Papers by Author: Shao Peng Wu

Abstract: The static shear creep behavior of asphalt mastic containing recycled red brick powder (RBP) is investigated in this paper. The used mastic consists of asphalt and filler at a mass ratio of 1:1. Dynamic Shear Rheometer (DSR) performed the static shear creep tests at 0°C. The static shear creep behavior of RBP asphalt mastic was analyzed and modeled based on Burgers model. It is concluded that the introduction of RBP results in smaller deformation, higher static shear creep stiffness modulus of asphalt mastic at 0°C. It was also indicated that Burgers model can well explain the static shear creep behavior of RBP asphalt mastic.

Abstract: Ultraviolet(UV) radiation is one of the main factors induce asphalt aged in the field in-service. Asphalt mortar greatly affects the pavement performance. It is scarce that studies concerning UV aging on the performance of asphalt mortar. In this paper, asphalt mortar with a 1.0 F/A (filler to asphalt)after UV aging were subjected to the test of the Dynamic Shear Rheometer (DSR).Effects of UV aging on the High-Temperature and fatigue performances of asphalt mortar were studied by using the rutting parameter G*/sinδ, fatigue parameter G*sinδ and dynamic viscosity. The results show UV aging had prominent effect on asphalt mortar’s properties, with the decrease of film thickness and increase of UV aging temperature, the ability of rut resistance enhances and fatigue performance weakens.

Abstract: Raw materials, such as SBS modified asphalt, graphite powder and crumb rubber were selected to blend with aggregate mixture to product electrically conductive asphalt concrete. Experimental results demonstrated the stress or strain had a great influence on the resistance of conductive asphalt concrete, which exhibited sensitive piezoresistivity. In fact, the piezoresistivity reflects the change in microstructure. The reason for piezoresistivity may involve proximity effect, microcrack and the dislocation of conductive paths due to shear strength of aggregates. With further study on the variation of the resistance, it is hopeful to explore the microstructure change of asphalt concrete under dynamic compressive stress. Therefore this new-style asphalt concrete has extensively practical foreground in fatigue damage testing, highway traffic intelligent monitoring and so on.

Abstract: The waterproof-adhesive layer plays an important role in cement concrete bridge pavement. The adhesive strength of the layer between the cement concrete deck and the asphalt pavement may affect the bridge’s service performance directly. In the study, the direct shearing-strength experiment between the asphalt pavement, waterproof adhesive layer and the cement concrete deck was done in a laboratory. Some testing parameters were considered, including different loading speed, surface processing mode of the cement concrete deck and adhesive materials. The result shows that the coarser the surface of the cement concrete deck is, the larger the shearing strength of the adhesive material is at the same temperature. The loading speed of the shearing test has important effect on the shearing strength. The rapid loading speed can cause high shearing strength. Especially, the experiment datum indicates that the relationship between the loading speed of the test and the shearing strength can be described using the power exponent. Ultimately, the study is aimed at providing bridge engineers with an efficient testing method that attempts to increase the prediction accuracy of adhesive strength for more reliable design.

Abstract: The use of gneiss as aggregates might help meet the pavement constructing demands. However, the study of the pavement performances of gneiss asphalt mixture is few. In this paper, the microstructure of gneiss aggregate was studied by Scanning Electron Microscopy (SEM). And the pavement performances of gneiss asphalt mixture with different improving measure were characterized by means of Indirect Tensile Strength Test and Four-Point Bending Fatigue Test. Gneiss is flaky, surface texture rougher and imporosity characteristic in microstructure, resulting to its adhesion and processing property are poor. Experiment results indicate that the use of hydrated lime replacing limestone power partly in filler can improve pavement properties of the gneiss asphalt mixtures distinctly.

Abstract: Additives are always added into silicone rubber to improve properties. As a sealant, it is well known that the adhesion property is a key aspect of the sealant system. The effect of additives on the adhesion properties of silicone rubber sealant are discussed in this study. The results showed that the adhesive properties of samples with single coupling agent are lower than that with multiple coupling agents. The adhesive properties of sample first increase with increasing amount of coupling agent and then decrease linearly. The adhesion strength of SR sealant decreased with the amount of the plasticizer and filler added into the silicone rubber has little influence on the adhesion strength of silicone rubber.

Abstract: Flexible pavement-asphalt mixture plays an important role in structures of the primary road and bridge at present. However, the mixture is a type of viscoelstic material and is sensitive to environment temperature, especially a high temperature. The permanent deformation due to high temperature and the material’s viscoelastic shorten the service life of the road and even lead to traffic accident. Therefore it is necessary to analyze the pavement’s mechanical performance. In the study, the viscoelastic constitutive equation of the mixture is transformed to Prony Series. The objective of this study is to characterize the stability of asphalt pavement at high temperatures with a three-dimensional finite element and accurately predict the pavement’s strain and stress in vehicle load.

Abstract: With global climate becoming warmer more and more attention is being paid to cold materials. Lower surface temperature contributes to decrease the temperature of the ambient air as heat convection intensity from a cooler surface is lower. Such temperature reductions can have significant impacts on cooling energy consumption in urban areas, a fact of particular importance in hot climate cities. The black surface of asphalt pavement absorbs more heat from the sun, and higher temperature of pavement surface contributes to increase the effect of the urban heat island, but affects the performance and life span of a pavement. Asphalt pavements form an integral part of any transportation system and are typically engineered to last 15 years or more, but many have been failing early due to potholes, cracks, raveling and other problems. Cool pavement are mainly aimed to decrease the effect of asphalt pavement on the urban heat island, but the influence of cold materials on the high-temperature performance of asphalt concrete pavement is paid little attention relatively. In this paper, it’s discussed that the effect of asphalt-pavement high temperature and its improving measures. And the mechanism of cool pavements is introduced, and possible technologies applied to asphalt pavements are reviewed. The idea of asphalt concrete pavement with automatic temperature-control is put forward.

Abstract: One micro-powder rubber (styrene butadiene rubber-SBR) at three concentration levels are used for manufacturing polymer modified asphalt with a mixing technique. The effects of concentration of modifiers and mixing temperature on the mechanical properties of the compounds are investigated. Based on a limited study, test results indicate that micro-powder rubbers have positive effect on the performance of asphalt in low temperature. Soft point, penetration and ductility show that the ideal percentage of rubber additive (7 wt. %) and preparing temperature (210°C) are brought forward. The fluorescence microscopy test indicates that rubbers are homogeneous dispersed in asphalt and have a little dissolving at the surface of the ultra-fine rubbers. The difference between soft point values in the high temperature storage stability test is only 0.2~0.5°C, which proves that modified asphalts have good storage stability. Complex modulus master curves are drawn to analyze and compare the rheological properties of various modified asphalts. Results indicate that modified asphalt binders have more excellent properties at both high and low temperatures, compared with original asphalt.

Abstract: Porous asphalt is one of the most functional structures for the surface layer of asphalt pavement, which has already shown excellent noise reduction property for its 20% air voids in the structure. However, mechanical degradation is also monitored because of the high air voids, for example, permanent deformation in high service temperature and cracking in low service temperature. The Tafpack Super (TPS) additive was used in this study and expected to improve the resistance to permanent deformation and low-temperature cracking of porous asphalt mixture. Unconfined static uniaxial creep test and three-point bending test were conducted to study the effects of TPS additive on the permanent deformation and anti-cracking property of porous asphalt mixture, respectively. Experimental results showed that the TPS additive decreased the creep deformation and increased the creep stiffness modulus in uniaxial creep test. TPS additive had little effect on the brittleness temperature porous asphalt mixtures as shown in three-point bending testing. However, the flexural strength-strain response curve indicated that with the increase of TPS additive, porous asphalt mixtures exhibited better resistance to cracking. Porous asphalt mixtures with TPS additive indicate excellent temperature susceptibility and can be applied to a wider field of road engineering.