Void Filling

Mainmark offers a variety of means to fill underground voids and holes to stabilise strata in tunnels and to strengthen the foundation ground under buildings and other on-ground structures.

void filling in progress

‘Voids’ can mean anything from cracks and crevices, to the huge volume voids caused by a major tunnel collapse. Holes and voids can be either concealed or open cavities that present themselves naturally as a result of erosion and geological change, or due to building, mining, and other commercial or industrial ground activity. Ranging from small to large, all holes and voids underneath structures will contain air, and possibly water, which can dangerous and cause instability. Filling these spaces can prevent wider damage to the ground, on-ground structures, and the surrounding environment. Some holes and voids may need to be backfilled after operations cease, to prevent them becoming a hazard.

Holes are often dug in mining, building, and infrastructure works, while voids may develop over time due to leaks and weather eroding sub-soils underneath a structure. Something as simple as a leaking pipe may wash away surrounding earth, creating voids (or an empty space) around the pipeline. Filling holes and voids ultimately aims to stabilise mines, tunnels, buildings, bridge approaches, bridge abutments, and other operating or decommissioned structures.

Likely causes:

  • Construction holes and excavation
  • Erosion
  • Flooding
  • Joints in culverts
  • Land slippage
  • Leaking pipes washing away sub-soils
  • Abandoned tanks and pipelines
  • Mining and commercial operations
  • Poorly compacted fill
  • Water ingress
  • Earthquake and seismic activity, often resulting in liquefaction 

Filling voids can re-support and prevent water ingress and erosion in critical infrastructure including rail, roads, highways, approach slabs, bridge approaches, bridge abutments, and airport runways. Mainmark offers a variety of means to fill underground voids to stabilise strata in tunnels and to strengthen the foundation ground under buildings and other on-ground structures.

Filling voids can also address site problems during excavation and construction works, or emerging issues in existing warehousing, manufacturing, service and processing facilities.

We can also assist in decommissioning old infrastructure, including void filling of abandoned or redundant boreholes, culverts, tanks, manholes, pipes, and caverns. Voids around smaller pipelines are filled and leaks sealed from above using our Teretek engineered resin solution. If required, pipes can also be re-aligned and pavements re-supported.

Our solution allows minimising operational downtime or continuing occupancy. We concentrate on achieving the fastest response time possible, choosing applications and materials with the least impact and allowing the quickest recovery times for our clients.

We assess each situation to determine the best course of action and the best material to use, taking into account hazardous environments. Smaller voids in underground rock strata are generally filled with a materials like urea silicate, polyurethane resin or our proprietary Teretek engineered resin solution, that not only fill the voids but also ‘glues’ the surrounding rock together. Alternatively, when greater supportive strength is required larger voids can be filled with urea silicate expanding resin.

Large voids can be filled very quickly and economically using a very-low-density fill material from our unique Terefil range. The void fill material is an engineered light-weight cementitious fill. Terefil can be used across a variety of void-filling situations, such as filling voids behind seawalls, quick-support, easy-flow backfill for service trenches, abandoned fuel tanks, pipelines and manholes.

Benefits of Mainmark’s methods to fill holes and voids:

  • Adaptable and versatile, can be used in almost any structure or geotechnical situation
  • Suitable for broad range of buildings and assets from mass void fill to pipe decommissioning to subgrade alternative
  • Quickly and safely decommissioning culverts, pipes and tunnels
  • Stabilising bridge approaches and bridge abutments
  • Retaining wall and wing wall back-fill
  • Efficient and economical back-filling of services trenches and manholes
  • Savings on materials and labour costs
  • Delivers a fast and controlled outcome
  • Strength and density characteristics can be tailored to meet each individual project deliverables
  • Lightweight material reduces the pressure on retaining walls, bridge approaches, and slip planes