What Is Flowable Fill?

The name comes from the flowable consistency of the materials, cement, slag or fly ash, sand, and water. Because it self-compacts into a low strength material, flowable fill concrete is a common backfill alternative to using compacted granular fill.

Volumetric vs. Barrel Truck

Using a volumetric concrete mixer for flowable fill concrete offers several key benefits over a traditional barrel truck. The quality of the mix is superior due to the rapid and consistent mixing speed in a volumetric mixer, ensuring a uniform product. Additionally, volumetric mixers have less clean-out compared to barrel trucks, as a significant amount of product tends to stick to the drum in traditional methods, leading to wastage and mess. Many barrel truck companies are reluctant to deliver flowable fill due to these issues, but with a volumetric mixer, you can get the exact amount you need, when you need it, making the process more efficient and cost-effective.

Expedite Utility Work With Flowable Fill Concrete

Whether you work directly in the sector or as a contractor, consumer demand for tele communication, electricity, gas, water, and other energy and utility industry products is ever increasing. This constant need heightens the drive to provide installation and repairs in a timely manner, no matter the location. The flexibility of flowable fill concrete touches every aspect of a project, especially when utilizing a volumetric mixer truck.

When Can It Be Used?

This type of concrete gained popularity because of the significant savings with equipment, labor costs, and time. Traditional compacted fill requires skilled employees, equipment, and time to properly place, compact, and test the material. But, self-compacting and self-leveling concrete, such as flowable fill, ensures 100-percent compaction — even in areas where granular fill would be nearly impossible to compact.

A common example is OSHA trenches five feet or more in depth. Shoring the sides is required for the safety and stability of the structure and anyone in or around it. Yet, flowable fill allows you to remove employees and shoring from the trench and pour the concrete. Safety risks diminish while once inaccessible areas are now filled and ready for use.

How Flowable Fill Is Used

While this type of concrete is commonly used for underground applications, it’s also suitable for many above-ground applications, such as:

Backfill

• Conduit encasement
• Retaining walls
• Road cuts
• Utility trenches

Structural Fill

• Conduit bedding
• Floor-slab base
• Foundation sub-base
• Sub footing

Other Uses

• Abandoned mines
• Erosion control
• Voids under pavement
• Underground tanks

Benefits Of Using Flowable Fill Concrete

The main benefits are directly related to efficiency and safety. Yet, any project or structure which uses this type of concrete can take advantage of eliminated settlement problems, no on-site material storage, and excavation if necessary. On average, these projects need half of the equipment, manpower, and money compared to using traditional fill.

Variables For Flowable Fill

As with any concrete-centric project, there are many variables to account for when choosing the appropriate flowable fill mix design.

Color

Color is frequently used as a visual safety warning to anyone who unearths the concrete, such as buried utilities. By marking buried utilities with a lasting color-coded flowable fill, the safety of future excavation operations is ensured. Crews and operators have an accurate and timely visual warning, allowing them to properly identify the type of the line based on the backfill color.

The American Public Works Association uses eight colors in its Uniform Color Code to denote backfill:

• White: Proposed excavation
• Pink: Temporary survey markings
• Red: Cables, conduit and lighting cables, and electric power lines
• Yellow: Gas, oil, petroleum or gaseous materials, and steam
• Orange: Alarm or signal lines, cables or conduit, and communication
• Blue: Potable water
• Purple: Irrigation and slurry lines and reclaimed water
• Green: Drain lines and sewers

Flowability

The fluidity of these mixtures allows it to flow long distances, to even the hardest to reach places. Plus, it can be adjusted without vibration.

Flowable Fill Strength

American Society for Testing and Materials (ASTM) standards C403 or D6024 are commonly cited when estimating the load carrying ability of the flowable fill.

Questions about the positive impact a volumetric mixer can have on your concrete operation? Contact us today to learn more!