Use of Alkali Activated Volcanic Ash Binder for Soil Improvement

Abstract In the present work an insight into the mechanical improvement of a clayey soil induced by the treatment with an alkali-activated binder (AAB) based on a volcanic ash is presented. The evolution of physical and mechanical performance of the AAB treated soil is investigated by performing ultrasonic wave velocities (UWV) and uniaxial compressive strength tests (UCS). The experimental evidence at sample volume is interpreted taking into account the chemical-physical evolution of the binder and its interactions with clayey soil particles by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The addition of alkali-activated binder increases the stiffness and the shear strength of the soil over curing time. Microstructural tests highlight the high reactivity of the whole system (soil + volcanic ash) to promote the neo-formation of minerals responsible for the mechanical improvement of treated soil.