Utilization of urea as an accessible superplasticizer on the moon for lunar geopolymer mixtures

Pilehvar, Shima; Arnhof, Marlies; Pamies, Ramón; Valentini, Luca; Kjøniksen, Anna–Lena

doi:10.1016/j.jclepro.2019.119177

Cited by 81 publications

(18 citation statements)

References 36 publications

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“…As a result, they were able to flow freely in the fresh paste and act as "lubricant" to enhance the flowability of MgO paste. In fact, similar results have also been observed in PC and geopolymer mixes [30,31]. increased by 19% when compared to the control mix (W0.5).…”

Section: Flowabilitysupporting

confidence: 84%

Bacteria-induced internal carbonation of reactive magnesia cement

Xiao

Goh

Unluer

et al. 2021

Construction and Building Materials

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Section: Flowabilitysupporting

confidence: 84%

Bacteria-induced internal carbonation of reactive magnesia cement

Xiao

Goh

Unluer

et al. 2021

Construction and Building Materials

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“…Moreover, to enhance the HB interaction between urea and CG minerals, CG grinding in the presence of urea was also conducted. Laboratory trials of workability and buildability in a reference [ 35 ] showed that the urea dosage corresponding to 3% of the regolith mass was optimal. Therefore, in this work, the urea was added with a mass ratio of 1%, 3%, and 5% to CG.…”

Section: Methodsmentioning

confidence: 99%

“…Recently, the urea, potentially obtained from human urine, was reported to act as an effective SP for 3D printing of lunar geopolymer mixtures to attain the required workability of extrusion and shape retention [ 35 ]. Besides, urea was also used to improve the rheological behavior of the kaolinite [ 36 ], which is a clay mineral commonly contained in CG [ 25 ].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Performance Optimization of Grouting Backfill Material Based on Mechanically Ground Coal Gangue Utilizing Urea and Quicklime

Wang

Zhang

et al. 2023

Materials

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Previously conducted studies have established that grouting backfill in mining-induced overburden bed separation and mined-out areas with broken rocks provides an efficient strategy to control strata movement and surface subsidence caused by underground mining. Grouting backfill materials (GBMs) based on coal gangue (CG) are highly desirable in coal mining for accessibility to abundant CG and urgent demand for CG disposal. However, CG is generally employed as coarse aggregate due to rather rigid and inert properties, limiting its application in GBMs. Herein, to reduce reliance on fine aggregates, such as fly ash and clay, cemented GBM formulations using ground CG powder as a dominant component were proposed. Urea and quicklime were utilized as additives to optimize slurry transportability and compressive strength. Besides typical grinding without additives, CG powder was also prepared via grinding with urea, intending to enhance the hydrogen bonding (HB) interaction between urea and minerals contained in CG. The effect of grinding time and urea on CG particle size and phase composition was investigated. Then, the dependence of slurry transportability and compressive strength on grinding time, solid concentration, urea, and quicklime dosage were revealed. It has been experimentally proved that grinding for 30~90 min significantly decreased CG particle size and even induced crystal deformation of dolomite and kaolinite. For GBMs, urea improved slurry flowability, possibly caused by decreased water absorption on the CG surface and the release of water encapsulated in hydrated cement particles. Moreover, quicklime strengthened GBM bodies, which could be explained by an accelerated pozzolanic reaction between CG powder and additional CH supplied by quicklime hydration. G60U3-based GBM-B2 with 5% quicklime provided a stable and smooth slurry with a bleeding rate of 1.25%, a slump flow of 205 mm, and a hardened body with a seven-day UCS of 1.51 MPa.

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“…From these results, it was inferred that careful selection of the curing scheme is essential to maximize the strength of geopolymers manufactured on the moon, and importantly, the processing must also be practical on the lunar surface. Pilehvar et al (2020Pilehvar et al ( , 2021 found that when conducting durability tests, the compressive strength of geopolymers increased when repeatedly exposed to a low-hightemperature cycle similar to that experienced on the lunar surface [21,51]. The compressive strength of geopolymer was found to increase by a factor of 6 or more when exposed to a thermal cycle of −80~114 • C in air and vacuum.…”

Section: Compressive Strength and Durability Of Lunar Regolith Simula...mentioning

confidence: 97%

A Review on Geopolymer Technology for Lunar Base Construction

Lee

Riessen

2022

Materials

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Geopolymer is a synthetic amorphous aluminosilicate material that can be used as an inorganic binder to replace ordinary Portland cement. Geopolymer is produced by mixing aluminosilicate source materials with alkali activators and curing the mixture either at ambient or low temperatures. Geopolymer research for lunar-based construction is actively underway to enable astronauts to stay on the moon for long periods. This research has been spurred on by earnest discussions of in situ resource utilization (ISRU). Recent research shows that the lunar regolith simulant-based geopolymers have high application potential to protect astronauts from the harsh moon environment. However, not all the simulants perfectly reproduce the lunar regolith, and the characteristics of the lunar regolith vary depending on the site. Issues remain regarding the applicability of geopolymer technology to contribute to ISRU through an elaborate and systematic plan of experiments. In this paper, the potential of geopolymers is assessed as a lunar-based construction material with the latest research results. Future work to develop the lunar regolith-based geopolymer technology is also proposed.

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Utilization of urea as an accessible superplasticizer on the moon for lunar geopolymer mixtures

Cited by 81 publications

References 36 publications

Bacteria-induced internal carbonation of reactive magnesia cement

Bacteria-induced internal carbonation of reactive magnesia cement

Experimental Study on Performance Optimization of Grouting Backfill Material Based on Mechanically Ground Coal Gangue Utilizing Urea and Quicklime

A Review on Geopolymer Technology for Lunar Base Construction

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