{
  "spore": "profile",
  "id": "geopolymer-lunar-concrete",
  "spore_version": "0.2",
  "family": "geopolymer",
  "name": "Geopolymer lunar concrete (alkali-activated regolith)",
  "role": "Binder that sets lunar regolith simulant with an alkaline solution instead of Portland cement",
  "category": "regolith",
  "type": "lunar-concrete",
  "summary": "Geopolymer lunar concrete is a binder that sets lunar regolith simulant with an alkaline solution of sodium silicate and sodium hydroxide, in place of Portland cement. NASA's 2022 Earth Day deck concludes that geopolymer concrete is a feasible material for lunar surface infrastructure, and it tabulates the amorphous content, Si/Al ratio and particle size of five regolith simulants. The sources read for this profile print no compressive strength value, and the 2022 conference abstract reports a noticeable decline in strength when curing is done at reduced pressure.",
  "best_for": "Concept studies of lunar construction that use regolith as found, with an activator the 2022 abstract says could largely be produced in situ (laboratory stage only)",
  "weakest_at": "No strength value is printed in any source read; strength falls when curing pressure is reduced, and no flight or vacuum test values were found",
  "identity": {
    "formula": "Alkali-activated aluminosilicate binder (geopolymer): lunar regolith simulant activated by sodium silicate and sodium hydroxide; no single formula",
    "designations": [],
    "source": "nasa-deck-2022",
    "where": "Slide 8 (aluminosilicate glassy sources and alkaline solution); Slide 9 (geopolymer definition cites Duxson et al. 2007)"
  },
  "tags": {
    "environments": [],
    "stresses": [],
    "applications": [
      "structures",
      "habitats-and-suits"
    ]
  },
  "properties": [
    {
      "benchmark": "amorphous_content",
      "label": "Amorphous content, JSC-1A lunar mare simulant",
      "value": 49.9,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "simulant": "JSC-1A, lunar mare regolith simulant",
        "form": "as tabulated in the deck"
      },
      "method": "XRD phase table on the slide; the slide does not state how the amorphous fraction was quantified",
      "status": "ground",
      "source": "nasa-deck-2022",
      "where": "Slide 18, Amorphous column, JSC-1A row",
      "source_detail": {
        "title": "Geopolymer Concrete: A greener alternative on Earth and a feasible material for the Moon (Earth Day 2022 presentation)",
        "id": "NTRS 20220005876; authors Collins, Radlinska, Edmunson, Fiske, Strutzenberg",
        "url": "https://ntrs.nasa.gov/api/citations/20220005876/downloads/Earth%20Day%202022%20Geopolymer%20Concrete.pdf",
        "year": 2022,
        "kind": "report",
        "license": "Not stated on the slides"
      }
    },
    {
      "benchmark": "amorphous_content",
      "label": "Amorphous content, JSC-2A lunar mare simulant",
      "value": 51,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "simulant": "JSC-2A, lunar mare regolith simulant",
        "form": "as tabulated in the deck"
      },
      "method": "XRD phase table on the slide; the slide does not state how the amorphous fraction was quantified",
      "status": "ground",
      "source": "nasa-deck-2022",
      "where": "Slide 18, Amorphous column, JSC-2A row",
      "source_detail": {
        "title": "Geopolymer Concrete: A greener alternative on Earth and a feasible material for the Moon (Earth Day 2022 presentation)",
        "id": "NTRS 20220005876; authors Collins, Radlinska, Edmunson, Fiske, Strutzenberg",
        "url": "https://ntrs.nasa.gov/api/citations/20220005876/downloads/Earth%20Day%202022%20Geopolymer%20Concrete.pdf",
        "year": 2022,
        "kind": "report",
        "license": "Not stated on the slides"
      }
    },
    {
      "benchmark": "amorphous_content",
      "label": "Amorphous content, OPRL2N lunar mare simulant",
      "value": 45.4,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "simulant": "OPRL2N, lunar mare regolith simulant",
        "form": "as tabulated in the deck"
      },
      "method": "XRD phase table on the slide; the slide does not state how the amorphous fraction was quantified",
      "status": "ground",
      "source": "nasa-deck-2022",
      "where": "Slide 18, Amorphous column, OPRL2N row",
      "source_detail": {
        "title": "Geopolymer Concrete: A greener alternative on Earth and a feasible material for the Moon (Earth Day 2022 presentation)",
        "id": "NTRS 20220005876; authors Collins, Radlinska, Edmunson, Fiske, Strutzenberg",
        "url": "https://ntrs.nasa.gov/api/citations/20220005876/downloads/Earth%20Day%202022%20Geopolymer%20Concrete.pdf",
        "year": 2022,
        "kind": "report",
        "license": "Not stated on the slides"
      }
    },
    {
      "benchmark": "amorphous_content",
      "label": "Amorphous content, OPRH2N lunar highlands simulant",
      "value": 26.5,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "simulant": "OPRH2N, lunar highlands regolith simulant",
        "form": "as tabulated in the deck"
      },
      "method": "XRD phase table on the slide; the slide does not state how the amorphous fraction was quantified",
      "status": "ground",
      "source": "nasa-deck-2022",
      "where": "Slide 18, Amorphous column, OPRH2N row",
      "source_detail": {
        "title": "Geopolymer Concrete: A greener alternative on Earth and a feasible material for the Moon (Earth Day 2022 presentation)",
        "id": "NTRS 20220005876; authors Collins, Radlinska, Edmunson, Fiske, Strutzenberg",
        "url": "https://ntrs.nasa.gov/api/citations/20220005876/downloads/Earth%20Day%202022%20Geopolymer%20Concrete.pdf",
        "year": 2022,
        "kind": "report",
        "license": "Not stated on the slides"
      }
    },
    {
      "benchmark": "amorphous_content",
      "label": "Amorphous content, EAC-1A lunar simulant",
      "value": 26.2,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "simulant": "EAC-1A, lunar regolith simulant",
        "form": "as tabulated in the deck"
      },
      "method": "XRD phase table on the slide; the slide does not state how the amorphous fraction was quantified",
      "status": "ground",
      "source": "nasa-deck-2022",
      "where": "Slide 18, Amorphous column, EAC-1A row",
      "source_detail": {
        "title": "Geopolymer Concrete: A greener alternative on Earth and a feasible material for the Moon (Earth Day 2022 presentation)",
        "id": "NTRS 20220005876; authors Collins, Radlinska, Edmunson, Fiske, Strutzenberg",
        "url": "https://ntrs.nasa.gov/api/citations/20220005876/downloads/Earth%20Day%202022%20Geopolymer%20Concrete.pdf",
        "year": 2022,
        "kind": "report",
        "license": "Not stated on the slides"
      }
    },
    {
      "benchmark": "si_al_ratio",
      "label": "Si/Al ratio, JSC-1A simulant",
      "value": 2.5,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "simulant": "JSC-1A",
        "basis": "oxide composition as tabulated"
      },
      "method": "Printed Si/Al column of the oxide table; the table gives SiO2 and Al2O3 without units, so only the ratio is recorded",
      "status": "ground",
      "source": "nasa-deck-2022",
      "where": "Slide 19, Si/Al column, JSC-1A row",
      "source_detail": {
        "title": "Geopolymer Concrete: A greener alternative on Earth and a feasible material for the Moon (Earth Day 2022 presentation)",
        "id": "NTRS 20220005876; authors Collins, Radlinska, Edmunson, Fiske, Strutzenberg",
        "url": "https://ntrs.nasa.gov/api/citations/20220005876/downloads/Earth%20Day%202022%20Geopolymer%20Concrete.pdf",
        "year": 2022,
        "kind": "report",
        "license": "Not stated on the slides"
      }
    },
    {
      "benchmark": "si_al_ratio",
      "label": "Si/Al ratio, OPRL2N lunar mare simulant",
      "value": 2.44,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "simulant": "OPRL2N",
        "basis": "oxide composition as tabulated"
      },
      "method": "Printed Si/Al column of the oxide table; the table gives SiO2 and Al2O3 without units, so only the ratio is recorded",
      "status": "ground",
      "source": "nasa-deck-2022",
      "where": "Slide 19, Si/Al column, OPRL2N row",
      "source_detail": {
        "title": "Geopolymer Concrete: A greener alternative on Earth and a feasible material for the Moon (Earth Day 2022 presentation)",
        "id": "NTRS 20220005876; authors Collins, Radlinska, Edmunson, Fiske, Strutzenberg",
        "url": "https://ntrs.nasa.gov/api/citations/20220005876/downloads/Earth%20Day%202022%20Geopolymer%20Concrete.pdf",
        "year": 2022,
        "kind": "report",
        "license": "Not stated on the slides"
      }
    },
    {
      "benchmark": "si_al_ratio",
      "label": "Si/Al ratio, OPRH2N lunar highlands simulant",
      "value": 1.63,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "simulant": "OPRH2N",
        "basis": "oxide composition as tabulated"
      },
      "method": "Printed Si/Al column of the oxide table; the table gives SiO2 and Al2O3 without units, so only the ratio is recorded",
      "status": "ground",
      "source": "nasa-deck-2022",
      "where": "Slide 19, Si/Al column, OPRH2N row",
      "source_detail": {
        "title": "Geopolymer Concrete: A greener alternative on Earth and a feasible material for the Moon (Earth Day 2022 presentation)",
        "id": "NTRS 20220005876; authors Collins, Radlinska, Edmunson, Fiske, Strutzenberg",
        "url": "https://ntrs.nasa.gov/api/citations/20220005876/downloads/Earth%20Day%202022%20Geopolymer%20Concrete.pdf",
        "year": 2022,
        "kind": "report",
        "license": "Not stated on the slides"
      }
    },
    {
      "benchmark": "particle_size_d50",
      "label": "Median particle size (D50), OPRL2N lunar mare simulant",
      "value": 58,
      "bound": "exact",
      "unit": "µm",
      "scope": "material",
      "conditions": {
        "simulant": "OPRL2N",
        "measurement": "laser particle size distribution, as named in the deck"
      },
      "method": "Printed D50 column of the particle size table on the slide",
      "status": "ground",
      "source": "nasa-deck-2022",
      "where": "Slide 19, D50 (µm) column, OPRL2N row",
      "source_detail": {
        "title": "Geopolymer Concrete: A greener alternative on Earth and a feasible material for the Moon (Earth Day 2022 presentation)",
        "id": "NTRS 20220005876; authors Collins, Radlinska, Edmunson, Fiske, Strutzenberg",
        "url": "https://ntrs.nasa.gov/api/citations/20220005876/downloads/Earth%20Day%202022%20Geopolymer%20Concrete.pdf",
        "year": 2022,
        "kind": "report",
        "license": "Not stated on the slides"
      }
    },
    {
      "benchmark": "particle_size_d50",
      "label": "Median particle size (D50), OPRH2N lunar highlands simulant",
      "value": 46.2,
      "bound": "exact",
      "unit": "µm",
      "scope": "material",
      "conditions": {
        "simulant": "OPRH2N",
        "measurement": "laser particle size distribution, as named in the deck"
      },
      "method": "Printed D50 column of the particle size table on the slide",
      "status": "ground",
      "source": "nasa-deck-2022",
      "where": "Slide 19, D50 (µm) column, OPRH2N row",
      "source_detail": {
        "title": "Geopolymer Concrete: A greener alternative on Earth and a feasible material for the Moon (Earth Day 2022 presentation)",
        "id": "NTRS 20220005876; authors Collins, Radlinska, Edmunson, Fiske, Strutzenberg",
        "url": "https://ntrs.nasa.gov/api/citations/20220005876/downloads/Earth%20Day%202022%20Geopolymer%20Concrete.pdf",
        "year": 2022,
        "kind": "report",
        "license": "Not stated on the slides"
      }
    },
    {
      "benchmark": "activator_ph",
      "label": "pH of the reference alkaline activator",
      "value": 14.31,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "activator": "sodium silicate and 10 M sodium hydroxide mixture",
        "silicate_ratio_SiO2_Na2O": 2,
        "solution_to_simulant": 0.35
      },
      "method": "Printed on the mix footnote of the slide with the compressive strength chart; the slide gives no measurement method",
      "status": "ground",
      "note": "The pH is a property of the activator solution, not of the hardened concrete.",
      "source": "nasa-deck-2022",
      "where": "Slide 21, mix footnote",
      "source_detail": {
        "title": "Geopolymer Concrete: A greener alternative on Earth and a feasible material for the Moon (Earth Day 2022 presentation)",
        "id": "NTRS 20220005876; authors Collins, Radlinska, Edmunson, Fiske, Strutzenberg",
        "url": "https://ntrs.nasa.gov/api/citations/20220005876/downloads/Earth%20Day%202022%20Geopolymer%20Concrete.pdf",
        "year": 2022,
        "kind": "report",
        "license": "Not stated on the slides"
      }
    },
    {
      "benchmark": "sio2_na2o_ratio",
      "label": "SiO2/Na2O ratio of the sodium silicate in the reference mix",
      "value": 2,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "activator": "sodium silicate with 10 M sodium hydroxide"
      },
      "method": "Printed on the mix footnote of the slide with the compressive strength chart",
      "status": "ground",
      "source": "nasa-deck-2022",
      "where": "Slide 21, mix footnote",
      "source_detail": {
        "title": "Geopolymer Concrete: A greener alternative on Earth and a feasible material for the Moon (Earth Day 2022 presentation)",
        "id": "NTRS 20220005876; authors Collins, Radlinska, Edmunson, Fiske, Strutzenberg",
        "url": "https://ntrs.nasa.gov/api/citations/20220005876/downloads/Earth%20Day%202022%20Geopolymer%20Concrete.pdf",
        "year": 2022,
        "kind": "report",
        "license": "Not stated on the slides"
      }
    },
    {
      "benchmark": "solution_to_solid_ratio",
      "label": "Solution to simulant ratio in the reference mix",
      "value": 0.35,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "simulant": "lunar regolith simulant (type not specified on the slide)"
      },
      "method": "Printed on the mix footnote of the slide with the compressive strength chart",
      "status": "ground",
      "note": "The slide does not say whether the ratio is by mass or by volume, so no unit is assumed.",
      "source": "nasa-deck-2022",
      "where": "Slide 21, mix footnote",
      "source_detail": {
        "title": "Geopolymer Concrete: A greener alternative on Earth and a feasible material for the Moon (Earth Day 2022 presentation)",
        "id": "NTRS 20220005876; authors Collins, Radlinska, Edmunson, Fiske, Strutzenberg",
        "url": "https://ntrs.nasa.gov/api/citations/20220005876/downloads/Earth%20Day%202022%20Geopolymer%20Concrete.pdf",
        "year": 2022,
        "kind": "report",
        "license": "Not stated on the slides"
      }
    },
    {
      "benchmark": "curing_temperature",
      "label": "Reference mix cure temperature (process condition, not a material property)",
      "value": 80,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "cure_time": "three days, as printed on the slide",
        "mix": "reference geopolymer mix on the slide"
      },
      "method": "Printed cure condition on the mix footnote of the slide with the compressive strength chart",
      "status": "ground",
      "source": "nasa-deck-2022",
      "where": "Slide 21, mix footnote (Cured at 80°C for three days)",
      "source_detail": {
        "title": "Geopolymer Concrete: A greener alternative on Earth and a feasible material for the Moon (Earth Day 2022 presentation)",
        "id": "NTRS 20220005876; authors Collins, Radlinska, Edmunson, Fiske, Strutzenberg",
        "url": "https://ntrs.nasa.gov/api/citations/20220005876/downloads/Earth%20Day%202022%20Geopolymer%20Concrete.pdf",
        "year": 2022,
        "kind": "report",
        "license": "Not stated on the slides"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Vacuum exposure after curing (lunar surface condition)",
      "headline": "Vacuum exposure limited further reaction and strength gain, compared with controls kept in the laboratory (qualitative)",
      "effect": "Samples cured for different lengths of time were placed in a vacuum chamber, and their weight change and compressive strength were tracked against laboratory-stored controls. The 2022 abstract says exposure to the vacuum limits further reaction and strength gain. No numerical degradation values are printed in the abstract.",
      "rating": "unknown",
      "conditions": {
        "exposure": "vacuum chamber, pressure as stated in the abstract",
        "materials": "geopolymer lunar concrete from the two regolith simulants OPRL2N and OPRH2N"
      },
      "source": "ntrs-2022-13413",
      "where": "Abstract"
    }
  ],
  "risks": {
    "hazards": [],
    "failure_risks": [
      {
        "mode": "Lower strength after curing at reduced pressure",
        "trigger": "Curing at reduced pressure in a vacuum chamber",
        "consequence": "The 2022 abstract reports a noticeable decline in strength with a reduction in pressure, and says vacuum exposure limits further reaction and strength gain.",
        "severity": "moderate",
        "source": "ntrs-2022-13413",
        "where": "Abstract"
      }
    ],
    "side_effects": [],
    "handling": [
      {
        "text": "The 2022 abstract says printed lunar infrastructure would need a temporary environmental enclosure during construction and curing, and that data are needed to set benchmark enclosure conditions.",
        "source": "ntrs-2022-13413",
        "where": "Abstract"
      }
    ],
    "mitigations": []
  },
  "uses": [
    {
      "application": "structures",
      "device": "Lunar habitats, roads and landing pads (concept)",
      "example": "The 2022 conference abstract proposes geopolymer concrete for lunar habitats, roads and landing pads, made from regolith as found mixed with sodium silicate and sodium hydroxide.",
      "source": "ntrs-2022-13413",
      "where": "Abstract"
    },
    {
      "application": "structures",
      "device": "Lunar surface infrastructure (concept)",
      "example": "The Earth Day 2022 deck concludes that geopolymer concrete is a feasible material for constructing infrastructure on the lunar surface.",
      "source": "nasa-deck-2022",
      "where": "Slide 22, Conclusions"
    }
  ],
  "supply": [],
  "media": [],
  "documents": [
    {
      "title": "Geopolymer Concrete: A greener alternative on Earth and a feasible material for the Moon (Earth Day 2022 presentation, NTRS 20220005876)",
      "type": "report",
      "url": "https://ntrs.nasa.gov/api/citations/20220005876/downloads/Earth%20Day%202022%20Geopolymer%20Concrete.pdf",
      "year": 2022
    },
    {
      "title": "Geopolymer Lunar Concrete under Reduced-Pressure Curing and Vacuum Exposure (NTRS 20220013413, IAC 2022 conference paper)",
      "type": "paper",
      "url": "https://ntrs.nasa.gov/citations/20220013413",
      "year": 2022
    }
  ],
  "gaps": [
    "No compressive strength, flexural strength or density value is printed in any source read in this run. The strength chart on slide 21 plots two simulant mixes against age, but it prints no data values, so none are recorded.",
    "Hazard data for the sodium hydroxide and sodium silicate activators were not found. The PubChem pages returned a browser verification check, so risks.hazards is empty.",
    "No producer, abundance or critical-mineral data are recorded. The Earth Day deck credits PQ Corporation for providing the sodium silicate, but gives no production shares or country data, so supply is empty.",
    "The 'tested on the ISS' claim in the profile brief was not found in the two NASA documents read. The deck acknowledges a microgravity cement solidification project, but names no ISS test result.",
    "The 2022 conference paper was read from its NTRS citation page through a summarising fetch. Its PDF link returned an error, so its quoted phrases were not checked word for word against the paper.",
    "The simulant SiO2 and Al2O3 values on slide 19 have no units printed in the table, so they are not recorded. Only the printed Si/Al ratios are kept.",
    "The pH, SiO2/Na2O ratio, solution-to-simulant ratio and 80 C cure come from one mix footnote on slide 21. The slide gives no measurement method beyond the mix description.",
    "Environment figures on slide 14 (gravity, temperature range, and an atmospheric pressure printed with an exponent) describe the lunar surface, not the material, and are left out.",
    "Benchmarks amorphous_content, si_al_ratio, particle_size_d50, activator_ph, sio2_na2o_ratio, solution_to_solid_ratio and curing_temperature are not in spores/property-canon.yaml and are used as snake_case names.",
    "Only three sources are cited, below the eight required for the full-grade bar. There is no ageing, durability, radiation or flight data and no corrosion test beyond the vacuum statement.",
    "Wikipedia (Geopolymer) was read for the definition and history of the term but yielded no lunar or grade-specific numbers, so it is not cited as a value source."
  ],
  "story": {
    "why": "Geopolymer lunar concrete is proposed as a binder for lunar construction that does not rely on Portland cement. NASA's deck says the calcium content of lunar regolith is minimal for making ordinary Portland cement, and it proposes regolith in its as-is condition as the main mass of the mix. The work so far has used regolith simulants, not returned lunar samples, and the deck notes that no simulant is a perfect match for real lunar regolith.",
    "uses": [
      {
        "where": "Lunar habitats, roads and landing pads (concept)",
        "line": "The 2022 conference abstract proposes geopolymer concrete for these uses, with regolith used as found and mixed with sodium silicate and sodium hydroxide."
      },
      {
        "where": "Lunar surface infrastructure",
        "line": "The Earth Day 2022 deck concludes that geopolymer concrete is a feasible material for constructing infrastructure on the lunar surface."
      }
    ],
    "can_do": [
      {
        "label": "Uses lunar regolith as found",
        "line": "The deck states the goal is to use as much in-situ lunar resources as possible, with regolith in its as-is condition making up most of the mass.",
        "scope": "material"
      },
      {
        "label": "Amorphous feedstock",
        "line": "The deck's table gives amorphous content from 26.2% (EAC-1A) to 49.9% (JSC-1A) across the five simulants (slide 18). It notes that the mare simulants have a higher amorphous content than most Apollo samples.",
        "benchmark": "amorphous_content",
        "scope": "material"
      },
      {
        "label": "Alkaline activation",
        "line": "The reference activator mixture has a pH of 14.31 (slide 21).",
        "benchmark": "activator_ph",
        "scope": "material"
      },
      {
        "label": "Curing",
        "line": "The reference mix is cured at 80°C for three days (slide 21). The 2022 abstract reports a noticeable decline in strength when curing pressure is reduced.",
        "benchmark": "curing_temperature",
        "scope": "material"
      }
    ],
    "compare": "The deck lists geopolymer concrete among ways to reduce concrete's CO2 emissions, and it says geopolymers will not replace Portland cement across the board. Against Portland cement, the sources read here give no strength or durability numbers to compare, so the comparison rests on mix chemistry and on the reference mix conditions only. The table compares the feedstock and activator values this profile records.",
    "compare_rows": [
      {
        "label": "Amorphous content of the feedstock (26.2% to 49.9%)",
        "benchmark": "amorphous_content",
        "scope": "material"
      },
      {
        "label": "Activator pH (reference mix)",
        "benchmark": "activator_ph",
        "scope": "material"
      },
      {
        "label": "Median particle size, OPRL2N (D50)",
        "benchmark": "particle_size_d50",
        "scope": "material"
      }
    ],
    "handling": [
      "Printed lunar infrastructure would need a temporary environmental enclosure during construction and curing, according to the 2022 abstract.",
      "Use lunar regolith simulants for laboratory work. The deck says no simulant is a perfect match for real lunar regolith.",
      "Curing at reduced pressure lowers strength, so curing conditions should be held constant when comparing mixes."
    ],
    "good_for": [
      "Concept studies that use regolith as found and an activator that the 2022 abstract says could largely be produced in situ.",
      "Laboratory comparisons of regolith simulants, since the deck measures five simulants side by side."
    ],
    "watch_out": [
      "No strength value is printed in any source read, and strength falls when curing is done at reduced pressure.",
      "Simulant only. The deck says no lunar regolith simulant is a perfect match for real lunar regolith.",
      "Mix and activator values come from one footnote in the deck, with no measurement method beyond the mix description."
    ],
    "verdict": "A feasible concept according to NASA's own deck, supported so far by simulant chemistry and mix conditions only. No strength number was recorded, so the verdict does not rest on strength.",
    "recipe": {
      "line": "Geopolymer lunar concrete is made by mixing a glassy aluminosilicate powder, here lunar regolith simulant, with an alkaline solution. The reference mix on slide 21 uses a sodium silicate and 10 M sodium hydroxide solution, and it is cured at 80°C for three days.",
      "parts": [
        {
          "name": "Lunar regolith simulant",
          "role": "Aluminosilicate source. Its amorphous (glassy) content runs from 26.2% to 49.9% across the five simulants on slide 18, and the glassy part is what reacts with the activator."
        },
        {
          "name": "Sodium silicate",
          "role": "Part of the alkaline solution. The reference mix sets its SiO2/Na2O ratio, recorded in the properties from slide 21. PQ Corporation supplied the sodium silicate, according to the deck's acknowledgements."
        },
        {
          "name": "Sodium hydroxide",
          "role": "Part of the alkaline solution, at a concentration of 10 M in the reference mix (slide 21)."
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "No hazard classification for the activators was read in this run, so this profile does not state one.",
        "points": [
          {
            "label": "Activators",
            "line": "The sodium hydroxide and sodium silicate in the mix were not checked against a safety data sheet or a chemical database entry here. Treat the alkaline solution as a chemical that needs its own safety data sheet before handling."
          },
          {
            "label": "Dust",
            "line": "The sources read here do not discuss dust from regolith simulant, so no dust guidance is given."
          }
        ],
        "level": 0,
        "verdict": "Hazard data not found in this run"
      },
      {
        "title": "Handling in construction concepts",
        "lead": "These points come from the 2022 conference abstract, which describes a concept, not a built structure.",
        "points": [
          {
            "label": "Curing enclosure",
            "line": "Printed lunar infrastructure would need a temporary environmental enclosure during construction and curing. The abstract says the benchmark enclosure conditions still need data."
          },
          {
            "label": "Reduced pressure",
            "line": "The abstract reports a noticeable decline in strength when curing is done at reduced pressure."
          }
        ]
      }
    ]
  },
  "updated": "2026-10-16",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 0,
    "unreachable": 0,
    "caveats": 0
  },
  "sources": {
    "nasa-deck-2022": {
      "title": "Geopolymer Concrete: A greener alternative on Earth and a feasible material for the Moon (Earth Day 2022 presentation)",
      "id": "NTRS 20220005876; authors Collins, Radlinska, Edmunson, Fiske, Strutzenberg",
      "url": "https://ntrs.nasa.gov/api/citations/20220005876/downloads/Earth%20Day%202022%20Geopolymer%20Concrete.pdf",
      "year": 2022,
      "kind": "report",
      "license": "Not stated on the slides"
    },
    "ntrs-2022-13413": {
      "title": "Geopolymer Lunar Concrete under Reduced-Pressure Curing and Vacuum Exposure",
      "id": "NTRS 20220013413; IAC 2022 conference paper (Collins, Edmunson, Fiske, Bilen, Radlinska)",
      "url": "https://ntrs.nasa.gov/citations/20220013413",
      "year": 2022,
      "kind": "paper",
      "license": "Not stated on the citation page"
    },
    "wikipedia-geopolymer": {
      "title": "Geopolymer (Wikipedia article)",
      "id": "en.wikipedia.org, Geopolymer",
      "url": "https://en.wikipedia.org/wiki/Geopolymer",
      "year": 2026,
      "kind": "web",
      "license": "CC BY-SA (Wikipedia text)"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/geopolymer-lunar-concrete/"
}