Proposed Compaction Procedure for Dry Process Crumb Rubber Modified Asphalt Mixtures Using Air Void Content and Expansion Ratio

2014 ◽  
Vol 42 (2) ◽  
pp. 20120337 ◽  
Author(s):  
Miao Yu ◽  
Guoxiong Wu ◽  
Jinchuan Zhou ◽  
Said Easa
Keyword(s):  
Crumb Rubber ◽  
Expansion Ratio ◽  
Asphalt Mixtures ◽  
Void Content ◽  
Dry Process ◽  
Modified Asphalt ◽  
Air Void ◽  
Air 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.

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.

Moisture Sensitivity of Asphalt Mixtures using Cycling Pore Pressure Conditioning

2019 ◽  
Vol 2673 (2) ◽  
pp. 294-303 ◽  
Author(s):  
Pajtim Sulejmani ◽  
Safwat Said ◽  
Sven Agardh ◽  
Abubeker Ahmed
Keyword(s):  
Pore Pressure ◽  
Complex Modulus ◽  
Moisture Damage ◽  
Climate Impacts ◽  
Binder Content ◽  
Asphalt Mixtures ◽  
Void Content ◽  
Premature Failure ◽  
Air Void ◽  
Air Void Content

One of the major causes of premature failure in asphalt pavements is moisture damage. Asphalt mixtures designed without considering climate impacts may suffer from durability problems caused by movement of water inside the asphalt mixture. Rolling traffic over wet pavement builds up pore pressure in the mixture, which will consequently accelerate deterioration. The objective of the study was to assess the moisture damage to asphalt concrete mixtures by means of complex modulus testing of dry and moisture-conditioned asphalt specimens with various mixture compositions. The asphalt mixtures were conditioned with the Moisture Induced Sensitivity Tester (MIST), which aims to replicate pore pressure in field conditions. The results showed a decline in stiffness modulus and a reduction in elastic properties after MIST conditioning. In addition, the results indicated that binder content and air void content had a significant influence on the reduction in stiffness. To capture the relationship between air void content, binder content, and the reduction in stiffness, a relationship was developed and validated with measurements on cores extracted in the field.

scholarly journals Influence of Air Void Content on Moisture Damage Susceptibility of Asphalt Mixtures

2014 ◽  
Vol 2446 (1) ◽  
pp. 8-16 ◽  
Author(s):  
A. Varveri ◽  
S. Avgerinopoulos ◽  
C. Kasbergen ◽  
A. Scarpas ◽  
A. Collop
Keyword(s):  
Moisture Damage ◽  
Asphalt Mixtures ◽  
Void Content ◽  
Damage Susceptibility ◽  
Air Void ◽  
Air Void Content

scholarly journals A review of the best experience on crumb rubber – dry process modified asphalt mixture performance

2021 ◽  
Author(s):  
Ovidijus Šernas ◽  
Audrius Vaitkus ◽  
Deimantė Kilaitė
Keyword(s):  
Asphalt Mixture ◽  
Crumb Rubber ◽  
Asphalt Mixtures ◽  
Waste Products ◽  
Dry Process ◽  
Modified Asphalt ◽  
Wet Process ◽  
Water Sensitivity ◽  
Modification Process ◽  
Dry Modification

The use of crumb rubber made from end of life tyres for asphalt mixtures modification in order to improve their properties or just utilize waste products may be considered as potential solution. Crumb rubber can be used as a bitumen modifier (wet process) or supplementary component of the asphalt mixture (dry process). Dry modification process has more potential due relatively unsophisticated technology and higher possible to use amount of crumb rubber comparing to the wet process. The performance of asphalt mixtures modified by dry process mainly depends on several factors as crumb rubber type, content and size. However, limited number of publications reported the results of dry method crumb rubber modified asphalt mixtures performance. This paper summarizes the latest findings from literature review on the modification technologies and specifications related to dry modification process, the effect of crumb rubber type and amount on modified asphalt mixture performance in terms of stiffness, rutting resistance, water sensitivity, resistance to fatigue and low temperature cracking. The algorithm of crumb rubber modified asphalt mix design was introduced.

Effect of Addition of Dry Crumb Rubber on the Performance of Terminal Blend Crumb Rubber Modified Asphalt Mixtures

2017 ◽  
Vol 2633 (1) ◽  
pp. 90-97 ◽  
Author(s):  
Salih Kocak ◽  
M. Emin Kutay
Keyword(s):  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Crumb Rubber ◽  
Asphalt Mixtures ◽  
Fine Aggregate ◽  
Dry Process ◽  
Modified Asphalt ◽  
Wet Process ◽  
Low Temperature Cracking ◽  
Linear Viscoelastic

Three major methods are used to produce crumb rubber modified asphalt pavement: the dry process (CRDry), the terminal blend process (CRTB), and the wet process (CRWet). Although the CRDry process replaces the portion of fine aggregate in the asphalt mixture with crumb rubber (CR) particles, the CRWet process incorporates CR particles into hot liquid asphalt before it is mixed with aggregates. CRTB is known as a special type of CRWet process in which the CR is blended with asphalt binder at the asphalt terminal. In general, the CRWet process can integrate 15% to 22% CR by weight of the binder. This amount ranges from 10% to 12% in the CRTB process as a result of the limitations associated with transportation and pumping. This study investigated the feasibility of increasing the CR content of CRTB modified asphalt mixtures. The addition to the mixture of about 0.5% CR (by weight of the mix) through the CRDry process doubled the amount of rubber to be found in a conventional CRTB mix. The relative performances of the CRTB and the CRTB+CRDry processes [i.e., crumb rubber hybrid (CRHY)] were investigated with respect to their linear viscoelastic properties, rutting susceptibility, moisture damage, resistance to fatigue, and low temperature cracking. It was shown that it was possible to increase the amount of CR in the mixture through the use of the CRHY method proposed here, without adverse effect on the performance of the mixture.

scholarly journals Effect of Rejuvenators on the Workability and Performances of Reclaimed Asphalt Mixtures

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6385
Author(s):  
Wei Tang ◽  
Xin Yu ◽  
Ning Li ◽  
Fuqiang Dong ◽  
Zhongyuan Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Temperature Stability ◽  
Asphalt Mixtures ◽  
Asphalt Binders ◽  
Void Content ◽  
High Temperature Stability ◽  
Moisture Susceptibility ◽  
Reclaimed Asphalt ◽  
Air Void ◽  
Air Void Content

The use of rejuvenators has enhanced the workability of asphalt mixtures containing the reclaimed asphalt pavement (RAP). This conclusion is based on the determination of viscosity of asphalt binders, while not validated from reclaimed asphalt mixtures. In this study, the effect of two rejuvenators (ordinary and emulsified rejuvenator) on the workability of reclaimed asphalt mixtures was evaluated by measuring the mixing torque and determining the air void content of reclaimed mixtures. In addition, their effects on the performances of reclaimed mixture were studied via the three indexes tests, rutting test and freeze-thaw splitting tests. The experimental results show that mixing torque and air void content of reclaimed mixtures with the emulsified rejuvenator is 4% and 6% lower than that with the ordinary rejuvenator, respectively. This indicates that improvement of the workability of reclaimed mixtures can be achieved by using an emulsified rejuvenator, but not by an ordinary rejuvenator. That is also the reason that at least 20% greater high-temperature stability is found for reclaimed mixtures by using the emulsified rejuvenator than using the ordinary rejuvenator. In addition, reclaimed mixtures with the emulsified rejuvenator show similar moisture susceptibility to that with the ordinary rejuvenator. This study provides a feasible method to assess the workability effect of rejuvenators on reclaimed mixtures directly and recommends the use of an emulsified rejuvenator to improve the workability and high-temperature stability of reclaimed mixtures.

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