Muthukumar Mayakrishnan

To mitigate environmental impacts and promote sustainability in highway construction, this study investigates the optimization of blending conditions and the performance evaluation of bio-modified asphalt binder incorporating bio-asphalt derived from the pyrolysis of waste cooking oil (WCO) and low-density polyethylene (LDPE). A response surface approach was employed to optimize key blending parameters—temperature, speed, and time—based on critical physical properties of the binder. Furthermore, the optimized bio-asphalt binder was further evaluated through rheological performance tests (multiple stress creep recovery and linear amplitude sweep) and mechanical performance tests (Marshall stability, tensile strength ratio, resilient modulus, indirect tensile fatigue, and dynamic creep). The optimal conditions were identified as 130°C, 1000 rpm, and 42.37 min. Statistical validation using ANOVA, residual analysis, leverage, and Cook’s distance confirmed the model’s reliability, with prediction errors remaining below 5%. The bio-modified asphalt binder exhibited enhanced elastic recovery and reduced non-recoverable creep compliance (Jnr), indicating superior resistance to permanent deformation in comparison with the control asphalt binder. Additionally, the bio-modified asphalt mixture demonstrates superior Marshall stability, resilient modulus, tensile strength ratio, retained stability, and resistance to deformation in comparison with the control asphalt binder. These results demonstrate the potential of bio-asphalt as a viable, eco-friendly modifier for asphalt binders in tropical climates.

Helical piles have lately emerged as a viable alternative foundation solution in offshore geotechnical applications. The helical piles are typically installed in groups to resist large loads from the structures and may encounter combined loading due to some factor such as the waves from the water surrounding it. Recent research works on group helical piles focused mostly on piles embedded in sand and their response to individual loading regimes. This research has been carried out to examine the behaviour of the helical pile groups embedded in soft clay subjected to combined uplift and lateral loading considering three different configurations (rectangular, triangular, and square) and different spacings between the helical piles (2 to 5 times the helix diameter). A three-dimensional finite element model is developed to predict the load-displacement response of the group and is validated against the 1 g laboratory scale model test results. The findings from the analyses reveal that the influence of combined loading reduces the lateral capacity of the group helical pile. The spacing between the helical piles also has a substantial impact on the response to combined loading. The role of critical spacing ratio for various configurations has also been discussed in this paper.