Effects of cement and foam addition on chemo-mechanical behaviour of lightweight cemented soil (LWCS)

Abstract

One of the main problems encountered in civil engineering is the management of large amounts of excavated soil, especially when the mechanical properties of this soil are not suitable for its reuse as a construction material. However, the excavated soil could represent a resource if appropriately improved. A suitable solution is the addition of cement and foam to produce lightweight cemented soils (LWCS). In this paper, an insight into the influence of foam on chemo-mineralogical and microstructural features of soil-cement-water system is presented. Time dependent mineralogical and microstructural changes have been monitored by means of X-Ray Diffraction, Thermo-gravimetric analysis and Mercury Intrusion Porosimetry. The present study shows that addition of foam does not alter the chemo-physical evolution of the soil-cement-water system. Large voids are present in the samples as footprint of air bubbles upon mixing, thus increasing porosity. Macroscopic behaviour of treated samples has been investigated by direct shear and oedometric tests. Chemo-physical evolution induced by cement addition is the major responsible for mechanical improvement showed by treated samples. Porosity of samples induced by foam addition plays a key role in the mechanical response of LWCS, inducing a transition of stress-strain behaviour from brittle and dilative to ductile and contractive as a function of increasing foam content.

Effects of wetting and drying cycles on the mechanical behaviour of Lightweight Cemented Soils

“…Studies on the effects of cement, foam and initial water content on unit weight and shear strength of LWCS have been performed, shedding light on the evolution of physical and mechanical properties as a function of treatment parameters [4,5,6]. Moreover, an insight into the role of foam content on chemo-physical evolution and microstructural features of the system on mechanical behaviour of LWCSs has been provided by [7], which highlighted that addition of foam does not alter chemo-physical evolution of the soil-cementwater system in terms of either cement hydration or pozzolanic reactions.…”