North Bondi Residential Apartments, Sydney

Installer/Applicator: Structural Building Management
Specifying Engineers: Cardno

North Bondi is in the eastern suburbs of Sydney; located on the coast of New South Wales and a short distance away from the world-famous Bondi Beach. Being a mostly residential area, a block of apartments was recently brought to the attention of the team at Structural Building Management as needing repairs to the structure of the building.

Challenges
As this building was situated extremely close to the Tasman Sea, this block of residential units was heavily affected by what is known as concrete spalling AKA “concrete cancer” – the rusting of steel reinforcement contained within a concrete slab. Balconies and columns throughout the building were affected and treatment was required to fix the issue.

This residential building still required access for residents to go about their daily lives and activities, so minimal disruption was required with a relatively quick turnaround. On top of that, a solution was required to slow the progression of any future concrete spalling / (cancer) in these rehabilitated areas.

Solution
In conjunction with the specifying engineers, Cardno, ARDEX Australia provided a concrete repair system to remediate the current issues as well as assisting in the prevention of the steel and concrete from becoming damaged so quickly again. The team at Structural Building Management were engaged to carry out rectification works to the unit block.

The affected areas for rectification were broken-out and removed, prior to being primed with ARDEX WR Prime (as this product enhances the performance of the following repair mortar and promotes tenacious adhesion to the host surface).
Approximately 2500 litres of ARDEX BR 340 Microtec® fibre-reinforced structural concrete patching and repair mortar was installed. The BR 340 repair mortar contains an active corrosion inhibitor (for ongoing protection of the reinforcement bar within the repair area).

To assist in retarding any future damage to the reinforcement within the concrete, ARDEX BRX 60 LO sacrificial anodes were installed. ARDEX BRX 60 LO are ‘sacrificial’ zinc anodes that provide control to limit corrosion rates of bars embedded in the concrete.

It took approximately 12 weeks for Structural Building Management to complete repairs and to rectify the issues caused by concrete cancer.