Our Brief
In the early 2000s, Brisbane City Council redeveloped the Roma Street goods and train yard.
The project was a monstrous undertaking. 16 hectares of land was reshaped to accommodate the planting of over 100,000 shrubs, 1,200 fully matured trees, 1,800 unique species of plants and over 250 ferns. Ten kilometres of concrete walkway was also laid down to make it easy for the public to get around, explore and enjoy the environment.
The project was a success. What previously appeared ugly and desolate was transformed into the iconic Roma Street Parkland. However, over two decades, concrete stairs and walkways around the park had begun to sink unevenly, creating trip hazards. They posed a danger to the health and safety of the public.
Buildfix was tasked with releveling these heavy, prefabricated concrete stairs and thick, industrial concrete slabs by Brisbane City Council. While we were at work, Roma Street Parkland’s cafe had to stay open and foot traffic could not be stopped.
Our Challenge
While Buildfix usually works on residential structures, this was a challenge we found so interesting we couldn't turn it away.
Determining the cause of sinking proved to be more difficult than usual. No single event related to the sinking of concrete in Roma Street Parkland had ever been documented by Brisbane City Council.
At first, our structural engineer determined that sinking had been caused by public use and exposure to Brisbane’s intense tropical downpours. But after a careful investigation our structural engineer was able to identify the true source of the problem — a flawed drainage system near the grounds.
On the day of repairs, our technicians dug under stairs and slabs around Roma Street Parkland to find water had pooled underneath them. With nowhere to go, the water had eroded the soil and created large voids in the ground.
Our Solution
As the uneven sinking of slabs and stairs had created trip hazards for the public, we had to underpin and lift them back to evenness. We also had to stop these heavy, industrial blocks of concrete from sinking again.
To do this, we used our proprietary geopolymer resin solution, GeoPoly™. By drilling access holes in strategically chosen spots, we were able to inject GeoPoly™ directly into the eroded soil.
Not only did we solidify the ground, we also filled the voids underneath the concrete. In turn, we were able to achieve an incredible 30mm lift.
The Outcome
Buildfix successfully fulfilled the requirements of Brisbane City Council’s brief, saving them tens of thousands of dollars.
The cafe stayed open and the public continued to enjoy the park while we were at work. In the end, heavy concrete stairs and walkway slabs were lifted back into their previous positions. Only a few small access holes, unrecognisable to the public and in no way a blemish to the park, remain.
To this day, the concrete slabs and stairs around Roma Street Parkland have stayed level. No injuries have occurred and there have been no further signs of subsidence at all.
