# Open3DCP v1.5

**Open Data Standard for 3D Concrete Printing**

> **v1.5 (2026-04-16):** Pigment columns: `iron_oxide_pigment`, `titanium_dioxide_pigment`, `chromium_oxide_pigment`, `carbon_black_pigment`, `pigment_other`. Pigments are ultra-fine (~1 um), used at 1-5% in architectural 3DCP, with significant impact on packing, water demand, and microstructure. Total: 239 columns.
>
> **v1.4 (2026-04-16):** Alkali-activated material (AAM) columns: `sodium_hydroxide`, `sodium_silicate`, `potassium_hydroxide`, `potassium_silicate`, `activator_ms_ratio`, `na2o_dosage_pct`, `nano_clay`, `mineral_powder`, `mwcnt`, `graphene_oxide`, `rice_husk_ash`, `recycled_sand`. Total: 234 columns.
>
> **v1.3 (2026-04-16):** Added `cellulose_fiber`, `sorptivity_secondary_mm_sqrt_s`. Removed 3 redundant columns. Total: 222 columns.
>
> **v1.2 (2026-04-15):** 11 durability/transport columns (ASTM C642, C1202, C666, C157, C1585, C231, interlayer bond). Claude prompt caching for extraction. Relaxed minimum-bar gate: accepts any measurement, not just compressive.
>
> **v1.1 (2026-04-15):** Added `cement_type_2/3/4`, `hpmc`, `vma`, `shrinkage_reducer`, `pe_fiber`. 150+ material aliases seeded.

A flat database schema for 3D-printable concrete (3DCP) mix design data. Open3DCP captures materials, process parameters, fresh-state rheology, hardened mechanical properties, durability performance, and environmental impact in a single table designed for direct ML training.

---

## Design Principles

1. **Flat schema** -- Every feature is a named column, no JSON parsing required for ML.
2. **Mass-percent basis** -- All material quantities stored as mass-% of total wet mix (water included). Consistent across datasets, eliminates density assumptions.
3. **ASTM/RILEM-aligned** -- Column naming follows established standards: ASTM C150 (cement types), ASTM C618 (fly ash), ASTM C989 (slag), ASTM C1240 (silica fume), ASTM C33 (aggregate grading by fineness modulus).
4. **3DCP-native** -- First-class columns for print process parameters (nozzle, layer, speed, pump), rheology (yield stress, thixotropy, open time), and interlayer properties that don't exist in conventional concrete schemas.
5. **Multi-age** -- Companion `strength_measurements` table stores multi-age data (1, 3, 7, 14, 28, 56, 90, 365 days).

---

## Units Convention

All values in Open3DCP are stored in **SI/metric units**. This is consistent with international research practice and simplifies ML training (no mixed-unit columns). For US users accustomed to imperial units, a conversion reference:

| Metric (stored) | US Equivalent | Conversion |
|-----------------|---------------|------------|
| MPa | psi | 1 MPa = 145.04 psi |
| mm | inches | 25.4 mm = 1 inch |
| kg/m3 | lb/yd3 | 1 kg/m3 = 1.686 lb/yd3 |
| bar | psi | 1 bar = 14.504 psi |
| meters | feet | 1 m = 3.281 ft |
| C | F | F = C × 9/5 + 32 |
| m/s | mph | 1 m/s = 2.237 mph |
| Pa | psi | 1 Pa = 0.000145 psi |

---

## Main Table: `mix_designs`

### Identity & Versioning

| Column | Type | Description |
|--------|------|-------------|
| `id` | integer | Auto-increment primary key |
| `mix_id` | varchar | Unique human-readable identifier |
| `name` | varchar | Descriptive name |
| `parent_mix_id` | varchar | Links to parent formulation if this is a variant or iteration |
| `version` | varchar | Formulation version string |
| `created_at` | timestamptz | Record creation timestamp |

### Binder Materials (mass-% of total wet mix)

Cements are classified by ASTM C150 / EN 197-1 type. SCMs follow their respective ASTM standards.

| Column | Type | Description | Standard |
|--------|------|-------------|----------|
| `cement_type_1` | real | General purpose Portland cement | ASTM C150 Type I |
| `cement_type_1_2` | real | General purpose / moderate sulfate resistance (most commonly sold cement in the US) | ASTM C150 Type I/II |
| `cement_type_1l` | real | Portland-limestone cement (6-20% limestone) | ASTM C595 / EN 197-1 CEM II/A-L |
| `cement_type_2` | real | Moderate sulfate resistance, moderate heat of hydration | ASTM C150 Type II |
| `cement_type_3` | real | High early strength / rapid hardening | ASTM C150 Type III |
| `cement_type_4` | real | Low heat of hydration (rarely manufactured) | ASTM C150 Type IV |
| `cement_type_5` | real | High sulfate resistance (required in sulfate-rich soils, common in western US) | ASTM C150 Type V |
| `cac` | real | Calcium aluminate cement (Ciment Fondu) | EN 14647 |
| `csa_cement` | real | Calcium sulfoaluminate cement | -- |
| `fly_ash` | real | Fly ash (class not specified in source) | -- |
| `fly_ash_type_f` | real | Class F fly ash (SiO2+Al2O3+Fe2O3 ≥ 70%) | ASTM C618 |
| `fly_ash_type_c` | real | Class C fly ash (SiO2+Al2O3+Fe2O3 ≥ 50%) | ASTM C618 |
| `silica_fume` | real | Silica fume / microsilica | ASTM C1240 |
| `nano_silica` | real | Nano-SiO2 (colloidal or fumed, <100 nm) | -- |
| `slag` | real | Ground granulated blast furnace slag (GGBS) | ASTM C989 |
| `metakaolin` | real | Calcined kaolin clay | ASTM C618 Class N |
| `limestone` | real | Limestone filler / calcium carbonate | EN 12620 |
| `pumice` | real | Natural pozzolan (pumice) | ASTM C618 Class N |
| `bottom_ash` | real | Coal bottom ash | -- |
| `rice_husk_ash` | real | Rice husk ash (pozzolan) | -- |

### Alkali Activators (mass-% of total wet mix)

For alkali-activated materials (AAM), the activator solution replaces water as the liquid phase. Record activator components as mass-% of total wet mix (including activator solution mass). Use `activator_ms_ratio` and `na2o_dosage_pct` to capture the key AAM design parameters.

| Column | Type | Description |
|--------|------|-------------|
| `sodium_hydroxide` | real | NaOH (mass-%, purity-adjusted solids) |
| `sodium_silicate` | real | Sodium silicate solution / waterglass (mass-%, as-delivered liquid) |
| `potassium_hydroxide` | real | KOH (mass-%, purity-adjusted solids) |
| `potassium_silicate` | real | Potassium silicate solution (mass-%, as-delivered liquid) |
| `activator_ms_ratio` | real | SiO2/Na2O molar modulus of the activator solution |
| `na2o_dosage_pct` | real | Na2O as % of binder mass (common AAM reporting convention) |

### Additional Modifiers (mass-% of total wet mix)

| Column | Type | Description |
|--------|------|-------------|
| `nano_clay` | real | Nano clay / montmorillonite / nanoclay (rheology modifier for AAM and OPC 3DCP) |
| `mineral_powder` | real | Generic mineral powder / filler (common in Chinese 3DCP literature) |
| `mwcnt` | real | Multi-walled carbon nanotubes |
| `graphene_oxide` | real | Graphene oxide / reduced graphene oxide (rGO) |
| `recycled_sand` | real | Recycled concrete aggregate sand |

### Pigments (mass-% of total wet mix)

Pigments are ultra-fine particles (~1 um) used at 1-5% in architectural 3DCP. At these dosages they significantly affect particle packing, water demand, and microstructure due to their high surface area and surface energy. The schema tracks pigment mass-% separately from fillers because their rheological and microstructural effects are distinct from inert fillers.

| Column | Type | Description |
|--------|------|-------------|
| `iron_oxide_pigment` | real | Iron oxide pigment — red (Fe2O3), yellow (FeOOH), black (Fe3O4), or brown blends. Most common concrete pigment. |
| `titanium_dioxide_pigment` | real | TiO2 white pigment. Also used for photocatalytic self-cleaning surfaces. |
| `chromium_oxide_pigment` | real | Cr2O3 green pigment |
| `carbon_black_pigment` | real | Carbon black pigment (distinct from coal bottom ash or fly ash) |
| `pigment_other` | real | Other/unspecified pigment (record type in `provenance_notes`) |

### Aggregate Materials (mass-% of total wet mix)

Sand is classified using US industry ordering terms. Fineness modulus (FM) ranges are adapted from ASTM C33 grading principles; note that ASTM C33 defines fine aggregate as FM 2.3-3.1 without further subdivision. Coarse aggregates are limited to pumpable sizes for 3DCP (ASTM C33 Size #8 and #89). Larger aggregates (Size #7 and above) are omitted as they cannot be pumped by standard 3DCP equipment; contact us for custom large-aggregate schema extensions.

| Column | Type | Description | ASTM C33 / FM | Typical US Order Name |
|--------|------|-------------|---------------|----------------------|
| `mason_sand` | real | Very fine sand, high fines content | FM 1.0-1.8 | Mason sand / plaster sand |
| `fine_sand` | real | Fine concrete sand | FM 1.6-2.2 | Fine sand |
| `concrete_sand` | real | Standard concrete sand (most common in US 3DCP) | FM 2.3-3.0 | Concrete sand / C33 sand |
| `coarse_sand` | real | Coarse washed sand | FM 3.1-3.7 | Coarse sand / torpedo sand |
| `agg_size_89` | real | Very fine gravel (3/8" - #16 sieve, 9.5-1.18 mm) | ASTM C33 Size #89 | #89 stone |
| `agg_size_8` | real | Fine pea gravel (3/8" - #8 sieve, 9.5-2.36 mm) | ASTM C33 Size #8 | Pea gravel / #8 stone |
| `agg_size_7` | real | 1/2" - #4 (12.5-4.75 mm) | ASTM C33 Size #7 | #7 stone |
| `agg_size_67` | real | 3/4" - #4 (19-4.75 mm) | ASTM C33 Size #67 | Common structural |
| `agg_size_6` | real | 3/4" - 3/8" (19-9.5 mm) | ASTM C33 Size #6 | #6 stone |
| `agg_size_57` | real | 1" - #4 (25-4.75 mm) | ASTM C33 Size #57 | Most common US concrete |
| `agg_size_5` | real | 1" - 1/2" (25-12.5 mm) | ASTM C33 Size #5 | #5 stone |
| `agg_size_467` | real | 1.5" - #4 (37.5-4.75 mm) | ASTM C33 Size #467 | Common ready-mix |
| `agg_size_4` | real | 1.5" - 3/4" (37.5-19 mm) | ASTM C33 Size #4 | #4 stone |
| `agg_size_357` | real | 2" - #4 (50-4.75 mm) | ASTM C33 Size #357 | Crusher run |
| `agg_size_3` | real | 2" - 1" (50-25 mm) | ASTM C33 Size #3 | #3 stone |
| `agg_size_2` | real | 2.5" - 1.5" (63-37.5 mm) | ASTM C33 Size #2 | #2 stone |
| `agg_size_1` | real | 3.5" - 1.5" (90-37.5 mm) | ASTM C33 Size #1 | Large stone |

Note: Most 3DCP systems are limited to Size #8 or smaller due to pump and nozzle constraints. Sizes #7 and above are included for large-nozzle systems, conventional concrete compatibility, and completeness as a global standard.

### Fiber Reinforcement (mass-% of total wet mix)

| Column | Type | Description |
|--------|------|-------------|
| `steel_fiber` | real | Steel fiber (hooked, crimped, or micro) |
| `pp_fiber` | real | Polypropylene fiber |
| `glass_fiber` | real | Alkali-resistant glass fiber |
| `carbon_fiber` | real | Carbon fiber |
| `pva_fiber` | real | Polyvinyl alcohol fiber |
| `basalt_fiber` | real | Basalt fiber |
| `nylon_fiber` | real | Nylon fiber |
| `aramid_fiber` | real | Aramid fiber (Kevlar) |
| `cellulose_fiber` | real | Natural cellulose fiber per ASTM D7357 |
| `fiber_length_mm` | real | Fiber length (mm). Industry example: Dramix 3D 65/35 = 35 mm |
| `fiber_diameter_mm` | real | Fiber diameter (mm). Required to calculate aspect ratio |
| `fiber_aspect_ratio` | real | Length-to-diameter ratio (L/d). THE key fiber performance parameter. Example: Dramix 65/35 has L/d = 65 |
| `fiber_tensile_strength_mpa` | real | Fiber tensile strength as specified by supplier |

### Chemical Admixtures (mass-% of total wet mix)

**Important:** Admixture values in this schema represent **solids content by mass-%** of total wet mix. Most commercial admixtures are sold as liquid solutions (typically 20-40% solids by weight). When recording data from a liquid product, convert to solids content using the manufacturer's technical data sheet. For example, a PCE superplasticizer dosed at 1.0% liquid with 30% solids content should be recorded as 0.3% in this schema.

| Column | Type | Description |
|--------|------|-------------|
| `superplasticizer` | real | High-range water reducer (PCE, SNF, SMF) -- ASTM C494 Type F/G. Record as solids content. |
| `water_reducer` | real | Mid/normal-range water reducer -- ASTM C494 Type A |
| `accelerator` | real | Set/strength accelerator -- ASTM C494 Type C/E |
| `calcium_formate` | real | Organic salt accelerator (Ca(HCOO)2), promotes early C3S hydration. Used as set accelerator; not formally classified under ASTM C494 |
| `retarder` | real | Set retarder -- ASTM C494 Type B/D |
| `air_entrainer` | real | Air-entraining admixture -- ASTM C260 |
| `vma` | real | Viscosity-modifying admixture (generic) |
| `shrinkage_reducer` | real | Shrinkage-reducing admixture |
| `corrosion_inhibitor` | real | Corrosion-inhibiting admixture |

### Clay / VMA Additives (mass-% of total wet mix)

Specialized rheology modifiers for 3DCP thixotropy and shape retention.

| Column | Type | Description | Mineral Class |
|--------|------|-------------|---------------|
| `hpmc` | real | Hydroxypropyl methylcellulose (cellulose ether VMA) | Organic polymer |
| `sepiolite_clay` | real | Sepiolite clay (fiber-network thixotropy) | Chain silicate |
| `attapulgite` | real | Attapulgite / palygorskite (fiber-network, US domestic) | Chain silicate |
| `calcium_bentonite` | real | Calcium bentonite (low-moderate swell) | Smectite |

### Water & Ratios

| Column | Type | Description |
|--------|------|-------------|
| `water` | real | Total mix water (mass-% of total wet mix) |
| `w_c_ratio` | real | Water-to-cement ratio (water / cement only) |
| `w_b_ratio` | real | Water-to-binder ratio (water / all cementitious materials) |
| `a_b_ratio` | real | Aggregate-to-binder ratio |
| `water_premix_pct` | real | % of water added during pre-mix phase |
| `water_temperature_c` | real | Water temperature at mixing (C) |

### Test Conditions

| Column | Type | Description |
|--------|------|-------------|
| `design_strength_mpa` | real | Specified/target compressive strength (f'c) the mix is designed to achieve. This is the number on a concrete order ticket. |
| `test_age_days` | integer | Age at testing (default: 28) |
| `specimen_prep` | varchar | Specimen preparation method |
| `specimen_geometry` | varchar | Specimen shape (see standard geometries below) |
| `specimen_length_mm` | real | Specimen dimension L |
| `specimen_width_mm` | real | Specimen dimension W |
| `specimen_height_mm` | real | Specimen dimension H |
| `test_orientation` | varchar | Loading direction relative to print layers |
| `test_orientation_code` | varchar | Coded orientation (X, Y, Z, XY_45, CAST) |
| `test_method_code` | varchar | Test standard reference (e.g., ASTM C39, EN 12390-3) |
| `n_specimens` | integer | Number of specimens averaged |
| `curing_regime` | varchar | Curing description (moist, sealed, ambient, steam) |
| `curing_regime_code` | varchar | Coded curing regime |
| `curing_temperature_c` | real | Curing temperature (C) |
| `curing_humidity_pct` | real | Curing relative humidity (%) |
| `curing_duration_days` | real | Curing duration in days |

**Standard specimen geometries:** 3DCP research commonly uses mortar-scale specimens (smaller than standard concrete specimens due to printable mix proportions and nozzle constraints). Both standard concrete and mortar geometries are listed below.

| Geometry | Dimensions (mm) | Dimensions (in) | Test | Standard |
|----------|-----------------|-----------------|------|----------|
| **Mortar specimens (common in 3DCP)** | | | | |
| Mortar cube | 50 × 50 × 50 | 2" × 2" × 2" | Compressive | ASTM C109 |
| Mortar prism | 40 × 40 × 160 | 1.6" × 1.6" × 6.3" | Flexural / Compressive | EN 196-1 |
| Mini cylinder | 50 dia × 100 | 2" dia × 4" | Compressive | -- |
| Dog-bone (uniaxial tension) | varies | varies | Direct tensile | -- |
| **Standard concrete specimens** | | | | |
| Cylinder (small) | 100 dia × 200 | 4" dia × 8" | Compressive | ASTM C39 |
| Cylinder (standard) | 150 dia × 300 | 6" dia × 12" | Compressive | ASTM C39 |
| Cube | 150 × 150 × 150 | 6" × 6" × 6" | Compressive | EN 12390-3 |
| Beam | 150 × 150 × 500 | 6" × 6" × 20" | Flexural | ASTM C78 |
| Split cylinder | 150 dia × 300 | 6" dia × 12" | Splitting tensile | ASTM C496 |

### 3DCP Process Parameters

These columns capture the full extrusion printing process. Null for cast specimens.

| Column | Type | Description | Unit |
|--------|------|-------------|------|
| `is_3d_printed` | boolean | True if specimen was 3D printed (false = cast/moulded) | -- |
| `print_speed_mm_s` | real | Nozzle travel speed | mm/s |
| `layer_height_mm` | real | Deposited layer height | mm |
| `layer_time_gap_s` | real | Time interval between successive layers | seconds |
| `nozzle_diameter_mm` | real | Nozzle exit diameter | mm |
| `nozzle_shape` | varchar | Nozzle cross-section (circular, rectangular, custom) | -- |
| `nozzle_area_mm2` | real | Nozzle exit area | mm2 |
| `filament_width_mm` | real | Deposited filament width | mm |
| `layer_width_mm` | real | Layer width after deposition | mm |
| `extrusion_rate_l_min` | real | Volumetric extrusion rate | L/min |
| `num_layers` | integer | Total number of printed layers | -- |
| `path_length_mm` | real | Total toolpath length per layer | mm |
| `infill_pattern` | varchar | Internal fill pattern (solid, zigzag, contour) | -- |
| `contour_count` | integer | Number of perimeter contours | -- |
| `print_direction` | varchar | Primary print path direction | -- |

### Pumping System

| Column | Type | Description | Unit |
|--------|------|-------------|------|
| `pump_type` | varchar | Pump mechanism (piston, progressive cavity, peristaltic) | -- |
| `pump_pressure_bar` | real | Pump outlet pressure | bar |
| `pump_rotational_speed_rpm` | real | Pump motor speed | rpm |
| `pump_distance_m` | real | Hose length from pump to nozzle | m |
| `pipe_diameter_mm` | real | Delivery hose internal diameter | mm |
| `pumping_duration_s` | real | Total pumping time | seconds |

### Mixing Process

| Column | Type | Description | Unit |
|--------|------|-------------|------|
| `mixing_time_s` | real | Total mixing duration | seconds |
| `mixing_speed_rpm` | real | Mixer blade speed | rpm |
| `mixer_type` | varchar | Mixer type (pan, planetary, twin-shaft, continuous) | -- |
| `shear_rate_per_s` | real | Applied shear rate during mixing | 1/s |
| `admixture_addition_point` | varchar | When admixtures were added (dry, wet, delayed) | -- |

### Environmental Conditions

| Column | Type | Description | Unit |
|--------|------|-------------|------|
| `mix_temperature_c` | real | Concrete temperature at mixing | C |
| `ambient_temperature_c` | real | Ambient air temperature during printing | C |
| `ambient_humidity_pct` | real | Ambient relative humidity during printing | % |
| `wind_speed_m_s` | real | Wind speed during outdoor printing | m/s |

### Target Properties -- Fresh State

| Column | Type | Description | Unit | Test Method |
|--------|------|-------------|------|-------------|
| `slump_mm` | real | Slump height | mm | ASTM C143 |
| `spread_mm` | real | Slump flow spread diameter | mm | ASTM C1611 |
| `yield_stress_pa` | real | Static yield stress | Pa | Rheometer |
| `plastic_viscosity_pa_s` | real | Plastic viscosity | Pa.s | Rheometer |
| `static_yield_stress_pa` | real | Static yield stress (at rest) | Pa | Rheometer |
| `dynamic_yield_stress_pa` | real | Dynamic yield stress (during flow) | Pa | Rheometer |
| `thixotropy_pa_per_s` | real | Structural buildup rate (Athix) | Pa/s | Rheometer |
| `structuration_rate_pa_per_s` | real | Structuration rate | Pa/s | Rheometer |
| `open_time_min` | real | Workable window before set | minutes | -- |
| `green_strength_kpa` | real | Strength of fresh concrete (buildability) | kPa | -- |
| `air_content_fresh_pct` | real | Fresh-state air content | % | ASTM C231 |
| `unit_weight_fresh_kg_m3` | real | Fresh unit weight | kg/m3 | ASTM C138 |
| `setting_time_initial_min` | real | Initial set (Vicat needle) | minutes | ASTM C191 |
| `setting_time_final_min` | real | Final set (Vicat needle) | minutes | ASTM C191 |
| `bleeding_pct` | real | Bleeding water (% of mix water) | % | ASTM C232 |
| `temperature_fresh_c` | real | Concrete temperature at discharge | C | -- |
| `j_ring_mm` | real | J-Ring passing ability | mm | ASTM C1621 |
| `v_funnel_s` | real | V-Funnel flow time | seconds | EN 12350-9 |
| `l_box_ratio` | real | L-Box passing ratio (H2/H1) | -- | EN 12350-10 |
| `segregation_resistance_pct` | real | Sieve segregation | % | EN 12350-11 |

### Target Properties -- Mechanical (Hardened)

| Column | Type | Description | Unit | Test Method |
|--------|------|-------------|------|-------------|
| `compressive_strength_mpa` | real | Compressive strength | MPa | ASTM C39 / EN 12390-3 |
| `tensile_strength_mpa` | real | Direct tensile strength | MPa | ASTM C496 |
| `splitting_tensile_mpa` | real | Splitting tensile (Brazilian) | MPa | ASTM C496 |
| `flexural_strength_mpa` | real | Flexural (modulus of rupture) | MPa | ASTM C78 |
| `elastic_modulus_gpa` | real | Static elastic modulus | GPa | ASTM C469 |
| `bond_strength_mpa` | real | Bond / pull-off strength | MPa | ASTM C1583 |
| `fracture_energy_n_m` | real | Fracture energy (GF) | N/m | RILEM FMC-50 |
| `toughness_index` | real | Toughness index (I5, I10, I20) | -- | ASTM C1018 |
| `impact_resistance_j` | real | Impact energy | J | ACI 544.2R |
| `fatigue_life_cycles` | real | Fatigue life (cycles to failure) | -- | -- |
| `density_hardened_kg_m3` | real | Hardened density | kg/m3 | ASTM C642 |
| `poissons_ratio` | real | Poisson's ratio | -- | ASTM C469 |

### Target Properties -- 3DCP Interlayer

| Column | Type | Description | Unit |
|--------|------|-------------|------|
| `interlayer_bond_mpa` | real | Tensile bond between printed layers (pull-off) | MPa | ASTM C1583 |
| `interlayer_shear_mpa` | real | Shear strength at layer interface | MPa | — |
| `air_content_deposited_pct` | real | Air content in deposited filament | % |
| `void_area_fraction_pct` | real | Void fraction at interlayer zone | % |
| `surface_roughness_avg` | real | Surface roughness of printed layer | -- |
| `surface_moisture_state` | varchar | Surface condition at interface (dry, SSD, wet) | -- |
| `surface_treatment` | varchar | Interface treatment (none, scratch, bonding agent) | -- |

### Target Properties -- Durability

| Column | Type | Description | Unit | Test Method |
|--------|------|-------------|------|-------------|
| `chloride_rcpt_coulombs` | real | Rapid chloride permeability (total charge) | Coulombs | ASTM C1202 |
| `chloride_migration_coeff` | real | Non-steady-state chloride migration | m2/s | NT BUILD 492 |
| `chloride_diffusion_coeff` | real | Apparent chloride diffusion | m2/s | ASTM C1556 |
| `carbonation_depth_1yr_mm` | real | Carbonation front depth at 1 year | mm | EN 12390-12 |
| `carbonation_rate_coeff` | real | Carbonation rate coefficient (KAC) | mm/sqrt(day) | EN 12390-12 |
| `drying_shrinkage_28d_ue` | real | 28-day drying shrinkage | microstrain | ASTM C157 |
| `autogenous_shrinkage_ue` | real | Autogenous shrinkage | microstrain | ASTM C1698 |
| `creep_coefficient` | real | Creep coefficient (phi) | -- | ASTM C512 |
| `freeze_thaw_cycles` | real | Cycles to 60% relative dynamic modulus | -- | ASTM C666 |
| `freeze_thaw_durability_factor` | real | Durability factor | -- | ASTM C666 |
| `freeze_thaw_mass_loss_pct` | real | Mass loss after freeze-thaw | % | -- |
| `sulfate_expansion_6mo_pct` | real | 6-month sulfate expansion | % | ASTM C1012 |
| `sulfate_expansion_12mo_pct` | real | 12-month sulfate expansion | % | ASTM C1012 |
| `asr_expansion_14d_pct` | real | 14-day ASR mortar bar expansion | % | ASTM C1260 |
| `asr_expansion_1yr_pct` | real | 1-year ASR concrete prism expansion | % | ASTM C1293 |
| `abrasion_depth_mm` | real | Abrasion depth | mm | ASTM C779 |
| `water_penetration_depth_mm` | real | Water penetration under pressure | mm | EN 12390-8 |
| `electrical_resistivity_kohm_cm` | real | Surface resistivity | kohm.cm | ASTM C1876 |
| `porosity_pct` | real | Total porosity (MIP or vacuum saturation) | % | ASTM C642 |
| `water_absorption_pct` | real | Water absorption by immersion | % | ASTM C642 |
| `sorptivity_mm_sqrt_s` | real | Sorptivity — initial rate (first 6 hours) | mm/sqrt(s) | ASTM C1585 |
| `sorptivity_secondary_mm_sqrt_s` | real | Sorptivity — secondary rate (day 1–7). Critical for 3DCP interlayer moisture transport. | mm/sqrt(s) | ASTM C1585 |
| `oxygen_permeability_m2` | real | Oxygen permeability coefficient | m2 | -- |
| `scaling_resistance_kg_m2` | real | De-icing salt scaling mass loss | kg/m2 | ASTM C672 |
| `corrosion_rate_ua_cm2` | real | Corrosion current density (Icorr) | uA/cm2 | ASTM C876 |
| `half_cell_potential_mv` | real | Half-cell corrosion potential | mV | ASTM C876 |
| `heat_of_hydration_kj_kg` | real | Heat of hydration | kJ/kg | ASTM C186 |

### Target Properties -- Thermal & Environmental

| Column | Type | Description | Unit |
|--------|------|-------------|------|
| `thermal_conductivity_w_mk` | real | Thermal conductivity | W/(m.K) |
| `specific_heat_j_kg_k` | real | Specific heat capacity | J/(kg.K) |
| `coeff_thermal_expansion_ue_c` | real | Coefficient of thermal expansion | microstrain/C |
| `fire_resistance_min` | real | Fire resistance duration (ASTM E119) | minutes | ASTM E119 |
| `embodied_carbon_kg_co2_m3` | real | Embodied CO2 (cradle-to-gate) | kg CO2/m3 |
| `embodied_energy_mj_m3` | real | Embodied energy | MJ/m3 |

### Target Properties -- Microstructure

| Column | Type | Description | Unit |
|--------|------|-------------|------|
| `degree_of_hydration` | real | Degree of hydration (0-1) | -- |
| `calcium_hydroxide_pct` | real | Ca(OH)2 content (TGA/XRD) | % |
| `pore_size_distribution_nm` | real | Critical pore diameter (MIP) | nm |

### Data Provenance

| Column | Type | Description |
|--------|------|-------------|
| `doi` | varchar | Digital Object Identifier of source publication |
| `source_citation` | varchar | Full citation string (for sources without DOI: theses, conference papers, internal reports) |
| `measurement_confidence` | varchar | Data reliability: `measured` (direct lab measurement), `calculated` (derived from other properties), `estimated` (approximated or inferred), `reported` (taken from literature without independent verification) |
| `lab_name` | varchar | Laboratory that performed the tests (enables inter-laboratory comparison) |
| `provenance_notes` | text | Free-text notes on data origin or quality concerns |

### Data Quality Flags

| Column | Type | Description |
|--------|------|-------------|
| `is_training_ready` | boolean | Record passes quality gates and is eligible for ML training |
| `is_synthetic` | boolean | True if generated by ML/optimization, not from real lab measurements |
| `outlier_flag` | boolean | Statistical outlier detected during quality audit |

### Exposure Classification (EN 206 / ACI 318)

| Column | Type | Description |
|--------|------|-------------|
| `exposure_class_freeze` | varchar | Freeze-thaw exposure (e.g., XF1-XF4) |
| `exposure_class_sulfate` | varchar | Sulfate exposure (e.g., S0-S3) |
| `exposure_class_chloride` | varchar | Chloride exposure (e.g., XD1-XD3, XS1-XS3) |
| `exposure_class_water` | varchar | Waterproofing requirement |
| `exposure_class_asr` | varchar | ASR risk classification |

---

## Units Convention

All material quantities are in **mass-% of total wet mix** (cement + SCMs + aggregates + water + admixtures + fibers = ~100%).

This convention was chosen because:
- It eliminates density assumptions required for kg/m3 conversion
- It is directly comparable across datasets with different total binder contents
- It normalizes naturally to a fixed scale (0-100%)

---

## Companion Tables

| Table | Purpose |
|-------|---------|
| `strength_measurements` | Multi-age strength data (1-365 days) linked by formulation ID |
| `sources` | Publication metadata (DOI, journal, year, license) |
| `test_methods` | Controlled vocabulary of test standards |
| `curing_regimes` | Standard curing condition definitions |

---

## Disclaimers

### Standards References

This document references published standards from ASTM International, the European Committee for Standardization (CEN/EN), the American Concrete Institute (ACI), RILEM, and other standards organizations. These references are provided for identification and context only.

**Open3DCP is not a substitute for any referenced standard.** Column names and descriptions reference standard designations (e.g., ASTM C39, EN 12390-3) to indicate the test method or material classification a column is intended to represent. This does not imply endorsement, certification, or affiliation with any standards organization.

Users are responsible for obtaining and complying with the full text of any applicable standard. Standards are copyrighted documents published by their respective organizations and must be purchased or accessed through authorized channels.

### Trademarks

ASTM and ASTM International are trademarks of ASTM International. ACI is a trademark of the American Concrete Institute. RILEM is a trademark of the International Union of Laboratories and Experts in Construction Materials, Systems and Structures. All other trademarks are the property of their respective owners. Use of these names in Open3DCP is for identification purposes only and does not imply endorsement.

### Data Accuracy

Open3DCP defines a data format, not a dataset. Sunnyday Technologies makes no representations or warranties regarding the accuracy, completeness, or fitness for purpose of any data stored in this schema format. Users are solely responsible for validating data quality and suitability for their intended application.

**This schema is not intended for use as a basis for structural design, construction specifications, or regulatory compliance.** Mix designs derived from data stored in this format must be independently validated through laboratory testing by qualified professionals before use in any construction application.

### No Professional Advice

Nothing in this document constitutes engineering advice, materials science consulting, or professional recommendations. Concrete mix design for construction applications requires the involvement of licensed professional engineers and compliance with applicable building codes (IBC, Eurocode, local codes of jurisdiction).

---

## License

**Apache License, Version 2.0** ([Apache-2.0](https://www.apache.org/licenses/LICENSE-2.0)).

You are free to use, adapt, and redistribute this schema for any purpose, including commercial use, provided you give appropriate credit to Sunnyday Technologies. The Apache 2.0 license includes an express grant of patent rights from contributors to users.

---

## Citation

If you use Open3DCP in your research, please cite:

> Sunnyday Technologies (2026). Open3DCP: Open Data Standard for 3D Concrete Printing. https://github.com/sunnyday-technologies/Open3DCP

---

*Open3DCP v1.3 -- Last updated: 2026-04-16*
*Maintained by [Sunnyday Technologies](https://sunn3d.com), Wisconsin, USA*