Shengyue Wang

Thermal Conduction and Insulation Modification in Asphalt-Based Composites

The relationship between thermal conductivity and properties of mixing particles is required for quantitative study of heat transfer processes in asphalt-based materials. In this paper, we measured the effective thermal conductivity of asphalt-based materials with thermal conduction (graphite) and insulation (cenosphere) powders modification. By taking account of the particle shape, volume fraction, the thermal conductivity of filling particles and base asphalt, we present a new differential effective medium formula to predict the thermal conductivity modification in asphalt-based composite. Our theoretical predications are in good agreement with the experiment data. The new model can be applied for predicting the thermal properties of asphalt-based mixture, which is available for most of thermal modification in two-phase composites.

The Regeneration of Aged SBS Modified Asphalt via Re-reticulating SBS Particles Under Gamma Irradiation

The damaged reticulation structure of SBS modifier was considered to be a main reason for the deterioration of pavement performances. The authors regenerated the damaged reticulation structure of aged SBS modified asphalt (SBS MA) by a gamma irradiation technology and assessed its potential applications. Changes of morphologies and chemical components in regenerated SBS MA were investigated by polarizing microscopy and Fourier transform infrared spectroscopy, respectively. Physical properties of regenerated SBS MA were measured to assess its potential applications. Results showed that reticulations were largely restored after 40 kGy irradiation and met the demand of pavement performances.

Inhibition and Removal of Thin Ice on the Surface of Asphalt Pavements by Hydrophobic Method

In order to reduce the surface adhesion of thin ice and asphalt pavements and remove the ice easily via vehicle rolling, an organic silicon rubber coating was prepared and successfully used to achieve a highly hydrophobic surface on asphalt pavement. Indoor and outdoor tests showed that the coating could reach more than 90° of contact angle, displaying an excellent hydrophobic property. Ice-breaking test indicated that, under a small strike, the coating could make the thin ice split in a radial crack way. Under repeated strikes, these cracks extended and linked to each other. An outdoor ice-removing test also verified that the ice growing on the coated asphalt pavements became loose, and was easy to separate from the pavement surface after vehicle rolling. Besides, since some of the coating was left within the texture of the pavement, asphalt pavement could keep high hydropobicity for a long time. This was confirmed by the high contact angle after spraying the coating for 12 months and the low wettability after spraying the coating for 20 months. Since the coating belongs to a conventional rubber structure, it had a limited effect on the skid resistance of asphalt pavement. Due to the potentials in removing ice from asphalt pavement, it is expected to provide an environmental method for removing ice by using the high hydrophobicity of the coating.

Improving the performance of asphalt mixture by addition of short-thin wheat straw pieces

To reduce costs and prevent environmental pollution in the fabrication process of straws fibrosis, a simple and efficient method of straw-reinforced asphalt concrete is proposed, which adds short-thin wheat straw pieces (SWSPs) into asphalt mixture directly. The road performances of wheat straw asphalt mixture (WSAM) are evaluated by means of three-point flexural test, rutting test, freeze thaw split test and the test of fracture toughness. The results show that when the SWSPs content is between 0.1% and 0.2%, the flexural strength of asphalt mixture increases by 23%, the dynamic stability by 48% (reaching 1592 times), fracture toughness by 27% while the rut depth decreases by 44%. It is indicated that high temperature stability of the asphalt mixture and low temperature crack resistance are intensified by adding an appropriate amount of SWSPs, and the results of freeze thaw split test manifest that the moisture susceptibility of WSAM is weaker.

Intensifying the Road Performance of Asphalt Concrete by Matching the Size Distribution of Short-Thin Straw Pieces and Aggregate Framework

In order to reduce costs and prevent environmental pollution in the fabrication process of straws fibrosis, a simple and efficient method of straw reinforcing asphalt concrete is proposed, which means to add short-thin straw pieces (STSP) into asphalt mixture directly by matching the size distribution of STSP and the aggregate spacing of asphalt mixtures. The road performances were testified in terms of the properties of bending, rutting and Marshall stability of the prepared straw asphalt concrete (SAC) samples. The results show that the flexural strength of asphalt mixture increased by 6%, the dynamic stability increased by 54% (reached 1,592 times) while the rut depth decreased by 24%. In addition, based on the analysis of the adhesion, shear lag and bridging effect of STSP, etc., a mechanism of enhancement is illustrated.

Temperature Effects on the Correlations between Tire-Pavement Noises and Pavement Surface Characteristics

The correlations between tire-pavement noises and pavement surface characteristics have been investigated for many decades, but temperature effects on these correlations are not clear yet. The objective of this paper was to investigate temperature effects on correlations between noise levels and surface characteristics correlations. Tire-pavement noises were measured quarterly by on-board sound intensity (OBSI) method on four types of asphalt pavements on the 2009 National Center for Asphalt Technology (NCAT) test track. Air and pavement temperatures were also recorded during those noise measurements. Four pavement surface characteristics (texture, porosity, roughness, and stiffness) were correlated with noise levels using a linear regression method. Temperature effects were established by comparing correlation coefficients between noise levels and surface characteristics with/without temperature correction. The results showed that, air temperature influenced the correlations between noise levels and surface textures, and temperature corrections were necessary to be taken before analysis. It would be benefit to data processing during tire-pavement noise research.

Deflecting Easy-axis of Fe3O4 Single Crystal Nanowires by Magnetic-field-induced Method

In order to control the orientation of easy-axis of magnetic nanowires, Fe 3 O 4 single crystal nanowires with easy-axis perpendicular to wire-axis were prepared successfully by means of a magnetic-field-induced method. Analysis of X-ray diffraction and electron diffraction pattern showed that there was a wide-angle deflection of easy-axis in the prepared Fe 3 O 4 nanowires. A high saturation magnetization (82 emu/g) of the Fe 3 O 4 nanowires was achieved at room temperature. The benefits and mechanism of the deflection of easy-axis from its wire-axis in Fe 3 O 4 single crystal nanowires were discussed. The results are expected to broaden the magnetic properties of traditional ferrite nanowires.