Case 4
- Introduction
- Causes of Defects
- Good Practices
- Standards
- Maintenance and Diagnostics
- Remedial
- Similar Cases
- References
Cause of Defects
Defective concrete – honeycomb
A dense and good quality concrete can resist water penetration naturally. However having honeycomb voids will weaken the concrete structure substantially.
Honeycombs may have been formed due to poor workmanship during casting as well as insufficient vibration provided after being placed, allowing excessive segregation in the plastic concrete. As the heavier components settle, water will rise. Voids will be formed after the water dries up.
Poor workmanship during concrete casting
Poor workmanship during concrete casting may lead to concrete cracking. For example, if the curing of concrete is not done properly and there would be excessive rapid evaporation of water from the surface of the concrete that will lead to plastic shrinkage cracks on the surface.
In addition early thermal contractions may also induce in formation of micro-cracks. It may be formed when the concrete dissipates heat of hydration and adjacent structures posed external restrain on the concrete causing the formation of cracks upon contraction.
Poor maintenance
Air gaps in concrete slab that are less compact, could allow water seepage via capillary raction. Water may run through the concrete to accummulate in between the concrete structure and the layer of paint on ceiling soffit. When the defect is left unattended, the presence of water encourages the growth of fungi.