Quality Control and Troubleshooting in Formwork

Module 6: Quality Control and Troubleshooting in Formwork

1. Inspection Protocols

Ensuring formwork integrity before concrete pouring is critical to prevent failures. A structured inspection process includes:

• Leak Checks

• Method: Use a flashlight to inspect joints, seams, and tie holes for gaps.

• Solution: Apply silicone sealant or foam strips to prevent grout leakage.

• Consequence of Failure: Honeycombing or surface defects in concrete.

• Alignment Verification

• Tools: Laser levels, theodolites, or digital inclinometers.

• Tolerances:

• Vertical (±3mm per 3m height).

• Horizontal (±2mm per 1m span).

• Consequence of Failure: Misaligned structures requiring costly corrections.

• Stability Assessment

• Checks:

• Base support on compacted soil or shoring.

• Bracing tightness (no loose wedges or unsecured props).

• Load Test: Apply 1.2x design load for 24 hours to detect deflection.

2. Common Failures & Fixes

Even with proper design, formwork can fail due to material flaws, overloading, or execution errors.

• Bulging (Localized Deformation)

• Causes: Insufficient bracing, excessive concrete pressure, or weak sheathing.

• Remedial Actions:

1. Stop pouring and install additional walers/braces.

2. Use thicker plywood (e.g., upgrade from 18mm to 21mm).

• Blowouts (Formwork Bursting)

• Causes:

1. Inadequate tie-rod spacing or snapped ties.

2. Rapid pouring rate exceeding formwork capacity.

• Emergency Response:

1. Evacuate workers immediately.

2. Shore up failed sections with hydraulic jacks.

3. Remove damaged concrete and re-form.

• Remedial Actions for Minor Defects

• Surface Imperfections: Grinding or patching after demolding.

• Structural Non-Compliance: Supplemental post-pour supports (e.g., steel plates for under-strength sections).

Preventive Measures

• Pre-Pour Checklist:

• Verify all ties, braces, and supports.

• Confirm concrete pour rate matches formwork design.

• Real-Time Monitoring:

• Pressure sensors in high-risk wall forms.

• Drones for aerial inspections of large formwork areas.

Case Study: Avoidable Collapse

• Incident: A bridge pier formwork failed due to missing diagonal braces.

• Lesson: Mandate peer reviews of critical formwork setups.

Key Takeaways:

1. Inspect thrice: Before, during, and after pouring.

2. Bulging precedes blowouts—act at first signs of deformation.

3. Document inspections to assign liability and improve future designs.