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2018 SUSTAINABILITY AWARDS

EXCELLENCE IN COMMERCIAL CONCRETE CONSTRUCTION
ALLIED CONCRETE for
Structural Lightweight Concrete at AUT’s ETD Building

02 Oct 2018

Embodying the disciplines of engineering, design and technology, AUT’s ETD Building is comprised of a 12-level tower and a 5-level podium.  The design by architects Jasmax seeks to reduce the overall carbon footprint of the building.

Most commercial buildings use approximately 200 kilowatt hours of energy per square metre, but the EDT Building will use around half that. To help realise this objective a high performance external precast concrete facade was selected.

Due to structural requirements, it was decided to use lightweight concrete to keep the mass of the elements down. The main challenge faced by Allied Concrete was achieving a target structural strength of 40MPa in lightweight concrete and matching the finish with surrounding conventional panels.

Expanded glass light weight aggregates made from post-consumer recycled glass were selected - a first for New Zealand. 40MPa mix was approximately 22% lighter and 20MPa mix was around 35% lighter than conventional concrete. Special loading and mixing techniques were required, while extra care was needed during casting to prevent the lightweight aggregate from floating to the surface.

 

JUDGES' CITATION

Seeking a reduction in the carbon footprint of any structure is often ‘easier said than done’, but in this instance the objective of halving the kilowatt hours of energy per m² consumed was achieved by harnessing concrete’s adaptability. To bring the façade design to-life required the durability of concrete as a cladding (and shading) material, but at a weight that would not compromise the structure. The use of expanded glass aggregate made from post-consumer recycled glass allowed for lightweight panels to be manufactured. The ‘win-win’ of achieving a high-performance energy efficient design and accounting for a waste product relied on concrete’s versatility in partnership with skilled construction professionals.

SUBMITTED BY Allied Concrete

CLIENT Auckland University of Technology (AUT)

STRUCTURAL ENGINEER BECA

ARCHITECT Jasmax

CONTRACTOR Fletcher Construction and Concretec New Zealand