Shutang Liu

Orthogonal Test Research of Asphalt Rubber Modified by Warm Asphalt Additive

The research incorporates the technology of warm mix asphalt into asphalt rubber (forming into warm asphalt rubber) and evaluates the performance of warm asphalt rubber (WAR) binders. Crumb rubber modifiers (CRMs) of three particle sizes and one warm asphalt additive (WAA) are employed, and an orthogonal diagram is used to arrange the tests. The analysis shows that the bigger particle size and content of CRM all have positive effects on softening point, penetration index(PI), viscosity, temperature susceptibility described by viscosity, and low temperature property of WAR. But WAA content only produces positive impacts on softening point and PI; it cannot dramatically reduce the viscosity at high temperatures, and cannot improve the low temperature property of WAR. So employing WAA to reduce energy consumption for CRM-asphalt producing might be invalid.

Rutting-Resistance Performance of SBS and Anti-Rutting Additive Composite-Modified Asphalt-Concrete Mixtures

To improve the rutting resistance of the middle hot-mix asphalt (HMA) surface layer, composite modification of asphalt-concrete (AC) mixture by styrene–butadiene–styrene (SBS) and anti-rutting additive (ARA) was studied. First, the wheel-tracking test, bending test, and indirect tensile test were conducted to evaluate the effect of three dosages of ARA on the high-temperature performance, low-temperature performance, and moisture susceptibility of SBS-modified AC mixture and the optimum dosage of ARA was determined. Then the high-temperature rutting-resistance performance of composite-modified AC mixtures was studied through the dynamic modulus test and uniaxial creep test. The results showed that the high-temperature performance of composite-modified AC mixture was significantly improved, but the low-temperature performance and moisture susceptibility were slightly declined compared to the control mixture (SBS-modified AC mixture without ARA). The values of E*/sinφ of composite-modified AC mixture were larger than those of the control mixture at various test temperatures and loading frequencies. The values of permanent deformation and creep rate of composite-modified AC mixtures were smaller than those of the control mixture. In conclusion, composite-modified AC mixture has excellent high-temperature stability.

Slope Stability Analysis of the Embankment Filled with River Sand and Weathered Mudstone Rock

To solve the shortage of land resources and the lacking of soil in expressway construction, the application feasibility of river sand and weathered mudstone rock (WMR) used for filling embankment with steep slope (slope ratio is 1:1) were evaluated in this paper. 24 kinds of embankment schemes in terms of the combinations of the river sand and WMR with different embankment heights were designed. The slope stability analyses of these embankments were conducted using numerical calculation method. The results show that the safety factors of river sand embankments with 3–4 m slope protection width (SPW) and composite embankment with 3 m SPW can meet the requirements, provided the embankment height is less than 8 m. While considering comprehensively the vertical deformation, location of potential sliding surface, and economic cost, the river sand embankment with 3 m SPW is the optimal scheme. When the embankment height exceeds 8 m, the increase of SPW has no obvious positive effect on the increase of safety factor.