Bridge Strengthening Project: Complex Civil

Across the ACT we are faced with bridges that are aging, damaged or due to changes in bridge design standards, no longer have the weight capacities to support our growing population into the future. Upgrading these deteriorating assets is a highly specialised and technically unique undertaking; it requires a great deal of precise engineering and skillful application by an experienced on-site team. With the Federal Government’s commitment of $360 million over five years to fund the renewal of bridges Australian wide, we are now seeing these critical upgrades moving forward across Canberra.

The custom-designed hydraulic lifting trolley system.

Bridges 5179 and 5128 along the Monaro highway are an example; changes in the bridge design standards have meant that the bridge required a large increase in its load capacity. Complex Civil took on this strengthening project and were faced with a very unique situation; as the bridge was unable to be closed for any large period of time they needed to develop a method of upgrading this bridge during continual use and without dramatically obstructing the flow of traffic.

The project involved the fabrication and installation of custom-made welded steel beams being bolted between the existing girders onto fabricated bearing pads and seating brackets. Using a custom-designed hydraulic lifting trolley system, the beams were moved into place onto the bearing pads. The steel beams would then need to be epoxy grouted onto the underside of the culvert to compensate for the age-related bowing in the bridge that prevented the steel beams from sitting flush against the surface.

Vertically pumping grout into the void on the underside of the culvert.

This is where CE became involved; due to the vertical continuous pumping that was required to fill the void between the bridge and the steel beams, it was difficult to find a product off the shelf that would perform as required to fill the entire void in a single pour without epoxy curing in the pump. However if these beams were left in place without the grout the bridge would not receive the full support of the steel and dramatically reduce the increase in capacity.

CE worked closely with the chemists from Epimax and the engineers from Complex Civil to devise a solution and after a number of trials offsite, we were able to determine the correct formula of epoxy and aggregate to create a continuous flow and allow the mix to be pumped vertically into the voids whilst maintaining the required final strength requirements.

As a result of the incredible work Complex Civil completed on this project, they won the 2018 Master Builders Association Building Excellence Award for Bridgeworks and ACT Civil Contractors Federation award for Projects under 5 million dollars. We at CE Construction Solutions are proud to have been able to have been so closely involved with this achievement of ingenuity.