scholarly journals Evaluation of top-down crack propagation in asphalt pavement under dual tire loading

2019 ◽  
Vol 46 (8) ◽  
pp. 704-711
Author(s):  
Mohsen Alae ◽  
Hamzeh F. Haghshenas ◽  
Yanqing Zhao
Keyword(s):  
Asphalt Concrete ◽  
Asphalt Pavement ◽  
Propagation Rate ◽  
Base Layer ◽  
Major Type ◽  
Fracture Mechanisms ◽  
Top Down ◽  
Pavement Distress ◽  
Paris Law

Top-down cracking (TDC) has been recognized worldwide and is regarded as a major type of asphalt pavement distress. In this study, fracture mechanisms behind the TDC propagation and fatigue life of pavements were investigated under dual tire loads using finite element (FE) analysis. By considering the most influencing factors on TDC propagation, stress intensity factors (SIF), including KI and KII, were calculated at critical transverse locations. According to Modes I and II SIF, a greater SIF indicates a faster rate of TDC propagation. The SIF results indicated that considering temperature gradient in asphalt concrete (AC) layer is necessary in determination of critical SIF, and KI and KII are not distributed uniformly within the AC depth. In addition, TDC growth rate significantly depends on AC thickness and base layer type. Finally, the number of load repetitions for TDC propagation rate at different transverse locations is predicted based on Paris’ law equation.

EXPERIENCE ON IMPLEMENTATION OF HOT IN-PLACE RECYCLING OF ASPHALT CONCRETE IN UKRAINE

2018 ◽  
pp. 28-36
Author(s):  
Vasyl Nagaychuk ◽  
Sergii Illiash ◽  
Tatyana Tereshchenko
Keyword(s):  
Asphalt Concrete ◽  
Surface Defects ◽  
Asphalt Pavement ◽  
Field Testing ◽  
Alternative Methods ◽  
Base Layer ◽  
Laboratory Evaluation ◽  
Recycled Asphalt ◽  
Pavement Rehabilitation ◽  
Road Pavement

Rehabilitation of asphalt concrete layers of road pavements using HIR technologies enables effective elimination of surface defects (rutting, cracking, raveling, bleeding (flushing)) including defects caused by the non-conformity of asphalt concrete to the standard specifications. Due to the economical and ecological advantages, HIR technologies belong to the present-day effective alternative methods of rehabilitation of asphalt concrete pavements. In Ukraine, HIR technologies were first applied on intermediate repair works on an area of the international road I-01 “Kyiv-Chernihiv-Novyye Yarylovichi” in the 2013. Now, HIR technologies have been applied on repair works on numerical objects including areas on such state motor roads as I-01, I-06, N-09, R-10, R-67. The presented paper analyzes the results of monitoring of materials and technologies which was aimed on HIR performance investigation supported by State Road Agency of Ukraine (Ukravtodor) throughout 2014-2018. The results of monitoring of HIR technologies including laboratory evaluation of materials and also field testing of the rehabilitated pavements led to the conclusions fitted by the world-wide experience on implementation of HIR technologies. 1. Being applied to the structurally sound pavements, HIR provides effective elimination of surface defects of flexible pavement to a depth of (50-60) mm including defects caused by the non-conformity of asphalt concrete to the standard specifications. However, HIR is not suitable for existing asphalt pavements which have too much variation in asphalt concrete composition and thickness within the project limits. 2. The efficiency of asphalt pavement rehabilitation using HIR technologies largely depends on precise engineering consideration which determines the efficiency of preparatory (repair) works including some special works such as: – correction of cracks in case of cracking that extends below the depth of hot recycling; – re-compaction of an unbound base layer(s) in case of the insufficient compaction causing “alligatored” network-like cracking of asphalt pavement. 3. Proper technical and working conditions of the rehabilitated pavement during the nominal life cycle could be maintained by overlaying the surface treatment using bituminous emulsion materials or by single-pass overlaying a new hot-mixed asphalt concrete layer. Investigations accomplished during the implementation of HIR technologies allow enhance quality of recycled materials and also promote the entire adaptation of HIR technologies to the Ukrainian standards. Keywords: asphalt pavement rehabilitation, hot in-place recycling, recycled asphalt concrete, field testing, road pavement strength measurement, rutting measurement.

Mitigation of permanent deformation in base layer containing recycled asphalt aggregates

2013 ◽  
Vol 40 (2) ◽  
pp. 181-187 ◽  
Author(s):  
Jean-Pascal Bilodeau ◽  
Guy Doré ◽  
Jonas Depatie
Keyword(s):  
Asphalt Concrete ◽  
Deformation Behaviour ◽  
Permanent Deformation ◽  
Design Procedure ◽  
Base Layer ◽  
Repeated Loading ◽  
Recycled Asphalt ◽  
Thickness Increase ◽  
Permanent Strain ◽  
Pavement Base

The use of recycled asphalt pavement (RAP) aggregates as replacement for new materials in the pavement base weakens the layer in regards to the resistance to permanent deformation under repeated loading. A mechanistic based design procedure is proposed to ensure that base layers containing RAP particles have a similar rutting behaviour to base layers made of virgin aggregates. The design procedure allows calculating an asphalt concrete thickness increase that is based on permanent deformation behaviour of base materials. The calculation approach is based on multistage triaxial permanent deformation tests performed on granular material samples with varied RAP content. The tests allowed proposing an equation that relates permanent strain rate, RAP content, and deviatoric stress, which is the basis of the design procedure. Design charts are proposed to select adequate thickness increase for the asphalt concrete layer according to the expected RAP content in the base layer and asphalt concrete modulus.

Abstract 107: Depletion of Plasmacytoid Dendritic Cells Inhibits Experimental Abdominal Aortic Aneurysms

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Baohui Xu ◽  
Haojun Xuan ◽  
Naoki Fujimura ◽  
Sara A Michie ◽  
Ronald L Dalman
Keyword(s):  
Dendritic Cells ◽  
Inflammatory Diseases ◽  
Myeloid Cells ◽  
Abdominal Aortic Aneurysms ◽  
Plasmacytoid Dendritic Cells ◽  
Aortic Aneurysms ◽  
Major Type ◽  
Abdominal Aortic

Introduction: Abdominal aortic aneurysms (AAA) manifest histologic features consistent with other chronic inflammatory diseases. Infiltrating mural myeloid cells (e.g. macrophages) are already recognized as important contributors to aneurysm pathogenesis, however, the role of plasmacytoid dendritic cells (pDC), major type 1 interferon-producing myeloid cells involving in autoimmune diseases and atherosclerosis, has not been previously investigated in this context. Methods and Results: AAAs were created in 12 week old male C57BL/6J mice by transient intra-aortic infusion of porcine pancreatic elastase (PPE). AAA development and progression were assessed via serial ultrasound determination of aortic diameter in vivo , and histology at sacrifice. The fraction of circulating leukocytes identified as pDCs was significantly increased immediately following PPE infusion (aneurysm initiation). Treatment with mPDCA-1 mAb (400 μg i.p. q.o.d.), beginning one day prior to PPE infusion, depleted more than 90% of bone marrow, spleen and peripheral blood pDCs (data not shown) and suppressed subsequent aneurysm development and progression compared to that noted in PPE-infused mice treated with control mAb. mPDCA-1 treatment promoted aortic medial elastin and smooth muscle preservation, while limiting mural macrophage accumulation and neocapillary formation. Conclusion: These findings suggest a role for plasmacytoid dendritic cells in promoting the initiation and progression of experimental abdominal aortic aneurysms.

Analysis of Weighting Coefficients of Post-Assessment Indexes for Cold Recycling Engineering of Asphalt Pavement Based on Hierarchy Analytic Procedure

2012 ◽  
Vol 204-208 ◽  
pp. 1857-1863
Author(s):  
Min Jiang Zhang ◽  
Wen Bo Zhang ◽  
Bao Yang Yu
Keyword(s):  
Asphalt Pavement ◽  
Base Layer ◽  
Environmental Benefit ◽  
Analytic Hierarchy ◽  
Analytic Procedure ◽  
The Road ◽  
Technology Project ◽  
Recycling Technology ◽  
Cold Recycling ◽  
Post Assessment

Based on the theory of hierarchy analysis, the post-assessment indexes system of cold recycling technology project have been established, and the hierarchy analytic procedure have been used to determine the weighing coefficients for post-assessment indexes of cold recycling engineering of asphalt pavement, and the weighing values for various levels factors were given for the cold recycling base layer project of highway of Shenyang-Yingkou. Considering the road performance and economic benefit, societal and environmental benefit, the analytic hierarchy procedure (AHP) method can effectively avoid making wrong decisions subjectively and made it more scientific and reasonable to determine the weighing values of post-assessment indexes, and it is an effective method to determine the weighing values for post-assessment indexes of the cold recycling technology project.

scholarly journals Research and Analysis on the Principle in Plant Cold Recycling for Foamed Bitumen and Mixture Performance

2021 ◽  
Vol 4 (6) ◽  
Author(s):  
Zecheng Ni ◽  
Shijing Chen ◽  
Yihuan Li ◽  
Hongxi Peng ◽  
Jiawen Liang ◽  
...  
Keyword(s):  
Asphalt Concrete ◽  
Asphalt Pavement ◽  
External Factors ◽  
Asphalt Pavements ◽  
Huge Amount ◽  
Construction Waste ◽  
The Road ◽  
Road Performance ◽  
Foamed Bitumen ◽  
Cold Recycling

The early asphalt pavement in our country severely reduced the road performance due to various external factors during the use process. According to incomplete statistics, there are more asphalt pavements that need to be renovated and repaired every year in China, and the amount of construction waste such as asphalt concrete and other construction waste reaches 1,000. About ten thousand tons. If such a huge amount of construction waste is not used, it will inevitably cause great pollution to the environment. If it can be reused, not only will it be environmentally friendly and energy-saving, it will also save more than one billion yuan in costs. In view of the above problems, this article conducts related Research and Analysis on the Principle in Plant Cold Recycling for Foamed Bitumen and Mixture Performance to provide reference for future projects.

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