This study presents analytical and experimental approaches to identify packing factors for polydisperse granular materials that maximize structural strength. The findings indicate that structural strength depends not only on the packing density but also on the particle-size distribution. A higher percentage of large particles correlates with greater structural strength, even for packings with identical density values. Therefore, this study proposes that the criterion for optimal packing should prioritize the maximum structural strength instead of the maximum packing density. This criterion is derived from proposed coordination numbers for polydisperse granular materials, which account for both the compaction degree and the proportion of particles of varying sizes. Physical experiments were conducted to measure the densities of packings with different particle-size distributions, and the experimental results were compared with analytical simulations using the discrete-element method. These comparisons indicate qualitative agreement between experimental and analytical data.

PURPOSES: The objective of this study is to evaluate the physical properties of recycled asphalt mixtures reinforced with glass fiber. METHODS: Firstly, mixing design was conducted on recycled asphalt mixture for use of 50% recycled aggregate. Various laboratory tests were performed on four types of recycled asphalt mixtures with different glass fiber content to evaluate the physical properties. The laboratory tests include indirect tensile strength test, dynamic modulus test, Hamburg wheel tracking test and tensile-strength ratio to evaluate cracks, rutting and moisture resistance of mixtures. RESULTS: The indirect tensile strength of fiber reinforced glass increased about 139.4%. As a result of comparing the master curves obtained by the dynamic modulus test, the elasticity was low in the low temperature region and high in the high temperature region when the glass fiber was reinforced. The glass fiber contents of PEGS 0.3%, Micro PPGF 0.1% and Macro PPGF 0.3% showed the highest moisture resistance and rutting resistance. CONCLUSIONS : The test results show that use of glass fiber reinforcement can increase the resistance to cracking, rutting, and moisture damage of asphalt mixtures. It is also necessary to validate the long-term performance of recycled asphalt mixtures with glass fiber using full scale pavement testing and field trial construction.