Terefil® from Mainmark is the most advanced structural lightweight polymer modified cement grout

Terefil is a unique, specialist material that can solve a wide variety of geotechnical challenges in the infrastructure, construction and mining industries. It’s a lightweight concrete fill that’s ideal for use as a flowable fill where cellular concrete, foam concrete or foam cement would otherwise be used.

However, Terefil’s capabilities as a structural fill material far surpass those of granular fills or aggregate materials. As it’s a flowable grout, it’s ideal when site access is limited or project schedules are tight. Typically, it is used to fill large holes and voids, abandoned pipes and mineshafts, sinkholes, landslip repair and backfill retaining walls.

Terefil is a solution that can be used as void fill or structural fill material. The concrete grout mix is highly-flowable, so it can be pumped over long distances, overcoming many site access issues. The lower pumping pressures also reduce the risk of damage to nearby pipes or other in-ground structures such as an abandoned pipe.

What is Terefil?

Like all Mainmark products, Terefil is environmentally inert and cost-effective. It uses much less water than traditional options such as cellular lightweight concrete or foam concrete methods.

Terefil is a structural fill that contains a uniformly distributed matrix of air bubbles generated by mixing cement slurry with stable, pre-formed hydrocarbon foam. Cementitious products encapsulate the air bubbles, then dissipate, leaving a lightweight concrete mix that provides the perfect lightweight backfill or lightweight concrete fill.

This Controlled Low Strength Material (CLSM) is a void filling foam that is far more stable, has a greater lift thickness, and can be pumped greater distances through a grouting pipe than typical concrete void fillers.

How it works

Terefil is pumped through an application hose and directly applied to the area to be treated. The highly-flowable Terefil can be placed quickly, often within an hour. Once in place and set, Terefil is environmentally inert and continues to gain strength over time without adding significant weight to potentially overstressed subgrade soil.

Site access challenges can be overcome simply by using longer hoses to apply the Terefil solution.

What applications can Terefil be used for?

The aerated lightweight concrete can be used in a variety of situations. For example, when considering what to use for retaining wall support, Terefil provides the perfect retaining wall backfill. The pervious concrete can be used in place of traditional foam fills methods, as well as retaining wall fill. When looking for concrete to fill a hole, the light concrete mix is also an ideal large hole filler including sinkholes.

Terefil has been used successfully for projects including:

Terefil is lightweight, self-levelling, and cost effective. The density and strength are matched to the specific job requirements to deliver the required engineered outcomes, making Terefil a versatile and reliable solution. Terefil’s lightweight attribute reduces the pressure on retaining walls, bridge approaches, and slip planes.

Choose a pervious or impervious mix to suit your application, delivering field drainage or sub-base filtration.

Terefil is fast and easy to place, offers negligible shrinkage* and no capillary separation. Water is consumed during hydration into the mix. It can completely stabilise soil without disturbing or redirecting natural water flow.

Terefil is ideal for time-sensitive projects, able to be placed quickly and accurately. Once in place, Terefil can withstand heavy loads including large machinery and vehicular traffic. It doesn’t require compaction, so it is ideal for when future settlement can’t be tolerated.

*Typically shrinkage is between 0.1% – 0.3%, subject to strength.



Highly-flowable concrete grout mix

Can be pumped over long distances

Overcomes many site access issues

Ideal for a variety of applications

This cementitious grout is perfect for many uses including as retaining wall fill, a large hole filler, or as permeable sub-grade


The density and strength are matched to the specific job requirements to deliver the required engineered outcomes, while reducing pressure on retaining walls, bridge approaches, and slip planes

Pervious or impervious

Choose the mix that suits your application, delivering field drainage or sub-base filtration

Easy to use

Ideal for time-sensitive projects