On many Portland Metro and Pacific Northwest specs, “cellular concrete” or “cellular grout” shows up as a single line item. That is incomplete. Permeable and non-permeable cellular fills are different products — different foam chemistries, different drainage behavior after set — not a field switch on the same truck.
This note is for engineers and contractors deciding which one belongs on the plans. It is not a mix design and not a substitute for the engineer of record.
Same family, different drainage intent
Both products start the same way: a cement slurry plus preformed foam, placed by hose, controlled mainly by cast density at placement. After the foam dissipates and the paste hydrates, you get a hardened cellular mass — light, flowable when fresh, cementitious when set.
The fork is what happens to water after the fill hardens:
- Non-permeable (closed-cell / non-permeating) — the air-cell structure is intended to limit water transmission through the mass. Common for pipe and tank abandonment, many foundation and abutment backfills, and fills where the void should not become a drain path.
- Permeable (PLDCC / open-cell) — specialized open-cell foam chemistry leaves interconnected pathways so water can move through the set mass. Used when drainage through the fill is part of the design: permeable wall backfill, drainage layers, some road-base or field applications, and other jobs where flow-through is specified.
Say which one you want in writing. If the documents are silent, ask before the foam generator starts.
When non-permeable is the usual call
Most abandonment and many structural backfill jobs want a permanent fill that does not act like a French drain through the mass:
- Full-pipe, culvert, and tank decommissioning where groundwater should not short-circuit through the abandoned void
- Foundation and abutment backfill where the engineer is controlling load and lateral pressure, not designing the fill as a drainage medium
- Annular / slip-liner grouting when the intent is a sealed annular space, not a permeable sleeve
Volume Concrete’s featured Cellular Backfill packet example is about 38 pcf, non-permeating, with packet maturity on the order of 104 / 144 / 180 psi at 7 / 14 / 28 days for that specific mix. That is the design Volume stands behind when that mix is ordered. Density still ranges from about 27 pcf upward (toward ~100 pcf) when the engineer specifies a different cast density.
Important limit: closed-cell fill is not automatic waterproofing. Walls still need the drains, weep systems, and collection the structure was designed with. Do not treat “non-permeable cellular” as a substitute for a waterproofing membrane or a designed drainage plane.
When permeable (PLDCC) belongs on the plans
Specify open-cell / permeable cellular concrete only when water is meant to move through the set fill:
- Retaining-wall or foundation backfill designed as a drainage layer
- Permeable road or paving bases where cellular fill is the engineered drainable layer
- Sports-field, landscaping, or similar bases that need both light weight and permeability
- Other geotech applications where the engineer’s drainage calc assumes flow through the cellular mass
Industry open-cell processes (for example Aerix AQUAERiX-type PLDCC) are a different foam system from closed-cell abandonment foam. Density bands in manufacturer literature are often still in a lightweight geotech range, but confirm project-specific mix data — do not copy a closed-cell packet strength into a permeable line item.
If the job needs both load reduction and drainage, that is an engineering choice: permeable cellular fill, conventional drain rock plus a lighter non-permeable fill elsewhere, or another designed system. It is not “use the same foam and hope.”
Cast density still comes first
Whether the fill is permeable or not, write cast density at placement in pcf. “Lightweight” and “cellular” are not numbers.
Cellular Backfill starts at about 27 pcf and is dialed upward when higher density or strength is required. Industry practice often puts many abandonment and annular jobs in roughly the mid-20s to mid-40s pcf, and many wall / abutment backfills in roughly the ~30–50 pcf band when load reduction and flowability matter — but your plans need the project number.
If the documents also need a minimum strength, write the age and the psi. Density still comes first. Do not invent a psi table from memory. Use the on-site density explorer for Aerix chart interpolations when you are planning. Volume designs and guarantees the mix delivered to your project specs.
Neat cement mixes emphasize the lightest, most pumpable band; fine sand raises density and strength when the engineer wants a sanded family. Sand vs neat is a second knob — orthogonal to permeable vs not.
Buoyancy, lifts, and fluid pressure (both products)
Fresh water is about 62.4 pcf. Any fill cast well below that is lighter than the water it can displace. In a flooded excavation, pipe, or tank, lightweight cellular fill can float or lift if placement is not staged and anchored as designed. Treat buoyancy as a design item whenever specified density is ≪ 62.4 pcf — for permeable and non-permeable alike.
While plastic, cellular concrete exerts full fluid hydrostatic pressure (cast density × depth). Forms, bulkheads, liners, and thin walls must resist that load during placement. After set (often within roughly 8–24 hours depending on conditions), that fluid pressure drops for permanent design purposes.
Placement is usually done in lifts. A typical starting point is about 4 feet unless the foam system and the engineer allow more. Thicker lifts are possible with the right foam. They are not a default on a deep tank or tall abutment.
Spec sheet: collect this before dispatch
A useful cellular call that involves this choice usually includes:
- Permeable or non-permeable (required — do not leave blank)
- Target cast density (pcf)
- Minimum strength only if required (and at what age)
- Volume (yd³) or geometry we can estimate
- Application — pipe, annular / slip-liner, tank, foundation, abutment, drainage backfill, void
- Pump access — staging, hose run, elevation, lift limits
- Water table / buoyancy concerns and drainage intent
- Sand or neat if the engineer cares about mix family
- Testing / submittals expected (cast-density logs, cylinders, foam or cement certs)
Phone for dispatch: (971) 219-8604.
Volume estimating for pipes, annular spaces, and common tanks: use the site calculators. Optional overage covers hose waste and irregular voids — agree on it before dispatch.
Standards awareness — not a certificate wall
Literature and test methods cellular specs often cite include ASTM C495, ASTM C796, ASTM C869, and ACI 523.1R. Volume’s Cellular Backfill mixes are developed in accordance with ACI 301 and ASTM C685, C1602, C150, and C1600.
That is standards awareness, not a wall of invented certificates. If the job needs cylinders or a named acceptance criterion, put it in the documents.
How we cover the Portland Metro and PNW
Cellular Backfill is a product line of Volume Concrete LLC. Production uses volumetric trucks and mobile silos — Type IL cement (Ash Grove Durkee OR in the featured packet), Aerix foam systems, sand optional, permeable and non-permeable as specified. Everyday ready-mix stays in Greater Portland Metro; cellular jobs travel the Pacific Northwest when this product is on the ticket. Home base is Estacada, Oregon (city only — no plant street published here).
Confirm the jobsite on the call. Service area details live on the service area page.
Public NAP (billing / postal, not a plant street):
Volume Concrete LLC
4230 SE King Rd. #211
Milwaukie, OR 97222
(971) 219-8604
If you are writing a cellular fill spec and the only open question is whether water should move through the set mass, pick permeable or non-permeable on purpose — then call with density, volume, and access. Same facts sit on the calculators, density explorer, and related notes on pipe/tank abandonment, foundation/abutment backfill, and cellular vs CLSM.