ACI Concrete Mix Design Calculator (Absolute Volume Method)

This professional-grade calculator implements the ACI 211.1 Absolute Volume Method to proportion concrete mixes. It’s built for structural engineers, mix designers, QC technicians, and contractors who need fast, traceable, and accessible results in SI or US units.

Authoritative Data Source and Methodology

Primary Reference: ACI Committee 211, “ACI 211.1 — Standard Practice for Selecting Proportions for Normal, Heavyweight, and Mass Concrete” (e.g., ACI 211.1-91, reapproved 2009 and subsequent editions). American Concrete Institute, Farmington Hills, MI. https://www.concrete.org

Tutti i calcoli si basano rigorosamente sulle formule e sui dati forniti da questa fonte.

This tool operationalizes the Absolute Volume Method per ACI 211.1: the sum of absolute volumes of all ingredients plus entrained air equals the target concrete volume (1 m³ or 1 yd³). Users should obtain water contents and coarse aggregate bulk volume fractions from the standard ACI tables, project specifications, or laboratory trial mixes.

The Formula Explained

Given a unit concrete volume V = 1 (m³ or yd³), water content W, water–cement ratio r, air content a (%), coarse aggregate bulk fraction φ (from ACI table), dry-rodded unit weight γDRUW, and specific gravities G:

1) Cement mass: \( C = \dfrac{W}{r} \)

2) Unit water density: \( \rho_w = \begin{cases}1000 \;\text{kg/m}^3 & \text{(SI)} \\ 1684.8 \;\text{lb/yd}^3 & \text{(US)}\end{cases} \)

3) Volumes (in same unit as V): \( V_w = \dfrac{W}{\rho_w}, \quad V_c = \dfrac{C}{G_c \,\rho_w}, \quad V_a = \dfrac{a}{100} \)

4) Coarse aggregate mass per unit: \( M_{ca}^{OD} = \phi \cdot \gamma_{DRUW} \cdot \begin{cases}1 & \text{(SI, m}^3) \\ 27 & \text{(US, ft}^3/\text{yd}^3)\end{cases} \)

5) Coarse aggregate absolute volume: \( V_{ca} = \dfrac{M_{ca}^{OD}}{G_{ca}\,\rho_w} \)

6) Fine aggregate absolute volume (by remainder): \( V_{fa} = 1 - (V_w + V_c + V_a + V_{ca}) \)

7) Fine aggregate SSD mass: \( M_{fa}^{SSD} = V_{fa} \cdot G_{fa} \cdot \rho_w \)

8) Moisture corrections (optional), using absorptions A (%) and actual moistures m (%), both over OD basis:
\( M_{ca}^{batched} = M_{ca}^{OD} \cdot \left(1 + \dfrac{m_{ca}}{100}\right) \)
\( M_{fa}^{OD} = \dfrac{M_{fa}^{SSD}}{1 + A_{fa}/100},\quad M_{fa}^{batched} = M_{fa}^{OD}\cdot\left(1 + \dfrac{m_{fa}}{100}\right) \)
Aggregate water contribution: \( \Delta W = M_{fa}^{OD}\!\left(\dfrac{m_{fa}-A_{fa}}{100}\right) + M_{ca}^{OD}\!\left(\dfrac{m_{ca}-A_{ca}}{100}\right) \)
Batch water to add: \( W_{batch} = W - \Delta W \)

Glossary of Variables

  • W: Mixing water content per unit concrete (kg/m³ or lb/yd³)
  • r (w/c): Water–cement ratio by mass (–)
  • C: Cement content per unit concrete (kg/m³ or lb/yd³)
  • a: Entrained air content (%) as percent of concrete volume
  • φ: Coarse aggregate bulk volume fraction (volume of dry-rodded CA per unit volume of concrete)
  • γDRUW: Dry-rodded unit weight of coarse aggregate (kg/m³ or lb/ft³)
  • G: Specific gravity (SSD) of cement or aggregate (–)
  • Vw, Vc, Vca, Vfa: Absolute volumes (m³ or yd³) per unit concrete volume
  • McaOD: Coarse aggregate oven-dry mass (kg/m³ or lb/yd³)
  • MfaSSD: Fine aggregate SSD mass (kg/m³ or lb/yd³)
  • Absorption A (%), Moisture m (%): Over OD basis

How It Works: A Step-by-Step Example

Assume SI units, 1 m³ of concrete, W = 180 kg/m³, w/c = 0.50, a = 2.0%, φ = 0.67 (19 mm MNSA), γDRUW = 1600 kg/m³, Gc=3.15, Gfa=2.65, Gca=2.65.

  1. Cement: C = 180 / 0.50 = 360 kg/m³.
  2. Volumes: ρw = 1000 kg/m³. Vw = 180/1000 = 0.180 m³; Vc = 360/(3.15·1000) ≈ 0.114 m³; Va = 0.020 m³.
  3. Coarse aggregate OD mass: McaOD = φ·γDRUW = 0.67·1600 ≈ 1072 kg/m³.
  4. Coarse aggregate volume: Vca = 1072/(2.65·1000) ≈ 0.405 m³.
  5. Fine aggregate volume: Vfa = 1 − (0.180 + 0.114 + 0.020 + 0.405) = 0.281 m³.
  6. Fine aggregate mass (SSD): MfaSSD = 0.281·2.65·1000 ≈ 744 kg/m³.
  7. Optional moisture: if Afa = 1.5%, mfa = 3.0%, Aca = 0.8%, mca = 1.0% then aggregate water contribution ΔW ≈ MfaOD·(3.0−1.5)% + McaOD·(1.0−0.8)% ⇒ Wbatch ≈ 180 − ΔW.

Always verify φ and W from ACI tables or trial mixes; then adjust via field QC.

Frequently Asked Questions (FAQ)

Does this tool enforce any durability limits?

No. Enter w/c and air content according to ACI 318 exposure classes and your specification. The tool performs the arithmetic precisely.

Where do I get the coarse aggregate fraction φ?

From ACI 211.1 Table for the dry-rodded coarse aggregate volume fraction (depends on fineness modulus and MNSA). Use lab trial mixes for final verification.

Can I use supplementary cementitious materials (SCMs)?

Yes, in practice. Treat total binder as “cement” for preliminary proportioning, then refine with SCM replacement percentages and adjust water demand accordingly.

What happens if the fine aggregate volume becomes negative?

Your inputs are infeasible (too much water/cement/air/coarse aggregate). Reduce water or φ, or adjust w/c and air content.

How accurate is the moisture correction?

It follows standard OD/SSD adjustments. Use daily moisture tests to supply accurate absorption and actual moisture values.

Which unit density of water is used?

1000 kg/m³ for SI and 1684.8 lb/yd³ for US customary (62.4 lb/ft³ × 27 ft³/yd³).

Tool developed by Ugo Candido. Content verified by CodeConcrete Editorial.
Last reviewed for accuracy on: .