Structural study of metakaolin-phosphate geopolymers prepared with wide range of Al/P molar ratios

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389013%3A_____%2F25%3A00638851" target="_blank" >RIV/61389013:_____/25:00638851 - isvavai.cz</a>

Alternative codes found

RIV/68407700:21110/25:00385617

Result on the web

<a href="https://www.mdpi.com/2073-4360/17/17/2358" target="_blank" >https://www.mdpi.com/2073-4360/17/17/2358</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3390/polym17172358" target="_blank" >10.3390/polym17172358</a>

Result language

angličtina

Original language name

Structural study of metakaolin-phosphate geopolymers prepared with wide range of Al/P molar ratios

Original language description

Geopolymers represent an innovative and environmentally sustainable alternative to traditional construction materials, offering significant potential for reducing anthropogenic CO2 emissions. Among these, phosphoric acid-activated metakaolin-based systems have attracted increasing attention for their chemical and thermal resilience. In this study, we present a comprehensive structural and mechanical evaluation of metakaolin-based geopolymers synthesized across a wide range of Al/P molar ratios (0.8–4.0). Six formulations were systematically prepared and analyzed using X-ray powder diffraction (XRPD), small-angle X-ray scattering (SAXS), Fourier-transform infrared spectroscopy (FTIR), solid-state nuclear magnetic resonance (ssNMR), and complementary mechanical testing. The novelty of this work lies in the integrated mapping of composition–structure–property relationships across the broad Al/P spectrum under controlled synthesis, combined with the rare application of SAXS to reveal composition-dependent nanoscale domains (~18–50 nm). We identify a stoichiometric window at Al/P ≈ 1.5, where complete acid consumption leads to a structurally homogeneous AlVI–O–P network, yielding the highest compressive strength. In contrast, acid-rich systems exhibit divergent flexural and compressive behaviors, with enhanced flexural strength linked to hydrated silica domains arising from metakaolin dealumination, quantitatively tracked by 29Si MAS NMR. XRPD further reveals the formation of uncommon Si–P crystalline phases (SiP2O7, Si5P6O25) under low-temperature curing in acid-rich compositions. Together, these findings provide new insights into the nanoscale structuring, phase evolution, and stoichiometric control of silica–alumino–phosphate geopolymers, highlighting strategies for optimizing their performance in demanding thermal and chemical environments.

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

10404 - Polymer science

Project

<a href="/en/project/GA24-11171S" target="_blank" >GA24-11171S: Acid-activated geopolymers based on clay precursors: preparation, structure, environmental assessment</a><br>

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2025

Confidentiality

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

Name of the periodical

Polymers

ISSN

2073-4360

e-ISSN

2073-4360

Volume of the periodical

17

Issue of the periodical within the volume

17

Country of publishing house

CH - SWITZERLAND

Number of pages

20

Pages from-to

2358

UT code for WoS article

001571332900001

EID of the result in the Scopus database

2-s2.0-105016099816