Improving the Consolidation Characteristics of Saline Sabkha Soil by Adding Bitumen

Abstract

The rapid economic and population growth, increase in constructions, and a small selection of appropriate soil resources in Kuwait have made it necessary to research soil stabilization methods because the existing soils are currently unsuitable in their natural conditions. In this study, the consolidation characteristics of sabkha soil samples in southern Kuwait mixed with 0%, 4%, 8%, and 10% bitumen with respect to soil dry weight were investigated. For this purpose, an experimental program, including soil characterization tests, modified Proctor compaction test, one-dimensional consolidation test, and collapsibility test, was executed. Results indicate that increasing the bitumen percentage improves the compressibility characteristics of sabkha soil. Upon the addition of 10% bitumen, the yield stress increased from 25 to 34 kPa, compression index slightly increased from 0.02774 to 0.03145, and swelling index decreased from 0.0119 to 0003. Further, there was a considerable reduction in the collapse potential from 1.192 to 0.301 upon the addition of 10% bitumen. Thus, it is evident that the disadvantageous characteristics of sabkha soil can be mitigated. The results support the possibility of recycling the sabkha soil, thereby contributing toward addressing the environmental issues associated with the disposal of excavated sabkha soil.

Reducing Corrosive Anion Dissolution in Sabkha Soil Under Long-Term Leaching by Bitumen Addition

“…Soil aggregation is expected to be due to the effect of the adsorbed bitumen on the soil particle surfaces. Similar results have been observed in various studies on contaminated oil residue and bitumen-stabilized soils and have been attributed to an adsorbed viscous layer [14,15]. The plasticity properties of natural and bitumen-stabilized soil samples have been determined and presented in Table 1.…”

“…Different specimens were air-dried, weighed, and mixed with 0%, 4%, and 12% of bitumen by weight. These percentages were selected according to previous investigations that revealed that optimum bitumen contents were lying from 3% to 12% [14,15]. The cut-back bitumen was made of a certain percentage of bitumen and an added percentage of kerosene, based on the manufacturer's specification.…”

“…The leached cell comprised a hollow plexiglass cylinder with a 3.0-mm-thick wall, an outer diameter of 110 mm, and a total length of 125 mm. Based on several previous works [14,15,16], distilled water was utilized in the leaching process since it has greater leaching capability than brackish water and a negligible concentration of ions to reduce the impact on the chemical analysis. The representative sabkha samples were prepared considering their compaction parameters obtained from the modified compaction assessments for the sabkha and bitumen-mixed sabkha soil samples.…”

“…The sample was percolated the next day from the top to the bottom under a pressure of 5 psi (34.5 kPa). The applied pressure reflected a 3.5 m water head, selected based on the authors' knowledge of these soils to increase the leached pore volumes at a suitable time [1,15,16], The pore volume of the tested soil in the leached cell was determined by assuming that it was equal to the amount of water needed to fill the soil pores. This amount is equal to the product of the bulk volume and the total porosity.…”

“…Previous research has focused on the investigation of sabkha soil [13][14]15,16], reporting an increase in soil permeability with continuous salt dissolution. This increase in soil permeability owing to leaching causes a significant collapse of the soil skeleton because of the softening, dissolution, and effusion of salts from the sabkha soil skeleton [17].…”