‘Voids’ can mean anything from cracks and crevices, up to the huge volume voids caused by a major tunnel collapse. Holes and voids can be either concealed or open cavities that present naturally as a result of erosion and geological changes, 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 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.

What causes holes and voids?

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

Earthquake and seismic activity, often resulting in liquefaction

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

How to fix holes and voids

Mainmark has a number of solutions to address void-filling such as polyurethane grouting. We assess each situation to determine the best course of action and the best material to use. Smaller voids in underground rock strata are generally filled with a material like urea silicate or polyurethane resin that not only fills the void but also ‘glues’ the surrounding rock together. Urea silicate is the natural choice for coal mines due to its lower exothermic reaction temperature. Alternatively, when greater supportive strength is required large voids can be filled with urea silicate expanding resin.

Lightweight polymer modified cement is another option as the void fill material. Massive voids can be filled quickly and economically using a very low-density synthetic or cementitious-based fill material from our unique Terefil range. This solution can also be used across a variety of void-filling situations, including abandoned fuel tanks, pipelines, and manholes, voids behind seawalls, and quick-support, easy-flow backfill for service trenches.


Holes and Voids under Commercial and Industrial Structures

Mainmark has a number of solutions to fill underground voids, which stabilise and strengthen the foundation ground under buildings and other on-ground structures. Filling voids can address site problems during excavation and construction works, or emerging issues in existing warehousing, manufacturing, service and processing facilities.

In commercial operations, minimising downtime is the most important aspect. 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.

Another option as the void fill material is an engineered light-weight cementitious fill. Massive voids can be filled very quickly and economically using a very-low-density fill material from our unique Terefil range. 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:

Stabilising worksites in building and construction efficiently to minimise downtime

Addressing land slippage around facilities for a safer working environment

Filling abandoned underground fuel tanks safely and economically; tanks can later be removed, transported whole and cut up safely

Filling pipelines uphill or downhill without the filler spilling out

Retaining wall and wing wall backfill

Strengthening the foundation ground under buildings and other on-ground structures

Stabilising access routes

Mainmark hole and void filling methods used for Commercial and Industrial structures: