It’s a Double Deck Pour at Collie Bridge!
The Collie River bridge concrete deck pour has now been completed. Or should we say concrete deck pours because there are two separate bridges at this unique section of the Bunbury Outer Ring Road (BORR).
Published: 05 June 2024, Updated: 05 June 2024
The Collie River bridge is more accurately described as the Collie River bridges. Or, as the team likes to call it, “the Twin Bridge”.
Unlike other bridges on BORR, there are two spans going over the Collie River—one for each direction of traffic. So, when it came to pouring the concrete decks of the bridges, each span needed to be completed separately.
Understanding Deck Pours
Deck construction falls under the category of FRP works. The methodology of FRP works is used to ensure the structural integrity and durability of the bridge.
This stands for:
- Form
- Reinforcement; and
- Pour
But what do each of those components actually mean?
Steel reinforcement and formwork for the Collie River bridge deck
Formwork
The formwork refers to the use of moulds into which the concrete is poured. The formwork holds the concrete in place until it hardens enough to support itself independently.
Reinforcement work
As its name suggests, the use of reinforcement is to ‘reinforce’ the strength and durability of the concrete surrounding it. Most commonly, and on the Collie River bridges, steel bars are used in the form of a mesh. These bars are often referred to as rebars—short for reinforcing bars—and are preferred for their high tensile strength.
The rebars are placed carefully and accurately within the bridge’s design specifications and are ready for the last stage of the FRP works.
Pour work
Last comes the actual concrete pour. The concrete is poured over and compacted into the formwork.
The purpose of compacting is to ensure that any air pockets are removed before the concrete sets. Once completed, the concrete is left to harden before it is finished and cured to achieve full strength.
Concrete deck on the Collie River bridge
Deck pour at the Collie River bridge
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