Maintenance, Repair and Renovation Techniques
What this domain tests
This domain tests whether you can distinguish maintenance types, identify the cause of a defect before choosing a remedy, and name the correct repair technique for cracks, dampness, spalled concrete and corroded reinforcement.
Core rules and concepts
- Maintenance types: preventive, routine, breakdown, and special (for heritage or post-disaster work).
- Cracks: hairline and shrinkage cracks are non-structural and are filled with polymer putty; wider or moving cracks need diagnosis, stitching with dowels, or epoxy injection.
- Dampness: find the source first (leaking pipe, terrace, DPC, rising damp), then use surface waterproof coating, integral waterproofing in new mortar, or injection grouting.
- Concrete repair: remove loose and carbonated concrete, clean reinforcement, apply rust converter and bonding agent, then re-plaster or gunite/shotcrete; jacketing or FRP wrapping restores structural capacity.
- Non-destructive testing: rebound hammer for surface hardness, ultrasonic pulse velocity for internal quality, cover meter for reinforcement depth.
- Renovation changes the finish or layout; repair restores serviceability; alteration changes the structure and needs design approval.
Worked example
Epoxy injection for a 3 m long, 2 mm wide hairline-to-fine crack. Injection ports are placed at about 300 mm spacing, so ports = (3000 ÷ 300) + 1 = 11. Grout volume is roughly length × width × depth = 3 × 0.002 × 0.05 = 0.0003 m³, that is 0.3 litre, but order at least a small kit because mixing and wastage dominate.
Traps that cost marks
Repairing a crack without identifying whether it is active; plastering over rust-stained concrete; treating rising damp with paint alone; using rebound hammer readings as proof of strength without calibration.