Flowable Fill

Flowable Fill, technically called a “Controlled Low-Strength Material” (CLSM), is a fluid, self-leveling, low-strength material used for backfill and as a replacement for granular sub-base. Delivered in a ready mix truck, flowable fills ease of placement, labor savings, easy excavation and versatility make it the preferred fill for today’s time, safety, cost, and environmentally-aware contractors.

The American Concrete Institute, in document ACI 116R, defines CLSM as materials that result in a compressive strength of 1200 psi or less. It is most commonly used as a self-compacting, cementitious-based material used as an alternate backfill instead of compacted soil (excavatable). County Materials has supplied flowable fill for challenging and diverse project applications, such as papermill rebuilds, road crossings, pipeline jobs, abandonded underground piping, crawl spaces under foundations, and more. Mix designs can be customized to your needs to meet required strengths and set times. Consult your County Materials’ sales representative for more detailed information.


Common Uses for Flowable Fill:

BackfillStructural FillOther Uses
Sewer Trenches Road Base Uderground Storage Tanks
Utility trenches Mud Jacking Slope Stabilization
Building Excavation Sub Footing Soil Erosion Control
Bridge Abutments Floor Slab Base Mud Mats
Conduit Trenches Pipe Bedding Abandoned Sewers and Tanks


Reduced In-Place Cost The flowing, self-leveling consistency of flowable fill requires no placing in lifts.  Tamping or compacting is eliminated.
Minimizes Settlement Flowable fill assures high density backfill and reduces costly maintenance due to settlement.  Flowable fill flows readily in and around pipes and tanks without voids.
Worker Safety Fewer workers are subjected to trench failures and it can be subsequently cut or trenched without caving in or running.
Easily Removed

Can be made to be easily excavatable without larger construction equipment.

Durable More stable and less permeable than alternate compacted backfill, reducing erosion and washouts
Versatile Adjustable to meet fill requirements.  Can be normal density (> 50 lbs/ft3) or lower density, (<50 lbs/ft3) for reducing weight or for reducing thermal transfer.
Flowable Fill

American Concrete Institute Certified Concrete Contractors

ACI Concrete Flatwork Certification Program

County Materials is a strong advocate for continuing education and a leader in providing industry resources and education for our customers.

The ACI began the Concrete Flatwork Finisher/Technician certification program in 1987 to provide a basis for certifying concrete finishers and improve the quality of concrete construction. More project owners and construction professionals specify that contractors have ACI-certified flatwork finishers onsite performing the work; they recognize the value of using ACI-certified finishers and technicians. ACI recertification is necessary every five years, and requires successful completion of a written examination. More information about the ACI Concrete Flatwork Certification Program is available at:


The following professional concrete contractors have successfully completed the American Concrete Institute (ACI) Concrete Flatwork Certification Program:
(Year listed after each certified business indicates the year they achieved certification)

  • Alan Iatonni Masonry (Irma, WI) Ph 715.297.776
  • Firkus Masonry (Stevens Point, WI) (2015)
  • Huotari Construction Ph 715.748.4000
  • SK Masonry (Stevens Point, WI) Ph 715.340.4449

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