Evaluation of mechanical properties and aging index of 10-year field aged asphalt materials

Abstract: Ten years’ field aged asphalt specimens have collected and being detailed studied. The aging index, viscoelastic behavior of aged binder recovered from the cored specimens, indirect tensile strength and residual fatigue life of the top layer and underneath layer were studied. Saturates, Aromatics, Resins and Asphaltenes (SARA) analysis and Fourier Transform Infrared Analysis (FTIR), viscoelastic analysis, Indirect Tensile (IDT) resilient modulus and fatigue test were performed.

Both SARA, FTIR and viscoelastic analysis indicates that traffic loading does have positive degradation influence on asphalt binder. FTIR shows that traffic loading has limited influence on the chemic changes of S=O compounds, while has positive contribution on degrading the C=C bonds and hence promotes the oxidize aging. Although surface layer can protect underneath asphalt layer from aging, 10-year field aging would introduce significant deterioration onto the underneath layer. The effective aging depth can go as deep as to the second layer. Fatigue tests illustrate that 10-year service has resulted in very weak asphalt pavement surface. Its fatigue life is very sensitive to traffic loading.

Keywords: Asphalt pavement; Aging index; Asphalt aging; Asphalt binder; Residual mechanical property

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S.P. Wu, Z.J. Zhao, Y. Xiao* (Corresponding Author), M.W. Yi, Z.W. Chen, M.L. Li. Evaluation of mechanical properties and aging index of 10-year field aged asphalt materials, Construction and Building Materials, Volume 155, 30 November 2017, P: 1158-1167.

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NSFC Grant received on Antiskid Surfacing Research

We have successfully received a NSFC Grant on Antiskid Surface design. The Grant title is Theoretic Design on Closest Packing based Antiskid Surface in Airfield for Preventing Hydroplaning, with a financial support from 201801 to 202012. Detail information of this grant will be updated here soon.

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Oral Presentation in ICPT2017 Conference, on VOC reduction

During 8-10 August 2017, Dr. Xiao and Yongshuang Long attended the 10th International Conference on Road and Airfield Pavement Technology (10th ICPT 2017) in The Hong Kong Polytechnic University. This conference is a longstanding event that brings together road and airport pavement researchers, engineers, and governmental officials to promote pavement technological advancement worldwide. The objectives of ICPT is to promote pavement technological advancement worldwide, with special emphasis in pavement technological development in developing countries, by encouraging exchange and transfer of pavement technology among professionals and researchers of different countries and regions, through organizing technology transfer activities such as international conferences.

In 2011, Dr. Xiao had joined the 7th ICPT conference when he was a PhD candidate in Delft University of Technology.

It was very proud for Dr. Xiao to get an opportunity to give an oral presentation in ICPT 2017 conference. His presentation title was Design Synthetic Ca(OH)2-incorporated Zeolite as Effective VOCs Inhibitor for Bitumen Materials. This presentation focus on presenting the research results by using self synthesized Ca(OH)2-incorporated Zeolite to reduce the VOC emissions from bituminous materials. After Dr. Xiao’s presentation, Jiří Jaromír Klemeš, one of the Co-Editors-in-Chief for Journal of Cleaner Production, expressed great interest on our research and had then gave some valuable comments. Related work will be published soon.

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Using Activated Carbon to Reduce the Volatile Organic Compounds from Bituminous Materials

Abstract: The objective of this research is to characterize the reduction of volatile organic compounds (VOCs) from bituminous materials resulted from activated carbon. A gas chromatography-mass spectrometer (GC-MS) was used to separate VOC components, and ultraviolet-visible spectrophotometry (UV-Vis) was conducted to quantify the amount of VOCs. Results indicated that activated carbon had an excellent suppression effect on VOCs’ emission process. Adding activated carbon to the bitumen binder did not change its chemical compounds, but did result in a significant reduction of VOCs. The weight of VOCs from the bitumen binder reduced by around 30% when it was modified with activated carbon. Half of VOC emissions can be reduced by introducing activated carbon into styrene-butadiene-styrene (SBS)-modified bitumen. A scanning electron microscope (SEM) showed the high porosity and large internal surface area in the active carbon, resulting in lower VOC emissions when it was introduced into bituminous materials.

Find it via ASCE Library

Y. Xiao, M. Wan, K.J. Jenkins, S.P. Wu, P.Q. Cui. Using Activated Carbon to Reduce the Volatile Organic Compounds from Bituminous Materials, Journal of Materials in Civil Engineering, Volume 29, Issue 10, (Oct. 2017), 04017166.

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The Rejuvenating Effect in Hot Asphalt Recycling by Mortar Transfer Ratio and Image Analysis

Abstract: Using a rejuvenator to improve the performance of asphalt pavement is an effective and economic way of hot asphalt recycling. This research analyzes the rejuvenating effect on aged asphalt by means of a Mortar Transfer Ratio (MTR) test, which concerns the ratio of asphalt mortar that moves from recycled aggregates (RAP aggregates) to fresh added aggregates when aged asphalt is treated with a regenerating agent and comes into contact with fresh aggregates. The proposed MTR test analyzes the regeneration in terms of the softening degree on aged asphalt when the rejuvenator is applied. The covered area ratio is studied with an image analyzing tool to understand the possibility of mortar transferring from RAP aggregates to fresh aggregates. Additionally, a micro-crack closure test is conducted and observed through a microscope. The repairing ability and diffusion characteristics of micro-cracks can therefore be analyzed. The test results demonstrate that the proposed mortar transfer ratio is a feasible way to evaluate rejuvenator diffusion during hot recycling. The mortar transfer ratio and uncovered area ratio on fresh aggregates are compatible, and can be used to quantify the contribution of the rejuvenator. Within a certain temperature range, the diffusing effect of the rejuvenator is better when the diffusing temperature is higher. The diffusion time of the rejuvenator is optimum when diffusion occurs for 4–8 h. When the rejuvenator is properly applied, the rough and cracking surface can be repaired, resulting in better covered aggregates. The micro-closure analysis visually indicates that rejuvenators can be used to repair the RAP aggregates during hot recycling.

Keywords: rejuvenator; mortar transfer ratio; micro-cracks; preventive maintenance

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