Version 1
: Received: 17 November 2023 / Approved: 17 November 2023 / Online: 20 November 2023 (10:47:45 CET)
Version 2
: Received: 31 December 2023 / Approved: 2 January 2024 / Online: 2 January 2024 (07:55:29 CET)
How to cite:
Al-hadj, H.Z.; Rochette, P.; Allafouza, A.B. Petrographic and Mechanical Study of Aggregates from Central Chad: a case for Natural Selection of hard rocks. Preprints2023, 2023111189. https://doi.org/10.20944/preprints202311.1189.v2
Al-hadj, H.Z.; Rochette, P.; Allafouza, A.B. Petrographic and Mechanical Study of Aggregates from Central Chad: a case for Natural Selection of hard rocks. Preprints 2023, 2023111189. https://doi.org/10.20944/preprints202311.1189.v2
Al-hadj, H.Z.; Rochette, P.; Allafouza, A.B. Petrographic and Mechanical Study of Aggregates from Central Chad: a case for Natural Selection of hard rocks. Preprints2023, 2023111189. https://doi.org/10.20944/preprints202311.1189.v2
APA Style
Al-hadj, H.Z., Rochette, P., & Allafouza, A.B. (2024). Petrographic and Mechanical Study of Aggregates from Central Chad: a case for Natural Selection of hard rocks. Preprints. https://doi.org/10.20944/preprints202311.1189.v2
Chicago/Turabian Style
Al-hadj, H.Z., Pierre Rochette and Annour Birké Allafouza. 2024 "Petrographic and Mechanical Study of Aggregates from Central Chad: a case for Natural Selection of hard rocks" Preprints. https://doi.org/10.20944/preprints202311.1189.v2
Abstract
This study focusses on the geological formations of the Alfallé massif located approximately 75km east of the town of N'Goura, in the Hadjer-Lamis Province of Chad (13°N, 17°E), and their ability to provide good quality aggregates in an area with poor hard rock ressources. We investigated the petrographic and mechanical characteristics of these formations in a resource perspective. The massif is made up of three lithologies: alkali feldspar megacrystalline granite, biotite-rich fine grained quartz monzonite and biotite-rich fine grained gneiss. Alkali feldspar megacrystalline granite is composed of quartz (30%), orthoclase (30%), plagioclase (20%), biotite (15%) and opaque minerals (≈5%). Micro-monzonite is composed of quartz (15-20%), orthoclase (20-25%), plagioclase (18-25%), biotite (20-25%) and opaque minerals (≈4%). The biotite gneiss is composed of quartz (25-30%), alkali feldspars (25-27%), plagioclase (17%), biotite (25-27%) and opaque minerals (≈5%). The mechanical characteristics of the aggregates show that the aggregates studied have specific density values of between 2.58 and 2.75g/cm3 with an average value of 2.66g/cm3, a Los-Angeles coefficient of 11.2% to 28.9% with an average value of 20.1% and a wet Micro-Deval coefficient of 5.2% to 10.8% with an average value of 7.6%. The values obtained indicate that the materials studied have excellent to satisfactory properties, and that Alfallé massif provide the best characteristics among six different quarrying area in Central Chad. We propose that such rare residual reliefs within the mega-Chad paleolake area reach optimal mechanical properties through a natural selection process, specific of the paleolake erosional conditions.
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Commenter: Pierre Rochette
Commenter's Conflict of Interests: Author