Investigation of the Strength Development in Tunisian Phosphogypsum-Stabilized Sensitive Clayey Soils: Assess of Geotechnical Properties and Environmental Impact
According to the previous works, the addition of Tunisian phosphogypsum and cement to the clayey soils is able to improve the geotechnical properties of these soils. This addition reduces the swelling problems by making the soil more resistant to water. The degree of success of such a treatment remains dependent on several parameters such as particle size, plasticity, and the chemical and mineralogical composition of soils and the dosage of hydraulic binders. The experimental approach adopted within the framework of this study was oriented towards the characterization of the behavior of three different soil samples in the presence of phosphogypsum and cement at different proportions. To observe this effect, some geotechnical tests were performed such as the Proctor test and the CBR test. The results have shown the improvement in the maximum dry unit weight and the optimum water content depends on the quality of the soil (% clay fraction). The CBR index was influenced by this addition taking into account the properties of the studied soils especially the mineralogical composition. Therefore, to confirm our results, an application of this technique was realized on a real scale.
This work proved the reliability of the addition of phosphogypsum and cement to a clay soil with well-defined characteristics. Knowing that the use of the phosphogypsum did not introduce any contamination at the lower layers, either by the heavy metals or by the radioactive elements. The stabilization of sensitive clayey soils with phosphogypsum and cement depends on the quality of the soil to be stabilized, the criteria of the phosphogypsum to be used and the appropriate dosage.
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