Case 5 – old

Maintenance and Diagnostics

Maintenance

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 remove these defects [10]. 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 [11].

The important factors to be noted for cracks are:

• width, direction and location
• whether live, dead or growing
• isolated or random
• widespread or confined to particular areas
• associated with other defects or rain entry
• surface erosion effects

Diagnostics of Defect

Mechanical strain gauge

To determine if the crack is live or not [1]

Thermography

Thermography can be used to identify the position of cracks.[12]

Microscopy

Optical microscope can can be used to measure the width of cracks

Fiberscope

Fiberscope can be used to inspect deep and narrow cracks in the concrete.

Ultrasonic Pulse Velocity

UPV can be used to estimate the depth of cracks.[13]

Petrography

Petrography permits analysis of cement content, cement/water ratio, carbonation, cracking, porosity and permeability of concrete [14]. A core should be cut from the area to be investigated. The thin section is then examined under a combination of plain and cross polarized light using a petrographic microscope.