Application of Dynamic Replacement to Lateritic Clay

Dynamic replacement (DR) is a widespread technique used in several countries to improve soils with characteristics such as low bearing capacity, high compressibility and collapsibility. No published scientific report describes its application to saprolite or a lateritic soil. To fill this technical and scientific gap, this study was conducted to analyse the behaviour of typical lateritic clayey soils subjected to improvement by DR, with and without the addition of top layers and compacted soil-cement mixtures, on a prototype scale. The magnitude of the effects of sand column depth and reinforcement layer height were examined at six study points (SPs). The columns were composed of granular soil (sand from Osorio, Brazil) treated with early strength cement and compacted. They were subjected to plate testing with a D-pl (plate diameter) of 300 mm applied to the superficial soil. The sand column depth did not significantly affect the stiffness or ultimate capacity at the SPs. The reinforcement layer height improved the bearing capacity of the natural soil by 200-1200% and increased soil stiffness. All improved layers failed with plate punching, and flexible layers (150 mm reinforcement layer height) manifested clear radial cracking. Punching rupture occurred at SPs with no improved layer.