scholarly journals COMPARISON OF TWO ASPHALT MIXTURES USING COMPLEX MODULUS TEST IN LIBYAN WEATHER

2019 ◽  
Vol 10 (1) ◽  
pp. 82-92
Author(s):  
Khlifa Saad El atrash ◽  
Gabriel J. Assaf
Keyword(s):  
Laboratory Experiments ◽  
Complex Modulus ◽  
Asphalt Mixtures ◽  
Traffic Load ◽  
Asphalt Binders ◽  
Loading Frequency ◽  
Content Increase ◽  
Aggregate Gradation ◽  
Load Effects ◽  
Phase Angles

The complex modulus test is dependent on temperature and loading frequency. Thus, the results produced from this test will give a more accurate representation of traffic load effects on asphalt pavement. Laboratory experiments were conducted on two different asphalt mixtures for road research projects (Libya/Roads). All specimens had the same mixtures of aggregate gradation GB-20 incorporated with two different asphalt binders PG70-10 and B (60/70). To obtain the master curve, there were some errors at low temperatures (-25, -10 ºC) and high temperature (54 ºC), so these values were discarded. In addition, 2-complex modulus (CM) and phase angles (Phi) in the test were measured at temperatures of -25, -10, -5, 10, 25, 35, and 54ºC, as well as frequencies of 25, 10, 5, 1, 0.5 and 0.1 Hz. The results displayed the influence of the type of binder on the rheology of the mixtures and gradation on the intensity. Hence, using binder PG 70-10 in Libyan asphalt roads may reduce the binder content, increase the mixture workability, and decrease the thermal cracking. The intrinsic characteristics related to binder properties and weather temperature exhibited the most significant impact on the predicted dynamic modulus. Keywords: complex modulus, frequencies, temperatures, sinusoidal, phase angles

Investigation of Rheological Properties of Asphalt Binders Containing Conductive Fillers

2008 ◽  
Vol 385-387 ◽  
pp. 753-756 ◽  
Author(s):  
Shao Peng Wu ◽  
Bo Li ◽  
Jun Feng Huang ◽  
Zhi Fei Liu
Keyword(s):  
Rheological Properties ◽  
Complex Modulus ◽  
Asphalt Binder ◽  
Conductive Filler ◽  
Asphalt Mixtures ◽  
Asphalt Binders ◽  
Asphalt Pavements ◽  
Strain Sensing ◽  
Lower Temperature ◽  
Phase Angles

It is currently interesting to use thermal or electrical conductive asphalt mixtures for snow-melting and maintenance of asphalt pavements in winter or strain-sensing application. Graphite is the principal conductive filler for asphalt mixtures. The addition of Graphite not only makes asphalts conductive but also has effects on other properties. Considering the visco-elastic property of asphalt, the effects of graphite on rheological properties of asphalt binders were investigated by Viscosity Test(VT) and Dynamic Shear Rheometer(DSR). The results of Viscosity Test indicate that viscosity of asphalt binder increases with an increasing amount of graphite. And the effect is more prominent at higher amount and lower temperature. It means that graphite makes asphalt binders stiffer. The results from DSR tests present that the values of complex modulus increase while phase angles decrease under a proper amount of graphite. It infers that proper amount of graphite can make asphalt a more elastic like material. And the results of rutting parameter point out that graphite can improve the rutting resistance of asphalts.

Damage and Thixotropy in Asphalt Mixture and Binder Fatigue Tests

2012 ◽  
Vol 2293 (1) ◽  
pp. 8-17 ◽  
Author(s):  
Félix Pérez-Jiménez ◽  
Ramon Botella ◽  
Rodrigo Miró
Keyword(s):  
Cyclic Loading ◽  
Strain Amplitude ◽  
Fatigue Testing ◽  
Complex Modulus ◽  
Asphalt Mixture ◽  
Viscoelastic Behavior ◽  
Fatigue Cracking ◽  
Asphalt Mixtures ◽  
Asphalt Binders ◽  
Irreversible Damage

Fatigue cracking is considered one of the main damage mechanisms in asphalt pavement design. Design methods use fatigue laws obtained by laboratory testing of the materials involved. Typically, these tests consist of subjecting the asphalt mixture to cyclic loading until failure occurs. However, failure is associated not with specimen fracture (which is unusual), but with a slight decrease in the mechanical properties of the material, usually in the complex modulus. As a consequence, it is important to differentiate between real damage to the material and changes in its viscoelastic behavior and thixotropy. It is also crucial to account for the healing that occurs in asphalt material after rest periods. The above considerations are important in the fatigue testing of asphalt binders because these materials show pronounced viscoelastic behavior and thixotropy, especially when subjected to cyclic loading. This paper demonstrates that in many cases what is taken for fatigue failure during testing (i.e., a decrease in the complex modulus below half of its initial value) is actually thixotropy. Thus, the complex modulus can be recovered by reducing the loading or, as in this study, the strain applied. In contrast, asphalt mixtures experience irreversible damage, and depending on the asphalt binder, the thixotropic effects are more or less pronounced. This paper analyzes the failure criteria currently used in the fatigue testing of asphalt mixtures and binders and evaluates the parameters chosen, namely, complex modulus (G*) and phase angle (δ) to characterize asphalt binders (G*sin δ). A cyclic uniaxial tension–compression test under strain-controlled conditions was performed. Three test modalities were used: time sweeps (constant strain amplitude until total failure), increasing strain sweeps (increase in strain amplitude every 5,000 cycles), and up-and-down strain sweeps (alternating increases and decreases in strain amplitude).

scholarly journals Deformation Parameters and Fatigue of the Recycled Asphalt Mixtures

2015 ◽  
Vol 11 (2) ◽  
pp. 115-120
Author(s):  
Juraj Šrámek
Keyword(s):  
Complex Modulus ◽  
Permanent Deformation ◽  
Asphalt Mixtures ◽  
Test Method ◽  
Traffic Load ◽  
Bending Test ◽  
Recycled Asphalt ◽  
The Road ◽  
Dynamic Methods ◽  
Deformation Complex

Abstract The deformational properties of asphalt mixtures measured by dynamic methods and fatigue allow a design the road to suit the expected traffic load. Quality of mixtures is also expressed by the resistance to permanent deformation. Complex modulus of stiffness and fatigue can reliably characterize the proposed mixture of asphalt pavement. The complex modulus (E*) measurement of asphalt mixtures are carried out in laboratory of Department of Construction Management at University of Žilina by two-point bending test method on trapezoid-shaped samples. Today, the fatigue is verified on trapezoid-shaped samples and is assessed by proportional strain at 1 million cycles (ε6). The test equipment and software is used to evaluate fatigue and deformation characteristics.

Effect of Fineness Modulus and Uniformity Coefficient on the Complex Modulus Function of Asphalt Concrete

2017 ◽  
Author(s):  
A. S. M. Asifur Rahman ◽  
Rafiqul A. Tarefder
Keyword(s):  
Asphalt Concrete ◽  
Complex Modulus ◽  
Superposition Principle ◽  
Asphalt Binders ◽  
Modulus Function ◽  
Aggregate Gradation ◽  
Factors Affecting ◽  
Uniformity Coefficient ◽  
Time Temperature Superposition Principle ◽  
Fineness Modulus

Different material attributes such as mix volumetrics, aggregate gradations, and binder characteristics are the factors affecting viscoelastic material functions of asphalt concrete. In this study, the effects of aggregate gradation on the complex modulus function of asphalt concrete are determined. The two distinct properties of the aggregate blend considered in this study are the fineness modulus and the uniformity coefficient. A total of 54, plant produced, asphalt concrete mixtures with asphalt binders having various performance grades and sources were collected from the manufacturing plants. The asphalt-aggregate mixtures were then compacted, cored, and sawed to cylindrical specimens. Three cylindrical specimens from each of the asphalt-aggregate mixtures were prepared and tested in the laboratory for complex or dynamic modulus. After that, average mastercurves of complex modulus and phase angle were generated by applying time-temperature superposition principle. Study showed that the complex modulus function of asphalt concrete is significantly related to the fineness modulus and uniformity coefficient of the aggregate blends used in the asphalt-aggregate mixture.

scholarly journals Mechanical Characteristics of Graphene Nanoplatelets-Modified Asphalt Mixes: A Comparison with Polymer- and Not-Modified Asphalt Mixes

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2434
Author(s):  
Laura Moretti ◽  
Nico Fabrizi ◽  
Nicola Fiore ◽  
Antonio D’Andrea
Keyword(s):  
Fatigue Resistance ◽  
Graphene Nanoplatelets ◽  
Asphalt Mixtures ◽  
Asphalt Binders ◽  
Asphalt Mixes ◽  
Modified Asphalt ◽  
Bituminous Mixtures ◽  
Water Sensitivity ◽  
Polymer Modified Asphalt ◽  
Mechanical Performances

In recent years, nanotechnology has sparked an interest in nanomodification of bituminous materials to increase the viscosity of asphalt binders and improves the rutting and fatigue resistance of asphalt mixtures. This paper presents the experimental results of laboratory tests on bituminous mixtures laid on a 1052 m-long test section built in Rome, Italy. Four asphalt mixtures for wearing and binder layer were considered: two polymer modified asphalt concretes (the former modified with the additive Superplast and the latter modified with styrene–butadiene–styrene), a “hard” graphene nanoplatelets (GNPs) modified asphalt concrete and a not-modified mixture. The indirect tensile strength, water sensitivity, stiffness modulus, and fatigue resistance of the mixtures were tested and compared. A statistical analysis based on the results has shown that the mixtures with GNPs have higher mechanical performances than the others: GNP could significantly improve the tested mechanical performances; further studies will be carried out to investigate its effect on rutting and skid resistance.

Dynamic Viscoelastic Properties of SBS Modified Asphalt Based on DSR Testing

2012 ◽  
Vol 598 ◽  
pp. 473-476 ◽  
Author(s):  
Yong Mei Guo ◽  
Wei Chen
Keyword(s):  
Complex Modulus ◽  
Superposition Principle ◽  
Asphalt Binder ◽  
Asphalt Binders ◽  
Frequency Range ◽  
Master Curves ◽  
Temperature Property ◽  
Low Frequencies ◽  
High Temperature Property ◽  
Frequency Sweeps

Five SBS modified asphalts and one base asphalt were selected to carry out frequency sweeps over a wider frequency range using the dynamic shear rheometer (DSR). Six asphalt binders were subjected to sinusoidal loading at 30°C-90°C within the linear viscoelastic limits, and master curves of complex modulus (G*) and phase angle (δ) could be constructed by means of the time-temperature superposition principle (TTSP). The results show that the G* values of SBS modified asphalts are significantly greater than those of base asphalt at low frequencies, but are slightly smaller at high frequencies. Compared with the base asphalt, SBS modified asphalts have narrower master curves of complex modulus, and their phase angles are much smaller within the whole frequency range. This indicates that various properties of SBS modified asphalts, such as high-temperature property, low-temperature property, temperature susceptibility and elastic recoverability, are superior to those of the base asphalt. The G* values of the rolling thin-film oven (RTFO) aged asphalt are larger than those of the unaged asphalt in the whole range of frequencies, demonstrating that the anti-rutting performance of asphalt binder is improved after short-term aging.

scholarly journals Characteristic dynamic traffic load effects in bridges

2009 ◽  
Vol 31 (7) ◽  
pp. 1607-1612 ◽  
Author(s):  
Eugene J. OBrien ◽  
Paraic Rattigan ◽  
Arturo González ◽  
Jason Dowling ◽  
Aleš Žnidarič
Keyword(s):  
Traffic Load ◽  
Dynamic Traffic ◽  
Load Effects ◽  
Characteristic Dynamic

Dynamic Properties of Asphalt Binders Containing Fiber Modifiers

2010 ◽  
Vol 97-101 ◽  
pp. 724-727 ◽  
Author(s):  
Qun Shan Ye ◽  
Shao Peng Wu
Keyword(s):  
Shear Test ◽  
Dynamic Properties ◽  
Asphalt Binder ◽  
Asphalt Binders ◽  
Test Results ◽  
Modified Asphalt ◽  
Rate Versus ◽  
Complex Shear ◽  
Creep Modulus ◽  
Phase Angles

Dynamic shear test and creep shear test were employed to investigate the dynamic properties of various fiber modified asphalt binders with the fiber content of 1.0%. The test results indicate that complex shear modulus of asphalt binders containing fibers are increased while the phase angles are decreased greatly, which implies that the asphalt binder is reinforced by the addition of fibers and the elastic property of asphalt binder is improved significantly, especially at high frequency levels. The total strain during loading period and the residual strain after the creep shear test of asphalt binders are reduced greatly by the addition of fibers. Furthermore, the creep modulus of fiber modified asphalt binders is increased and the development rate versus loading time of creep modulus is decreased.

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