Sustainability is at the heart of 333 George Street, an 18-storey building in Sydney's CBD featuring a mix of retail and office tenants. Central to achieving the goal of achieving a 5 Star Green Star rating is the selection of Boral's innovative ENVISIA® concrete for the building's suspended post-tensioned floor plates, columns and core walls.
333 George Street was the first commercial project to use ENVISIA® in super-structure elements, chosen for its reduced carbon and high early strength qualities. Typical cement replacement levels in post-tensioned concrete are 20 per cent, but ENVISIA® achieved a minimum of 60 per cent cement replacement. This was estimated to have saved about 700 tonnes of CO2 emissions.
ENVISIA® was used to build the columns, core walls and suspended post-tensioned slabs where drying shrinkage was a critical factor in the design. ENVISIA® achieved the 22MPa strength needed after four days, allowing construction to continue at a rapid pace required in modern projects, compared to the five or six days that would be expected from concrete with this high level of cement replacement.