Effect of the Air Void Content on the Compression Process of Hot-Mixed Asphalt Based on Micromechanical Modeling

This study characterized the impacts of air voids on the low-temperature cracking behavior of dense-graded asphalt concrete. Virtual low-temperature bending beam test for dense-graded asphalt concrete was built and executed by discrete element method and PFC3D (particle flow code in three dimensions). Virtual tests were applied to analyze the impacts by content, distribution, and size of air voids on the low-temperature properties of dense-graded asphalt concrete. The results revealed that higher air void content results in worse low-temperature property of dense-graded asphalt concrete, especially when the air void content exceeds the designed air content; even with the same designed air void content, different distributing condition of air voids within asphalt concrete leads to different low-temperature properties of asphalt concrete, especially when the air void content in the central-lower part of testing sample varies. Bigger size of single air void which tends to form interconnected air voids within asphalt concrete has more harmful impacts on the low-temperature properties of asphalt concrete. Thus, to achieve satisfied low-temperature properties of dense-graded asphalt concrete, it is critical to ensure the designed air void content, improve the distribution of air voids, and reduce the interconnected air voids for dense-graded asphalt concrete.

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

Remote Sensing ◽

10.3390/rs13132613 ◽

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.

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Study of High-Temperature Properties of Asphalt Mixtures Used for Bridge Pavement with Concrete Deck

Materials ◽

10.3390/ma14154238 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4238

Author(s):

Piotr Pokorski ◽

Piotr Radziszewski ◽

Michał Sarnowski

Keyword(s):

Permanent Deformation ◽

Asphalt Mixture ◽

Binder Content ◽

Void Content ◽

Concrete Bridge ◽

Asphalt Mixes ◽

Protective Layers ◽

Concrete Bridge Decks ◽

Air Void ◽

Air Void Content

The paper presents the issue of resistance to permanent deformations of bridge pavements placed upon concrete bridge decks. In Europe, bridge asphalt pavement usually consists of a wearing course and a protective layer, which are placed over the insulation (waterproofing). Protective layers of bridge pavement are commonly constructed using low air void content asphalt mixes as this provides the suitable tightness of such layers. Due to increased binder content, asphalt mixes for bridge pavement may have reduced resistance to permanent deformations. The article presents test results of resistance to permanent deformations of asphalt mixes for the protective layers. In order to determine the composition of mixtures with low air void content and resistance to permanent deformation, an experimental design was applied using a new concept of asphalt mix composition. Twenty-seven different asphalt mixture compositions were analyzed. The mixtures varied in terms of binder content, sand content and grit ratio. Resistance to permanent deformation was tested using the laboratory uniaxial cyclic compression method (dynamic load creep). On the basis of experimental results and statistical analysis, the functions of asphalt mixture permanent deformation resistance were established. This enabled a determination of suitable mixture compositions for protective layers for concrete bridge decks.

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Impact of Specimen Configuration and Characteristics on Illinois Flexibility Index

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198118792114 ◽

2018 ◽

Vol 2672 (28) ◽

pp. 383-393 ◽

Cited By ~ 4

Author(s):

Jose Rivera-Perez ◽

Hasan Ozer ◽

Imad L. Al-Qadi

Keyword(s):

Correction Factor ◽

Loading Rate ◽

Void Content ◽

Displacement Curve ◽

Specimen Thickness ◽

Index Test ◽

Notch Length ◽

Air Void ◽

Flexibility Index ◽

Air Void Content

The Illinois Department of Transportation adopted the Illinois Flexibility Index Test (I-FIT) to evaluate the cracking vulnerability of asphalt concrete (AC) mixtures that was often shown to increase with the addition of recycled materials such as reclaimed asphalt pavement and recycled asphalt shingles. The test consists of a semi-circular AC sample that has a notch, loaded along the symmetric axis. Fracture energy (FE), post-peak slope, and the flexibility index (FI) are computed from the load displacement curve. These results can be influenced by specimen geometry and test parameters such as loading rate, AC voids content, and so forth. Therefore, this study investigated the effect of notch length, specimen thickness, loading rate, and AC air void content on the I-FIT results. It was found that an increase in the specimen thickness or loading rate resulted in a steeper post-peak slope without affecting the FE. As a result, the FI decreased. An increase in the notch length or AC air void content resulted in a flatter post-peak slope, thus, increasing the FI. From the results, it was concluded that existing correction factors to address the variations caused by specimen thickness and air void content are appropriate. A correction factor to address notch length variations is proposed. A unique correction factor for loading rate could not be developed because of the varying rate dependency of each AC mixture.

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Enhanced Model for Continuous Dielectric-Based Asphalt Compaction Evaluation

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198118794068 ◽

2018 ◽

Vol 2672 (26) ◽

pp. 144-154 ◽

Cited By ~ 5

Author(s):

Kyle Hoegh ◽

Shongtao Dai ◽

Trevor Steiner ◽

Lev Khazanovich

Keyword(s):

Dielectric Constants ◽

Void Content ◽

Calibration Data ◽

Stable Model ◽

Asphalt Overlay ◽

Longitudinal Joint ◽

Asphalt Mix ◽

Pavement Construction ◽

Air Void ◽

Air Void Content

The compaction of asphalt concrete significantly affects long-term pavement performance. Although coring provides a relatively accurate way of assessing in-place density at specific locations, the coverage of the assessment is limited, especially at longitudinal joint locations. This can be particularly problematic because it is difficult to identify problematic locations that are likely to fail prematurely using current compaction assessment methods. Ground penetrating radar (GPR) provides an attractive nondestructive testing alternative for evaluation of compaction quality, especially with recent significant improvements in the GPR technology for this specific application. However, assessment of the air void content of the asphalt mix from the GPR-measured dielectric constant of the surface requires conversion of dielectric variation to air void content variation, which is the subject of this paper. An alternative to the commonly used model is proposed, leading to more justifiable predictions for low values of dielectric constants. The proposed model was used to interpret data from a 7-mi long asphalt overlay construction project. The results of the interpretation as compared with the results obtained with the conventional model show an improvement on the stability of the prediction at low air void contents, especially when core calibration data are limited and uncertainty is considered. These results are promising in the direction of reducing field cores necessary to have a stable model providing continuous compaction assessment of new asphalt pavement construction.

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Dynamic Characteristics and Chloride Resistance of Basalt and Polypropylene Fibers Reinforced Recycled Aggregate Concrete

Advances in Polymer Technology ◽

10.1155/2020/6029047 ◽

2020 ◽

Vol 2020 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Dong Lu ◽

Hui Cao ◽

Qiangru Shen ◽

Yue Gong ◽

Cheng Zhao ◽

...

Keyword(s):

Mechanical Properties ◽

Damping Ratio ◽

Recycled Aggregate Concrete ◽

Recycled Aggregate ◽

Void Content ◽

Polypropylene Fibers ◽

Aggregate Concrete ◽

Chloride Resistance ◽

Air Void ◽

Air Void Content

Fiber polymer has been extensively used to improve the mechanical properties and durability of concrete. However, the studies of the effect of fiber polymer on the dynamic performance of recycled aggregate concrete (RAC) is still very limited. In this study, we prepared two types of RAC formulations: RAC reinforced with basalt fibers (BFs) and RAC reinforced with polypropylene fibers (PPs), and compared the effects of fiber types and contents on the air void content, workability (slump), mechanical properties (compressive and flexural strength), dynamic characteristics (dynamic modulus of elasticity and damping ratio), and chloride resistance of RAC. The experimental results showed that the air void content and slump value decreased with the increase of replacement percentage of RCA and fiber contents. Adding PPs provided a more negative effect on the slump of RAC than BFs. The mixtures containing 0.2% PPs and BFs both obtained the highest flexural strength. The addition of PPs was more effective than BFs in improving the damping ratio of RAC, and the mixtures containing 0.3% PPs and BFs both obtained the highest damping ratio. Compared to the RAC without addition of fiber, the charge passed of specimen with addition of PPs approximately increased by 45%, while the specimen with addition of BFs approximately increased by 30%, when the fiber content was 0.3%. This study demonstrates the potential of using fiber to promote the dynamic properties of RAC.

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Specimen Geometry Study for Direct Tension Test Based on Mechanical Tests and Air Void Variation in Asphalt Concrete Specimens Compacted by Superpave Gyratory Compactor

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/1723-16 ◽

2000 ◽

Vol 1723 (1) ◽

pp. 125-132 ◽

Cited By ~ 28

Author(s):

Ghassan R. Chehab ◽

Emily O’Quinn ◽

Y. Richard Kim

Keyword(s):

Asphalt Concrete ◽

Tensile Testing ◽

Complex Modulus ◽

Specimen Geometry ◽

Uniaxial Tensile ◽

Void Content ◽

Uniaxial Tensile Testing ◽

Superpave Gyratory Compactor ◽

Air Void ◽

Air Void Content

Reliable materials characterization and performance prediction testing of asphalt concrete requires specimens that can be treated as statistically homogeneous and representative of the material being tested. The objective of this study was to select a proper specimen geometry that could be used for uniaxial tensile testing. Selection was based on the variation of air void content along the height of specimens cut and cored from specimens compacted by the Superpave gyratory compactor (SGC) and on the representative behavior under mechanical testing. From measurement and comparison of air void contents in cut and cored specimens, it was observed for several geometries that sections at the top and bottom and those adjacent to the mold walls have a higher air void content than do those in the middle. It is thus imperative that test specimens be cut and cored from larger-size SGC specimens. Complex modulus and constant crosshead-rate monotonic tests were conducted for four geometries—75 × 115, 75 × 150, 100 × 150, and 100 × 200 mm—to study the effect of geometry boundary conditions on responses. On the basis of graphical and statistical analysis, it was determined that there was an effect on the dynamic modulus at certain frequencies but no effect on the phase angle. Except for 75 × 115 mm, all geometries behaved similarly under the monotonic test. From these findings and other considerations, it is recommended that the 75- × 150-mm geometry, which is more conservative, and the 100- × 150-mm geometry be used for tensile testing.

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Use of Mechanistic Models to Investigate Fatigue Performance of Asphalt Mixtures

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/2507-12 ◽

2015 ◽

Vol 2507 (1) ◽

pp. 108-119 ◽

Cited By ~ 5

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.

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Evaluation air void content of drilled porous asphalt mixture cores using non-destructive X-ray computed tomography

10.1201/9781003222880-5 ◽

2021 ◽

pp. 48-58

Author(s):

T. Vieira ◽

J. Lundberg ◽

O. Eriksson ◽

A. Guarin ◽

S. Gong ◽

...

Keyword(s):

Computed Tomography ◽

Asphalt Mixture ◽

Void Content ◽

Porous Asphalt ◽

X Ray ◽

X Ray Computed ◽

Air Void ◽

Non Destructive ◽

Air Void Content

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Micro-Structure of Hot Mix Asphalt Containing the 35/50 Bitumen Viewed in Terms of Excess Moisture in the Underlying Course of Pavement

Materials ◽

10.3390/ma13102230 ◽

2020 ◽

Vol 13 (10) ◽

pp. 2230

Author(s):

Paweł Mieczkowski ◽

Bartosz Budziński ◽

Robert Jurczak

Keyword(s):

Fatigue Life ◽

Moisture Content ◽

Hot Mix Asphalt ◽

Complex Modulus ◽

Point Of View ◽

Base Layer ◽

Void Content ◽

Base Course ◽

Air Void ◽

Air Void Content

Compaction of Hot Mix Asphalt (HMA) is a process aimed at obtaining the desired performance properties. Attainment of the required compaction can be hampered by external factors, which includes the presence of water. Water is known to cause quick lowering of the HMA temperature. The bottom face of the asphalt layers of a pavement is a sensitive point from the fatigue life point of view. In the site conditions, it is often difficult to obtain the required air void content at the bottom of an asphalt layer and excessive moisture content in the base course lying beneath the asphalt layer can be one of the causes. This article presents the results of tests carried out on a test section on which HMA was placed on an unbound aggregate base layer of varying moisture content. The material used for the binder course was asphalt concrete mixture composed of aggregate of minus 16 mm grading and 35/50 bitumen. Being relatively hard it is the most often specified bitumen for binder courses and also base courses. One of its characteristics is a considerable increase of viscosity with decreasing temperature, which hampers the process of compaction. The bulk specific gravity was measured to determine the variations in the air void content through the specimens. The complex modulus of elasticity and fatigue life were the other parameters which were determined on the specimens with different air void contents. The test results show worsening of the properties which have a decisive bearing on the service life of pavement.

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