Geopolymer Injection – A cleaner and quicker treatment for building subsidence

Compared to traditional underpinning and piling techniques, geopolymer resin injection, a more modern method of subsidence correction, offers a cleaner and quicker treatment for buildings affected by subsidence.

Geopolymer resin injection begins by first drilling holes around the perimeter of the building at depths below its foundations and/or through concrete slabs. This is accomplished using handheld equipment ensuring accessibility both inside and outside the structure. Injection tubes are then inserted into the holes, through which geopolymer resin is injected. As the resin expands, it fills voids, compacts the soil and reinforces the ground. There’s no need for trench excavation, concrete mixing, heavy piling machinery, or the management of spoil collection and disposal, which are typically associated with traditional methods.

The minimal equipment required for geopolymer injection enables ground reinforcement through resin injection from both the exterior and interior of a building. This results in minimal disruption for the occupants within the building.

However, don’t just take our word for it, let’s see what some construction professionals thought when they chose Mainmark’s resin injection technology over more traditional methods.

Graham Eves, a consulting engineer, has his offices in an old village rectory built in the 1870s. It has minimal foundations built on clay soil with trees in proximity and was showing signs of subsidence. The shrinkage of clay soils, as their volume decreases in line with their moisture content, is a common cause of subsidence.

As is often the case, subsidence became evident through visible cracks that were notably thicker than hairline cracks resulting from foundation movement. These cracks exhibited a distinct diagonal pattern, being thicker at the top than at the bottom. Recognising these classic signs of subsidence
Graham wisely chose to take swift action and investigate the problem’s extent. The solution involved stabilising the foundations beneath the external walls and addressing load-bearing concerns related to some internal walls.

Mainmark’s Teretek® resin injection technology is an ideal solution for stabilising a building affected by subsidence. Initially, Graham was unaware of this treatment option and was concerned that he might have to rely on traditional underpinning techniques. These traditional methods would have been costly and time-consuming, with the potential to disrupt his business operations.

Then, by chance, he read an article in a Sunday paper that discussed the use of resin injection to address subsidence issues. This discovery piqued his interest, leading to further investigations and inquiries into the matter. Eventually, Graham decided to work with Mainmark, who successfully used their Teretek® geopolymer resin injection subsidence treatment to stabilise the ground under the old rectory in just six working days.

He was glad that he did and commented “Your guys did an excellent and tidy job despite some unusual ground conditions”.

When asked what impressed him the most Graham replied, “When they drilled through the carpet (which was glued to the concrete floor) – the holes are so discrete and there was no damage caused so there is no immediate need to replace the carpet”.

Jeff is a retired construction professional whose house is close to the river Ouse and sits near the York to Scarborough railway line. When the railway bridge over the river was replaced, the vibrations from the piling could be felt in the house and there was a concern that this could compromise ground stability.

This led Jeff to get a structural survey carried out on the house, which already had a history of subsidence, including cracks in the structure and sloping floors. As expected, the condition report confirmed that the house, built in 1926 on a reclaimed ash/clay substructure, was indeed showing signs of instability due to underlying poor ground conditions. The external walls of the masonry construction had vertical and horizontal cracks extending through the rendering into the brickwork, with some at the interfaces with the windows. Inside, the picture was similar with cracks in the internal walls of both the ground floor and first floor. There were also some cracks in the ceiling and on ground floor tiles.

When Jeff had a two-storey extension added there was a clue to the underlying reason for the subsidence. Due to the poor soil conditions, load bearing ground for traditional shallow foundations could not be found at a suitable depth and the extension had to be based on a raft foundation.

Jeff turned to Mainmark for a geopolymer solution that would be able to improve the ground conditions across the whole house without all the disruption associated with a more traditional approach.

It took only one day for the Mainmark team use their Teretek® geopolymer resin injection technology to treat the subsidence in line with the agreed treatment plan. The ground was stabilised with some lift achieved, ranging between one and three millimetres, to put the house back on a stable footing.

After the work was completed, Jeff said “I was pleased that I chose resin injection over traditional piling – the Mainmark engineers worked quickly, with no disruption to the house or its surroundings. I feel happy that the whole house is now on a stable footing, and I don’t have to worry about subsidence anymore”

We would be pleased to introduce you to Teretek®, a resin injection technology that construction professionals like Graham and Jeff are increasingly using as a clean, quick and non-disruptive alternative to traditional subsidence treatments. They are happy with the results, and we would like the opportunity to help you enjoy an equally hassle-free experience by treating subsidence using this modern resin injection technique.

If you would like more information on geopolymer injection subsidence treatments, please contact our experienced team of ground engineers at Mainmark.