Fast-Setting Flowable Fill - The Game Changer in Backfilling

Apr 14, 2021, 2:28 PM

Flowable fill has quickly emerged as a great innovation and a popular alternative when it comes to backfilling. But why is that? And what is flowable fill anyway? Let’s answer both these questions in this post!


What is Flowable Fill Concrete?

Flowable fill concrete is a self-levelling, self-compacting mixture that contains fine aggregate, water, fillers like slag or fly ash, and cement. Used as backfill in place of compacted soil fillers, it successfully fills up spaces in uneven excavations and hard-to-reach areas, such as those below the undercuts of existent slabs.                                                                                          

Additionally, it hardens in just a few hours without requiring layered compaction. Depending on what materials are available and what your specific construction-based requirements are your local ready-mix producer may suggest different mixtures.


6 Major Advantages of Using Fast-Setting Flowable Fill for your Next Project

Since it’s a chemical admixture made from a combination of different materials, the percentages of these materials can be adjusted for varying results. The design flexibility of flowable fill concrete, therefore, gives several benefits to the engineer, six of which we will briefly explain below:


Super-Quick Setting

Flowable fill is a definite time-saver but the results are even better when it's the fast-setting variant. As its name suggests, it takes far less time to set - only around 20 minutes - after which you can cover it with asphalt and concrete. All of this gets completed in little more than an hour - a fraction of the time it takes with typical flowable fill concrete. 


Easy Availability of Ingredients

You can easily mix up some flowable fill using readily available materials like cement, water, sand, and fly ash. Fly ash is a byproduct of coal burned by power plants. Considered a waste product, it proves useful for this purpose as it boosts the strength of concrete - in a cost-efficient manner. 


Convenient to Deliver and Apply

Thanks to mobile concrete mixers, you can have flowable fill delivered to any jobsite you desire, regardless of how remote or densely populated the area is. Moreover, you can pour it through various means like conveyors, pumps, chutes, or buckets. And since it’s self-levelling - it requires no compacting or spreading, nor do you have to demolish existing concrete. Simply add it to any cracks and crevices and save the land from settlement by providing stability to the soil below.


Suitable for Application in Any Weather

This solution can dispel water from trenches or similar places, eliminating the need for water pumps. In cold weather, you can use flowable fill after heating it, similar to ready-mixed concrete.



This self-levelling product basically does most of the work on its own, since it settles as soon as it’s poured. Therefore, all it needs is one person for placement, unlike conventional granular fill that requires at least two labourers to fulfil the duties of placement and compaction. This helps you save the time and cost of hiring backhoes and compactors.


Strong, Resilient, Multipurpose

Flowable fill boasts a greater load-carrying capacity in comparison with granular fill or compacted soil. This is due to decreased permeability, which allows it to gain compressive strengths over a thousand psi.

 Flowable fill mixtures can also be modified to fulfil various needs. For example, adding fly ash increases strength, whereas water boosts viability. Changing the quantities of admixtures in turn changes setting times.


Reap the Benefits of Flowable Fill with a Volumetric Concrete Mixer


A volumetric mixer truck is the best equipment for making flowable fill concrete. In fact, these mobile machines have been in use for this purpose for nearly as long as the innovation has been around. 

A majority of manufacturers provide a feature on their mixer trucks that allows them to produce low-strength flowable fill. All it takes is a flip of the switch to turn a high-strength concrete mixer into a low-strength flowable fill mixer. Due to this, many owners can partake in both concrete work and flowable fill businesses using the same machine.

What’s more, these mixer trucks are capable of achieving the perfect mixtures while producing the required amount. Of course, the yield quantity may change for different mixer trucks, but production rates can go as high as thousands of yards per hour.

In case you have any questions about all the benefits and opportunities that flowable fill or volumetric mixers can give, do not hesitate to get in touch with our experts.