Case 1
- Introduction
- Causes of Defects
- Good Practices
- Standards
- Maintenance and Diagnostics
- Remedial
- Similar Cases
- References
Maintenance and Diagnostics
Periodic inspection should be carried out for ponding and make visual observations of free-flowing water
towards the outlets. Ensure that water has drained off to avoid leftover ponding on the reinforced concrete. Drains should be inspected for efficiency prior to water washing in accordance with BS 8221-1, SS 509-1 or equivalent.
Regular cleaning of the granite surface is needed to remove dirt. Natural cleaner is suitable with high foaming jet (without pressure). It is recommended to avoid acidic, high alkaline and chlorinated products.
Recommended cleaning frequencies as:
- Commercial and institutes – 3 times a day
- Offices and industrial – twice a day
Dry cleaning methods are recommended over frequent wet cleaning methods in those areas which has little ventilation.
Diagnostics of Defect (see also NDT)
Microwave tomography is a technique to measure the moisture of various materials based on the relatively high dielectric constant of “water” in comparison to the dielectric properties of the material. An electrical field (microwave) is applied to the material, and the microwave induces oscillations of bipolar molecules (i.e., water). Water molecules will reflect and absorb an electrical field during oscillations. A higher electrical field reflected indicates higher water content.
The technique is non-destructive and applicable to wood, brickwork and concrete. The uniqueness of this technique is its ability to measure moisture content at various depths up to 110 mm, allowing the plotting of a 3-D contour of moisture content and facilitating the tracing of the water source.
Thermography can be used to identify the position of cracks. A range of crack widths, representing mechanical damage, has been induced under controlled laboratory conditions. 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.
