scholarly journals Evaluating RLWT Rutting Test of Asphalt Mixtures Based on Industrial Computerized Tomography

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Wenliang Wu ◽  
Zhi Li ◽  
Xiaoning Zhang ◽  
Minghui Li
Keyword(s):  
Internal Structure ◽  
Main Axis ◽  
Asphalt Mixtures ◽  
Ct Image ◽  
Air Voids ◽  
Aggregate Distribution ◽  
Compliance Testing ◽  
Before And After ◽  
Angle Alpha ◽  
Industrial Computerized Tomography

To eliminate the effects of image’s light and shade difference when separating and distinguishing the material composition, a method is put forward, namely, ring-type and partitions threshold segmentation. It means setting up different segment threshold for different areas of the same image and then combining these different areas into one image. Furthermore, by analyzing the CT image before and after the RLWT rutting test for the drilling specimen and Marshall specimen and taking the volume of air voids and the angle (alpha) between max main axis and X axis, the differences of two kinds of specimens’ macrotest results were discussed from internal structure distribution. Here, we show that there are differences between macrotest results of two kinds of specimens because of internal air voids and aggregate distribution, which should be considered for compliance testing.

scholarly journals Characterization of Three-Dimensional Internal Structure Evolution in Asphalt Mixtures during Freeze–Thaw Cycles

2021 ◽  
Vol 11 (9) ◽  
pp. 4316
Author(s):  
Gang Xu ◽  
Xianhua Chen ◽  
Xing Cai ◽  
Yunhong Yu ◽  
Jun Yang
Keyword(s):  
Internal Structure ◽  
Asphalt Mixture ◽  
Three Dimensional ◽  
Asphalt Mixtures ◽  
Structure Evolution ◽  
Void Content ◽  
3D Images ◽  
X Ray ◽  
Freeze Thaw ◽  
Before And After

This paper aims to characterize the three-dimensional (3D) internal structure evolution of asphalt mixtures under freeze–thaw cycles. Asphalt mixtures with three levels of design void content (3%, 5%, and 7%) were prepared in the laboratory. Subsequently, X-ray computed tomography (CT) tests were conducted to capture two-dimensional (2D) images of the internal structure of samples before and after freeze–thaw testing. A set of image processing techniques for reconstructing 3D images of the internal structure were utilized to extract the internal structure properties, which were then used to analyze the changes in the air void distributions and to evaluate the internal structure evolution under freeze–thaw cycles. 3D images reconstructed from X-ray CT images illustrated a dramatic degradation in the internal structure after cyclic freeze–thaw exposure. The change in internal structure occurs mainly in three ways: (1) expansion of existing individual voids, (2) combination of two separated air voids, and (3) generation of new voids. In addition, the parametric analysis of the three-dimensional reconstructed voids revealed that the asphalt mixture void ratio increased with the number of freeze–thaw cycles, while the larger the initial void content, the more pronounced the increase in the specimens. Therefore, asphalt mixture freeze–thaw resistance should be optimized in relation to the design void content.

scholarly journals A GPR-Based Pavement Density Profiler: Operating Principles and Applications

2021 ◽  
Vol 13 (13) ◽  
pp. 2613
Author(s):  
Nectaria Diamanti ◽  
A. Peter Annan ◽  
Steven R. Jackson ◽  
Dylan Klazinga
Keyword(s):  
Asphalt Pavement ◽  
Wave Impedance ◽  
Asphalt Mixtures ◽  
Void Content ◽  
Air Voids ◽  
New Instrument ◽  
Pavement Engineering ◽  
And Performance ◽  
Air Void ◽  
Air Void Content

Density is one of the most important parameters in the construction of asphalt mixtures and pavement engineering. When a mixture is properly designed and compacted, it will contain enough air voids to prevent plastic deformation but will have low enough air void content to prevent water ingress and moisture damage. By mapping asphalt pavement density, areas with air void content outside of the acceptable range can be identified to predict its future life and performance. We describe a new instrument, the pavement density profiler (PDP) that has evolved from many years of making measurements of asphalt pavement properties. This instrument measures the electromagnetic (EM) wave impedance to infer the asphalt pavement density (or air void content) locally and over profiles.

A study on the change in image quality before and after an attenuation correction with the use of a CT image in a SPECT/CT scan

2012 ◽  
Vol 61 (12) ◽  
pp. 2060-2067
Author(s):  
Yong-Soon Park ◽  
Woo-Hyun Kim ◽  
Dong-Oh Shim ◽  
Ho-Sung Kim ◽  
Woon-Kwan Chung ◽  
...  
Keyword(s):  
Image Quality ◽  
Ct Scan ◽  
Attenuation Correction ◽  
Ct Image ◽  
Before And After

scholarly journals Variability of Air Voids and Mechanistic Properties of Plant-Produced Asphalt Mixtures

2004 ◽  
Vol 1891 (1) ◽  
pp. 85-97 ◽  
Author(s):  
Louay N. Mohammad ◽  
Zhong Wu ◽  
Chenggang Zhang ◽  
Mohammad J. Khattak ◽  
Chris Abadie
Keyword(s):  
Asphalt Mixtures ◽  
Air Voids

Study on the High Temperature Creep Behavior of 30Cr25Ni20 Heat-Resistant Steel

2019 ◽  
Vol 814 ◽  
pp. 157-162
Author(s):  
You Yang ◽  
Xiao Dong Wang ◽  
Wei Feng Tang
Keyword(s):  
High Temperature ◽  
Internal Structure ◽  
Creep Strain ◽  
High Temperature Creep ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Creep Fracture ◽  
Heat Resistant ◽  
Temperature Creep ◽  
Before And After

The high temperature creep test of heat-resisting steel 30Cr25Ni20 for automobile exhaust manifolds was carried out, and the creep strain-time curves at 650°C and 700°C in the different loads were obtained. The effects of different creep temperature and stress on creep life of materials were studied. The microstructure of the fracture after creep was observed by scanning electron microscopy. Microstructures before and after creep at different temperatures were compared by optical microscopy. The results show that the creep fracture life of heat-resistant steel decreases with the increase of stress at the same temperature. The creep fracture life decreases with the increase of temperature at the same stress, too. The fracture of heat-resistant steel shows good high temperature plasticity and a ductile fracture after creep. The fracture dimples become deeper with the increase of stress. At 650°Cand 700°C, the stress exponent is 8.6 and 6, respectively. When the sample was subjected to high temperature creep at 700°C, the precipitates increase obviously and the reticular structure became very large. At this point, the internal structure of the material is destroyed, and the matrix structure becomes unevenly distributed. The failure of the internal structure leads to the dramatic increase of the creep strain, and the failure of the internal structure will be more serious with the deformation of the sample.

scholarly journals Fracture Behavior Analysis of Semi-Circular Bending Test

2019 ◽  
Vol 271 ◽  
pp. 03007
Author(s):  
David Renteria ◽  
Shadi Saadeh ◽  
Enad Mahmoud
Keyword(s):  
Fracture Behavior ◽  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Bending Test ◽  
Random Generation ◽  
Crack Initiation And Propagation ◽  
Air Voids ◽  
Generation Technique ◽  
Initiation And Propagation ◽  
Scb Test

The objective of this paper is to investigate the effect of air voids on the fracture properties of asphalt mixtures using SCB test in Discrete Element Method (DEM). Superpave and Coarse Matrix High Binder (CMHB) mixtures gradation were used to generate the percentages of aggregate, mastic, and air voids within the specimens. Aggregates and air voids were randomly generated for each asphalt mixture case. Model results illustrate that the crack initiation and propagation is controlled by the location of the aggregate particles and air voids in the mixture. Additionally, the absence of air voids above the tip of the notch increases the stiffness of the sample and increase its resistance to failure. The novelty of using DEM and the random generation technique for generating numerical specimens proved to be a useful approach in investigating the properties of the mastic, aggregate and interface as they relate to fracture of asphalt mixtures.

Sewage Sludge as Raw-Material in Asphalt Mixtures

2013 ◽  
Vol 664 ◽  
pp. 638-643 ◽  
Author(s):  
Maria del Pilar Durante Ingunza ◽  
Olavo Francisco dos Santos Júnior ◽  
Sayonara Andrade Medeiros
Keyword(s):  
Mechanical Performance ◽  
Environmental Parameters ◽  
Empty Space ◽  
Asphalt Mixtures ◽  
International Standards ◽  
Raw Material ◽  
Air Voids ◽  
The One ◽  
Consequent Increase ◽  
Space Volume

The aim of this study is to assess the volumetric and mechanical behavior of concrete asphalt mixtures, using natural sludge as a partial substitute for the tiny aggregate and calcined sludge as filler. This assessment was performed based on technical and environmental parameters, using laboratory tests obeying current Brazilian norms, according to international standards. The addition of natural sludge to the mixtures has increased stability, increased air voids contents of the mixtures. The addition has compromised mixture adhesiveness. With respect to the addition of calcined sludge to the mixtures, the mixtures with calcined sludge displayed the same behavior as those with cement. It was observed decrease in empty space volume of the mixtures and consequent increase in empty space-bitumen relation and increased stability. The mixture addition of natural sludge that has the best mechanical and volumetric performance is the one with 7.5% of natural sludge in the granulometric composition of the mixture. The mixture with 1% of calcined sludge had the best volumetric and mechanical performance.

Use of Mechanistic Models to Investigate Fatigue Performance of Asphalt Mixtures

2015 ◽  
Vol 2507 (1) ◽  
pp. 108-119 ◽  
Author(s):  
Jong-Sub Lee ◽  
Nelson Gibson ◽  
Y. Richard Kim
Keyword(s):  
Damage Model ◽  
Asphalt Mixtures ◽  
Fatigue Performance ◽  
Void Content ◽  
Continuum Damage ◽  
Direct Tension ◽  
Air Voids ◽  
Viscoelastic Continuum Damage ◽  
Air Void ◽  
Air Void Content

Effects of design air void contents, design voids in mineral aggregate (VMA), and in-place air voids on the fatigue performance of asphalt mixtures were investigated with mechanistic analyses based on the viscoelastic continuum damage (VECD) analyses and the mechanistic–empirical pavement analysis using the AASHTOWare Pavement ME Design program. The VECD analyses included the simplified viscoelastic continuum damage model at the material level and two structural models: ( a) layered viscoelastic analysis and ( b) layered viscoelastic pavement analysis for critical distresses. The mix design of a 2013 accelerated loading facility test lane was selected to develop the volumetric mix designs with the design air voids of 3%, 4%, and 5%, design VMAs of 13%, 14%, and 15%, and in-place air void contents of 5%, 7%, and 9% with the Bailey method. Dynamic modulus and direct tension cyclic fatigue tests were performed in accordance with the AASHTO TP 107 procedure. The test results showed that the linear viscoelastic property was affected by the design VMA, design air void content, and in-place air void content in order of sensitivity. Also, the damage states at failure determined from the damage characteristic curves and the mechanistic fatigue predictions had consistent trends as observed for the design VMA, in-place air void, and design air void content in rank of sensitivity. Finally, the design VMA, in-place air void, and design air void parameters were found to be sensitive in the mechanistic analyses, whereas the parameter that was most sensitive in the pavement mechanistic–empirical analysis was the in-place air void content.

Influence of Air Voids on Mechanical Properties of Asphalt Mixtures

2011 ◽  
Vol 12 (3) ◽  
pp. 493-524 ◽  
Author(s):  
Emad Kassem ◽  
Eyad Masad ◽  
Robert Lytton ◽  
Arif Chowdhury
Keyword(s):  
Mechanical Properties ◽  
Asphalt Mixtures ◽  
Air Voids
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