Abstract
This paper presents the results of research aimed at studying the hydraulic and mechanical behavior of Finnish soft clays treated by quicklime. This research investigated the effect of water content and curing time on the characteristics of the compacted soil treated with 7% lime, with the aim of verifying the effectiveness of lime treatment and evaluating its possible re-use, thus avoiding landfill disposal. A laboratory-testing program was carried out both on treated and untreated soil, supported by microstructural investigation. Results have shown a general increase of the hydraulic conductivity due to the addition of lime, reduction of compressibility, and increase in the soil shear strength for a wide range of water contents (10%–40%), proving the effectiveness of the lime treatment. Lime addition to the compacted clay at high water contents (90%–130%) turned out to improve the mechanical characteristics to a lesser extent, while fractionated lime supply did not significantly improve the mechanical performance. The results of this research demonstrate that the re-use of sensitive clays, typically of high water contents, by lime addition require a drying process. Different drying procedures can be adopted (proposed in the paper) depending on the specific site conditions. However, the soil treatment is generally economically convenient in comparison to the disposal in waste landfills, which would represent the only alternative solution.
Highlights
Introduction and BackgroundThe limited availability of natural good-quality soil to be used as construction material and the recent boost in finding environmentally sustainable solutions to engineering problems lead the geotechnical engineering community to study and finalize techniques to re-use excavated soils
The lime stabilization technique offers both economic and environmental advantages when an excavated soil, suitable for lime treatment, is available on-site: there are no needs to supply good-quality soils from quarries and of landfill disposal of the in situ soil, as well as no environmental impact linked with transportation of soils
The sensitivity is defined as the ratio of the shear strength measured on an undisturbed sample and the shear strength on the same sample once remolded at the same water content
Summary
The limited availability of natural good-quality soil to be used as construction material and the recent boost in finding environmentally sustainable solutions to engineering problems lead the geotechnical engineering community to study and finalize techniques to re-use excavated soils. The lime stabilization technique offers both economic and environmental advantages when an excavated soil, suitable for lime treatment, is available on-site: there are no needs to supply good-quality soils from quarries and of landfill disposal of the in situ soil, as well as no environmental impact linked with transportation of soils (from quarry and to landfill). The typical high compressibility, low undrained shear strength, and high sensitivity often make the geotechnical design rather challenging. Given their susceptibility to changes in consistency when worked or remoulded, they are usually excavated and landfilled.
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