Thermally-induced chemical and physical transformations in metakaolin-based geopolymers

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A21110%2F25%3A00384684" target="_blank" >RIV/68407700:21110/25:00384684 - isvavai.cz</a>

Result on the web

<a href="https://doi.org/10.1007/s10973-025-14614-w" target="_blank" >https://doi.org/10.1007/s10973-025-14614-w</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1007/s10973-025-14614-w" target="_blank" >10.1007/s10973-025-14614-w</a>

Result language

angličtina

Original language name

Thermally-induced chemical and physical transformations in metakaolin-based geopolymers

Original language description

Geopolymers, prepared from metakaolin activated by potassium-based activators with corundum filler, were subjected to the temperatures up to 1200 degrees C. The Si/Al molar ratio of individual mixtures ranged between 1.0 and 1.9. The increasing Si/Al ratio caused higher strengths; material activated by KOH only (without added potassium silicate) achieved compressive strength 9.2 MPa and flexural strength 1 MPa, while the highest compressive strength had material with Si/Al ratio 1.8 (86.5 MPa) and highest flexural strength had material with Si/Al ratio 1.4 (3.6 MPa). The research on the impact of thermal loading (200 to 1200 degrees C) on the geopolymers was realized by thermogravimetry, thermodilatometry and by determination of residual mechanical properties, phase composition and pore size distribution. The compressive strength of all materials after heating increased significantly and reached its maximum between 800 degrees C and 1000 degrees C. The increase was more than 280% in the material with lowest added Si/Al ratio and it was between 90 and 136% in the materials with higher Al/Si ratios. The flexural strength of most materials decreased after heating to 200 degrees C with maximal decrease to 50-90% of original strength and after that flexural strength increased with residual flexural strength more than 1 MPa at 1200 degrees C in all materials. The thermal load up to 1200 degrees C promoted crystallization of new phases (leucite and mullite) which contributed to the increase of compressive strength. The porosity of geopolymers, determined by mercury porosimetry, gradually decreased upon the thermal loading, the smallest pores (with diameter 0.001-0.01 mu m) disappeared completely and sparse larger pores appeared between the newly formatted crystal phases. The tested materials proved excellent heat resistance and therefore they are very promising in the field of fire safety of buildings and also as a refractory material.

Czech name

—

Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

20501 - Materials engineering

Project

<a href="/en/project/GA23-04772S" target="_blank" >GA23-04772S: Physical and chemical processes in alkali activated ceramics exposed to high temperatures</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2025

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Journal of Thermal Analysis and Calorimetry

ISSN

1388-6150

e-ISSN

1588-2926

Volume of the periodical

150

Issue of the periodical within the volume

24

Country of publishing house

HU - HUNGARY

Number of pages

13

Pages from-to

19809-19821

UT code for WoS article

001552772600001

EID of the result in the Scopus database

2-s2.0-105013574472