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

instrument implementation / implementation-contract

# Concrete Mix Design Calculator (ACI Method, Simplified) implementation

A source-bound implementation contract for Concrete Mix Design Calculator (ACI Method, Simplified); deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t7-077

**Effect**: Computation or source lookup only

## Input and validation requirements

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.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "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."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/concrete-mix-design-calculator-aci-method-simplified/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/concrete-mix-design-calculator-aci-method-simplified/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/concrete-mix-design-calculator-aci-method-simplified/qualification/>)

## Sources and evidence

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

- `VERIFIED_LEDGER.json`

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