0800 873 835
New Zealand
Sub-industry
Office Building
Problems
Earthquake induced differential settlement
Location
Christchurch, NZ
Year
2014
Solutions
Ground Improvement
Technology
JOG Computer-Controlled Grouting
Teretek® Brings Turangi Home Back to Level Despite Underfloor Heating Challenge
Summary
A residential property on a sloping block in remote Omori, Turangi near Lake Taupo in New Zealand’s North Island, experienced subsidence due to voids under the slab. The settlement caused cracking through the home’s brick veneer, as well as settlement of the concrete patios.
The homeowner sought to address the subsidence and re-level the home to prevent further damage. There was also a requirement to retain the value of the home and ensure it remained safe to occupy. The project was complicated due to underfloor heating pipes located underneath the slab which made drilling into the floor difficult.
The homeowner contracted Mainmark to raise, re-support, and re-level the concrete slab using its proprietary engineered resin injection solution, Teretek®. Applied through very small, strategically placed injection holes, this solution allowed the project to be carried out without damaging the underfloor heating.
Mainmark’s Teretek® deep injection application method also helped improve the bearing capacity of the ground 500mm to 1000mm below the injection level, which provided additional ground strengthening to minimise the likelihood of further subsidence.
This project was completed in a single day.
Objectives
The home’s 100mm thick concrete slab had subsided by approximately 42mm across an 18m2 area. A 23 lineal metre wall had also settled by approximately 42mm. Mainmark was required to raise and re-level the home, and strengthen the underlying foundation soil, without using traditional underpinning techniques or excavation. Voids under the slab were to be filled and the foundation raised by 42mm to allow cracks in the brick veneer to close and bring the patios and floors back to level.
Due to the remote location of the property, and a client who was not on-site at the time of the project, Mainmark was required to communicate with the client remotely, keeping them informed with regular progress updates.
Solution
Mainmark used its proprietary engineered resin injection solution, Teretek®, to stabilise the foundation soil, raise and re-level the slab, and remediate cracked sections of the home. As the resin was injected into the ground, Mainmark used laser levels to monitor the slow and careful raising of the slab.
Teretek® is a unique two-in-one solution that helps to improve the ground beneath the home’s foundations while raising and re-levelling the foundation slab without the need for any excavation.
Mainmark’s technicians identified a number of injection points under the home and applied the Teretek® resin in a process similar to keyhole surgery. The Teretek® expanding polyurethane resin mix is injected through very small tubes into the ground beneath the footings. On entering the ground, the components
mix together and expand by chemical reaction, which help strengthen the ground and re-levels buildings quickly and with minimal disruption. The Mainmark team monitor the process carefully using laser levels to mitigate the risk of further damage during the lifting process.
Compared to traditional underpinning, Teretek® provided a cost-effective solution that was completed in a single day without any damage to the existing underfloor heating system.
Wayne Robertson, the homeowner, said, “We are very pleased with the work completed by Mainmark in re- levelling our Omori property. The team’s communication and management of this project were outstanding and I would highly recommend Mainmark to anyone requiring a similar service.”
Resources
Download a pdf version of this project here
Teretek® Brings Turangi Home Back to Level Despite Underfloor Heating Challenge
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Mainmark Ground Engineering (NZ) Ltd
