Case 2
- Introduction
- Causes of Defects
- Good Practices
- Standards
- Maintenance and Diagnostics
- Remedial
- Similar Cases
- References
Maintenance and Diagnostics
- Painted surface can be dust with a water-dampened cloth. If the surface is very soiled, wash with a solution of mild, non-abrasive detergent and warm water. Wring a cloth nearly dry and work on a small section at a time, then rinse with clear water. Dry the surface quickly before continuing.
- Periodic re-painting (about 5-7 years period) is required to keep the surface free from such flaking.
- In addition, regular inspections should be carried out periodically at regular intervals to detect the defects.
- High-tech instruments can also be used extensively to diagnose the defects and to take remedial action to keep the structure in good condition.
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.
Thermography
Thermography can be used to identify the position of water leakages. The method is based on the characteristics of heat flow phenomenon, in a conductive medium of specific geometry, which is intended to model predetermined boundary conditions.