Concrete & Structural Defects
Concrete Cracking
Concrete cracking encompasses structural and non-structural cracking caused by thermal movement, shrinkage, applied loading, differential settlement, reinforcement corrosion or design and construction deficiencies in Class 2 building elements.
Common Signs
- Visible surface or through cracks
- Map or pattern cracking
- Crack widening or movement over time
- Moisture penetration at crack locations
- Rust staining along cracks
- Efflorescence or salt deposits
Common Causes
- Thermal movement and shrinkage
- Structural loading and deflection
- Reinforcement corrosion
- Settlement or ground movement
- Poor mix design or curing
- Design or construction deficiency
Risk of Neglect
- Water and moisture ingress through cracks.
- Accelerated corrosion of reinforcement.
- Progressive structural deterioration.
- Crack widening and propagation over time.
- Failed waterproofing membranes at cracks.
- Increased remedial cost if left untreated.
- Potential structural capacity concerns.
Inspection Requirements
- Map and record all crack locations, orientations, widths and approximate depths.
- Measure crack widths using a crack gauge and note whether cracks taper or are consistent.
- Determine whether cracks are active (moving) or dormant using tell-tales or crack monitors.
- Inspect for associated moisture penetration, rust staining or efflorescence.
- Assess the likely cause — structural, thermal, shrinkage, corrosion-induced or movement-related.
- Obtain structural engineer assessment for cracks indicating structural distress.
- Consider crack injection feasibility versus rout and seal based on crack width and access.
Start Inspection Checklist
Create a project inspection record, add defect locations, upload photos, and save notes for scope writing.
Typical Repair Methodology
The repair approach depends on whether cracks are active or dormant and whether structural implications exist. The final scope must be confirmed by the project engineer before commencing works.
- 01.Confirm crack classification — active or dormant — before selecting repair method.
- 02.For dormant cracks: clean crack faces with compressed air to remove dust and debris.
- 03.Drill injection ports at regular intervals along the crack, typically 150–200mm centres.
- 04.Seal crack surface between ports with epoxy paste or surface seal and allow to cure.
- 05.For active cracks: use flexible polyurethane resin or sealant compatible with movement.
- 06.For structural cracks: obtain written engineer direction before proceeding with any repair.
- 07.Inject epoxy or polyurethane resin under controlled low pressure, starting from the lowest point.
- 08.Progress injection upward, closing each port after resin appears at the next location.
- 09.Allow resin to fully cure before removing ports and finishing the surface.
- 10.For fine surface cracks: rout to a defined profile, clean and apply flexible sealant.
- 11.Apply protective coating or sealer over repaired areas where required by the specification.
- 12.Monitor active cracks after repair and report any recurrence or further movement.
- 13.Record all crack locations, widths, repair products, batch numbers and QA photos.
Related Repair Systems
- PU injection resins
- Epoxy injection resins
- Crack injection ports
- Epoxy anchoring adhesives
- Polyurethane sealants
- Backer rods
- Abrasives, blades and tools
Open Repair Systems →