Introducing Terefirm® Resin Injection – the next generation in ground improvement, liquefaction mitigation and bearing capacity enhancement solutions

Remediating structures affected by serious ground issues, such as liquefaction, poor compaction or settlement, has up until now been a complex process. Weak ground can compromise building foundations and footings, putting the structure at risk of collapse. Ground improvement solutions that are currently available are limited, highly invasive, costly, time consuming and messy. If the ground improvement work requires a building tenant to relocate, the interruption to business can add further losses to both the business operator and building owner.

Now there is an exciting new alternative

Following years of extensive research and testing, Mainmark has developed a proven, non-invasive ground improvement and liquefaction mitigation solution that is new to the market. The Terefirm® Resin Injection technique for liquefaction mitigation uses ground remediation technologies to address underlying ground vulnerability and can be applied under existing structures, or directly into vacant ground in preparation for new construction.

A proven and extensively tested, non-invasive ground improvement solution

The release of internationally peer-reviewed research has found that resin injection is a proven method for increasing soil density, foundation bearing capacity and mitigating liquefaction. The full report is now available for review on the New Zealand Geotechnical Society website and information is also included in the MBIE Module 5: Ground Improvement of Soils Prone to Liquefaction. When applied beneath existing structures, Mainmark’s proprietary Terefirm® Resin Injection liquefaction mitigation technique delivers engineered resins to strengthen the ground, reduce the need for above-ground improvements and helps to increase the structure’s asset rating (including the New Zealand New Building Standard percentage rating). This new approach to remediating structures affected by serious ground issues can help to preserve existing buildings and infrastructure affected by soil displacement and liquefaction, providing an alternative to costly demolition and rebuilding.


Supa Centa ground improvement

The Northwood Supa Centa in Christchurch had suffered from serious earthquake damage including liquefaction and required extensive ground improvement work to densify the soil beneath the structures to help bring the existing building back to level. Mainmark was able to successfully remediate the retail centre back to 100% NBS while retailers including a busy supermarket, were able to continue trading virtually uninterrupted throughout the busy Christmas trading period.

How it works

Mainmark’s Terefirm® Resin Injection liquefaction mitigation and ground improvement techniques densifies the soil by injecting an aggressively expanding polyurethane resin mix into the ground. Terefirm® Resin Injection delivers secondary benefits with improvements in composite stiffness, cementation, and horizontal stress increases. The expanding resin is injected with pinpoint precision via small (12mm to 20mm) penetrations, and the process is fast, non-invasive, and clean.

Here’s what happens:

  • injection tubes are driven into the ground through small penetrations at regular intervals
  • material is injected into the target treatment zone at each injection point to create the resin soil matrix
  • the injection sequence is designed to suit site-specific conditions and can consist of ‘top down’ or ‘bottom up’, static or continuous injection
  • in a typical ‘bottom up’ process, the tube is withdrawn either in set stages with set volumes of material injected at each stage, or it is withdrawn slowly on a continuous basis, with set volumes of material being injected per unit length that the tube is withdrawn
  • during injection of the treatment zone, the low-viscosity resin both permeates the soil to a limited extent, and also penetrates under pressure along planes of weakness within the soil profile
  • the material reacts soon after injection, rapidly expanding to many times its original volume
  • the expansion of the injected material compacts the adjacent soils due to new material being introduced into a relatively constant soil volume
  • the resin distributes in a ‘veining’ pattern through the soil mass as dykes, sills, or networks of sheets or plates, typically tens of millimetres thick, as opposed to regular columns or ‘bulbs’ of material distributed down the vertical injection line
  • the process significantly improves soil density, stiffness, and strength.

Ideal for ground under all types of structures

Terefirm® Resin Injection methodology can be successfully applied not only to cleared sites but more importantly to ground beneath vulnerable buildings, structures and critical infrastructure, where the soil conditions are appropriate. Terefirm® Resin Injection is a proven solution for liquefaction mitigation in seismically active areas and for general bearing capacity enhancement under static conditions. Due to the low level of intrusion required to carry out the process, the solution is particularly beneficial for businesses that need to continue operating during remediation works.



Increases ground bearing capacity
  • Limits future damage from lateral spread, differential settlement, consolidation, or poorly-compacted fill. This protects existing investments and can improve the value of some properties that were previously affected by ground instability or liquefaction.
Rehabilitates foundation ground
  • Extends the structure’s lifespan and avoids the need to replace foundations or rebuild.
Strengthens the ground
  • Improves safety by reliably strengthening the ground, even in regions experiencing ongoing seismic activity.
Terefirm® resins are environmentally inert
  • Results in minimal environmental impact.
Keyhole surgery method
  • Reduces repair costs and delivers a fast, non-invasive, and less messy alternative to traditional underpinning or other ground improvement processes.
Delivery method perfected by Mainmark over 20 years
  • Delivers faster rehabilitation with full confidence in the product’s application and performance.
Resin backed by a 50-year product warranty
  • Providing assurance that Mainmark stands behind its proprietary solution.