Geological and geotechnical characterization of Ntambeng basalt massif used as aggregates in civil engineering (North-West Cameroon)

Abstract

Basalt massif outcrops in Ntambeng. Construction companies used these rocks extensively for various purposes such as structural loading, pavements, and wall cladding. This study aims to characterize both geological and geotechnical points of the Ntambeng basalt massif for their potential use as aggregates in civil engineering. The geological aspect is based on petrographic and structural analyses of the rock massif. Geotechnical characteristics: specific gravity, bulk density, water absorption, flakiness index, Los Angeles, Microdeval, uniaxial compressive strength, and tensile strength tests were determined on fresh and slightly weathered basalt collected on the field. The fresh basalt is dark grey, while the slightly weathered one is reddish-brown. The thin blade basalts are rich in olivine, clinopyroxene (augite), volcanic glass (quartz), opaque minerals, and plagioclase. The major direction of fracture is N98°E. The studied basalt massif has an average bulk density (1.51 g/cm3), and good quality of water absorption with an average of 1.41%. A satisfactory Los Angeles abrasion value for the fresh and those slightly weathered ones. Aggregate crushing value is limited for the fresh and then for those slightly weathered materials. Furthermore, the studied basalt has a medium compressive strength, a high tensile strength, a good rock quality designation (80.02%), and a high density of discontinuities index (15.02 cm). Given the foregoing, the Ntambeng basalt massif has good geotechnical characteristics; they can be used as aggregates in civil engineering.