Analysis of the deformational behavior of a clayey foundation soil stabilized with ladle furnace slag (LFS) using a finite element software

Abstract

The stabilization of soft clayey soils to improve their stress–strain behavior is one of the most widely used geotechnical engineering techniques. Traditionally, lime and cement have been used as stabilizers, although other products such as Ladle Furnace Slag (LFS) are now used, given the environmental imperative to reuse materials and to reduce both the consumption of raw materials and the use of landfill sites. LFS is a by-product of the steelmaking industry, with limited applicability in other industrial processes, but its chemical composition, rich in calcium, magnesium, silica, and alumina, mean that it may be used as a binder for clayey soils as a substitute for lime. This geo-mechanical research is focused on the analysis of the plastic behavior and the strength of a low bearing capacity clayey soil mix with 5% added LFS. The following properties were evaluated: plasticity (Atterberg limits), California Bearing Ratio (CBR), Unconfined Compression Strength (UCS), and direct shear strength. The evolution of UCS was verified through tests on samples held in a humid chamber at a constant relative humidity of 95% ± 5%. and temperature of 20 °C ± 3 °C, after 3, 7, 28, 54, and 90 days of curing. Based on the results, a numerical analysis was performed with a two-dimensional finite element software: RS2 (Rocscience). The behavior of a footing-foundation system supported on stabilized soil was modeled, with a plate load test geometry and with the laboratory parameters. The results, compared with those obtained with untreated soil and with a lime-stabilized soil, demonstrated that the LFS mix increased the stiffness of the layered soil (less settlement) and improved its bearing capacity. The applicability of LFS for soil stabilization and its use in geotechnical works such as foundations and embankments open up fields of application that are likely to offer satisfactory alternatives for these by-products.