Specs that only say “cellular concrete” leave the producer guessing which product family you mean. On Portland Metro and Pacific Northwest jobs, the first mix fork after cast density is usually neat cement versus cement + sand. Those bands are not interchangeable field switches — they change density range, strength potential, pump feel, and how the fill behaves in the ground.

This note is for engineers and contractors writing that choice into the documents. It is not a mix design and not a substitute for the engineer of record.

Two bands, one foam process

Cellular concrete and cellular grout are cement slurry plus preformed foam. The foam creates a stable air-cell matrix. Fresh, the material is flowable and self-consolidating. Hardened, it is a lightweight cementitious fill.

Within that process:

  • Neat cement mixes are cement + water slurry + foam (little or no aggregate). Industry practice often cites a cast-density band around ~20–60 pcf. That band maximizes lightweight benefit and pumpability. It is common for pipe and tank abandonment, annular / slip-liner grouting, and load-reduction backfill.
  • Cement + sand mixes add fine aggregate (sand) to raise density and strength, or to tune rheology. They sit higher on the density ladder — often into the ~90–125 pcf planning band on manufacturer charts — and behave closer to denser flowable fills while still using engineered foam.

Volume’s Cellular Backfill product line covers roughly 27–100 pcf, dialed upward when the engineer wants more density or strength. Featured packet example is about 38 pcf, non-permeating — a neat-cement-style lightweight fill Volume designs and guarantees to the agreed job specs when that mix is ordered. Sand is optional on the ticket when the documents call for a sanded band.

For a quick planning view across both bands, open the site density explorer. Treat the Aerix chart there as a manufacturer planning reference. Volume designs and guarantees the mix delivered to your project specs; the explorer is not a substitute for that guarantee.

When neat cement is usually the right call

Choose a neat (or lightly sanded) lightweight band when the job needs:

  1. Maximum load reduction on soft soils, abutments, or approach fills
  2. Pipe, culvert, or tank abandonment where flow into irregular voids matters more than high compressive strength
  3. Annular / slip-liner grouting where a lighter grout reduces uplift on the carrier compared with a heavy sand slurry
  4. Long hose runs at relatively low pump pressure compared with dense sand-cement CLSM
  5. Excavatability later — low-density cellular fills are often removable with conventional equipment, unlike over-strong aged lean concrete

Typical Portland cast targets in this band often land in the ~27–50 pcf range for abandonment and lightweight foundation / abutment backfill. Raise density within the neat band when buoyancy, cover, or a minimum strength note pushes you up — you do not automatically jump to a sanded mix just because the number moves from 30 to 45 pcf.

When sand belongs in the mix

Add sand (or otherwise move into a higher-density cellular band) when the engineer needs:

  1. Higher compressive strength than a light neat mix can deliver for the same acceptance age
  2. Higher unit weight for buoyancy control, cover, or traffic / surcharge criteria
  3. Rheology that a particular foam system and pump prefer at that density
  4. A fill that still uses foam technology but sits closer to conventional CLSM / flowable fill mass

Do not add coarse aggregate to “make it more like concrete.” Coarse rock defeats the lightweight purpose. Fine sand is the usual optional aggregate.

Also keep permeable vs non-permeable separate from the sand question. Open-cell (PLDCC) and closed-cell products are different chemistries. Sand does not turn a non-permeating fill into a drain layer.

Cast density stays the primary knob

Whether neat or sanded, field QC on cellular jobs is usually cast density (pcf) at the hose, not a vague “lightweight” label and not oven-dry density from a lab report.

  • Strength generally rises as density rises (more paste matrix, less air).
  • ACI / industry minimum strength tables at a given max density are floors, not typical producer averages.
  • Specify a minimum strength only when the structure or utility criteria need it — and name the age.
  • Day of placement, producers adjust foam-to-slurry ratio to stay on the cast-density target.

If cylinders are required, low-density specimens are fragile. Industry practice uses 3×6 in. cylinders, careful handling (do not rod like normal concrete), and ASTM C495-type prep — not oven-drying before crush.

Pumpability and placement still follow the same rules

Neat lightweight mixes are often easier to pump long distances than heavy sand slurry. That does not erase placement physics:

  • While plastic, cellular fill exerts full fluid hydrostatic pressure (cast density × depth) on forms, bulkheads, and liners
  • Typical lifts are about 4 ft unless the foam manufacturer and engineer of record allow more
  • Pipe and tank fills need bulkheads and high-point vents
  • Below the water table, cast density well under 62.4 pcf means buoyancy design — anchors, cover, geometry, staged lifts, or a higher specified density

What to write on the plans (and collect before dispatch)

A useful cellular call usually includes:

  1. Target cast density (pcf)
  2. Neat cement vs cement + sand (or an explicit density band that implies it)
  3. Permeable or non-permeable (different products, not a field switch)
  4. Minimum strength only if required (and at what age)
  5. Volume (yd³) or geometry we can estimate
  6. Application — pipe, annular / slip-liner, tank, foundation, abutment, void
  7. Lift thickness / sequence and any hold between lifts
  8. Pump access — staging, hose run, elevation
  9. Water table / buoyancy concerns
  10. Testing / submittals (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. For density planning across neat and sanded bands, open the density explorer.

Standards awareness — not a certificate wall

Literature cellular specs often cite includes 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 — standards awareness, not a certificate wall.

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. Featured 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 — the design Volume stands behind when that mix is ordered.

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 the documents only say “cellular” or “lightweight fill,” add cast density in pcf, neat vs sanded (or the density band), permeable vs not, volume, and access.