Engineering Properties of Asphalt Mixtures and their Relationship to Performance

Author(s):  
RL Davis
Author(s):  
Jhony Habbouche ◽  
Elie Y. Hajj ◽  
Peter E. Sebaaly ◽  
Adam J. Hand

Florida Department of Transportation uses the 1993 AASHTO guide to conduct new and rehabilitation designs for all the state’s flexible pavements. Based on previous experience, a structural layer coefficient of 0.44 was found to be well representative of the department’s conventional polymer-modified (PMA) asphalt concrete (AC) mixtures. If the positive impact of the polymer on the layer is assumed to be maintained at higher contents, then the use of high polymer-modified (HP) asphalt binder may lead to a higher AC structural layer coefficient and a reduced AC layer thickness for the same design traffic and serviceability design loss. The objective of this paper was to determine a fatigue-based structural layer coefficient for asphalt mixtures that contain HP binder using comprehensive mechanistic analyses. This approach relied on combining measured engineering properties and performance characteristics of AC mixtures with advanced flexible pavement modeling (3D-Move). A total of eight PMA and eight HP AC mixtures were designed and evaluated in the laboratory. Overall, the HP AC mixtures showed similar or lower dynamic modulus and better fatigue performance models when compared with those of their respective PMA AC mixtures. However, the fatigue-based structural layer coefficients, determined via mechanistic analysis using the service life approach, ranged between 0.33 (lower than 0.44) and 1.32 (greater than 0.44). Using advanced statistical analyses, a fatigue-based structural layer coefficient of 0.54 was determined for HP AC mixtures. This coefficient should still be verified for other modes of distress.


Author(s):  
Gerald A. Huber ◽  
Xishun Zhang ◽  
Robin Fontaine

The Strategic Highway Research Program (SHRP) spent $50 million researching asphalt binders and asphalt mixtures and provided three main products: an asphalt binder specification, an asphalt mixture specification, and Superpave, an asphalt mixture design system that encompasses both the binder and mixture specification. SHRP researchers have provided tools that promise more robust asphalt mixtures with reduced risk of premature failure. Implementation of the specifications and mix design system will require overcoming several obstacles. Superpave must be demonstrated to be practical and easy to use. The impact of Superpave aggregate requirements on aggregate availability must be determined. The Superpave gyratory compaction procedure has been uniquely defined and then calibrated to traffic volume. The reasonableness of this approach must be tested in widespread application. Perhaps the largest implementation hurdle exists in the performance models. Expensive test equipment is necessary to do the performance-based tests. The performance predictions must be established as reasonable to justify the cost. A highway reconstruction project containing three Superpave Level 1 mix designs is documented including quality control done with the Superpave gyratory compactor. Superpave Level 2 performance-based tests were carried out to predict permanent deformation of the design and the mixture as constructed. The performance-based engineering properties obtained from the tests are evaluated, and the reasonableness of the performance prediction models is discussed.


2010 ◽  
Vol 37 (11) ◽  
pp. 1414-1422 ◽  
Author(s):  
Feipeng Xiao ◽  
Serji Amirkhanian ◽  
Bradley Putman ◽  
Junan Shen

An improved understanding of the rheological and engineering properties of a rubberized asphalt concrete (RAC) pavement that contains reclaimed asphalt pavement (RAP) is important to stimulating the use of these recycled and by-product materials in asphalt mixtures. The uses of RAP and rubberized asphalt in the past have proven to be economical, environmentally sound, and effective in hot mix asphalt (HMA) mixtures across the US and the world. The objective of this research was to investigate the binder and mixture performance characteristics of these modified asphalt mixtures through a series of laboratory tests to evaluate properties such as the fatigue factor G*sinδ, rutting resistance, resilient modulus, and fatigue life. The results of the experiments indicated that the use of RAP and crumb rubber in HMA can effectively improve the engineering properties of these mixes.


Recycling ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 49
Author(s):  
Nuha Mashaan ◽  
Amin Chegenizadeh ◽  
Hamid Nikraz

Commercial polymers have been used in pavement modification for decades; however, a major drawback of these polymers is their high cost. Waste plastic polymers could be used as a sustainable and cost-effective additive for improving asphalt properties, attaining combined environmental–economic benefits. Since 2019, in Australia, trial segments of roads have been built using waste materials, including plastic, requiring that laboratory evaluations first be carried out. This study aims to examine and evaluate the effect of using a domestic waste plastic, polyethylene terephthalate (PET), in modifying C320 bitumen. The assessment of several contents of PET-modified bitumen is carried out in two phases: modified bitumen binders and modified asphalt mixtures. Dynamic shear rheometer (DSR) and rolling thin film oven tests (RTFOT) were utilised to investigate the engineering properties and visco-elastic behaviour of plastic-modified bitumen binders. For evaluating the engineering properties of the plastic-modified asphalt mixtures, the Marshall stability, Marshall flow, Marshall quotient and rutting tests were conducted. The results demonstrated that 6–8% is the ideal percentage of waste plastic proposed to amend and enhance the stiffness and elasticity behaviour of asphalt binders. Furthermore, the 8% waste PET-modified asphalt mixture showed the most improvement in stability and rutting resistance, as indicated by increased Marshal stability, increased Marshall quotient and decreased rut depth. Future fatigue and modulus stiffness tests on waste plastic-modified asphalt mixtures are suggested to further investigate the mechanical properties.


Author(s):  
Jian-Shiuh Chen ◽  
Han-Chang Ho ◽  
Yen-Yu Lin

The two primary factors that drive the use of reclaimed asphalt pavement (RAP) are economic savings and environmental benefits. However, highway agencies are concerned about the use of a high percentage of RAP in asphalt pavements. This study addressed issues related to the production, construction, properties, and performance of asphalt pavements that contain high percentages of RAP. Mixtures that contained up to 40% RAP were successfully designed, produced, and constructed after proper procedures were followed and attention to detail was paid during design, production, and construction. A separate drum for drying and heating RAP, called a parallel heating system, was used to produce high RAP content asphalt mixtures in a batch plant. Rejuvenating agents were mixed directly in a surge bin to allow the rejuvenator enough time to diffuse into aged RAP binder. Comprehensive laboratory tests were performed to evaluate the air voids, the resilient modulus, the rut depth, and the Cantabro weight loss of asphalt mixtures with high RAP content. A test road was constructed in 2014 to monitor how high RAP asphalt pavements would perform under real traffic and environmental conditions. An in-depth investigation was conducted of pavement performance, including cracking, friction, and rutting. The engineering properties of plant-produced mixtures and field cores were well correlated with the pavement performance of the test road. Test results indicated that high RAP content asphalt mixtures could perform as satisfactorily as those produced with virgin materials to meet in-service requirements.


Author(s):  
Mohammad Jamal Khattak ◽  
Gilbert Y. Baladi

A large research program sponsored by the Michigan Department of Transportation was designed and completed to evaluate the effect of polymer modification on the various properties of asphalt mixtures. These include the micro- and macrostructural, morphological, chemical, and engineering properties. Some of the engineering properties of the styrene-butadiene-styrene and styrene-etylene-butylene-styrene polymer-modified asphalt mixtures are presented and discussed. The elastic, fatigue, tensile, and permanent deformation properties were investigated at 60, 25, and –5°C. It was found that, for some polymer systems, the fatigue life and the indirect tensile strength increased considerably at 25°C while the elastic properties at -5°C were not affected by the addition of polymer. The implication of this is that the use of some polymer systems in asphalt mixtures enhances their fatigue cracking and rutting resistance without affecting the low temperature cracking potential.


2019 ◽  
Vol 1 (1) ◽  
Author(s):  
Mohd Rosli Mohd Hasan ◽  
Zhanping You ◽  
Mohd Khairul Idham Mohd Satar ◽  
Muhammad Naqiuddin Mohd Warid ◽  
Nurul Hidayah Mohd Kamaruddin ◽  
...  

This study was conducted to assess the performance of modified asphalt binders and engineering properties of mixtures prepared with incorporation 3 vol% and 6 vol% of calcium carbonate (CaCO3), linear low-density polyethylene (LLDPE), and combinations of CaCO3 and LLDPE. The rheological properties of control and modified asphalt binders were evaluated using a series of testing such as rotational viscometer (RV), multiple stress creep recovery (MSCR) and bending beam rheometer (BBR) tests. Meanwhile, four-point beam fatigue test, the dynamic modulus (E*) test and tensile strength ratio (TSR) test were conducted to assess the engineering properties of asphalt mixtures. Based on the findings, the RV and MSCR test result shows that all modified asphalt binders have improved performance in comparison to the neat asphalt binders in terms of higher viscosity and improved permanent deformation resistance. A higher amount of CaCO3 and LLDPE have led modified asphalt binders to better recovery percentage, except the asphalt binders modified using a combination of CaCO3 and LLDPE. However, the inclusion of LLDPE into asphalt binder has lowered the thermal cracking resistance. The incorporation of CaCO3 in asphalt mixtures was found beneficial, especially in improving the ability to resist fatigue cracking of asphalt mixture. In contrast, asphalt mixtures show better moisture sensitivity through the addition of LLDPE. The addition of LLDPE has significantly enhanced the indirect tensile strength values and tensile strength ratio of asphalt mixtures.


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