Hydraulic conductivity and strength of foamed cement-stabilized marine clay

Abstract

In traditional soft ground improvement of cement stabilized columns, strength was paid more attention than hydraulic conductivity, but the latter can improve the settlement uniformity and long term safety. This study introduced the pore-making technology referring the foaming concrete/mortar in an attempt to improve the hydraulic conductivity of the stabilized marine clays. The flexible wall permeameter and unconfined compressive strength (UCS) tests were conducted to depict the macro behaviour, and then the mercury intrusion porosimetry (MIP) tests and scanning electron microscopy (SEM) tests were performed to clarify the micro-structures. The hydraulic conductivity of foamed cement-stabilized marine clay at a given cement ratio (20%–50%) and density (900–1400 kg/m3) was found to be approximately 100–1000 times of that of (cement stabilized) clays without foaming, whereas the strength decreased only by 2–4 times. Microstructure investigation indicated that the hydraulic conductivity of foamed cement-stabilized marine clays was mainly dominated by the macro pore volume (>1 μm). Furthermore, a greater cement ratio and more active metakaolin additives enable developing an innovative material for columns that satisfy both the strength and hydraulic conductivity requirement.