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Void filling

Advanced void filling solutions

Void filling is a critical aspect of ensuring the safety, stability and longevity of buildings and infrastructure. It addresses a wide range of issues, from subsidence and ground instability to pipe abandonment. Mainmark offers comprehensive void filling solutions. Depending on project requirements, we offer Teretek® resin injection, JOG computer-controlled grouting and Terefil® lightweight cementitious fill technologies. These methods can be used to:

  • Mass fill voids – Large underground voids that are the result of subsidence, erosion or human activity such as mining
  • Support foundations – Providing stability and preventing further settlement, ensuring the structural integrity of a structure
  • Improve soil – Increasing the soil’s load-bearing capacity, enabling it to support multi-storey buildings, bridges and other heavy structures
  • Lift and re-level structures – As a solution for subsidence, gently bringing buildings back to the correct position.
  • Decommission underground services – Such as pipes, sewer lines, storage tanks, drainage systems and utility tunnels.

The choice of void filling materials and methods is based on void size, location and site-specific requirements. Not only are our methods usually more cost-effective than traditional alternatives, but they also minimise disruptions, allowing businesses to continue operations.

When is void filling required?

Void filling is critical for addressing potentially dangerous situations and maintaining the structural integrity of structures. A void left untreated can cause a wide range of problems, including:

  • Subsidence – The ground beneath a building sinking or shrinking, potentially causing foundations to fail and buildings to suffer structural damage.
  • Soil destabilisation – The loss of structural integrity of the soil, this happens when soil particles lose their ability to maintain a stable and cohesive structure, often the result of drought, erosion, flooding or compaction.
  • Water ingress – Residual fluids from decommissioned pipes leaking into the environment. This can cause the ground to collapse or sinkholes to form. It can also lead to the contamination of groundwater.

Mainmark’s void filling methods provide an effective solution for these issues, helping to achieve compliance and avoid liabilities and penalties while offering peace of mind and long-term reliability.

Our swift, cost-effective and reliable solutions are suitable for a wide range of commercial and industrial applications, from factories and warehouses to offices and social housing, as well as residential homes.

Void filling technologies

Find out more about our void filling technologies

Teretek® – Void filling with resin injection

Teretek® resin injection technology is a swift and non-invasive solution suitable for void filling in commercial or residential applications. With the Teretek® resin injection technology method, we drill small holes into the ground. Through these holes, we inject our resin formula, to fill voids and cracks, stabilise the ground and, if needed, restore the structure to its correct level. Void filling projects using Teretek® resin injection technology can be completed with minimal disruption.

Teretek® resin injection technology

Void filling with Terefil® lightweight cellular concrete

Terefil® is a technology used to create lightweight, cellular concrete for large void fills. Terefil material densities can range from 500 to 1,500 kg/m3 with strengths ranging from 0.5 to 5 MPa. The material sets within hours of placement and is flowable and self-levelling. Terefil® is routinely used for pipe infrastructure abandonment, retaining wall backfill, and shallow ground improvement via soil replacement in soft or liquefiable soil

Terefil® lightweight cellular concrete

JOG computer-controlled grouting for void filling

JOG computer-controlled grouting uses a multi-point injection technique to insert cementitious grout materials under foundations. It can be used under commercial buildings ranging from single-storey shops to high-rise structures. The injected materials have a controlled set time which allows for the precise lifting of a structure.

JOG computer-controlled grouting

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Mainmark technology benefits

Benefits of Mainmark’s treatments for void filling


With Mainmark void filling solutions, works are carried out quickly, with minimal disruption to ongoing operations.

Varied density choices

We provide void filling materials across a wide density range, from 30 to 1500 kg/m3.

Designed strengths

Our void filling materials can be designed for strengths ranging from 50 kPa to more than 20 MPa.

Variable flow properties

Our void filling materials have variable set times, from seconds to hours, and can be pumped over long distances.

Soil stabilisation FAQ’s
What happens with unlevel driveways, floors and hardstand areas?

After the application of the Mainmark solution, unlevel surfaces will become aligned again as the ground underneath is strengthened and re-supported. Simple cosmetic repairs may be required.

Will there be a mess?

Very little, if any. We use Teretek® engineered Resin Injection technology, which is likened to “keyhole surgery”, or JOG Computer-Controlled Grouting, with no major excavation and minimal disruption or mess. The injection holes required are very small.

How long does it take?

Each project is different and depends on the required amount of lift, area for correction, building construction, and ground conditions. Most projects can be completed in a day or two, and we can work at night or on one area at a time, so your business can keep operating.

Do i need to send my workers home?

No, most projects don’t require you to vacate the premises or even move furniture or equipment. For the most part, you can keep operating as normal. Driveways can often be driven on in as little as 30 minutes after treatment.

What warranty will i get?

The materials we use have been developed for use underground and have been specifically engineered to resist shrinkage and deterioration. Teretek® is warranted by Mainmark for an industry-leading period of 50 years.

Is it safe and environmentally friendly?

Injected Teretek® and JOG materials are environmentally inert and have no detrimental effects on the environment.

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Mainmark Ground Engineering (UK) Ltd.

CRN: 09372443

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