Canterbury Today issue 119

Page 17

Scanning the land? Stake Consulting Limited is a great example of how cutting edge technology combined with Kiwi innovation is helping in the rebuild of Christchurch. Stake Consulting is believed to be the only concrete repair/building consultancy company in New Zealand operating a ground penetrating radar (GPR) machine to detect slumps and voids through concrete slabs and walls. Buried voids may present a structural risk in the future, so for peace of mind and risk mitigation, void detection is a must for residential and commercial property owners alike. Stake Consulting was established in response to the September 2010 earthquake, and has already scanned concrete slabs under about 1250 homes and buildings damaged by the quakes.

Concrete GPR machine Stake Consulting’s high resolution, ground penetrating radar allows the scanning of any concrete structure simply and safely. The company believes it has the best piece of equipment in New Zealand and highly qualified, certified technicians to operate it. Stake Consulting uses the GPR for scanning floors to see what’s happening with the subfloor and if it’s dropped away from the floor. It has used the GPR on a large number of houses, as well as a wide range of commercial buildings including high rises and public buildings. Following on from the GPR void detection work, Stake Consulting can then undertake sub-floor thixatropic grout injection work. The GPR will, in the hands of a skilled operator, tell you the exact volume of the voids underneath the concrete slab. Stake’s slab jacking team can then come in and fills the void. A special waterproof (essential for watertightness and longevity of repair) thixatropic grout is injected under the floor. If the floor has sunk or slumped Stake can lift it back up into position. About 98 percent of homes that we have scanned in certain areas have voids in them and to lower future risk they all should be filled. GPR is a real-time NDT technique that can also quickly locate the position of post tension cables, rebar, and electrical conduits embedded in concrete, eliminating dangers associated with cutting or drilling, and the high costs required for their repair if cut or damaged.

Carbon fibre structural repairs Stake Consulting is the New Zealand distributor for Fortress Stabilization Systems, which manufactures carbon-fibre reinforcement systems designed to stabilise and strengthen concrete and other structures that may have fractured or stressed. Fortress Stabilization Systems have been used for everything from foundation repair, concrete crack repair, concrete reinforcement, bowed basement and foundation walls, reinforcing concrete in roads and bridges, restoring the structural integrity of commercial buildings, both post and pre-construction, and even stabilising mine shafts.

South Island expansion Stake Consulting’s workload is continuing to grow as the Christchurch rebuild slowly gets underway. While the GPR machine has been busy, it has not yet reached capacity. The main rebuild contractors have put systems in place for this void detection service where it is used as a risk management tool. If they don’t get the floors scanned and checked on the hills, it is a risk for them later on if there’s a problem. Stake Consulting’s medium/long-term goal is to expand beyond Christchurch and move further south, as building owners, engineers and councils throughout the South Island begin working on strengthening their old and historic buildings to bring them up to code.

Stake Consulting’s range of high tech concrete repair services include: • Void detection in concrete slabs using the latest high-resolution groundpenetrating radar • The GPR machine can locate voids, anomalies, cables, electrical conduits and in-slab heating systems, embedded rebar and steel reinforcing, when drilling into the slab is required • Filling voids under concrete slabs and lifting them back into place • Lifting and replacing (if required) foundations/piles for both wooden floor and concrete slab homes • Carbon-fibre reinforcement systems designed to stabilise and strengthen concrete • Epoxy pressure injection for cracks in structural concrete • Synchronised multi-port manifold jacking systems.