Geopolymer lunar concrete (alkali-activated regolith)
Alkali-activated aluminosilicate binder (geopolymer): lunar regolith simulant activated by sodium silicate and sodium hydroxide
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.
Evidence level
2 of 5
Lab-measured
- 0Predicted only. No one has made it, or no measurement exists.
- 1Calculated. Only calculated or predicted values from sources.
- 2Lab-measured. Measured properties with their conditions stated.
- 3Space-relevant tests. Measured in conditions relevant to space, such as vacuum or atomic oxygen.
- 4Ground-qualified. Qualified for an application on the ground.
- 5Flown or field-proven. Flight or field results exist.
Amorphous feedstock
49.9 %
Alkaline activation
14.31 -
Curing
80 °C
Recipe, share of the weight
- not statedLunar regolith simulant
- not statedSodium silicate
- not statedSodium hydroxide
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
Risk at a glance
- People None found. Hazard data not found in this run
- If it fails Moderate. Lower strength after curing at reduced pressure
- Corrosion No data. No corrosion data recorded
Why it exists
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.
Where it's used
Lunar habitats, roads and landing pads (concept)
The 2022 conference abstract proposes geopolymer concrete for these uses, with regolith used as found and mixed with sodium silicate and sodium hydroxide.
Lunar surface infrastructure
The Earth Day 2022 deck concludes that geopolymer concrete is a feasible material for constructing infrastructure on the lunar surface.
Recipe
Alkali-activated aluminosilicate binder (geopolymer): lunar regolith simulant activated by sodium silicate and sodium hydroxide; no single formula
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.
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Lunar regolith simulant | not stated | 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. |
| Sodium silicate | not stated | 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. |
| Sodium hydroxide | not stated | Part of the alkaline solution, at a concentration of 10 M in the reference mix (slide 21). |
Weight shares are as printed in the sources.
What it can do
Uses lunar regolith as found
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.
Amorphous feedstock
49.9 %
measured
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.
Alkaline activation
14.31 -
measured
The reference activator mixture has a pH of 14.31 (slide 21).
Curing
80 °C
measured
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.
How it compares
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.
The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details.
| Measurement | Geopolymer lunar concrete (alkali-activated regolith) |
|---|---|
| Thermal behavior and safety | |
| SiO2/Na2O ratio of the sodium silicate in the reference mix | 2 -12 |
| Temperature behavior | |
| Reference mix cure temperature (process condition, not a material property) | 80 °C14 |
| Other measurements | |
| Amorphous content, JSC-1A lunar mare simulant | 49.9 %1 |
| Amorphous content, JSC-2A lunar mare simulant | 51 %2 |
| Amorphous content, OPRL2N lunar mare simulant | 45.4 %3 |
| Amorphous content, OPRH2N lunar highlands simulant | 26.5 %4 |
| Amorphous content, EAC-1A lunar simulant | 26.2 %5 |
| Si/Al ratio, JSC-1A simulant | 2.5 -6 |
| Si/Al ratio, OPRL2N lunar mare simulant | 2.44 -7 |
| Si/Al ratio, OPRH2N lunar highlands simulant | 1.63 -8 |
| Median particle size (D50), OPRL2N lunar mare simulant | 58 µm9 |
| Median particle size (D50), OPRH2N lunar highlands simulant | 46.2 µm10 |
| pH of the reference alkaline activator | 14.31 -11 |
| Solution to simulant ratio in the reference mix | 0.35 -13 |
Why choose it, and why not
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 for
- 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.
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.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Amorphous content, JSC-1A lunar mare simulant | XRD phase table on the slide; the slide does not state how the amorphous fraction was quantified | simulant JSC-1A, lunar mare regolith simulantform as tabulated in the deck | — |
| 2 | Amorphous content, JSC-2A lunar mare simulant | XRD phase table on the slide; the slide does not state how the amorphous fraction was quantified | simulant JSC-2A, lunar mare regolith simulantform as tabulated in the deck | — |
| 3 | Amorphous content, OPRL2N lunar mare simulant | XRD phase table on the slide; the slide does not state how the amorphous fraction was quantified | simulant OPRL2N, lunar mare regolith simulantform as tabulated in the deck | — |
| 4 | Amorphous content, OPRH2N lunar highlands simulant | XRD phase table on the slide; the slide does not state how the amorphous fraction was quantified | simulant OPRH2N, lunar highlands regolith simulantform as tabulated in the deck | — |
| 5 | Amorphous content, EAC-1A lunar simulant | XRD phase table on the slide; the slide does not state how the amorphous fraction was quantified | simulant EAC-1A, lunar regolith simulantform as tabulated in the deck | — |
| 6 | Si/Al ratio, JSC-1A simulant | Printed Si/Al column of the oxide table; the table gives SiO2 and Al2O3 without units, so only the ratio is recorded | simulant JSC-1Abasis oxide composition as tabulated | — |
| 7 | Si/Al ratio, OPRL2N lunar mare simulant | Printed Si/Al column of the oxide table; the table gives SiO2 and Al2O3 without units, so only the ratio is recorded | simulant OPRL2Nbasis oxide composition as tabulated | — |
| 8 | Si/Al ratio, OPRH2N lunar highlands simulant | Printed Si/Al column of the oxide table; the table gives SiO2 and Al2O3 without units, so only the ratio is recorded | simulant OPRH2Nbasis oxide composition as tabulated | — |
| 9 | Median particle size (D50), OPRL2N lunar mare simulant | Printed D50 column of the particle size table on the slide | simulant OPRL2Nmeasurement laser particle size distribution, as named in the deck | — |
| 10 | Median particle size (D50), OPRH2N lunar highlands simulant | Printed D50 column of the particle size table on the slide | simulant OPRH2Nmeasurement laser particle size distribution, as named in the deck | — |
| 11 | pH of the reference alkaline activator | Printed on the mix footnote of the slide with the compressive strength chart; the slide gives no measurement method | activator sodium silicate and 10 M sodium hydroxide mixturesilicate ratio SiO2 Na2O 2solution to simulant 0.35 | The pH is a property of the activator solution, not of the hardened concrete. |
| 12 | SiO2/Na2O ratio of the sodium silicate in the reference mix | Printed on the mix footnote of the slide with the compressive strength chart | activator sodium silicate with 10 M sodium hydroxide | — |
| 13 | Solution to simulant ratio in the reference mix | Printed on the mix footnote of the slide with the compressive strength chart | simulant lunar regolith simulant (type not specified on the slide) | The slide does not say whether the ratio is by mass or by volume, so no unit is assumed. |
| 14 | Reference mix cure temperature (process condition, not a material property) | Printed cure condition on the mix footnote of the slide with the compressive strength chart | cure time three days, as printed on the slidemix reference geopolymer mix on the slide | — |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Vacuum exposure after curing (lunar surface condition) | not rated | Vacuum exposure limited further reaction and strength gain, compared with controls kept in the laboratory (qualitative)1 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Vacuum exposure after curing (lunar surface condition) | 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. | exposure vacuum chamber, pressure as stated in the abstractmaterials geopolymer lunar concrete from the two regolith simulants OPRL2N and OPRH2N |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
No hazard classification for the activators was read in this run, so this profile does not state one.
- Activators
- 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.
- Dust
- The sources read here do not discuss dust from regolith simulant, so no dust guidance is given.
Handling in construction concepts
These points come from the 2022 conference abstract, which describes a concept, not a built structure.
- Curing enclosure
- Printed lunar infrastructure would need a temporary environmental enclosure during construction and curing. The abstract says the benchmark enclosure conditions still need data.
- Reduced pressure
- The abstract reports a noticeable decline in strength when curing is done at reduced pressure.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Lower strength after curing at reduced pressuremoderate severity | Curing at reduced pressure in a vacuum chamberThe 2022 abstract reports a noticeable decline in strength with a reduction in pressure, and says vacuum exposure limits further reaction and strength gain. |
Handling and storage
- 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.
Documents
Datasheets, safety data sheets, papers and standards you can open.
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
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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
status: draft
author: assistant
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'
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
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
- benchmark: amorphous_content
label: Amorphous content, JSC-2A lunar mare simulant
value: 51
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
- benchmark: amorphous_content
label: Amorphous content, OPRL2N lunar mare simulant
value: 45.4
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
- benchmark: amorphous_content
label: Amorphous content, OPRH2N lunar highlands simulant
value: 26.5
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
- benchmark: amorphous_content
label: Amorphous content, EAC-1A lunar simulant
value: 26.2
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
- benchmark: si_al_ratio
label: Si/Al ratio, JSC-1A simulant
value: 2.5
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
- benchmark: si_al_ratio
label: Si/Al ratio, OPRL2N lunar mare simulant
value: 2.44
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
- benchmark: si_al_ratio
label: Si/Al ratio, OPRH2N lunar highlands simulant
value: 1.63
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
- benchmark: particle_size_d50
label: Median particle size (D50), OPRL2N lunar mare simulant
value: 58
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
- benchmark: particle_size_d50
label: Median particle size (D50), OPRH2N lunar highlands simulant
value: 46.2
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
- benchmark: activator_ph
label: pH of the reference alkaline activator
value: 14.31
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
- benchmark: sio2_na2o_ratio
label: SiO2/Na2O ratio of the sodium silicate in the reference mix
value: 2
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
- benchmark: solution_to_solid_ratio
label: Solution to simulant ratio in the reference mix
value: 0.35
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
- benchmark: curing_temperature
label: Reference mix cure temperature (process condition, not a material property)
value: 80
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)
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.
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)
story:
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
level: 0
verdict: Hazard data not found in this run
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.
- 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.
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.
- label: Amorphous feedstock
benchmark: amorphous_content
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.
- label: Alkaline activation
benchmark: activator_ph
line: The reference activator mixture has a pH of 14.31 (slide 21).
- label: Curing
benchmark: curing_temperature
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.
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
- label: Activator pH (reference mix)
benchmark: activator_ph
- label: Median particle size, OPRL2N (D50)
benchmark: particle_size_d50
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.
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.
| # | Source | Type | Year | Used for |
|---|---|---|---|---|
| Geopolymer Concrete: A greener alternative on Earth and a feasible material for the Moon (Earth Day 2022 presentation) | report | 2022 | 16 values | |
| Geopolymer Lunar Concrete under Reduced-Pressure Curing and Vacuum Exposure | paper | 2022 | 4 values | |
| Geopolymer (Wikipedia article) | web | 2026 | 0 values |