Mechanical and statistical evaluation of performance properties of sulfur modified foamed asphalt for local soil stabilization

With the development of road construction techniques, the foamed asphalt (FA) technology is considered a very effective, sustainable, and improved engineering solution. Furthermore, the utilization of sulfur in asphalt concrete has also been successful for building the test pavement sections on several highways worldwide. This research emphasized the locally available sulfur, which is available in abundant quantities in the Kingdom of Saudi Arabia, to be used as a raw material in the pavement construction. So, in the current study, we explored the possibility of using FA produced by a ratio of 30 / 70 sulfur asphalt for the local soil stabilization. The locally available soils, viz., marl, dune sand, and sabkha, were stabilized using SFA and were compared with the regular FA. Keeping in mind the specification requirements, the designed asphalt mixtures using the soils were compared for evaluation in performance properties. The results of material properties, FA, Marshall mix design, indirect tensile strength (ITS), and resilient modulus (Mr) tests for different percentages (3, 6, 9, 12, and 15) of the soils were evaluated. Results showed that ITS strength of SFA Sabka soil reaches to 315 kN, the SFA for marl sand increased to 640 kN, and for dune sand 83 kN. The Marshall Stability values are higher at 7% optimum binder content and increasing the value up to 30 kN for Marl soil. A two-factor factorial analysis of variance was conducted to assess the significance and reliability of the primary variables (FA and SFA) and the material types (sabkha, dune sand, and marl soil) on the mixture performance tests outcomes. The use of SFA improved ITS and Marshall stability in marl and dry sabkha soil conditions and have variable effects in soaked condition for sabkha and dune sand. The statistical analysis of the ITS, revealed that modified SFA exerts a greater influence on dry ITS than FA with p < 0.05. The Mr value increases with increased pressure and decreases with elevated temperature. A linear relationship and good correlation exist between the Mr and deviator stress (σd) for all the soils, justified by the higher R2 values. Hence, the generated models in this study can be effectively used to forecast the Mr of soils at higher stress levels.