Advancements in Heavy Metal Stabilization: A Comparative Study on Zinc Immobilization in Glass-Portland Cement Binders

• Published in: Materials 2024-06, Vol.17 (12), p.2867
• Main Authors: Bouchikhi, Abdelhadi, Safhi, Amine El Mahdi, Maherzi, Walid, Mamindy-Pajany, Yannick, Kunther, Wolfgang, Benzerzour, Mahfoud, Abriak, Nor-Edine
• Format: Article
• Language: English
• Subjects: Adsorption; Cement; Cement hydration; Comparative studies; Curing; Equilibrium; Heavy metals; Immobilization; Pollutants; Polymers; Portland cements; Stabilization; Transmutation; Tricalcium silicate; Zinc
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma17122867

Recent literature has exhibited a growing interest in the utilization of ground glass powder (GP) as a supplementary cementitious material (SCM). Yet, the application of SCMs in stabilizing heavy metallic and metalloid elements remains underexplored. This research zeroes in on zinc stabilization using a binder amalgam of GP and ordinary Portland cement (OPC). This study juxtaposes the stability of zinc in a recomposed binder consisting of 30% GP and 70% OPC (denoted as 30GP-M) against a reference binder of 100% CEM I 52.5 N (labeled reference mortar, RM) across curing intervals of 1, 28, and 90 days. Remarkably, the findings indicate a heightened kinetic immobilization of Zn at 90 days in the presence of GP-surging up to 40% in contrast to RM. Advanced microstructural analyses delineate the stabilization locales for Zn, including on the periphery of hydrated C S particles (Zn-C S), within GP-reactive sites (Si*-O-Zn), and amid C-S-H gel structures, i.e., (C/Zn)-S-H. A matrix with 30% GP bolsters the hydration process of C S vis-à-vis the RM matrix. Probing deeper, the microstructural characterization underscores GP's prowess in Zn immobilization, particularly at the interaction zone with the paste. In the Zn milieu, it was discerning a transmutation-some products born from the GP-Portlandite reaction morph into GP-calcium-zincate.