ABOUT THE INTERNATIONAL CONCRETE ABSTRACTS PORTAL

  • The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

International Concrete Abstracts Portal

  


Title: Synthesis and Microstructural Characterization of Fully-Reacted Potassium-Poly(sialate-Siloxo) Geopolymeric Cement Matrix

Author(s): Zhang Yunsheng, Sun Wei, and Li Zongjin

Publication: Materials Journal

Volume: 105

Issue: 2

Appears on pages(s): 156-164

Keywords: microstructure; preparation; strength.

DOI: 10.14359/19756

Date: 3/1/2008

Abstract:
In this paper, a total of nine potassium-poly(sialate-siloxo) (K-PSS) geopolymeric cement matrixes, with different molar ratios of SiO2/Al2O3, K2O/Al2O3, and H2O/K2O, is designated to investigate the influence of the three ratios on mechanical properties and microstructure in accordance with the orthogonal design principle. The experimental results show that SiO2/Al2O3 has the most significant effect on compressive strength among the three ratios. The highest compressive strength (5.04 ksi [34.8MPa]) can be achieved when SiO2/Al2O3 = 4.5, K2O/Al2O3 = 0.8 and H2O/K2O = 5.0. Comparing the infrared (IR) spectra of nine K-PSS geopolymeric cement matrixes also indicates that the geopolymeric cement matrix with the highest strength is the most fully-reacted one and possesses the largest amount of geopolymeric products. Subsequently, X-ray powder diffraction (XRD), environment-scanning electron microscope equipped with energy dispersion X-ray analysis (ESEM-EDXA), transmission electron microscopy-electron diffraction spectroscopy (TEM-EDS), and magic angle spinning nuclear magnetic resonance spectroscopy (MAS-NMR) techniques are employed to further characterize the microstructure of the fully-reacted geopolymeric cement matrix. The microscopic analysis reveals that the fully-reacted K-PSS geopolymeric cement matrix possesses structural characteristics similar to glassy or gel substances in having a wide range of Si endowments, but predominantly the framework molecular chains of Si partially replaced by four-coordinated Al tetrahedral. A three-dimensional (3D) molecular structural model is also proposed based on the decomposition of MAS-NMR spectrum of the fully-reacted K-PSS geopolymeric cement matrix synthesized from the optimum mixture proportion.