Effects of elevated temperature on pumice based geopolymer composites

Abstract

Aluminosilicate type materials can be activated in alkaline environment and can produce geopolymer cements with low environmental impacts. Geopolymers are believed to provide good fire resistance so the effects of elevated temperatures on mechanical and microstructural properties of pumice based geopolymer were investigated in this study. Pumice based geopolymer was exposed to elevated temperatures of 100, 200, 300, 400, 500, 600, 700 and 800°C for 3 h. The residual strength of these specimens were determined after cooling at room temperature as well as ultrasonic pulse velocity, and the density of pumice based geopolymer pastes before and after exposing to high temperature was determined. Microstructures of these samples were investigated by Fourier transform infrared for all temperatures and SEM analyses for samples that were exposed to 200, 400, 600 and 800°C. Specimens, which were initially grey, turned whitish accompanied by the appearance of cracks as temperatures increased to 600 and 800°C. Consequently, compressive strength losses in geopolymer paste were increased with increasing temperature level. On the other hand, compressive strength of geopolymer paste was less affected by high temperature in comparison with the ordinary Portland cement. As a result of this study, it is concluded that pumice based geopolymer is useful in compressive strength losses exposed to elevated temperatures.

Physical and mechanical properties of fly ash‐based geopolymer with disposable medical mask reinforcement

“…Then, as the temperature increased, the density gradually decreased, which might be due to water evaporation and the increase in porosity as temperature increased. This behavior was also observed by other researchers 38,39,44 for pumice‐based GP composites and metakaolin‐based GP composites at elevated temperatures.…”

The effects of silica modulus and aging on compressive strength of pumice-based geopolymer composites

“…Needle shape sodium crystals are seen in theFig. 4that they have not used up completely in the produced geopolymer along with sodium alimunosilicate hydrate gel (N-A-S-H) and medium geopolymeric matter produced in the geopolymerization[22].At constant Na 2 O content i.e. Na 2 O = 4%, with increasing in silica modulus from 0.52, 0.60 to 0.68, compressive strength increases to 8.68, 10.6 and 9.55 MPa, respectively and if Na 2 O = 7% with increasing in silica modulus from 0.52, 0.60 to 0.68, compressive strength increases to 14.32, 18.78 and 17.98 MPa, respectively and at Na 2 O = 10% with increasing in silica modulus from 0.52, 0.60 to 0.68, compressive strength increases to 24.08, 29.16 and 40.28 MPa, respectively.…”

Phase and dimensional stability of volcanic ash-based phosphate inorganic polymers at elevated temperatures

“…Moreover, the superior thermal stability of geopolymer compared to Portland cement has also increased the interest in that material for high-temperature applications [5]. However, this characteristic is closely related to the type of aluminosilicate used as well as the synthesis conditions [6][7][8]. For example, an addition of calcium sources to Metakaolin (MK) improves the thermal resistance of geopolymers in terms of compressive strength compared to solely MK-based geopolymers when exposed at 1000 °C [9].…”