john holland - Kings Square Commercial Tower 1
Two years after the building was completed the owners (Dexus Property Group) commissioned a report which identified cracking in the “corner fins” or “blade walls”. The report concluded that these were most likely as result of:
Stress cracking, which is typically restricted to the corner fins at floor slab levels and believed to be caused by the ‘draw in’ resulting from the post-tensioning process.
Various crack remediation processes were discussed however as the existing finish was an “off form” concrete surface it was apparent that these repairs would become highly visible so some form of final surface treatment would be necessary to leave a uniform finish. A “painted” surface was not considered as the client wanted something that would be durable and emulate the existing natural finish.
Nawkaw West submitted a proposal using the Nawkaw colour staining process that could meet these requirements using the following methodology.
Cracks were mechanically ground out with a V profile (10mmx10mm) then filled with Sika Epoxy repair mortar Sikadur 31 or equivalent
Surface was then skim coated with Aftek cementitious fairing coat and sanded back ready for the subsequent application of Nawtone/NECT90 colour stain.
Provision of Nawkaw colour staining to all 4x blade walls after the crack remediation.
We believe it has achieved an outstanding result in the overall presentation of the building and our client Dexus has expressed their satisfaction with the outcome.
