Papers by Author: Ran Liu

Abstract: We fabricated mono-dispersed β-quartz GeO₂ by microemulsion synthesis at room temperature. The obtained particles were 300 nm sized GeO₂ walnut and hollow waxberry shaped GeO₂ which were consisted of nanosphere with average size of 20 nm. The evolution of high pressure studies were devoted in a diamond anvil (DAC) cell by Angle Dispersed X-ray Diffraction (ADXD) at room temperature. A phase transformation of β-GeO₂ to amorphous GeO₂ was detected in walnut GeO₂, while the waxberry GeO₂ was found to transform to monoclinic phase directly. It is strongly suggested that size effect played a key role in the high-pressure transformation from the amorphous and monoclinic phase. By fitting the compression data to the BirchMurnaghan equation of state, the bulk moduli of the walnut and waxberry shaped β-GeO₂ particles were determined to be 33±5, and 38±4 GPa with B₀ = 3, respectively.

Abstract: The effects of aging on the fatigue property of polymer modified asphalt mixtures are investigated in this paper. Two kinds of aging procedures are adopted for the aging of specimens prepared with polymer modified asphalt mixtures. One is the short-time aging which means that the hot asphalt mixtures was heated in the oven for 4 hours at 135°C before compacted; The other called natural aging, with the original specimen exposed in the sunlight and subjected to the rain and temperature change for 3, 6 and 9 months. Four-Point Bending Test was conducted to evaluate fatigue properties of aged asphalt mixtures at 15°C compared with the original specimens. Test results indicate that the fatigue line of aged specimens have the same tendency as the original asphalt mixtures. However, the life of aged specimen is decreased significantly when compared with the original ones, especially of the natural aged specimens.