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 - Backscattered electron
KW - Geopolymer
KW - Hot-pressing
KW - Pressure
KW - Temperature
KW - Ultra-high strength
UR - http://www.scopus.com/inward/record.url?scp=85073074160&partnerID=8YFLogxK
U2 - 10.1016/j.conbuildmat.2019.117106
DO - 10.1016/j.conbuildmat.2019.117106
M3 - Article
AN - SCOPUS:85073074160
SN - 0950-0618
VL - 231
JO - Construction and Building Materials
JF - Construction and Building Materials
M1 - 117106
ER -