Inputs
Formula used
This calculator uses a planning-level heuristic linking dosage to PI, clay content, and improvement ratios. Estimated binder dosage as a percent of dry soil mass:
dosage% = clamp( (2 + 0.08·PI + 0.03·Clay
+ 0.50·ln(max(1, CBRt/CBR0)) + 0.40·ln(max(1, UCSt/UCS0)))
· typeFactor · (FoS/1.2), 2, 15 )
Quantity uses Volume = Area·Depth and Dry soil mass = Volume·Dry density. Moisture adjustment uses OMC ≈ 8 + 0.15·PI. Confirm final dosage using lab trials and specifications.
How to use this calculator
- Enter PI, clay content, and current CBR and UCS values.
- Set target CBR and UCS from your design requirements.
- Provide area, depth, and dry density to estimate treated mass.
- Select stabilizer type and enter delivered unit cost.
- Press Submit to view results above the form.
- Download CSV/PDF for estimating sheets and reports.
Example data table
Example scenarios for quick benchmarking (illustrative).
| Case | Soil | PI | CBR 0→T | UCS 0→T (kPa) | Area (m²) | Depth (m) | Suggested stabilizer |
|---|---|---|---|---|---|---|---|
| A | CL | 18 | 4→12 | 150→350 | 1000 | 0.25 | Cement |
| B | CH | 35 | 2→8 | 120→300 | 700 | 0.30 | Lime |
| C | SM | 10 | 6→15 | 180→420 | 1200 | 0.20 | Fly ash |
Replace these values with your lab results for the most reliable planning estimate.
Design inputs that control dosage
Dosage responds most strongly to Plasticity Index, clay percentage, and the improvement ratio between existing and target strength. For example, raising PI from 15 to 30 can increase the estimated binder content by roughly 1.2–1.5 percentage points, depending on targets. A CBR jump from 4 to 12 represents a 3.0× ratio, which increases the logarithmic term and pushes the recommendation upward.
Mass, volume, and bill of quantities
Quantity calculations are anchored in treated volume and dry density. A 1,000 m² area treated to 0.25 m yields 250 m³. At 1,700 kg/m³, the dry mass is about 425 t. With an 8% dosage, the stabilizer requirement is near 34 t, a practical number for delivery planning and stockpile sizing.
Moisture adjustment and compaction readiness
The water estimate compares current moisture to an optimum moisture proxy based on PI. If field moisture is 10% and the estimated optimum is 13%, the calculator adds about 3% water by dry mass. For 425 t of soil, that is roughly 12,750 kg of water. Use this as a starting point; confirm with compaction curves and site weather.
Strength targets and conservative factors
Targets should match the curing age and acceptance method in your specification. A factor of safety increases dosage when variability is high, such as mixed borrow sources or wet-season placement. Moving FoS from 1.2 to 1.4 increases dosage by about 17%. Apply conservatism to the weakest stratum, not the average layer, to reduce rework risk.
Cost and carbon screening
The cost line multiplies binder tonnes by unit price. If cement costs 120 per tonne and dosage requires 34 t, the binder cost is about 4,080, excluding equipment and QA. The CO2e proxy helps compare options: cement typically carries a higher factor than industrial byproducts. Use it for alternatives analysis, not for formal reporting.
Production mixing controls
Field performance depends on distribution and curing. Maintain consistent spread rate, mix depth, and moisture conditioning. Verify with test strips and frequent density checks. If early UCS is low, adjust moisture, mixing energy, or dosage rather than extending compaction delay. Document daily quantities and results; this supports pay items, traceability, and acceptance decisions. Capture weather, haul sources, and mixing passes each shift.
FAQs
1) Is this dosage a final mix design?
No. It is a planning estimate based on PI, clay, and target improvements. Confirm dosage with laboratory trials, curing conditions, and project specifications before construction.
2) Which strength input should I trust more, CBR or UCS?
Use the metric tied to your acceptance criteria. Road subgrades often use soaked CBR, while treated layers may use UCS at a defined curing age. Enter both when available for balanced guidance.
3) Why does increasing targets raise dosage nonlinearly?
The calculator uses logarithmic improvement ratios. Large jumps, such as 3× or 4×, increase the ratio terms more than small improvements. This reflects diminishing returns typical in binder-treated soils.
4) What dry density should I use?
Use the lab maximum dry density for the intended compaction effort when available. If unknown, use a conservative estimate based on similar materials and update after compaction testing to refine quantities.
5) How should I interpret the water requirement?
It estimates added water needed to approach optimum moisture. It does not account for evaporation, rainfall, or binder hydration demand. Always verify moisture in the field and adjust during mixing and compaction.
6) Can I compare stabilizer types with this tool?
Yes, for early screening. Type factors and CO2e proxies help compare options quickly. Final selection should consider soil chemistry, availability, curing time, durability, and specification requirements.