Mechanochemical Optimization and Sulfation Resistance of Metakaolin-Gyratory Slag Geopolymer Cements in Marine Environments

International Journal of Chemistry | Vol. 6, No. 2, February 2015 | pp. 9–16

DOI: 10.46882/2015/IJC/000077

Article Type: Original Research Paper

Title: Mechanochemical Optimization and Sulfation Resistance of Metakaolin-Gyratory Slag Geopolymer Cements in Marine Environments

Names of Authors: T. S. Ani¹, A. M. L. Gonçalves²*

Authors’ Affiliations:
¹Department of Electronic and Chemical Engineering, Enugu State University of Science and Technology, Enugu, Nigeria.
²Department of Civil Engineering, University of Coimbra, Coimbra, Portugal.

Abstract: Concrete infrastructure exposed to marine conditions suffers heavy degradation due to seawater sulfate attacks, requiring the development of resistant binders. This research details the structural design and chemical resistance of binary geopolymer cements synthesized via the alkaline activation of metakaolin integrated with electric arc furnace slag (EAFS) at substitution levels ranging from 0% to 50%. Activation parameters were optimized using a mixture of sodium silicate and 14 M sodium hydroxide. Durability metrics were monitored by immersing cured specimens in 5% magnesium sulfate (MgSO₄) solutions for 180 days. Structural phase shifts were mapped utilizing X-ray diffraction (XRD), FT-IR spectroscopy, and Scanning Electron Microscopy (SEM). Compressive strength testing showed that geopolymer specimens prepared with 30% slag maintained a high compressive strength of 48.5 MPa post-immersion, suffering a minimal strength reduction (< 4.2%). XRD analyses confirmed the complete absence of expansive ettringite and gypsum minerals, which typically ruin standard Portland cement structures. SEM imaging revealed a highly dense crosslinked gel network, proving that these geopolymers are excellent alternative materials for marine infrastructure.

Keywords: Geopolymer; Metakaolin; Electric arc furnace slag; Sulfate resistance; Compressive strength; Microstructure

Manuscript Timeline: Received: April 10, 2014; Revised: May 22, 2014; Accepted: June 18, 2014; Published: February 06, 2015.

Citation: Ani, T. S., & Gonçalves, A. M. L. (2015). Mechanochemical Optimization and Sulfation Resistance of Metakaolin-Gyratory Slag Geopolymer Cements in Marine Environments. International Journal of Chemistry, 6(2), 9–16.

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