarry stones:
Cause misalignment
Result in bulging walls
Increase risk of collapse over time
5. Poor Finish and Higher Finishing Costs
Uneven surfaces need thick plaster to achieve smooth walls
Thick plaster adds dead load and cost
Increases chances of plaster cracking and debonding
6. Reduced Structural Integrity at Junctions
At corners, beam bearings, and lintel supports:
Irregular stones make it hard to achieve full bearing
Leads to crushing or cracking at critical points
7. Non-compliance with Building Standards
Most standards (including common Kenyan practice):
Require machine-cut stones or well-dressed masonry for superstructure
Irregular stones are typically approved for foundations only