Geopolymer Materials Based on Natural Pozzolans from the Moroccan Middle Atlas

Fadoua Elmahdoubi,Rachid Hakkou,Safaa Mabroum,Mounsif Ibnoussina

doi:10.3390/min11121344

Fadoua Elmahdoubi, Rachid Hakkou + Show 2 more

Open Access

https://doi.org/10.3390/min11121344

Copy DOI

Abstract

The pozzolans of the Moroccan Middle Atlas are derived from a low explosive volcanism, mostly strombolian. They are mainly composed of olivine and pyroxene, presenting a less homogeneous structure (irregular vesicles). The main target of this project is to study the use of natural pozzolans (NP) and metakaolin as precursors for the production of geopolymeric binders. The characterization of raw materials and elaborated geopolymers was carried out to study their mineralogical, chemical, microstructural, and mechanical properties. The studied pozzolans and kaolin were crushed, grinded, and sifted to get a fine grain size diameter of less than 100 µm. Then, they were calcined at 750 °C for 2 h to achieve an amorphous structure, increasing of their reactivity. Geopolymer production consists of mixing pozzolans and metakaolin with different amounts with an alkaline solution of sodium hydroxide and sodium silicates. The mass proportion of metakaolin (MK) used in this study was 10%, 20%, and 30%. In the present work, the amount of metakaolin was added as a source of alumina. The elaborated geopolymers were characterized using XRD, FTIR, TGA, and SEM analyses. The compressive strength was measured at 7, 14, and 28 days. The results showed interesting mechanical proprieties at about 18 MPa at 28 days with the mixture containing 20% MK. The addition of MK showed a significant increase in mechanical properties of the elaborated geopolymer. Meanwhile, the other results confirmed the training of new phases in addition to N-A-S-H gel. All these results indicate that the use of pozzolans in the production of geopolymers could be a great solution for the sustainable management of this mineral resource.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
The mineralogical composition was determined based on X-ray diffraction results of the XRD study (Table 1) show a high silicon oxide content of 35.42%, (XRD),The using a Bruker D8-advanced diffractometer with CuKa radiation, scanning step which is explained by the presence of augite and forsterite
Is in agreement with the formed chain of volcanoes in the Ifrane–Azrou region as well as the Timhdite plateau value of acompressive strength found in our study

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. (NP) is a volcanic aluminosilicate; its name originates from the city of Pozzuoli in. NPs are pyroclastic rocks formed by explosive volcanic eruptions. The pressure decreases, leading to the formation of a microporous structure caused by the release of gases dissolved in magma elements. The rapid cooling process results in their glassy structure [1,2]

Methods

Results

Conclusion