Research investigations at CSIRO show that pressure-moulded, steam-autoclaved, lightweight silica lime products are producible with a strength/density ratio at an age of one day, that is ten times that of ordinary concrete at an age of twenty-eight days. Pioneering adaptations of the principle involved are variously used in the current manufacture of high-quality concrete masonry units, calcium silicate bricks, durable pigmented interlocking pavers and durable asbestos-cement pipes, Melbourne 1964.

Australia Square Tower, 171 m high and 41 m diameter, constructed with insitu lightweight-aggregate concrete incorporating precast-panels of permanent formwork, Sydney, 1967.

Thirty-storey block of flats, erected by the Victorian Housing Commission with precast lightweight-aggregate concrete panels and post-tensioning applications, the project being rated as amongst the most sophisticated prefabricated concrete buildings in the world. Melbourne, 1969.

Trends in the 1970s were toward high-quality, warm-toned, controlled surface finishes and in situ concrete projects, incorporating off-white cements, coloured sands, super-plasticisers, and inhibited bleed-water movement between placed plastic concrete and the formwork.

Arch-shaped prestressed concrete cantilever truss bridge, 183 m main span, erected by progressively linking together precast concrete segments with a lightweight-aggregate concrete drop-in span. The cement content of the concrete is 450-565 kg/m³ and the structure is integrated by post-tensioning technique, The Rip Bridge, Brisbane Water, New South Wales, 1974.

MLC Centre, 68-storey 224 m stage-constructed concrete tower, built with a slip-formed services core and facaded with precast permanent-formwork panels encasing insitu concrete. Temporary support trusses to the spandrels during concreting have automatic deflection-control devices, and the coffered suspended floors are constructed without interim props by the Civil and Civic 'Progressive Strength' system, both innovations being of major structural significance, Sydney, 1974. The latter system received the principal award for an innovation for 'Excellence in Concrete 1973', from the Concrete Institute of Australia, because of its inceptive use in Nauru House, Melbourne, 1972.

The 976 m long Bowen Bridge, across the Derwent River, using match-cast concrete balanced-cantilever construction, comprises eight 109 m river spans and 48 m-56 m end spans of continuous, twin single-box girders that are connected with an in situ longitudinal joint. Massive pier foundations, including coffer dams and caissons up to 47 m deep, are of tremie, precast, in situ, reinforced, stressed and grouted forms of concrete construction. Holes drilled through tremie concrete plugs into bedrock before dewatering give pore-pressure relief and allow subsequent drainage. The piers at water level are topped with massive reinforced concrete caps, surmounted with two in situ reinforced concrete columns. The concrete variously contains a set-retarder for effective workability and placement of large volumes.

The superstructures reinforced concrete segments, containing prestressing ducts and diaphragms at piers, are precast with pumped concrete and hydrothermally cured overnight, using hot air blowers and humidifiers under cover. A two-month storage period allows shrinkage to occur prior to erection and jointing with epoxy resin under pressure, thereby reducing superstructure deflection due to creep. Concertina-type joints of 450 mm movement capacity are installed at the abutments.

Australian Academy of Technological Sciences and Engineering