Evaluation of Hollow Fibers Encapsulating a Rejuvenator in Asphalt Binder with Recycled Asphalt Shingles
Max Aguirre, Louisiana State UniversityShow Abstract
Marwa Hassan, Louisiana State University
Sharareh Shirzad, Louisiana State University
Samuel Cooper, Louisiana Department of Transportation and Development
Louay Mohammad, Louisiana State University
Self-healing products such as hollow-fibers filled with an asphalt rejuvenator present an emerging technology that would enhance an asphalt mixtures resistance to cracking damage. The objective of this study was to develop a fiber synthesis procedure to prepare sodium-alginate fibers containing an asphalt rejuvenator. An optimization procedure was conducted to identify the most suitable hollow-fibers for asphalt pavement applications by varying production parameters and testing the thermal stability and tensile strength of the different fibers. Furthermore, the effect of adding the developed fibers in asphalt binder blends containing post-consumer waste shingle Recycled Asphalt Shingle (RAS) extracted binder was evaluated using Superpave Performance Grading (PG), Multiple Stress Creep Recovery (MSCR) test, and force ductility test. Based on the optimization process of the fiber synthesis, it was observed that the selected fiber had adequate thermal stability and tensile strength to resist the typical compaction pressure and mixing temperature during asphalt mix production processes. The PG grading results showed that the addition of the developed fibers lowered both high and low temperature grading compared to the asphalt binder blend with extracted binder from RAS. Furthermore, the rutting resistance of the virgin binder was improved by the addition of the developed fibers. An enhancement in the ductility property of the virgin binder was achieved when the developed fibers were added to the asphalt binder blend with extracted binder from RAS.
Effect of Binder Modification and Recycled Asphalt Pavement on the Performance of Permeable Friction Course
Mark Brum, Massachusetts Department of TransportationShow Abstract
Walaa Mogawer, University of Massachusetts, Dartmouth
Kevin Stuart, Independent Consultant
Alexander Austerman, University of Massachusetts, Dartmouth
Permeable Friction Course (PFC) is a hot-mix asphalt that contains interconnecting voids that provide improved pavement surface drainage during rainfall. The objective of this study was to determine if PFC mixtures which incorporate reclaimed asphalt pavement (RAP) will provide performances that are similar to PFC mixtures which only use virgin materials and whether binder type will affect performance.
Utilizing current design specifications, PFCs were designed with RAP contents of 0, 15, and 25% and four asphalt binders. These mixtures were subject to a barrage of tests which measured their ability to resist draindown, abrasion, fatigue cracking, rutting, and moisture damage. Other testing determined permeability, porosity and workability. Rutting testing employed the industry standard Asphalt Pavement Analyzer (APA). Fatigue cracking and moisture susceptibility testing utilized the Semicircular Bending Test (SCB).
It was determined that it is possible to design a PFC incorporating RAP which will have good performance. However, this will only be achieved when the proper materials are used. The RAP must be properly fractionated and a modified binder such as asphalt rubber or a highly modified asphalt binder (HiMA) must be used. The mixture tests combined with Life Cycle Cost Analyses demonstrated that a PFC with up to 15% RAP combined with an asphalt rubber or HiMA has the ability to provide good performance and be cost effective. Furthermore, the use of 25% RAP in combination with these binders was only limited by the asphalt rubber not meeting the specification for permeability.
A Self-Healing Asphalt Mixture by the Action of Microcapsules That Is Ready to Be Used Onsite
Alvaro Garcia HernandezShow Abstract
This paper presents an investigation on a new type of calcium-alginate microcapsules for asphalt mixture self-healing purposes. Sunflower oil was encapsulated in a calcium-alginate structure. With this purpose, microcapsules have been built and their mechanical strength and composition were characterized. Microcapsule content of 0.5% of total weight of the asphalt mixture was incorporated in a standard asphalt mixture for base courses. The physical and mechanical properties of asphalt mixture containing these microcapsules have been evaluated for the first time. Results show that calcium-alginate microcapsules were strongly bonded to the mixture and they did not affect the mechanical performance of the asphalt mixture compared to asphalt mixtures without microcapsules. In addition, a new test method for evaluating asphalt self-healing was designed and applied to asphalt beams. The results showed that asphalt mixtures with microcapsules showed a crack recovery of 53% of its initial strength compared to 11% of those mixtures without microcapsules tested at three healing temperatures 5oC, 10oC and 20 oC.
Performance-Related Properties of Asphalt Mixture Modified with a Polymerized Pellet Mix Additive
Mohamad Zia Alavi, University of California, DavisShow Abstract
Hamidreza Sahebzamani, Kandovan Pars Company
Orang Farzaneh, University of Tehran
Serge Krafft, Eiffage
Polymer modified asphalt binders have been used for years to produce asphalt mixes with improved resistance to rutting, fatigue cracking, and thermal cracking. Special equipment and technique, which may not be always available, are required to produce polymer modified binders with desired engineering properties. Recently, a new approach is introduced to facilitate the use of polymers in asphalt mixtures. Polymer-binder additive, with 40% Styrene Butadiene Styrene [SBS], produced in pellet form can be directly incorporated to the mix during production in asphalt plant without the need for any special equipment. Logistically, this new form of mix additive simplifies and expands the use of polymers even for small paving projects. However, due to the novelty of technology more research is required to assess its efficacy. In this paper stiffness, rutting, fatigue, and thermal cracking resistance properties of asphalt mixes modified with polymerized pellet are compared to the mixes containing unmodified and polymer modified binders. The effects of long-term oxidative aging on stiffness and strength of mixes were also evaluated. Result of this study showed that the polymerized pellet mix additive had similar effects as the SBS polymer modified binder in improving asphalt mix performance-related properties.
Laboratory Performance of Asphalt Mixtures Containing Re-Refined Engine Oil Bottoms (REOB) Modified Asphalt Binders
Taesun You, Louisiana Transportation Research Center (LTRC)Show Abstract
Yucheng Shi, Louisiana State University
Louay Mohammad, Louisiana State University
Samuel Cooper, Louisiana Department of Transportation and Development
Increasing use of hardened oxidized asphalt binders in recycling materials such as recycled asphalt pavement (RAP) and recycled asphalt shingles (RAS) has increased the desire to use re-refined engine oil bottoms (REOB) as a recycling agent. However, conflicting conclusions on the effect of REOB on mixture performance have been reported in the literature. The objective of this study was to characterize the laboratory performance of conventional asphalt mixtures and mixtures containing re-refined engine oil bottoms (REOB) modified asphalt binders. Four 12.5-mm asphalt mixtures, containing 0-, 5-, 10-, and 15% REOB modified asphalt binders, were designed to meet Superpave design criteria. A suite of laboratory tests was utilized to ascertain the mechanistic behavior of the mixtures considered. Mechanistic tests were performed to evaluate the high-, intermediate-, low-temperature properties and moistures susceptibility of laboratory produced mixtures using the Hamburg Loaded-Wheel Tester (LWT), the Semi-Circular Bending (SCB) test, and the Thermal Stress Restrained Specimen (TSRST). Results showed that the addition of REOB did not adversely affect the rutting and moisture susceptibility of the mixtures. Similar low-temperature mixture performance was observed with REOB dosage up to 10%, while mixture with 15% REOB showed significantly reduced low-temperature cracking performance. The intermediate-temperature cracking resistance was reduced with an increase in REOB content.
Experimental Investigation of Properties of Graphite Nanoplatelet Modified Asphalt Binders and Mixtures
Jia-Liang Le, University of Minnesota, Twin CitiesShow Abstract
Mihai Marasteanu, University of Minnesota, Twin Cities
Mugurel Turos, University of Minnesota, Twin Cities
This paper presents a comprehensive set of experiments on the mechanical and compaction properties of asphalt binders and mixtures modified by graphite nanoplatelets (GNPs). The experiments involve three commercially available GNP materials with a relative low cost, which are suitable for large-scale industrial applications. This study shows that the addition of GNPs could effectively improve the mechanical properties of the asphalt binders and mixtures, such as flexural strength and fracture energy at low temperatures without compromising the properties at intermediate and high temperatures. Meanwhile, it is found that the GNPs could also significantly improve the compaction process of the asphalt mixtures by reducing the number of compaction (gyration) cycles for a target air void. This has significant implications on the construction cost and the durability of asphalt pavements. These observed improvements of mechanical and compaction properties make the GNP-modified asphalt binders and mixtures a new promising class of pavement materials for building more cost-effective and durable roads.
Laboratory Evaluation of Mixture Type on Highly Modified Asphalt Mixtures in Virginia
Benjamin Bowers, Virginia Department of TransportationShow Abstract
The work presented herein attempts to address reflective cracking of asphalt surfaced pavements through binder modification with a highly polymer (HP) modified asphalt binder. Nine asphalt mixtures ranging from fine dense-graded mixtures to stone matrix asphalt mixtures were investigated with conventional polymer modified binders and HP binder. The dynamic modulus test, overlay test (OT), and semi-circular bend (SCB) test are used to evaluate the mixtures. In the cracking tests, HP mixtures outperformed the conventionally modified control mixtures for the same mixture type. For HP mixtures, in general, SMA mixtures performed better in the cracking test than dense graded mixtures. One of the dense graded mixtures having larger NMAS performed better than the mixture with a smaller NMAS while the other having a larger NMAS was not significantly different in crack testing. Further, a discussion on the calculation of bulk specific gravity (Gmb) and percent air voids in a cut OT and SCB specimen using saturated surface dry or vacuum sealing methods is presented.
Effect of Bio-Based Oil on Performance of High-RAP Mixtures
Hamed Majidifard, University of Missouri, ColumbiaShow Abstract
Nader Tabatabaee, Sharif University of Technology
William Buttlar, University of Missouri, Columbia
The environmental and economic benefits of recycling asphalt pavements have received much attention in recent years. Because of the increase in the cost of raw materials and energy carriers, the reuse of large portions of reclaimed asphalt pavement (RAP) reduces the enormous waste and cost of hot-mix asphalt mixtures. Milling reduces the percent passing of the maximum size aggregate and increases the amount of fine aggregates and fillers. High-RAP mixtures are more prone to low temperature cracking and poor mixture workability because of the higher stiffness of RAP binder. To eliminate the excess fine aggregate and filler, the current study used 60% and 100% fractionated RAP with an organically-based recycling agent and crumb rubber to alleviate the aforementioned problems. Laboratory evaluation showed that increasing the amount of recycling agent in the high-RAP mixtures improved their workability and low temperature performance while decreasing moisture damage and rutting resistance. The long-term susceptibility to aging of recycled binder with organically-based recycling agent was also investigated. A procedure to obtain the optimum percentage of recycling agent was devised to strike a balance between the performance characteristics of mixtures with a high-RAP content.