The Civic Building
Concrete Etching, Auckland CBD

On a live construction site in the middle of Auckland’s CBD, the remediation programme at The Civic Building depended on something that sounds simple but rarely is in practice: concrete etched back to a consistent, fully exposed aggregate finish across every specified area. Concrete does not always weather, cure or age evenly across a large structure, so achieving that consistency needed a controlled process rather than a general clean-down, and it needed to happen without disrupting the trades and activity already running around it on a busy central-city programme.

BlastOff used controlled wet abrasive blasting to etch the surface, a method suited to producing even aggregate exposure while keeping dust and debris contained on an active site. Full containment was maintained throughout, and rather than treating the job as finished once the blasting stopped, each section was checked and verified against the required finish before being handed over. That verification step is what turned a blasting job into a remediation input the next trade could actually rely on.

The concrete came out etched to a uniform, fully exposed aggregate profile across the treated areas, handed to the main contractor on programme and with no rework required, feeding directly into the wider remediation programme underway at the building.

For other main contractors and remediation teams working on central-city sites, the practical takeaway is that aggregate exposure is not a cosmetic finish, it is a substrate specification, and it needs the same section-by-section verification a structural trade would expect. A comparable scoping conversation should cover how consistency will be checked across the treated areas, how containment will be managed around other trades on site, and what tolerance the following stage needs from the finished profile before concrete sandblasting work begins.