Effects of heat and pressure on hot-pressed geopolymer

Navid Ranjbar*, Amin Kashefi, Guang Ye, Mehdi Mehrali

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Hot-pressed geopolymers have been introduced as ultra-high early strength ceramic-like materials with an almost pore-less structure. This study investigates the combined effects of pressure and heat on geopolymerization kinetics, microstructure, physical properties, and mechanical performance of geopolymers. The results demonstrate that about 65% of the trapped air is easily removed from the fresh geopolymer matrix using an initial impact pressure. When the pre-compacted matrix is subjected to the hot-pressing, it is further densified in the range of 1–10% as a result of continuous free-water evaporation and compaction. This process not only reduces the size and volume of porosity but also changes the continuous pore network to a closed one. Besides, the increase in hot-pressing promotes higher geopolymer gel formation and accelerates the polycondensation which possesses relatively high mechanical strength up to 160 MPa immediately after the processing. Collectively, these results demonstrate that the hot-pressing technique is a promising processing route for designing geopolymer with a diverse range of mechanical properties in a short and fast manner.
Original languageEnglish
Article number117106
JournalConstruction and Building Materials
Volume231
Number of pages8
ISSN0950-0618
DOIs
Publication statusPublished - 2020

Keywords

  • Geopolymer
  • Hot-pressing
  • Temperature
  • Pressure
  • Backscattered electron
  • Ultra-high strength

Cite this

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title = "Effects of heat and pressure on hot-pressed geopolymer",
abstract = "Hot-pressed geopolymers have been introduced as ultra-high early strength ceramic-like materials with an almost pore-less structure. This study investigates the combined effects of pressure and heat on geopolymerization kinetics, microstructure, physical properties, and mechanical performance of geopolymers. The results demonstrate that about 65{\%} of the trapped air is easily removed from the fresh geopolymer matrix using an initial impact pressure. When the pre-compacted matrix is subjected to the hot-pressing, it is further densified in the range of 1–10{\%} as a result of continuous free-water evaporation and compaction. This process not only reduces the size and volume of porosity but also changes the continuous pore network to a closed one. Besides, the increase in hot-pressing promotes higher geopolymer gel formation and accelerates the polycondensation which possesses relatively high mechanical strength up to 160 MPa immediately after the processing. Collectively, these results demonstrate that the hot-pressing technique is a promising processing route for designing geopolymer with a diverse range of mechanical properties in a short and fast manner.",
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author = "Navid Ranjbar and Amin Kashefi and Guang Ye and Mehdi Mehrali",
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doi = "10.1016/j.conbuildmat.2019.117106",
language = "English",
volume = "231",
journal = "Construction and Building Materials",
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Effects of heat and pressure on hot-pressed geopolymer. / Ranjbar, Navid; Kashefi, Amin; Ye, Guang; Mehrali, Mehdi.

In: Construction and Building Materials, Vol. 231, 117106, 2020.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Effects of heat and pressure on hot-pressed geopolymer

AU - Ranjbar, Navid

AU - Kashefi, Amin

AU - Ye, Guang

AU - Mehrali, Mehdi

PY - 2020

Y1 - 2020

N2 - Hot-pressed geopolymers have been introduced as ultra-high early strength ceramic-like materials with an almost pore-less structure. This study investigates the combined effects of pressure and heat on geopolymerization kinetics, microstructure, physical properties, and mechanical performance of geopolymers. The results demonstrate that about 65% of the trapped air is easily removed from the fresh geopolymer matrix using an initial impact pressure. When the pre-compacted matrix is subjected to the hot-pressing, it is further densified in the range of 1–10% as a result of continuous free-water evaporation and compaction. This process not only reduces the size and volume of porosity but also changes the continuous pore network to a closed one. Besides, the increase in hot-pressing promotes higher geopolymer gel formation and accelerates the polycondensation which possesses relatively high mechanical strength up to 160 MPa immediately after the processing. Collectively, these results demonstrate that the hot-pressing technique is a promising processing route for designing geopolymer with a diverse range of mechanical properties in a short and fast manner.

AB - Hot-pressed geopolymers have been introduced as ultra-high early strength ceramic-like materials with an almost pore-less structure. This study investigates the combined effects of pressure and heat on geopolymerization kinetics, microstructure, physical properties, and mechanical performance of geopolymers. The results demonstrate that about 65% of the trapped air is easily removed from the fresh geopolymer matrix using an initial impact pressure. When the pre-compacted matrix is subjected to the hot-pressing, it is further densified in the range of 1–10% as a result of continuous free-water evaporation and compaction. This process not only reduces the size and volume of porosity but also changes the continuous pore network to a closed one. Besides, the increase in hot-pressing promotes higher geopolymer gel formation and accelerates the polycondensation which possesses relatively high mechanical strength up to 160 MPa immediately after the processing. Collectively, these results demonstrate that the hot-pressing technique is a promising processing route for designing geopolymer with a diverse range of mechanical properties in a short and fast manner.

KW - Geopolymer

KW - Hot-pressing

KW - Temperature

KW - Pressure

KW - Backscattered electron

KW - Ultra-high strength

U2 - 10.1016/j.conbuildmat.2019.117106

DO - 10.1016/j.conbuildmat.2019.117106

M3 - Journal article

VL - 231

JO - Construction and Building Materials

JF - Construction and Building Materials

SN - 0950-0618

M1 - 117106

ER -