Cracking on new Lakeview footpath 'expected and not uncommon': Alliance

Those responsible for new footpaths around the multibillion-dollar Lakeview precinct say no mistakes have been made in their construction and cracks that have appeared are "expected and not uncommon".

The cracking is said to be "shrinkage cracks" and nothing to do with ill-prepared concrete or ground - or cost-cutting.

According to Kā Huanui a Tāhuna - the alliance delivering required roading upgrades in preparation for the high-end central Queenstown development - "established methods" were used to try and control where the concrete would crack.

But the end result that passers-by are seeing now is here to stay.

A spokesperson for the Queenstown Lakes District Council, a member of the alliance and the lead authority on this project, acknowledges the cracking is not ideal.

The response comes ten days after Crux first asked questions about the cracking.

"Clearly the most desirable outcome of work like this is a crack-free footpath," the spokesperson says in a written response received today.

"However, some cracking is expected and not uncommon in concrete because it shrinks as it cures (and) hardens."

The spokesperson says the cracks have been identified as shrinkage cracks that have occurred despite the alliance having followed specifications at the location for saw cuts and joints, which are designed to induce cracking at specific locations and minimise the potential for "uncontrolled shrinkage cracks".

The alliance has been measuring and monitoring the cracks with a "crack gauge" to determine that it does not expect them to widen overtime, nor does it expect any new ones to appear.

"Once a shrinkage crack occurs it relieves the tension that has built up in the concrete during the curing process. It’s less common to see additional cracks occur after the initial cracking has formed," the spokesperson says.

"The cracks currently don’t pose a risk to safety, functionality or expected lifespan of the footpath."

The council has not sought any outside advice on the cracking, opting instead to talk with designers and constructors from within the alliance on the problem.

The council admits, 'the most desirable outcome' is a crack-free footpath.

However, the spokesperson does say the council will work with the alliance "before the 'defects period' or final sign off occurs to understand all factors and make a decision on whether further action is required".

In response to assertions the footpaths, which are located on sloping land, should have included steel reinforcing in there construction, the alliance disagrees, with the spokesperson saying the dimensions of the slabs used were within the limits for an unreinforced slab.

"In addition, a polyethene slip layer was specified and installed under the concrete slab to allow the slabs to ‘slide’ as they shrunk during the curing period."

Main image: Cracks are appearing on sections of new footpath on Queenstown's Thompson Street.