The Carinus Bridge structural holding measures project strengthened this essential infrastructure, using advanced Sika solutions.
As a vital 175m crossing over the Berg River, the bridge connects Velddrif to the West Coast Peninsula. Constructed in 1950, it features simply supported rib-beam decks with an 18m drop-in span, supported by half-joints.
Structural deterioration
Longitudinal threaded stress bars with corrosion protection strengthen the diaphragm.
Routine inspections revealed severe deterioration in the half-joints of the main span, including cracking, spalling and a concerning 20mm vertical displacement at half-joint 2. Chloride-induced corrosion of the bridge’s reinforcement and inadequate structural redundancy further exacerbated the degradation.
Recognising the need for urgent intervention, the Western Cape Government’s Transport Infrastructure Branch commissioned a collaborative effort with AECOM SA, Smart Civils Construction and Sika South Africa.
Innovative interventions
Soffit strengthening measures included using external CFRP materials and intermediate carbon-fibre fabric.
A thorough assessment identified critical structural shortcomings. A suite of advanced solutions was employed to address these issues:
- Carbon-fibre reinforced plates (CFRP) were applied to the sagging and hogging spans.
- Sika® CarboDur® S626 plates: 448m for external soffit reinforcement.
- Sika® CarboDur® S NSM plates: 320m for near-surface mounted reinforcement.
- CFRP plates were adhered using Sikadur®-30 epoxy adhesive, while SikaWrap®-300 C fabric and SikaWrap® FX-50C cords provided debonding and delamination prevention.
- The expansion joint gaps of the deteriorated half-joints were injected with a proprietary cementitious grout to restore structural integrity.
- Temporary restraints prevented destabilisation during the grout injection process, ensuring the safety and stability of the drop-in span until the grout cured.
- Core-drilled holes allowed for the installation of high-strength Dywidag WR 950/1050MPa prestress thread bars. The diaphragm thickness was increased by casting 400mm thick reinforced concrete diaphragm thickenings on either side of each half-joint, using self-compacting concrete.
The project received two highly commended awards at the 2024 Best Projects Awards ceremony in the specialist suppliers and consulting engineers categories.
The Carinus Bridge structural holding measures project ensured the continued safety and functionality of a vital transportation link.
For more information, contact Sika:
Tel: +27 31 792 6500
Email: headoffice@za.sika.com
Website: https://zaf.sika.com/