Source: https://guthlabs.ai/docs/instruments/concrete-mix-design-calculator-aci-method-simplified/

instrument / verified-clean

# Concrete Mix Design Calculator (ACI Method, Simplified)

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Inspectable records

[01**Overview**Purpose and lifecycle](<https://guthlabs.ai/docs/instruments/concrete-mix-design-calculator-aci-method-simplified/>)[02**Mechanism**Method and assumptions](<https://guthlabs.ai/docs/instruments/concrete-mix-design-calculator-aci-method-simplified/mechanism/>)[03**Implementation**Binding and validation](<https://guthlabs.ai/docs/instruments/concrete-mix-design-calculator-aci-method-simplified/implementation/>)[04**Qualification**Evidence and errata](<https://guthlabs.ai/docs/instruments/concrete-mix-design-calculator-aci-method-simplified/qualification/>)

## Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

**Area**: Mechanical, Civil & Structural Engineering — Statics/Dynamics, Strength of Materials, Machine Design, Civil, HVAC, Vibration

**Tranche**: tranche-7

**Evidence ID**: t7-077

**Ledger rows**: 1

No ledger note is attached.

## Review findings

NEEDS_REVIEW because the stated instrument inputs and formula description are insufficient to implement a reproducible ACI 211.1 design. The vectors use clearly identified representative ACI-style table fragments and added material-property assumptions solely to make the arithmetic independently computable. Production implementation must identify the exact ACI edition/table revision, include all required aggregate and air inputs, define interpolation and exposure-governing rules, apply moisture corrections, and check applicable ACI code limits.

### Formula and scope findings

- The specification does not provide the actual ACI 211.1 lookup-table values or define how to select between strength-based and exposure-based maximum water-cement ratios.

- Water-cement ratio is not determined solely by target f'c; the governing value must be the lower of the strength requirement and the applicable exposure limit, with applicable minimum cement and durability requirements also checked.

- A complete ACI absolute-volume design requires aggregate specific gravities, coarse-aggregate dry-rodded unit weight, fine-aggregate fineness modulus, entrapped or entrained air, and aggregate moisture/absorption corrections. These are absent from the declared inputs.

- A yield check based only on summed masses is not valid. Yield must be checked by absolute component volumes, and the fine aggregate quantity must be solved from the absolute-volume equation.

- The simplified method does not specify interpolation rules for target strength, slump, or aggregate size when values fall between table entries.

- ACI 211.1 mix design is not validated merely by a yield check; trial batches and measured slump, air, strength, and unit weight are required before structural use.

### Unit assumptions

- Test vectors use SI quantities per m³ unless explicitly marked yd³.

- Target compressive strength f'c is entered in psi because the referenced ACI strength table is conventionally tabulated in psi.

- Slump is entered in inches and nominal maximum aggregate size in inches.

- Water and aggregate quantities are SSD-basis quantities; no aggregate moisture or absorption correction is applied in these vectors.

- Cement specific gravity is assumed to be 3.15, coarse aggregate specific gravity 2.65, and fine aggregate specific gravity 2.60.

- Entrapped air is assumed to be 2.0% by volume for these non-air-entrained examples.

## Boundary hardening

**BREAK_CLAIMED** · SELF_FLAGGED

The calculator breaks on a zero maximum aggregate size because the required table lookup is undefined, and it is vulnerable to materially different behavior when target-strength units are entered without an explicit psi-versus-kPa convention.

## Errata and corrections

No applied erratum is attached to this unique-name record.

## Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

````
{
  "inputs": {
    "target_fc_psi": 4000,
    "slump_in": "3-4",
    "max_aggregate_size_in": 0.75,
    "exposure_class": "mild",
    "fine_aggregate_fineness_modulus": 2.8,
    "coarse_aggregate_dry_rodded_unit_weight_kg_m3": 1600,
    "output_unit": "kg/m3"
  },
  "expected_outputs": {
    "water_kg_m3": 205,
    "water_cement_ratio": 0.48,
    "cement_kg_m3": 427.083,
    "coarse_aggregate_kg_m3": 992,
    "fine_aggregate_kg_m3": 689.204,
    "absolute_volume_yield_m3": 1
  },
  "reference_data": {
    "water_kg_m3_for_non_air_entrained_concrete": {
      "slump_in": "3-4",
      "max_aggregate_size_in": 0.75,
      "value": 205,
      "source_convention": "ACI 211.1 water-content table, commonly reproduced standard value"
    },
    "strength_water_cement_ratio": {
      "target_fc_psi": 4000,
      "value": 0.48,
      "source_convention": "ACI 211.1 strength-to-w/c table, commonly reproduced standard value"
    },
    "exposure_max_water_cement_ratio": {
      "exposure_class": "mild",
      "value": 0.6,
      "source_convention": "ACI 318 durability convention, mild exposure maximum w/c"
    },
    "coarse_aggregate_volume_fraction": {
      "fine_aggregate_fineness_modulus": 2.8,
      "max_aggregate_size_in": 0.75,
      "value": 0.62,
      "source_convention": "ACI 211.1 coarse-aggregate volume table, commonly reproduced standard value"
    },
    "coarse_aggregate_dry_rodded_unit_weight_kg_m3": 1600,
    "source_convention_for_coarse_unit_weight": "Widely tabulated standard value for normal-weight aggregate",
    "cement_specific_gravity": 3.15,
    "source_convention_for_cement_specific_gravity": "Widely tabulated standard value",
    "coarse_aggregate_specific_gravity": 2.65,
    "source_convention_for_coarse_specific_gravity": "Widely tabulated standard value",
    "fine_aggregate_specific_gravity": 2.6,
    "source_convention_for_fine_specific_gravity": "Widely tabulated standard value",
    "entrapped_air_fraction": 0.02,
    "source_convention_for_air_fraction": "ACI 211.1 non-air-entrained normal-weight concrete design assumption"
  },
  "working": "1. Strength w/c = 0.48. Exposure limit = 0.60, so governing w/c = min(0.48, 0.60) = 0.48. 2. Cement = water/(w/c) = 205/0.48 = 427.083 kg/m³. 3. Coarse aggregate = 0.62 × 1600 = 992 kg/m³. 4. Cement volume = 427.083/(3.15×1000) = 0.135582 m³. Water volume = 205/1000 = 0.205000 m³. Coarse aggregate volume = 992/(2.65×1000) = 0.374340 m³. Air volume = 0.020000 m³. 5. Fine aggregate volume = 1.000000 − 0.135582 − 0.205000 − 0.374340 − 0.020000 = 0.265078 m³. Fine aggregate mass = 0.265078×2.60×1000 = 689.204 kg/m³. 6. Absolute-volume yield = 0.135582 + 0.205000 + 0.374340 + 0.265078 + 0.020000 = 1.000000 m³."
}
````

## Related workflows

No source-defined multi-instrument workflow membership is recorded.

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json · VERIFIED_CLEAN`

- `evidence-tranche7/tranche7-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`