Journal of Emerging Trends in Engineering and Applied Sciences: Research Areas

Article Title: Characterization of Lateralite Stabilizer by Atomic Absorption Spectroscopy (AAS), X-ray Photoelectron (XPS) and Scanning Electron Spectroscopy (SEM)
by A.O.Ogundalu, E.A. Meshida, G.L. Oyekan

Abstract:
The objective of this paper is to characterize Lateralite, a new soil stabilizing flux for fine-grained lateritic soils and expansive clays in order to improve the soil engineering properties for road pavement construction. It is also to establish the mechanism of stabilization of soils by Lateralite. Lateralite samples were mineralogically characterized by Atomic Absorption Spectroscopy (AAS), X-ray Photoelectron Spectroscopy (XPS), and Scanning Electron Spectroscopy (SEM). AAS gave the oxide composition of Lateralite as: Calcium Oxide (63.89%), Silicon Oxide (18.31%), Aluminium Oxide (5.89%), Ferrous oxide (1.67%), Magnesium oxide (1.56%), Sulphur oxide (1.22%), Potassium oxide (0.78%) and Sodium oxide (0.41%). XPS analysis detected ten (10) elements with Percentage Atomic Concentration, in descending order as: Oxygen (54.33%), Carbon (18.26%), Silicon (9.38%), Calcium (7.56%), Magnesium (4.08%), Aluminium (2.90%), Sodium (2.47%), Ferrous (0.44%), Sulphur (0.31%) and Nitrogen (0.27%). SEM detected eleven (11) elements. The distribution of chemical elements by atom in descending order is: Oxygen (57.9%), Calcium (21.13%), Silicon (11.08%), Aluminium (4.23%), Ferrous (1.89%), Sulphur (1.07%), Magnesium (1.02%), Sodium (0.99%), Potassium (0.35%), Tin (0.18%) and Barium (0.17%). All the three characterization techniques confirm the abundance of exchangeable calcium cations (Ca2+), over magnesium (Mg2+), aluminium (Al3+), sodium (Na+) and potassium (K+). The study established the abundance of divalent exchangeable cations (Calcium and Magnesium) in Lateralite as a stabilizer for lateritic and clayey soils. The significance of this is the possibility of pozzolanic reaction and cation exchange with alumina and silica in lateritic and clay soils which will result in stabilization of expansive clays and formation of cemented calcium compounds (calcium alumina hydrates and calcium silicate hydrate) with strong inter-particle bonds which are responsible for high strength. The potential impact of Lateralite is a stabilized soil with high shear strength for road pavement construction.

Keywords: Atomic Absorption Spectroscopy, X-ray Photoelectron Spectroscopy, Scanning Electron Microscopy, Lateralite, Exchangeable Cations

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