OPTIMIZING THE INCORPORATION OF PERIWINKLE SHELL FINE AGGREGATE IN HOT-MIX ASPHALT WEARING COURSE

Abstract

This study seeks to optimize the periwinkle shell aggregate content when used as fine aggregate in hot-mix asphalt. The Design-Expert 13 software was used for the optimization process. A custom-designed experiment was carried out and the data set was imported into the software for further analysis due to the nature of the study’s experimental data.  The control design comprised of one numeric factor (bitumen content) while the investigation design constituted two numeric factors (bitumen and periwinkle shell fine aggregate content). The responses were the stability, flow, bulk unit weight, per cent voids in the mineral aggregates, air-void voids in the bitumen content, indirect tensile strength and tensile strength ratio. The developed response models revealed that both factors generally had a significant effect on the HMA responses individually and interactively, with the periwinkle shells showing more influence. All statistical measures indicated that the models developed showed a good relationship between the factors and the responses. The analysis revealed that the optimum binder content for the control mix was determined to be 6.032%. In comparison, the optimum contents for the binder and the periwinkle shells were established to be 93.124% and 6.207% for the investigation mix respectively.