Ready Mixed Flowable Fill (RFF)

Ready Mixed Flowable Fill (RFF) is commonly a blend of cement, fly ash, sand and water. Typically it is designed as a low strength, flowable material requiring no subsequent vibration or tamping to achieve consolidation.

Benefits of Ready Mixed Flowable Fill (RFF)
Reduced in-place cost - The flowing, self-leveling consistency of Ready Mixed Flowable Fill (RFF) requires no placing in lifts, tamping or compacting. RFF is less labor intensive. Minimizes Settlement - RFF assures a high density backfill. . . and reduces costly maintenance due to settlement. Worker Safety - Fewer workers are subjected to trench failures. Versatile - RFF is adjustable to meet specific fill requirements. . . adjustable densities allow the production of a high slump material with good flow characteristics. Easily Removed - RFF mix designs can be adjusted to allow for re-excavation. Durable - Load carrying capabilities of RFF are typically higher than that of compacted granular backfill. It is more stable and less permeable than alternate compacted backfill, therefore reducing erosion or washouts. Readily Available - Manufactured by local ready mixed concrete producers. RFF is produced and transported using conventional equipment. . . it is mixed, delivered and through controlled discharge is flowed into place by the ready mix truck.



  • Sewer Trenches
  • Utility Trenches
  • Building Excavations
  • Bridge Abutments
  • Conduit Trenches

Structural Fill

  • Road Base
  • Mud Jacking
  • Sub Footing
  • Floor Slab Base
  • Pipe Bedding

Other Uses

  • Underground Storage Tanks
  • Slope Stabilization
  • Soil Erosion Control
  • Mud Mats
  • Abandoned Sewers

15 Reasons To Use Flowable Fill

Readily Available - Ready mixed concrete producers, using locally available materials, can produce flowable fill to meet most project specifications.

Easy to Deliver - Ready mix trucks can deliver specified quantities of flowable fill to the jobsite whenever their material is needed.

Ease of Placement - Depending on the type and location of void to be filled, flowable fill can be placed by chute, pump, conveyor or bucket. Because flowable fill is self-leveling, it needs little or no spreading or compacting. This speeds construction and reduces labor requirements.

Product Versatility - Flowable fill mix designs can be adjusted to meet specific fill requirements. Add more water to improve violability. Add more fly ash or cement to change strength. Admixtures can be added to adjust setting times and other performance characteristics. Adding foaming agents to flowable fill produces a lightweight, insulating fill material.

Strong and Durable - Load carrying capacities of flowable fill typically are higher than those of compacted soil or granular fill. Flowable fill is also less permeable, thus more resistant to erosion. For use as a permanent structural fill, flowable fill can be designed to achieve 28 day compressive strengths as high as 1200 psi.

Can Be Excavated - Flowable fill having compressive strengths of 50 to 100 psi can be easily excavated with conventional digging equipment, yet is strong enough for most backfilling needs.

Requires Little Field Inspection - During placement, soil backfill must be tested after each lift for sufficient compaction. Flowable fill is self-compacting, and does not need this extensive field testing.

Allows Fast Return to Traffic - Because flowable fill can be placed quickly, and can support traffic loads within several hours, it minimizes downtime for pavement repairs.

Will Not Settle - Flowable fill does not form voids during placement, and will not settle or rut under loading. This advantage is especially significant if the backfill is to be covered by pavement patch. Soil or granular fill, if not consolidated properly, may settle after a pavement patch is placed, and form cracks or dips in the pavement area.

Reduces Excavating - Flowable fill allows narrower trenches because it eliminates having to widen trenches to accomodate compaction equipment.

Improves Worker Safety - Workers can place flowable fill in a trench without entering the trench, reducing their exposure to possible cave-ins.

Allows All-Weather Construction - Flowable fill displaces any standing water left in a trench from rain or melting snow reducing the need for dewatering pumps. To place flowable fill in cold weather, heat the material, using the same methods for heating ready mixed concrete.

Reduces Equipment Needs - Unlike soil or granular backfill, flowable fill can be placed without loaders, rollers or tampers.

Requires No Storage - Because flowable fill is delivered by Ready-mix suppliers, there is no need to stockpile material at the jobsite.

Makes Use of a Wate By-Product - Flowable fill with fly ash makes use of an industrial waste material produced by power plants as they burn coal to generate electricity.