Adelaide based Badge Construction was contracted by Woolworths to deliver the new $80 million Brickworks Marketplace Development.
Work began in 2013, after more than two years of planning, with Badge Construction engaging more than 80 local subcontractors during the course of the 19,500 square metre project. This build included a Woolworths supermarket, Big W, Dan Murphy’s, as well as more than 41 speciality shops and 700 car parks.
Adelaide Resource Recovery, along with Holcim Australia was awarded the contract to supply the backfill required to prepare the site for the build.
As the site had previously been used to manufacture bricks, a large area of the site was a clay pit and needed to be back filled quickly, as the build for the new development could not get underway until this was done.
This was a large job, which required over 300,000 tonnes of backfill. Consequently, both companies delivered material every day for a 3 month period, during winter.
ARR provided approximately 165,000 tonnes of rubble for this project alone. In the early stages of this job, in excess of 5000 tonnes were delivered to the site per day by ARR, which, to put this in perspective, required the allocation of 30 trucks per day, to this one project.
While both ARR and Holcim Australia provided aggregate material for the backfill, as all of ARR’s rubble is recycled, that is, crushed from concrete and Holcim Australia’s is from a quarry, which is virgin rock based, the actual products that were delivered from each company were quite different in the way they behaved.
To balance the difference in these materials, the site was divided into quadrants. This ensured that when delivered to the site, the materials were stacked on a rotational basis, so that the anticipated difference in long term properties between the two materials was reduced or minimised.
The reasoning behind this delivery rotation was simple. When concrete is crushed in the recycling process, it re-releases a certain amount of cement, which will then reactivate and provide a firm base. Quarry material however does not have the same adhesive properties to bind it together.
Accordingly, when using recycled material as backfill it will provide a harder base than a base built using quarry materials.
Normally either recycled or quarry aggregate is used as backfill on a project, not both. We believe this to be the first time in Australia that a project of this size has been undertaken where recycled materials and quarry materials were used side by side.
As this project was undertaken in winter, it was confirmed that the solidity of the two rubbles was different when it rained. The quarry material retained moisture and therefore was susceptible to greater heave, whereas the recycled rubble, if compacted prior to being affected by rain, remained solid after compaction.