MassBloc® handy in a tight corner

The Rocla MassBloc® earth retention system recently helped a South Australian Council out of a tight corner during a road-widening project in the Adelaide Hills.

After excavating the steep roadside embankment, the City of Tea Tree Gully’s geotechnical engineer found that some areas of the embankment required stabilization.

However, the cut face ran so close to property boundaries that only a narrow strip of around 1.8 metres remained between the kerb and the embankment.

Using traditional gabion baskets would have meant encroaching on private property, so a shallow retaining wall became the preferred option. The MassBloc® system suggested itself because its precast blocks of permeable concrete have a depth of only 900mm.

Four separate sections of wall were constructed along the roadside with a total length of 120 metres and heights ranging up to 3 metres. Council’s own labour force built the walls, including base preparation, construction and backfilling. A compacted base was prepared, with a levelling strip of concrete, and the position of the blocks marked with paint.

When the blocks were delivered to site, they were placed directly using the truck-mounted crane on the delivery vehicle. The design of the wall, by Cardno MBK, included a requirement for backfilling with no-fines permeable concrete and reinforcement. To simplify this process, Rocla supplied blocks with precast holes for the galvanized reinforcement bars.

Tea Tree Gully Council engineer, Mark Konecny, said the council was very happy with the “quick, timely and environmentally sustainable solution.”