Abstract:

To diversify aggregate sources and maximize resource utilization in highway construction， siliceous sandstone from Southwest China was evaluated as an aggregate for high-grade asphalt pavement base layers. The mechanical properties of the aggregate and the performance of the resulting mixture were investigated. To determine the optimum asphalt-aggregate ratio， two design approaches were compared： the Marshall mix design and a balanced mix design approach， aiming to balance high-temperature deformation resistance with low-temperature cracking resistance. Results indicate that the siliceous sandstone aggregate meets all standard specification requirements， exhibiting a uniaxial compressive strength exceeding 80 MPa in the natural state and 42 MPa in the water-saturated state. The Marshall mix design and the balanced mix design yield optimum asphalt content of 4.1% and 3.8%， respectively. While both designs satisfied low-temperature performance requirements， the mixture designed via balanced mix design demonstrates a dynamic stability 44.2% higher than the mixture via Marshall mix design， indicating superior suitability for high-temperature regions. Replacing mineral filler with 1.4% to 2.0% 42.5-grade ordinary Portland cement （by mass） effectively addresses the insufficient water stability revealed by the initial immersion residual stability and freeze-thaw splitting tests. Consequently， the immersion residual stability and freeze-thaw splitting strength ratios are improved by 34.2% and 36.7%， respectively， meeting specification requirements. Finally， a dynamic modulus master curve was constructed using the Sigmoidal function based on the time-temperature superposition principle. At 20 ℃ and 5 Hz， the dynamic modulus is recorded at 5 614 MPa， indicating good bearing capacity. Its use as a base layer for high-grade asphalt pavement is reasonable and feasible.

Key words: siliceous sandstone, asphalt-treated base, balanced mix design, water stability, dynamic modulus master curve