ASSET MAINTENANCE
Mainmark’s Teretek® resin injection solution has been used to improve the structural integrity of a number of traffic bridges, including this two-lane concrete bridge Queensland which had become unlevel due to underlying ground settlement. Teretek was used to remediate the bridge so that it could continue to safely bear the weight of constant traffic, including heavy vehicles.
Why now is an ideal time to invest in essential infrastructure maintenance Extending the lifecycle of bridges, culverts, tunnels and arches There are currently billions of dollars being invested into infrastructure projects to help drive the economy out of a post-pandemic slump. However, while a flurry of new civil construction works will fuel growth, boosting jobs and productivity, it is equally important to service and maintain existing assets that provide essential services for Australian communities. An increasing number of structures are reaching the end of their expected 50-year lifecycle and ageing infrastructure has been identified as an urgent issue in Australia. Bridges and tunnels continue to absorb growing volumes of traffic, and culverts are showing signs of deterioration due to the environmental effects of extreme weather. To help extend the life of essential infrastructure, a range of engineered remediation solutions are able to help asset managers rejuvenate urban and rural infrastructure and complete scheduled maintenance works faster and more cost effectively than ever before. Regardless of how large or structurally solid an asset may be, every asset has a design life. Over the longer-term, these assets can degrade due to the environmental impact of geological changes in the ground, which in turn affect load bearing capacity. What happens beneath the ground can affect 24
Construction Engineering Australia • February 2021
foundations and cause serious structural issues. If left untreated, structural issues can be costly to fix, or may require demolition and rebuilding. However, a timely and proactive approach to remediation using engineered solutions can add years, if not decades, to an asset. Ground remediation can also help to preserve heritage assets for future generations as was the case in Tasmania after devastating floods caused millions of dollars in damage to public infrastructure including the Kimberley Rail Bridge which spans the Mersey River. The heritage listed bridge had partially collapsed after raging floodwaters caused the riverbed to erode (otherwise known as scour). Urgent works were required to rebuild sections of the bridge and remediate two original concrete piers. Before commencing the remediation work, a team of divers undertook an underwater 3D sonar survey to identify the extent of the damage. The survey revealed scour had eroded the edges of the piers exposing the underside of the pier’s footings where large voids had formed. Engineers considered several remediation options to help restore the bridge’s structural integrity, including the extreme measure of decommissioning the bridge and rebuilding it.
After a thorough review, Teretek®, an engineered resin injection solution from Mainmark, was selected to remediate and resupport the bridge piers. Teretek has excellent ground bearing and void filling capabilities and is also environmentally inert, an important consideration given Tasmania’s pristine waters. Teretek utilises a precise, discreet, and efficient delivery process with injections applied beneath existing structures in a procedure likened to keyhole surgery. The solution immediately expands on application, filling voids and increasing ground bearing capacity. The Kimberley Rail Bridge project was further complicated due to the extremely limited site access to the fast-flowing river. There was no road to the riverbank and the ground surrounding the embankment was soft soil. However, Mainmark was able to overcome the access issues by parking a single Mainmark rig containing all the equipment and injection hoses near the railway deck and injecting the solution into the treatment areas during predetermined safe times. Despite the project complexities, Mainmark successfully completed the work in a single day, providing a far quicker, extremely efficient and much less disruptive process compared to alternative methods. Mainmark’s Teretek resin injection solution has also been used to improve the structural