Engineering Geological Properties of Sandstone and Clay Formations in Tropical Sedimentary Terrains: Implications for Infrastructure Development

Abstract

Infrastructure development in tropical sedimentary terrains is increasingly constrained by weak subgrades, rapid pavement deterioration, slope instability, gully erosion, foundation settlement, and weathering-driven degradation of sandstone-clay sequences. These failures persist because engineering designs often treat lithology, geotechnics, groundwater, geomorphology, and climate as separate variables rather than interacting controls. This review addresses this limitation by evaluating how sandstone and clay formations influence infrastructure stability in tropical sedimentary environments. A structured review synthesis was conducted on studies dealing with sandstone durability, clay plasticity, grain-size distribution, Atterberg limits, ferruginization, groundwater effects, slope processes, pavement failure, quarry suitability, and sustainable geotechnical planning. The review integrated evidence from engineering geology, sedimentology, geotechnical testing, geomorphology, GIS-based hazard mapping, remote sensing, and emerging machine-learning approaches. Particular attention was given to index properties, strength behaviour, drainage response, weathering intensity, structural discontinuities, and climate-induced deterioration. The findings show that well-cemented quartz-rich sandstones can provide competent foundation and aggregate materials, whereas poorly cemented sandstone promotes infiltration, piping, erosion, and slope weakening. Clay-rich and shale-derived formations are the most critical engineering constraint because high fines, plasticity, low permeability, and moisture sensitivity reduce bearing performance and increase deformation. Reported evidence includes clay fractions of 50-70%, plasticity indices of 21-28%, soaked CBR as low as 1.03-1.60%, slope safety factors below unity, and rainfall-triggered failures after intense antecedent wetness. Ferruginization improves hardness but may redirect runoff when ferricrete restricts infiltration. The review therefore proposes integrated geological, geotechnical, hydrological, GIS, and climate-resilient assessment as the basis for safer infrastructure planning