Terefil® - The Number 1 Void Filling Solution For Difficult Structural Fill Applications
Mainmark’s proprietary Terefil is an advanced engineered fill material providing an excellent solution when granular fills or aggregate material options are too heavy, site access is limited, or project schedules are extremely tight.
Terefil is highly flowable, easily placed, and does not require compaction. It will fill voids and can be pumped for distances up to 1000 metres. Terefil contains a uniformly distributed cell structure encapsulated by cementitious materials creating an engineered, low density solution used across a wide range of civil, infrastructure, construction and mining projects.
Terefil can be designed to meet the project specific density and strength requirements.
Mainmark’s comprehensive range of void filling solutions include:
- Abandoned pipework, tunnel or culvert
- Annulus fill
- Underground tanks and voids
- Compensation rafts
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Fast, Economical, and Structural Void Filling Solutions
Features |
Benefits |
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Lightweight | Helping to reduce pressure on founding substrates, retaining walls, bridge approaches and slip planes. |
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Flowable and self-levelling | Terefil is able to completely fill annular spaces, and mass fill large voids (such as tanks, pipes, sink holes and abandoned mines) not leaving a void across the top of the space. |
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Rapid installation | Terefil can be placed at greater than 200m3 per day with up to 5 times fewer heavy vehicle movements required on site. |
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Cost-effective | Reduced transportation of material, reduced energy and water costs all provide significant cost savings. |
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Quality controlled | Providing the customer with a reliable, consistent product. Terefil density is measured by sampling the product as it is placed and strength testing can be undertaken in the lab at 7, 14 or 28 days or as required. |
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Environmentally inert and low carbon footprint | Terefil requires less raw material to be transported to site, reducing traffic congestion and fuel use. |
How Mainmark's Terefil® Solution fills the void?
Terefil® Void Fill
Terefil® from Mainmark is a lightweight, engineered void fill solution for pipes of every size.
Surpassing even the capabilities of cellular concrete or foam concrete, Terefil is a unique, specialist flowable fill material that can fill massive pipelines and concrete culverts quickly and cost-effectively. Due to its pumpability and self-compacting properties, Terefil can fill entire abandoned pipes, leaving no unfilled spaces, air pockets or gaps. Unlike other fills and grouts, Terefil doesn’t release any water as it sets, ensuring zero bleed and minimal shrinkage along the crown of the pipe. The solution provides firm contact between the material and the pipe as it sets, preventing the formation of underground cavities or voids as the pipe degrades over time.
Terefil is a lightweight concrete or flowable grout that travels easily through a grouting pipe to fill voids of any size, including large abandoned pipes and culverts. This innovative flowable fill makes it easy to apply regardless of the size or length of the pipe or culvert. Importantly, it means pipes can be filled and decommissioned even when access is extremely limited. Pipes can be filled from a single entry point with the highly-flowable grout applied very quickly. Terefil is the lightweight polymer-modified cementitious fill of choice for mission-critical projects, ideal for when granular fills or aggregate material options are too heavy, site access is limited, or project schedules are tight.Mainmark works fast to minimise downtime on site, with time spent on testing solutions and identifying the best formulation for the project before work begins.
Terefil is available as a pervious or impervious mix and can solve a large variety of civil and geotechnical challenges.
- Mass fill or large geological voids.
- Sinkholes or washouts.
- Abandonment of in-ground pipes, tanks, tunnels and mine shafts.
- Bridge approaches and landslip repairs.
- Backfill for swimming pool, retaining wall, service trench and manhole excavation.
- Permeable sub-grade beneath roads, major highways, airport runways, bridges, mine shafts and sporting facilities
Company Snapshot
35
Years Experience
987
Successful Projects
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Offices Worldwide
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Technical Engineers
Mainmark Fills Damaged Culvert at Brisbane Airport
Compared to traditional foam fills, the proprietary technology used in Terefil™ has increased stability, a greater lift height and can be pumped greater distances. Extensive compressibility testing has validated the ability of Terefil™ to resist cell collapse from pressure.
Mainmark used Terefil™, an air-entrained lightweight cementitious mass void fill material, to fill the culvert. The proprietary grout design mix was explicitly developed for the project. It was trial batched, cured and independently tested prior to the works to ensure pumpability and compliance with the project’s specifications. During the project, the grout was batched locally, augmented, and pumped on-site using a purpose-built pump and truck-mounted injection equipment.
Lightweight Terefil® Fills Redundant Culverts and Pipes in Newcastle
Senior project engineer for Diona, Gavin Bowen, had this to say: “Mainmark did a great job on the Terefil filling of the redundant stormwater culvert and pipes system in Mayfield. The crew were very efficient and very helpful to work with.”
Mainmark’s proprietary product, Terefil, is a technologically advanced, engineered, lightweight cementitious-based filler that is well suited to projects where alternative granular fills or aggregate material are considered too heavy.
Terefil is significantly lighter than standard grout fill, minimising pressure to surrounding structures and substrate soils, while at the same time, able to withstand significant pressure and maintain structural integrity under heavy loads, such as road traffic.
Terefil® Used to Abandon Pipeline at Iron Mine
Terefil® was the ideal material for this project due, in part, to its extremely low shrinkage rate and the lack of bleed water during curing time.
Mainmark was required to fill the pipes without exceeding 300kPa pressure on the pipes during a 12- hour continuous placement, and then cap the pipes on completion.
As the pipes could only be accessed through a single point, the project required a highly flowable fill material that would travel the length of the pipes to fill them completely. Work was required to be completed in a tight project timeframe of three
Underground Gas Main at Busy Melbourne Intersection Decommissioned with Terefil®
The Mainmark team was required to work within a tight work zone, approximately 3m by 10m, with additional access for two concrete agitator trucks that delivered material to the site.
Mainmark’s advanced engineered Terefil cementitious fill was used to fill a 300mm ‘T’ section of the gas main pipe. The ‘T’ shaped pipe had 2 major lengths; a 25m length section and a 100m length section.
A total of 10.2m³ of Terefil was required to completely fill the gas main pipe without any air pockets or gaps, with the cementitious fill placed at a density of 700kg/m³.
Brisbane Airport Case Study
Terefil® Void Fill


Darwin Building Refurbishment
A government owned facility was being refurbished in Darwin. Part of the scope of work included filling up a void below a suspended concrete slab.
A lightweight fill was required to ensure minimal overburden weight was applied to the ground. The fill must also have sufficient flowability to fill all void space. Terefil was selected, with a designed density of 600kg/m3.
A total of 375m3 of Terefil was placed, completely filling the void. The void was filled over 3 days of pumping.


Culvert Refurbishment
Mainmark were engaged to refurbish a large network of storm water culverts. Part of the overall refurbishment scope, was to fill the voiding that was discovered behind the concrete lined corrugated metal pipes.
A major challenge was the large pumping distance from the laydown point at the surface, to work face underground – over 200m. Mainmarks proprietary product, Terefil, was selected. The work was completed under a strict confined space management plan.