Effectiveness of Nanoclay in Stabilising Recycled High-Density Polyethene Modified Bituminous Mix

In recent years, increased traffic volume and severe environmental conditions have increased the requirement for improved performance in bituminous pavements. High-Density Polyethylene (HDPE) is one of the most commonly used Polyethylene. HDPE improves bituminous pavement's high-temperature performance. However, HDPE-modified binder has been observed to be associated with phase separation and poor workability, limiting its widespread application. Recently, nanomaterials have been used to balance the undesirable effects of polymers while enhancing the bituminous binder and mixture performance. Hence, the research aims at producing a stabilised and workable HDPE-modified binder using nanoclay. HDPE content of 2%, 4%, 6%, and 8% was used to modify the 80/100 base binder. Nanoclay content of 1%,2%, 3%, and 4% was used to stabilise the optimum HDPE-modified bitumen binder. The binders were tested using penetration, storage stability, ductility, softening point, and dynamic shear rheometer tests, while the bituminous mixtures were evaluated using volumetric and Marshall properties. Furthermore, microstructural tests were used to investigate the physical and chemical interactions between the additives and binders. Compared to the Kenya Roads Design Manual for Roads and Bridges Part III (RDMIII) specifications, the optimal dosage of HDPE was 4%, resulting in the highest Marshall stability of 13.9kN, lowest air voids of 4.9%, and 65.1% voids filled with binder, meeting all specifications. Additionally, adding 3% nanoclay to the optimal HDPE-modified binder showed superior performance, reducing viscosity by 47.8% and air voids by 12.3% while increasing Marshall stability by 30.2% and enhancing storage stability by 82.4% compared to the optimal HDPE-modified bituminous mix.