RESUMEN

This study aimed to investigate the efficiency of a geopolymer binder of the type of Na-poly(ferro-silico-aluminate) as a matrix for the stabilization of heavy metals along with their effect on the development of structural performances. The artificial contamination of soil with ions was carried out and used to prepare an alkali-activated iron-rich lateritic soil binder. Further, various microstructural analyses were carried out to explain the stabilization mechanism. The stabilization efficiency was assessed by leaching tests in de-ionized water and hydrochloric acid (0.1 M, HCl). Then, the physical properties were determined to evaluate the impact of heavy metals on the structural performance of the binder. Results demonstrated that the prepared geopolymer binder has the lowest stabilization capacity in an acidic medium (low pH) than in water with high pH. However, the stabilization of Cu ions was effective at 99%, while the Cd ion is barely retained in the matrix. Firstly, the mechanism consists of chemical bonds through ion exchange with sodium of the Na-poly(ferro-silico-aluminate) network. Secondly, through physical interaction with the pore network of the matrix, the heavy metals induced structural deterioration in the geopolymer matrix with a decrease in the compressive strength and bulk density and an increase of both apparent porosity and water absorption.

RESUMEN

The exploitation of volcanic rock quarries generates enormous waste, which causes the problem of disposal, leading to rising dust levels in quarries and depositions on nearby farms by runoffs. To address this issue, the development of sustainable solution for their valorization in construction industries is required. The present investigation aims to valorize granite (GW) and basalt (BW) quarry waste powders as partial replacement (up to 20 wt.%) of iron-rich aluminosilicates in the synthesis of geopolymer binders. Both synthesized series of samples were sealed and cured at 7, 14, and 28 days at room temperature before subjecting to various analytical techniques, including the mechanical properties, XRD, FT-IR, TG/DTG, and SEM-EDS. The results showed that both GW and BW powders are efficient to produce sufficient amounts of geopolymer binder, with ensure good cohesion and connectivity between different components within the final matrices. The values of compressive strength were 7.5-35.9 MPa and 6.2-39.7 MPa for laterite/granite and laterite/basalt geopolymer composites, denoted LGA and LBA, respectively. Moreover, the coexistence of the amorphous Na-aluminosilicate, Ca-aluminosilicate, and Na-polyferrosialate species is responsible for the mechanical properties development of the end-products. Based on the findings, the selected quarry wastes appeared to be sustainable and cost-effective materials for the synthesis of low-energy consumption binder, suitable for the production of construction materials.

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RESUMEN

The progress achieved with the use of volcanic ash for geopolymer synthesis has been critically reviewed in this paper. This consists of an overview of mineralogy and chemistry of volcanic ash. The role of chemical composition and mineral contents of volcanic ash on their reactivity during geopolymerization reaction and, consequently, mechanical properties have been accessed. An attempt has been made to establish a relationship between synthesis factors and final properties. A critical assessment of some synthesis conditions has been addressed and some practical recommendations given along with suggestions of future works that have to be done. All this has shown that there are still many works such as durability tests (carbonation, freeze-thaw, resistance, etc.), life cycle analysis, etc. that need to be done in order to satisfy both suitability and sustainability criteria for a large-scale or industrial application.

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