Brickworks Marketplace Ground Improvement, Adelaide-Paper

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The Brickworks Marketplace in Torrensville, Adelaide, converted a former brickworks and clay pit into a 17,000 m² shopping centre. The site contained extensive uncontrolled fill and a pit up to 6 m deep. Conventional excavation and replacement would have required importing more than 500,000 m³ of fill at prohibitive cost, so the project team retained and improved most existing fill and backfilled the pit using deep-lift compaction.<br /><br />Existing fill was treated with a 14-tonne High Energy Impact Compactor. Typically 20–50 passes were applied, with GPS settlement measurements and impact-response readings used to assess performance. The process induced about 100–200 mm of settlement in most areas. Problem zones—including deep kiln waste and a pit containing loose bricks—were excavated or specially treated; unsuitable brick fill was recycled into other fill.<br /><br />Trialling showed that fine crusher dust compacted poorly when wet and was rejected. The selected materials were 20 mm quarry rubble and recycled crushed concrete and bricks. Placed in lifts generally 0.7–1.0 m thick, these materials typically achieved near 100% of Standard maximum dry density after 20 impact-compactor passes.<br /><br />Plate-load testing of the deep-lift fill measured bearing capacities of 300–400 kPa and elastic moduli of 45–80 MPa, exceeding the project’s minimum requirements of 250 kPa and 40 MPa. Settlement monitoring, begun in February 2015, found that building and carpark settlements generally did not exceed 15 mm, within the specified limits.<br /><br />The project demonstrated that impact improvement of retained fill, combined with carefully selected recycled and quarry byproduct materials, could provide compliant ground conditions while reducing costs, imported materials, waste, and associated transport impacts.

Keywords

Brickworks Marketplace

Torrensville

Adelaide

shopping centre

deep-lift compaction

High Energy Impact Compactor

retained fill

recycled concrete

plate-load testing

ground improvement