| 1. |
- Ahmed, Abubeker W., et al.
(författare)
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An Algorithm to Estimate Rational Values of Phase Angles and Moduli of Asphalt Mixtures
- 2013
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Ingår i: International Journal of Pavement Research and Technology. - Taiwan : Chinese Society of Pavement Engineering. - 1996-6814 .- 1997-1400. ; 6:6, s. 745-754
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to develop and evaluate an algorithm based on Fast Fourier Transform (FFT) that can calculate rational values of phase angle (f) and moduli of the variants of asphalt mixtures for the data obtained from the different frequency sweep tests. f and moduli for ten different asphalt mixtures resulting in over 690 data points collected from both USA and Sweden were computed using FFT. Theoretical observations revealed that there were significant differences for f between FFT and other methods to the order of 10-50%; however, there was no difference in moduli estimates for any mix and was independent of the test. Precisely, the FFT method produced rational f for mixtures that deviate from conventional mixture properties. Furthermore, statistical comparisons corroborated the predicted f estimates indicative of significant differences between the analysis techniques; but, the moduli were unaffected by the analysis methods. The study successfully illustrated the FFT technique, a user-friendly analytical procedure that can obviate the errors in the rational estimation of the acutely sensitive viscoelastic parameters.
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| 2. |
- Biligiri, Krishna Prapoorna, et al.
(författare)
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Confined E * testing on poroelastic road surface mixtures
- 2012
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Ingår i: International Journal on Road Materials and Pavement Design. - : Taylor & Francis. - 1468-0629 .- 2164-7402. ; 13:2, s. 385-395
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Tidskriftsartikel (refereegranskat)abstract
- In Europe, poroelastic road surface (PERS) material is being tested to a level at which it can be applied on different types of roads as a noise-reducing pavement. Traffic noise reductions of around 10–12 dB have been achieved using PERS in comparison to a conventional dense asphalt concrete. The PERS material is designed as an open-graded mix to have at least 20% air voids by volume.The objective of this research study was to evaluate the effect of six different confinement levels on the E * dynamic modulus testing of PERS mixtures. The major aim of utilising confinement on PERS materials was specifically to simulate and assess field performance characteristics of those mixes in the laboratory. Furthermore, the choice for confinement is essential in order to obtain realistic test results for a porous or open-graded aggregate structure of the PERS mix. AASHTO TP 62-07 was utilised for dynamic modulus E * testing; for confined tests, a lateral air pressure was provided that simulated confining effect on the samples. Confined tests were conducted only on the two variants of the PERS mixtures that had about 50% or greater amount of aggregates by volume of the mix. Moduli (E *) and phase angle (φ) master curves were established using the test results.
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| 3. |
- Biligiri, Krishna Prapoorna, et al.
(författare)
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Understanding the fundamental material properties of low-noise poroelastic road surfaces
- 2013
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Ingår i: The international journal of pavement engineering. - : Taylor & Francis. - 1029-8436 .- 1477-268X. ; 14:1, s. 12-23
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Tidskriftsartikel (refereegranskat)abstract
- The main purpose of this study was to characterise the fundamental material (stiffness) properties of the poroelastic road surfaces (PERS) relevant to the pavement design. The research encompassed preparation of five variants of PERS mixtures in the laboratory based on the combinations of rubber, aggregate and binder components. Two standard test procedures were utilised: stress–strain sweep test and dynamic modulus E* test. First, stress–strain sweep test was performed at 1 mm/min strain rate to investigate the PERS mixtures' elastic characteristics. Hysteresis loops were plotted between force and strain change, which indicated that in all the mixes, the samples were stable to resist against higher hysteresis losses during successive cycles of testing. Also, lower losses were observed with increasing rubber contents; the results can be used in optimising the rubber content in the PERS to further assess rolling resistance and friction. Next, dynamic modulus E* test was performed on the PERS. The dynamic moduli varied based on the blending of rubber and aggregates proportion; the PERS mixes with higher amount of aggregates and lower amount of rubber had higher moduli. A comparison of moduli between the PERS mixtures and a typical asphalt concrete (AC) mix indicated that the PERS were softer than the AC mix by about 20–1500 times; the softness characteristics of the PERS would plausibly provide higher noise-dampening response. The methods employed so far covered stress–strain, and stiffness characteristics, which could be used in pavement design and the evaluation of rolling resistance and noise-reducing properties. Although this study is just a portion of a much more comprehensive laboratory test programme, these tests along with the upcoming laboratory tests are envisaged to aid in selecting the most promising PERS materials for the application on trafficked roads
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| 4. |
- Kalman, Björn, et al.
(författare)
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Project PERSUADE : optimization of poroelastic road surfaces in the laboratory
- 2011
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Ingår i: 40th International Congress and Exposition on Noise Control Engineering 2011 (INTER-NOISE 2011). - Tokyo : Institute of Noise Control Engineering of Japan (INCE/J), Acoustical Society of Japan (ASJ). - 9781618392800 ; , s. 699-707
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The paper gives a presentation of the Work Package 2 "Mixture optimization" of the European project PERSUADE; a project which aims at developing poroelastic road surfaces (PERS). The latter are assumed to provide a pavement material that provides exceptional tire/road noise reduction. The task of PERS mixture optimization is extremely complicated, as there are a multitude of variants that one would like to try, but resources allow testing only some of them. The WP2 scope of the work includes selecting test methods that reflect the performance of PERS. So far we have focused on mixes with both hard and rubber aggregates to get mixes which are polishing resistant. The paper presents the test methods we finally have chosen and the criteria we have put on the mixes to pass these tests. The paper discusses some test results briefly and acoustical absorption test results in particular. The paper is mainly a methodology description.
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| 5. |
- Prapoorna Biligiri, Krishna, et al.
(författare)
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Prediction of the Remaining Fatigue Life of Flexible Pavements Using Laboratory and Field Correlations
- 2015
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Ingår i: Journal of materials in civil engineering. - : American Society of Civil Engineers (ASCE). - 0899-1561 .- 1943-5533. ; 27:7
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Tidskriftsartikel (refereegranskat)abstract
- The main objective of this study was to develop comprehensive criteria to evaluate the remaining service life of existing roads as regards their field fatigue cracking characteristics using fracture mechanics principles and associated laboratory performance tests. Two basecourse layers were investigated for their residual fatigue lives: reference and modified stone mastic asphalt mixes. The two pavement systems’material characteristics using the actual field cores were estimated in the laboratory, including moduli, fatigue relationships, and crack propagation parameters. Additionally, field measurements encompassed collection of falling weight deflectometer deflections, temperature variations, and traffic counts. Fatigue lives of the two base course layers were predicted using the developed laboratory-based fatigue and crack propagation parametric relationships during one climatic period. The modified structure presented significantly longer fatigue life than the reference mix. This was indicative of the findings that the laboratory procedure(s) based on asphalt mixture properties’ fracture and fatigue mechanics such as crack initiation, and propagation modeling and relationships are useful for evaluating the pavement mix’s performance in the field as well. Overall, laboratory tests provided reliable information regarding residual life predictions in case it is difficult to actually perform field measurements and estimate the residual life of a pavement system. The criteria developed in this study should serve as guidelines for agencies to comprehend and understand a substantial amount of information regarding asphalt materials’ fatigue characterization so that it can be implemented as one of the quality control tests to assess the pavement design life.
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