Case 4
- Introduction
- Causes of Defects
- Good Practices
- Standards
- Maintenance and Diagnostics
- Remedial
- Similar Cases
- References
Maintenance and Diagnostics
Regular inspections should be carried out methodically at regular intervals to detect the defects. Checklists could be used so that defects can be recorded and monitored at their early stages and that they should not be left unattended. Cleaning of car parks should be carried out at appropriate intervals of time so as to ensure the removal of dirt before they stain on the surface permanently as:
- Daily spot cleaning to clear up oil spots on the drive way to prevent from becoming stubborn and difficult to clean off.
- The floor of the car park is scrubbed clean once a week
- The surface drains have to be flushed to clear silt and dirt twice a year to prevent blockages.
Diagnostics of Defect (see also NDT)
Thermography
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.
Ultrasonic Pulse Velocity (UPV)
UPV can identify non-homogeneous conditions such as voids, cracks and honeycombs using the optional hand-held terminal. This method can also be used to estimate the depth of cracks [18-19].
Microwave
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.
