Case 1
- Introduction
- Causes of Defects
- Good Practices
- Standards
- Maintenance and Diagnostics
- Remedial
- Similar Cases
- References
Maintenance and Diagnostics
- In general, good quality concrete does not require extensive maintenance. However, due to external factors it might have some defects even before reaching its design life.
- Regular inspections and checking should be hence carried out periodically at regular intervals to detect these defects and to take remedial action to keep the structure in good condition [19]. An efficient inspection system should be adopted to ensure the conduct of regular checks such as visual inspections periodically.
- Suitable instruments and techniques should be used to diagnose defects properly. Diagnosis involves a process in which experts investigate the buildings’ conditions, carry out tests, evaluate, make recommendations for remedial actions where necessary and predict the future performance of a building [20-21].
- For instance, following instruments and techniques can be used to detect water leakages in concrete structures.
Carry out regular cleaning by chemical and mechanical applications (e.g., alkaline or solvent cleaning
agents, hydrofluoric acid, air or water abrasive cleaning) and clear dirt regularly in accordance with SS 509-1, BS 8221-1 or equivalent. Remove moulds, lichens and other growths with a stiff brush and treat the residue with biocide chemicals. Use paint, which does not support mould growth. If affected, remove infected paint and sterilise the surface by applying a fungicide solution/algaecide solution to prevent recurrence in accordance with BS 6150, BS EN ISO 1513, SS 542 or equivalent.
Periodic re-painting (about 5-7 years period) is necessary so as to keep the surface free from such peeling.
Diagnostics of Defect (see also NDT)
Visual Inspection
Conduct a comprehensive visual inspection.
Age is not necessarily a main contributing factor to algae attack. More importantly determinants are the amount of exposure, susceptibility to attacks and surface treatments. A building that is orientated towards the North is most prone to biological attacks. Surfaces facing the morning sun are less prone to attack since surface temperature of the finish is raised above that suitable for algae growth.
Visual inspection of the building is sufficient to identify the affected areas.
The following tests can be used to assist with the diagnosis:
Hygrometer
Hygrometer can be used to measure the RH of the surrounding.
