Investigating the Use of Linear Low-Density Polyethylene in Modifying Bitumen to Improve the Performance of Flexible Pavements Along Climbing Lanes

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This study examined the concept of bitumen modification to improve the performance of flexible pavements against rutting on climbing lanes. Such sections are subjected to slow moving heavy traffic and prolonged loading time hence categorized as severely loaded sections. As pavement temperatures rise, the asphalt binder softens and is unable to withstand the loads, leading to deformation. A case study along Bweyogerere – Jinja road climbing lane revealed premature deterioration in form of instability rutting in the asphalt layer. Using mechanistic and empirical approaches, aggregates and bitumen were evaluated to understand the failure. While aggregates showed good performance, the bitumen susceptible to temperature variations which reduced stiffness at high temperatures. Modifying bitumen with 2% LLDPE reduced the temperature susceptibility and increased the stiffness modulus which showed improved resistance to permanent deformation without compromising durability of the asphalt mixture as portrayed from Marshall test results. The modified specimens exhibited a 16.7% increase in tensile strength and a 42% increase in air voids at refusal density signifying increased flexibility under heavy loads and extending service life thereby addressing premature deformation issues at the road section.