Case 1
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- Introduction
- Causes of Defects
- Good Practices
- Standards
- Maintenance and Diagnostics
- Remedial
- Similar Cases
- References
Cause of Defects
- Corrosion of steel reinforcement in concrete slab near penetration may occur as a result of water penetration into the concrete. Water seepage through the pipe penetration could be due to failure or lack of waterproofing membrane around the discontinuity. In general, durability of the membrane is 10-15 years.
- Chlorides or other dissolved salts present in the water will accelerate the rate of corrosion and soluble sulphates may cause sulphur attack on the concrete slab.
- Poor quality of concrete may also accelerate carbonation process of the concrete. Poor material such as permeable concrete, and poor workmanship or cold joint caused by hacking of the concrete for pipe penetration may weaken the durability of the concrete.
- The built-up stresses due to an increase in volume caused by the rusting of rebar, lead to cracks within concrete and spalling with the formation of more rust over time as shown in Figure 1.
- The volume increase can be as high as 7 times the original volume (Figure 2).
