scholarly journals Microfibre Reinforced Hot Mix Asphalt

2012 ◽  
Vol 1 (1) ◽  
pp. 60-67
Author(s):  
Josef Zak ◽  
Jiri Vavricka
Keyword(s):  
Crack Propagation ◽  
Bulk Density ◽  
Hot Mix Asphalt ◽  
Permanent Deformation ◽  
Tensile Stresses ◽  
Pavement Structure ◽  
Microfiber Reinforcement

Abstract Cracks are common disturbances in pavement structure. The ability of hot mix asphalt to withstand tensile stresses is limited. This paper presents influence of different microfiber reinforcement types ITERFIBRA to hot mix asphalt behaviour in its chosen properties. Bulk density of hot mix asphalt, stiffness , resistance to the permanent deformation and resistance to the crack propagation are taken into consideration.

scholarly journals Modelling Of Crack Propagation in Flexible Pavement Using X-FEM Method

2022 ◽  
Vol 961 (1) ◽  
pp. 012014
Author(s):  
Z A Alkaissi
Keyword(s):  
Crack Propagation ◽  
Permanent Deformation ◽  
Applied Pressure ◽  
Vertical Direction ◽  
Element Model ◽  
Flexible Pavement ◽  
Crack Edge ◽  
Tensile Stresses ◽  
Fem Method ◽  
Crack Zone

Abstract A research aim was to achieve a finite element model for predictive pavement cracking implementing ABAQUS software ver.6.12.1. A simulation model for pavement structure was implemented to analyze the propagation of cracks within flexible pavement. The X-FEM method adopted in this research based on the functions of interpolation that can characterize the displacements near the crack zone, initial crack was defined at the bottom of asphalt layer. The estimated results illustrated that X-FEM was efficient for the simulation of cracks in pavement structures without the need for re meshing during crack propagation evolution process. Finally, inclusive simulation results probed the considerable effect for improvement of bonding layers to enhance the service life of pavement in terms of decreasing the rate of crack propagation. The crack was propagated upwards from depth end of asphalt layer to pavement surface and deviated from center of applied pressure with an inclination of almost 300 in the third upper zone of asphalt layer while the pre-crack point was always located in the bottom of asphalt layer in pavement model because of the different characteristics of their bonding bases. In the crack zone the permanent deformation was increased gradually from the crack edge along vertical direction of crack spread due to tensile stresses concentration at the crack zone. The action of horizontal and vertical stresses affect crack propagation and growth vertically to the direction of higher horizontal tensile stresses, and along direction of higher compression vertical stresses.

Performance-based mix design of unmodified and lime-modified hot mix asphalt

2012 ◽  
Vol 39 (7) ◽  
pp. 824-833 ◽  
Author(s):  
Sangyum Lee ◽  
Cheolmin Baek ◽  
Je-Jin Park
Keyword(s):  
Performance Test ◽  
Hot Mix Asphalt ◽  
Permanent Deformation ◽  
Asphalt Mixture ◽  
Fatigue Cracking ◽  
Mix Design ◽  
Direct Tension ◽  
Element Analysis ◽  
Asphalt Content ◽  
National Cooperative

This paper presents the performance evaluation of unmodified and lime-modified hot mix asphalt (HMA) mixtures at varying asphalt content using asphalt mixture performance test developed from National Cooperative Highway Research Program project 9-19 and 9-29 and the viscoelastic continuum damage finite element analysis. Test methods adopted in this study are the dynamic modulus test for stiffness, the triaxial repeated load permanent deformation test for rutting, and the direct tension test for fatigue cracking. The findings from this study support conventional understanding of the effects of asphalt content and lime modification on the fatigue cracking and rutting performance. Finally, the optimum asphalt content for both lime-modified and unmodified mixtures are proposed based on the knowledge gleaned from the performance-based mix design methodology. With additional validation and calibration, the comprehensive methodology described in this paper may serve as the foundation for a performance-based HMA mix design and performance-related HMA specifications.

Crack Propagation Prediction Using Haensel Damage Model

2012 ◽  
Author(s):  
Piotr Bednarz ◽  
Jaroslaw Szwedowicz
Keyword(s):  
Cyclic Loading ◽  
Crack Initiation ◽  
Crack Propagation ◽  
Damage Model ◽  
Lifetime Prediction ◽  
Dissipated Energy ◽  
Mathematical Approach ◽  
Loading Conditions ◽  
Stored Energy ◽  
Tensile Stresses

The Haensel damage model correlates lifetime of a component until crack initiation to the dissipated and stored energy in the material during cyclic loading. The crack initiation is influenced by mean stresses. The Haensel damage model considers the mean stress effect by including compressive and tensile stresses in calculations of elastic strain energy during cyclic loading conditions. The goal of the paper is to extend the above model to predict crack propagation under large cyclic plasticity and non-proportional loading conditions. After voids initiation onset of necking, voids growth and linking takes place among them. During this process a mesocrack is created. This stage of fracture involves the same amount of released energy for new crack surface creation as dissipated energy for mesocrack initiation. The amount of dissipated and stored energy is related to the process zone size and to the number of cycles. Ilyushin’s postulate is used to calculate the amount of dissipated energy. In order to consider a contribution of tensile stresses only during loading to crack propagation, tensile/compressive split is performed for the stress tensor. One of the key drivers of this paper is to provide a straightforward engineering approach, which does not require explicit modelling of cracks. The proposed mathematical approach accounts for redistribution of stresses, strains and energy during crack propagation. This allows to approximate the observed effect of distribution of dissipated energy on the front of a crack tip. The developed approach is validated through FE (Finite Element) simulations of the Dowling and Begley experiment. The Haensel lifetime prediction of Dowling’s experiment is in good agreement with the experimental data and the explicit FE results. Finally, the proposed mathematical approach simplifies significantly the engineering effort for Nonlinear Fracture Mechanics lifetime prediction by avoiding the requirement to simulate real crack propagation using node base release methods, XFEM or remeshing procedures.

Development of Performance-Related Specifications for Hot-Mix Asphalt Pavements Through WesTrack

1997 ◽  
Vol 1575 (1) ◽  
pp. 85-91 ◽  
Author(s):  
Stephen B. Seeds ◽  
Rudramunniyappa Basavaraju ◽  
Jon A. Epps ◽  
Richard M. Weed
Keyword(s):  
Performance Prediction ◽  
Prediction Models ◽  
Hot Mix Asphalt ◽  
Permanent Deformation ◽  
Fatigue Cracking ◽  
Primary Objective ◽  
Pavement Performance ◽  
Void Content ◽  
Target Values ◽  
Pavement Performance Prediction

The primary objective of the FHWA-sponsored WesTrack project is to further the development of performance-related specifications for hotmix asphalt construction. This objective is being achieved, in part, through the accelerated loading of a full-scale test track facility in northern Nevada. Twenty-six hot-mix asphalt test sections constructed to meet the criteria set forth in a statistically based experiment design are providing performance data that will be used to improve existing (or develop new) pavement performance prediction relationships that better account for the effects that “off-target” values of asphalt content, air-void content, and aggregate gradation have on such distress factors as fatigue cracking, permanent deformation, roughness, raveling, and tirepavement friction. The concept of the planned new performance-related specification and how it will incorporate the modified pavement performance prediction models are described. The current plan for assessing contractor pay adjustments (i.e., penalties and bonuses) based on data collected from the as-constructed pavement is also discussed.

Performance Evaluation of Hot-Mix Asphalt Using Rotary Loaded-Wheel Testing

2005 ◽  
Vol 1929 (1) ◽  
pp. 157-164
Author(s):  
M. Shane Buchanan ◽  
Benjamin J. Smith
Keyword(s):  
Hot Mix Asphalt ◽  
Permanent Deformation ◽  
Asphalt Binder ◽  
Hydrated Lime ◽  
New Device ◽  
Proof Testing ◽  
Reasonable Prediction ◽  
The Cost ◽  
Performance Results ◽  
Transportation Agencies

Permanent deformation and moisture damage (i.e., rutting and stripping) are two predominant hot-mix asphalt (HMA) distresses. Rutting can be caused by many factors, including stripping, which result in reduced HMA shear strength. Hot-mix asphalt stripping evaluation is a source of significant industry discussion and debate. Transportation agencies use a number of methods to evaluate stripping, with many methods customized depending on local concerns and environmental conditions. Today, many agencies use some type of loaded-wheel testing, with associated mix “pass–fail” criteria, as part of the mix design acceptance procedure. This process is often referred to as “proof” testing and provides a higher confidence that the HMA mix will perform satisfactorily during service conditions. A new device, the rotary wheel tester, has been developed to evaluate the rutting and stripping performance of HMA mixes. This device operates on a principle similar to that of the Hamburg wheel tester: the main difference is that the specimen is loaded along its diameter instead of from the top. The cost of the rotary wheel tester is less than half that of the Hamburg wheel tester. Testing was conducted to determine whether the rotary wheel tester could distinguish between good- and poor-performing mixes and to determine whether PG 76-22 or PG 67-22 plus hydrated lime improved mix performance. Results indicate that the rotary wheel tester is an easy-to-use testing device that appears to provide reasonable prediction of the rutting and stripping performance of HMA mixes. It also appears that PG 76-22 asphalt binder improves mix performance to a greater extent than does PG 67-22 plus hydrated lime.

Laboratory-based Unified Permanent Deformation Model for Hot-Mix Asphalt Mixtures

2007 ◽  
Vol 35 (3) ◽  
pp. 13153 ◽  
Author(s):  
M. R. Mitchell ◽  
R. E. Link ◽  
Elie Y. Hajj ◽  
Raj V. Siddharthan ◽  
Peter E. Sebaaly ◽  
...  
Keyword(s):  
Hot Mix Asphalt ◽  
Permanent Deformation ◽  
Asphalt Mixtures ◽  
Deformation Model

Performance of Asphalt Rejuvenators in Hot-Mix Asphalt Containing Recycled Asphalt Shingles

2017 ◽  
Vol 2633 (1) ◽  
pp. 108-116 ◽  
Author(s):  
Max A. Aguirre ◽  
Marwa M. Hassan ◽  
Sharareh Shirzad ◽  
Louay N. Mohammad ◽  
Samuel B. Cooper
Keyword(s):  
Hot Mix Asphalt ◽  
Permanent Deformation ◽  
Fatigue Cracking ◽  
Strain Energy Release ◽  
Asphalt Mixtures ◽  
Bending Test ◽  
Test Results ◽  
Recycled Asphalt ◽  
Recycled Asphalt Shingles ◽  
Asphalt Shingles

The use of recycled asphalt shingles (RAS) in asphalt paving construction represents a sustainable approach to reduce virgin material consumption and negative environmental effects, as well as the cost of asphalt pavement. However, many challenges are yet to be addressed about the use of RAS in paving applications. This study evaluated the effect of the incorporation of postconsumer waste shingles and rejuvenators on the performance of hot-mix asphalt. Four asphalt rejuvenators—one bio-oil and three synthetic oils—were evaluated. A set of laboratory tests was conducted to characterize the performance of asphalt mixtures against permanent deformation and fatigue cracking. The addition of 5% RAS showed an improvement in permanent deformation when compared with a conventional mixture with no RAS. Yet the addition of asphalt rejuvenator products slightly decreased the performance against permanent deformation. On the basis of Hamburg wheel-tracking device test results, the addition of RAS did not adversely affect moisture resistance. Yet semicircular bending test results showed that the asphalt mixtures that contained asphalt rejuvenators had a lower critical strain energy release rate than the minimum threshold value (0.5 kJ/m2), which indicated a greater susceptibility to intermediate-temperature cracking.

Strategic Highway Research Program gyratory compaction for predicting air voids of Saskatchewan SPS-9A asphalt mixes after 10 years of performance in the field

2012 ◽  
Vol 39 (8) ◽  
pp. 897-905 ◽  
Author(s):  
Aziz Salifu ◽  
Curtis Berthelot ◽  
Ania Anthony ◽  
Brent Marjerison
Keyword(s):  
Asphalt Concrete ◽  
Material Properties ◽  
Hot Mix Asphalt ◽  
Permanent Deformation ◽  
Test Site ◽  
Asphalt Mixes ◽  
Air Voids ◽  
Need To Evaluate ◽  
Gyratory Compaction ◽  
Compaction Method

Many Saskatchewan provincial highways exhibit permanent deformation that is mostly attributed to reduction in air voids in hot mix asphalt concrete surfacing. The Saskatchewan Ministry of Highways and Infrastructure (MHI) currently use the Marshall compaction method for hot mix asphalt concrete (HMAC) design and placement quality control and quality assurance. It has been found that the Marshall compaction method does not accurately predict field air voids. Therefore, MHI identified the need to evaluate the SuperpaveTM gyratory compaction method to predict field air voids of typical Saskatchewan asphalt mixes. This paper presents a summary of laboratory and field volumetric as well as rapid triaxial mechanistic material properties of typical Saskatchewan asphalt mixes. This research considered seven asphalt mixes from the Radisson Specific Pavement Study (SPS)-9A test site comprising two conventional Saskatchewan Marshall Type 71 mixes, five SuperpaveTM mixes, and a SuperpaveTM recycled mix. This research determined that Marshall compaction and the gyratory compaction at 1.25° gyration angle underestimate the collapse of field air voids. This research also showed that the gyratory compaction method at 2.00° angle of gyration more accurately predicted field air voids of the asphalt mixes constructed as part of test site.

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