Structural Modification of Concrete Bridges using Hydrodemolition
Overview
iasgroup were engaged to undertake structural modification of bridges between Wyndham and Kunnunarra in Western Australia to allow for widening from single to double lanes. This required removal of the concrete side walls and a portion of the concrete deck prior to construction of the new lanes.
The client was seeking an alternative solution to traditional concrete breakout techniques, which would have cut existing steel reinforcement in the deck and required drilling of new holes for installation of new starter bars.
The client required the project to be completed with minimum disruption to traffic.
Scope
The key parameters of this project were:
| Structure | Concrete bridges |
| Application Type | Structural modification |
| Operating Environment | Remote |
| Quantity | 9 bridges |
| Excavation Cross Section Area |
Wall 30m (l) x 0.3m (w) x 0.5m (h) Deck 30m (l) x 0.6m (w) x 0.6m (d) |
| Excavation Volume | 275m3 |
| Excavation Mass | 600t |
| Method | Hydrodemolition |
Solution
- Remove side wall using ultra-high pressure water jet, with pressure at 40,000 psi
- Hydrodemolish portion of deck in order to expose existing steel reinforcement
Benefits
- Hydrodemolition enabled removal of concrete without causing damage to existing steel reinforcement or micro-cracking to remaining concrete
- Avoided need for time consuming and labour intensive drilling of holes every 200mm along bridge length for installation of new starter bars
- No scaffolding required
- Hydrodemolition cleaned and surface prepared steel reinforcement for bonding with new concrete
- Hydrodemoliton used to scabble the remaining concrete and road surface in preparation for new concrete and bitumen
- Improved safety (Remotely Operated Tool Capability)
- Increase in speed of concrete removal over traditional concrete breakout methods
- Project completed on time and safely with only partial road closure
