Download or read book Efficacy of Softener for Enhancing Fatigue and Low temperature Performance of Asphalt Binders with High RAP written by Sumon Roy and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of a higher percentage of reclaimed asphalt pavement (RAP) in asphalt concrete can lead to developing premature failure of asphalt pavements due to fatigue and/or low-temperature cracking. The incorporation of softening agents in asphalt binders can resolve these problems and enhance pavement durability. This study aims to evaluate the effectiveness of waste-based softening agents for enhancing the properties of asphalt mixes with high RAP contents. Waste cooking oil (WCO), and engine bottom oil (EBO) along with a commercial rejuvenator were investigated in this study. Three types of Performance Grade (PG) binders, each collected from two different sources, used in this study are PG 64-22, PG 70-22, and PG 76-22. These binders blended with different percentages of RAP binder (15, 25, 40, and 60%) were rejuvenated with different dosages (10, 15, and 20%) of the softening agents. Empirical tests (penetration), Acid-number (pH), Superpave tests, Multiple Stress Creep Recovery (MSCR), Atomic Force Microscope (AFM), Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Saturates, Aromatics, Resins, and Asphaltenes (SARA) analysis, and limited mixture performance tests (Texas Boiling) were conducted. The rejuvenated binders showed a significant reduction in the binders' viscosities, resulting in a reduction of production temperatures as well as the brittleness of the hard binders. The fatigue factors of the rejuvenated binders decreased noticeably, indicating the improvement of fatigue cracking resistance. The Bending Beam Rheometer (BBR) results revealed that the rejuvenated binders exhibited a significant reduction in stiffness while increasing the rate of stress relaxation. The chemical analysis results revealed the appearance of some distinct peaks and changes in the % fractions of chemical constituents. The AFM test results agreed with the Superpave test data and showed that morphologies of the rejuvenated binders were changed and nanomechanical properties were altered noticeably. The TBT results showed that the WCO-modified RAP blend showed better performance than EBO. About 10% of WCO was found to be optimum for surface mixes with 25% RAP while EBO was less effective. The findings of this study are expected to help pavement professionals in selecting appropriate rejuvenators in the construction of pavements with high RAP.

Download or read book Long Term Effectiveness of Recycling Agents to Improve Performance Properties of Asphalt Concrete written by Mahsa Tofighian and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recycled materials such as reclaimed asphalt pavement (RAP) have been incorporated into asphalt mixtures for many years. However, their usage has increased over time as they are seen as a way to reduce the cost of asphalt mixtures, save energy, and protect the environment. Similarly, there has been a growing focus on the utilization of recycled asphalt shingles (RAS) in asphalt mixtures, a pursuit undertaken by various state highway agencies. However, unless appropriate precautions are taken, as the proportion of RAP and RAS in the asphalt mixture is raised, the mixture becomes more brittle, leading to a higher risk of cracking and raveling in the asphalt pavement. Furthermore, the mixture becomes less workable and more challenging to compact in the field, increasing the potential for premature field failure. One strategy to incorporate more RAP and RAS into asphalt mixtures involves the use of specialized recycling agents (RAs), known as rejuvenating agents. Over time, asphalt mixtures undergo aging during construction and over the extended service life of asphalt pavements, resulting in the oxidation of the mix and the loss of a significant portion of the maltenes in the binder composition. Maltenes contribute to the softening effect of the binder, and these recycling agents, when used appropriately, are expected to compensate for this reduction in maltenes. The ultimate result of this rebalancing of components is the softening of the aged binder and an improvement in its resistance to cracking. This study investigates the long-term impact of bio-based and petroleum-based recycling agents (RA's) on recycled asphalt binders with varying levels of reclaimed asphalt pavement (RAP) and reclaimed asphalt shingles (RAS) content, specifically low (15%) and high (30%) RAP content and 0% and 5% RAS content. The rejuvenated binders underwent short-term and long-term aging through the use of a Rolling Thin Film Oven (RTFO) and Pressure Aging Vessel (PAV), respectively. The performance characteristics of these modified binders at various aging stages were assessed using a dynamic shear rheometer (DSR) and bending beam rheometer (BBR). The study revealed that all RA's used in this research maintained their effectiveness even after long-term aging, though the degree of effectiveness varied. Additionally, the results indicated that the petroleum-based RA required a higher dosage to achieve the same effect as the bio-based RA's. The findings from this research also demonstrated that when rejuvenators are added to mixtures with a high RAP content or a combination of RAP and RAS, the mixture's performance is enhanced in terms of low-temperature cracking and fatigue cracking. Nevertheless, it is crucial to extend this work to field pilot projects to ensure the effective application of these rejuvenating products.

Download or read book Improving Durability of Asphalt Mixes Produced with Reclaimed Asphalt Pavement Rap by Enhancing Binder Blending written by Hawraa Kadhim and published by . This book was released on 2019 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reclaimed Asphalt Pavement (RAP) has been favoured over virgin materials in the light of the unstable cost of virgin asphalt binders, shortage of quality aggregates, and compelling need to preserve the environment and natural resources. Mixes containing up to 20% RAP are commonly considered to have similar behaviour to virgin mixes. However, during the production process of HMA with RAP, the blending between aged and virgin binders would be partial, which would create heterogeneity in distribution of the aged recycled binder and the soft virgin binder in the HMA-RAP mixes. Hence, it is important to control the blending process between old and new binders to obtain more homogenous mix. Therefore, the main objectives of this research are to examine the kinematics of blending of aged and virgin binders by considering the time-temperature effect during mixing and silo-storage, and assess the thermo-mechanical behaviour of Hot Mix Asphalt (HMA) containing RAP at different blending states. The asphalt mixes used in this research were produced and collected at two plants (Plant 1) and (Plant 2) located in Ontario, Canada. Two Marshall mixes were produced and collected from Plant 1 including a surface course HL-3 containing 15 percent RAP and a base course HL-8 containing 30 percent RAP. These mixes were labelled as 1HL-3 and 1HL-8 respectively. In addition, two Marshall mixes were produced and collected from Plant 2 including a surface course HL-3 containing 20 percent RAP and a base course HL-8 containing 40 percent RAP. These mixes were labelled as 2HL-3 and 2HL-8 respectively. To investigate the impact of storage time on the blending progress and achieving a cohesive final binder, the mix samples were collected as a function of storage time in the silo. The first sampling was done immediately after production (t = 0-hour), and then at several time intervals of silo-storage; i.e., at 1, 4, 8, and 12 hours. In case of Plant 2, the samples were additionally collected after 24-hour of storage time. All samples were then kept in a storage room at 7ʻC until the day of compaction to minimize any further blending between aged and virgin binder. To understand the blending phenomena and its effect on the performance of the pavement, a multi-scale investigation is carried out. The blending was examined in terms of micro-mechanical and rheological properties. The microstructure of the blending zones were examined under The Environmental Scanning Electron Microscope (ESEM). In addition the effect of the silo-storage time on the rheology of the binders was investigated. The results indicate that increasing the interaction time and temperature between the aged and virgin binder significantly results in a better blending. The performance of RAP-HMA with respect to the silo-storage time was examined using Dynamic Modules Test, Thermal Stress Restrained Specimen Test (TSRST), Rutting Test, and Flexural Beam Fatigue Test. The experimental data indicates that samples collected after 12-hour of silo storage exhibited a reduction in the stiffness due to better blending of aged and virgin binder. In addition, the 12-hour samples showed enhancement in their fracture temperature, rutting depth, and fatigue life, accompanied with a better blending between their aged and virgin binder. On the other hand, the samples that collected after 24-hour silo-storage had a higher stiffness in comparison with the 8 and 12-hour samples. Moreover, the AASHTOWare Pavement Mechanistic-Empirical Design was utilized to examine the effect of the 12-hour silo-storage time on the long term performance of the pavements. Four pavement structures have been designed for this purpose. These pavements have the same structure of their granular A, granular B, and the subgrade. Yet, the first layer (surface course and base course) is a silo-storage time-dependent. The long-term field performance prediction indicates a slight improvement with the 12-hour pavements (Plant1 12hrs and Plant2 12hrs). However, it should be noted that AASHTOWare Pavement Mechanistic-Empirical Design does not appear to properly capture the effect of blending in the pavement performance. The collected experimental evidences unveils correlations between time-temperature effects and mixture performance. Based on these findings, the research provides practical recommendations to the professionals of the Canadian asphalt industry for a better use of RAP. Ultimately, this research recommends a 12-hour silo-storage time for the RAP-HMA for better performance and durability of the mixes.

Download or read book Evaluating the Effect of High RAP Content on Asphalt Mixtures and Binders Fatigue Behavior written by Umme Amina Mannan and published by . This book was released on 2018 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the main concerns with the application of reclaimed asphalt pavement (RAP) in the asphalt concrete pavement is fatigue cracking due to the stiffness increase with the addition of aged and stiff RAP binder. The purpose of this study is to evaluate fatigue performance of asphalt binder and mixtures with different RAP percentages (0, 15, 25, 35 and 40 %). Among these, 35 and 40 % RAP mixes are considered as high RAP content. This study describes the results of laboratory fatigue response of asphalt mixtures and extracted binders containing RAP to define the effect of RAP on the fatigue performance. To achieve this objective, mixes and binders were tested using the beam fatigue test and the time-sweep test, respectively. Test results were analyzed using two different fatigue approaches, reduction in stiffness and dissipated energy criteria. Results showed that a higher initial stiffness and initial dissipated energy initiate the fatigue failure faster. Since both binders and mixes show an increase in the stiffness and energy consumed per loading cycle with the addition of RAP, resulting mixes containing higher RAP have a very short fatigue life. Also, the fatigue endurance limit decreases drastically with the addition of RAP in the mix. The results comparing two different RAP sources showed that the RAP source has more prominent effect on the mix fatigue performance than the binder fatigue performance. Finally, the traditional fatigue life prediction model is modified to incorporate the effect of RAP in the fatigue equation. The modified regression model predicted reasonable fatigue life of the mixture with a coefficient of determination (R2) close to 1. The measured and predicted fatigue life results were found close to each other for both mix and binder containing RAP.

Download or read book An Evaluation of the Tensile Strength of Asphalt Binder and Mortar with Recycled Asphalt Additives at Low Temperatures written by Rogelio Gabriel Rodriguez and published by . This book was released on 2017 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: A standard grading system is used to evaluate the properties and expected performance of an asphalt binder. The most common grading system used in the US today is the performance grading (PG) system. This system prescribes an operational temperature range within which the binder is expected to perform satisfactorily without resulting in rutting, fatigue cracking or thermal cracking as a distress. On the low-temperature and thermal cracking end, this system uses both a metric related to stiffness and rate of relaxation (m-value) to establish a low temperature grade for a given asphalt binder. Although these parameters provide some information on the rate of relaxation and overall rigidity of the asphalt binder they don’t include an evaluation of the tensile strength of the asphalt binder. The tensile strength of the binder can furnish critical information about its resistance to cracking including thermal cracking. The asphalt industry has become particularly interested in the impact of recycled asphalt pavement (RAP) and additives such as rejuvenators on the behavior and performance of the material. The goal of this study was to evaluate the tensile strength characteristics of asphalt binders and composites in addition to their stiffness characteristics. The study was conducted in three parts: (1) the evaluation of tensile strength of asphalt binders with similar performance grades, (2) the evaluation of tensile strength of asphalt binders as a function of the amount of recycled asphalt binder added to the virgin binder, and (3) the influence of recycled asphalt and rejuvenators on the stiffness and tensile strength of asphalt mortars. In addition to these three objectives, this study also developed simplified methods to prepare and evaluate the tensile strength of asphalt binders and mortars as a material characterization tool to screen or evaluate the efficacy of RAP, rejuvenators, and other additives. Results show that similarly graded binders have a significant variability both in terms of their stiffness and strength and that rejuvenators can be used with RAP to achieve a balance of stiffness and strength.

Download or read book Effect of Recovered Binders from Recycled Shingles and Increased RAP Percentages on Resultant Binder PG written by Ramon Francis Bonaquist and published by . This book was released on 2011 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fundamental Evaluation of the Interaction Between RAS RAP and Virgin Asphalt Binders written by Munir D. Nazzal and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive laboratory testing program was conducted in this research project to examine the blending between reclaimed asphalt pavement (RAP)/recycled asphalt shingles (RAS) and virgin asphalt binders and to evaluate the factors that may affect fatigue and low-temperature cracking as well as moisture-induced damage in asphalt mixtures prepared using these materials. This project included two parts: a binder study and a mixture study. In the binder study, atomic force microscopy (AFM) was utilized to characterize the micromechanical properties of the interfacial zone that develops between the RAP/RAS binders and the virgin asphalt binders. Three virgin asphalt binders with different performance grades (PG 58-28, PG 64-28, and PG 64-22), three RAP sources, as well as manufacturing waste and tear-off RAS were used in this project. A new sample-preparation procedure was developed to simulate the blending between the RAS/RAP and the virgin asphalt binders that occurs during asphalt mixture production. The micro-structure, stiffness and the adhesive properties along the blending zone were evaluated for different combinations of RAP/RAS binders and virgin binders. In the mixture study, several asphalt mixtures were used to evaluate the effect of the incorporation of RAP and/or RAS on the mix performance, including a control mixture (no RAP or RAS), a mixture containing 30% RAP, a mixture containing 5% tear-off RAS, and a mixture containing 20% RAP and 3% tear-off RAS. All mixtures were designed to meet ODOT specifications for Item 442 (Superpave) Type A for heavy traffic intermediate course asphalt mixes. The resistance of the asphalt mixtures to fatigue cracking was evaluated using the semi-circular bend (SCB) and the indirect tensile strength (IDT) tests. The SCB test was performed using the Illinois Method and the Louisiana Method. In addition the potential for low-temperature cracking was evaluated using the asphalt concrete cracking device (ACCD), and the susceptibility of the asphalt mixtures to moisture-induced damage was evaluated using the AASHTO T 283 (modified Lottman) test. The AFM test results indicated that blending occurred to a varying degree between the RAP binders and the virgin binders for all RAP-virgin binder combinations. The average modulus of the blending zone depended on the properties of the RAP and the virgin binders. For all binders, a reduction in the adhesive bonding energy was also observed in the blending zone due to the presence of RAP. However, the adhesive properties of the blending zone were significantly higher than those in the RAP binders. Statistical analysis also indicated that the stiffness of the interface blending zone is affected by the properties of the RAP and virgin asphalt binders, while the adhesive properties of the interface blending zone is primarily affected by those of virgin binder used. A linear regression model was developed to predict the modulus and adhesive bonding energy of the blending zone in terms of RAP and virgin binder properties. The validation of the regression models suggested that these models can serve as a viable tool in selecting the virgin binder to be used in a RAP mixture based on the properties of the RAP binder. Finally, the AFM imaging and force spectroscopy experiments revealed very limited to no blending between manufacturing waste or tear-off RAS materials and the virgin binders considered. The asphalt mixture test results also showed that the use of tear-off RAS in intermediate asphalt mixes significantly reduced their resistance to low-temperature and fatigue cracking as well as moisture damage, which can be attributed to the limited blending observed in the AFM experiments between the RAS and the virgin asphalt binders.

Download or read book Investigation of the Effect of Oil Modification on Critical Characteristics of Asphalt Binders written by and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermally induced cracking of asphalt pavement continues to be a serious issue in cold climate regions as well as in areas which experience extreme daily temperature differentials. Low temperature cracking of asphalt pavements is attributed to thermal stresses and strains developed during cooling cycles. Improving asphalt binder low temperature fracture and stiffness properties continues to be a subject of particular concern. Therefore, significant amount of research has been focused on improving asphalt binder properties through modification. In recent years, wide ranges of oil based modifications have been introduced to improve asphalt binder performance, especially at the low service temperatures. Although, significant use of these oils is seen in practice, knowledge of the fundamental mechanisms of oil modification and their properties for achieving optimum characteristics is limited. Hence, this study focuses on better understanding of the effect of oil modifiers which would help better material selection and achieve optimum performance in terms of increasing the life span of pavements. In this study, the effect of oil modification on the rheological properties of the asphalt binder is investigated. To examine the effect of oil modification on binder characteristics, low temperature properties as well as high temperature performance of oil modified binders were evaluated. It is found that oils vary in their effects on asphalt binder performance. However, for all oils used in the study, adding an oil to binder can improve binder low temperature performance, and this result mainly attributed to the softening effect. In addition to that, a simple linear model is proposed to predict the performance grade of oil modified binder based on the properties of its constituents at high and low temperatures. Another part of this study focuses on the oil modification effect on asphalt binder thermal strain and stresses. A viscoelastic analytical procedure is combined with experimentally derived failure stress and strain envelopes to determine the controlling failure mechanism, strain tolerance or critical stress, in thermal cracking of oil modified binders. The low temperature failure results depict that oil modification has a good potential of improving the cracking resistance of asphalt binders during thermal cycles.

Download or read book Low Temperature Investigations on Asphalt Binder Performance written by Oluranti Paul Togunde and published by . This book was released on 2008 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis investigates and documents fundamental studies of highway materials (asphalt engineering properties) especially on different modified asphalt binders and mixtures in order to understand failure mechanisms at low temperature and superior performance of such asphalt binders with the aim of preventing premature cracking on Ontario highways. In addition, seven asphalt binders of different compositions were used as a template for study and this research work is tailored towards Superpave® performance-based specification testing with the aim of improving asphalt pavement performance under various conditions and consequently reducing premature cracking in order to achieve long lasting highways. Based on the actual applied pattern of Superpave® specification criteria, the mechanical responses of the binders are analyzed by extended bending beam rheometer (eBBR), tensile stress ductilometer (Petrotest DDA3®), compact tension test (Instron AsphaltPro®), double-edge-notched tension and single-edge-notched tension (MTS 810 universal testing machine) protocols. The objective of this study entails establishing and developing of a proper procedure for the testing of binders with the aim of ranking (grading) the performance after validation of laboratory and field experiments. Analysis of the results appears to show that the premature distress on the Highway 417 trial sections can be attributed to reversible aging tendency (wax crystallization) at low temperatures coupled with low fatigue resistance of the binders. The results suggest that different polymer modifications had significant influence on the performance of asphalt mix as demonstrated from the results obtained from essential and plastic work of fracture using double-edge-notch-tension test (DENT). Crack tip opening displacement (CTOD) parameter consistently show the performing grading of asphalt binder while compact tension test protocol provides plane strain fracture toughness (K1c) which could be used to rank binders with respect to fracture resistance at low temperature. Hence, CTOD is a promising parameter which can be used to establish performance ranking of the binders.

Download or read book Investigation of the Effect of Oil Modification on Asphalt Binders written by Amir Golalipour and published by LAP Lambert Academic Publishing. This book was released on 2014-07-21 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermally induced cracking of asphalt pavement continues to be a serious issue in cold climate regions as well as in areas which experience extreme daily temperature differentials. Low temperature cracking of asphalt pavements is attributed to thermal stresses and strains developed during cooling cycles. Improving asphalt binder low temperature fracture and stiffness properties continues to be a subject of particular concern. Therefore, significant amount of research has been focused on improving asphalt binder properties through modification. In recent years, wide ranges of oil based modifications have been introduced to improve asphalt binder performance, especially at the low service temperatures. Although, significant use of these oils is seen in practice, knowledge of the fundamental mechanisms of oil modification and their properties for achieving optimum characteristics is limited. Hence, this study focuses on better understanding of the effect of oil modifiers which would help better material selection and achieve optimum performance in terms of increasing the life span of pavements.

Download or read book Chemical Physical and Thermodynamic Properties of Neat and Polymer Modified Asphalt Binders written by Lawrence Michael France and published by . This book was released on 1997 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Interaction Between New and Age hardened Binders in Asphalt Mixes Containing High Quantities of Reclaimed Asphalt Pavement and Reclaimed Asphalt Shingles written by Yuan He and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As virgin pavement material sources become scarcer and costlier the use of higher quantities of reclaimed asphalt pavement (RAP) and reclaimed asphalt shingles (RAS) in the production of new asphalt mixes becomes increasingly desirable. RAP/RAS binder in the mix has different levels of aging. Through oxidation, the binder becomes stiffer and more rigid than virgin binder, and thus results in a pavement material that is more brittle and susceptible to fatigue and thermal cracking. The purpose of this dissertation study was to investigate the interactions between new and age binders and evaluate asphalt mixes performance. A major concern associated with the use of high percentages of RAP and/or RAS is the level of blending between virgin and age-hardened binders, because the performance of the mix can be highly influenced by the properties of the composite binder. The blending between new binder and age-hardened RAP binder can be explained through diffusion mechanisms. This research used asphalt binder testing and diffusion and aging theory to investigate the evolution of blending between virgin and RAP binders during asphalt mix production, storage, and placement. The rheological properties of a two-layer asphalt binder sample composed of virgin and simulated RAP binder were measured using a dynamic shear rheometer (DSR) after conditioning following hot mix asphalt (HMA) and warm mix asphalt (WMA) time-temperature paths during mixing and placement. The diffusion and aging coefficients for the composite binder were estimated by comparing measured shear stiffness values with those predicted using a diffusion model and considering asphalt binder aging over time. The diffusion model is solved numerically based on the finite control volume approach. Results show that the HMA results in nearly full blending of the new and aged binders following the time-temperature paths used in this study; while the WMA results in only partial blending. Traditionally, the properties of blended binders in asphalt mixes containing RAP and RAS are evaluated through rheological testing of the binder extracted and recovered from a mix. However, this approach has long been criticized for being labor intensive, for potentially altering the chemistry of the binder and consequently changing the binder rheology, for forcing blending of binders that may not have been present in the mix, and for creating hazardous material disposal issues. The research presented in this dissertation proposes an alternative approach for characterizing blended binders by testing the linear viscoelastic properties of a fine aggregate matrix (FAM) asphalt mix using a torsion bar fixture in a DSR. A procedure has been developed for preparation and testing of small FAM cylindrical FAM specimens. The results demonstrated that this testing is sensitive to FAM mixes made of different virgin binders, RAP/RAS contents, with and without rejuvenating agent. More importantly, FAM mix testing shows similar results as that from DSR binder testing and full mix testing in terms of rankings of master curves and Black diagrams. Statistical analysis (ANOVA) on stiffness values from FAM testing also provides the same conclusion to that at binder and mix levels. Therefore, FAM approach has the potential to be used as a substitute to stiffness testing for mix comparison purposes. It is also a less expensive and more efficient testing approach than the full mix testing.The combined effect of RAP, RAS, and different virgin binder sources and grades on performance of the blended binders and asphalt mixes was also investigated. Previous studies have indicated that RAP, RAS, and virgin binder grades each has certain effects on performance of the mix. The addition of RAP/RAS undermines fatigue and thermal performance and improves rutting resistance. The virgin binder grade should be carefully chosen based on the percentages of RAP/RAS in the mix. Results from unconfined RLT appears to show that reducing the binder grade when using more than 25 percent RAP results in rutting performance similar to the original grade. Therefore, it is likely safe for high temperatures if the binder grade is reduced to meet the low and intermediate temperature requirements. Asphalt binders contain different organic molecules, and thus their chemical compositions vary according to the source of the oil used in their production. Virgin binders from different sources blend differently with the age-harden oxidized binder in RAP/RAS. Therefore, depending on the level of blending between virgin and oxidized binders, the performance of the mixes could vary substantially. Findings from this work indicated that virgin binder source had some effect on the blended materials. Additional research that came from the testing approaches to complete the investigation of RAP/RAS with this dissertation were also investigated. All the asphalt mixes used in this study were designed following Caltrans modified Superpave mix design procedure and tested using an Asphalt Mixture Performance Tester (AMPT). The effects of specimen preparation variables in terms of compaction method, compaction level, test temperature, stress state, and deformation measurement location when using the AMPT to predict mix stiffness and permanent deformation were evaluated. The best approach using Superpave testing equipment that appears to best characterize expected rutting performance as defined by previous calibrated RSCH results were also investigated.

Download or read book Durability and Performance Characteristics of Hot Mix Asphalt Containing Polymer Additives written by Robert Y. Liang and published by . This book was released on 2001 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ohio Department of Transportation has adopted the hot mix asphalt concrete containing polymer modifiers for use in the interstate highway pavement. Among the various reasons cited for the adoption of polymer modifiers are the favorable field experiences by ODOT, extensive literatures reporting enhanced performance, such as rutting resistance, low temperature thermal cracking resistance, and possibly fatigue endurance. However, despite these favorable findings, there are still cases involving premature failure of hot mixtures containing polymer modifiers. Concerns regarding optimum polymer content, compatibility between polymer additives and asphalt cement, proper mixing and compaction procedure remain to be resolved. Furthermore, performance based specifications to ensure production of desirable final asphalt concrete product require additional development. Questions regarding the suitability of Superpave binder testing procedures for the polymer-modified binders need to be clarified.

Download or read book Fracture Properties and Fatigue Cracking Resistance of Asphalt Binders written by Arash Motamed and published by . This book was released on 2012 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several different types of modifiers are increasingly being used to improve the performance of asphalt binders or to achieve desired mixture production characteristics (e.g., Warm Mix Asphalt). However, current Superpave performance specifications do not accurately reflect the performance characteristics of these modified binders. The main objective of this study was to evaluate the inherent fatigue cracking resistance of asphalt binders in the form of a matrix with rigid particle inclusions. The underlying rationale for this approach was to subject the binders to a state of stress that is similar to the one in a full asphalt mixture. This was achieved by fabricating and testing composite specimens of the asphalt binders and glass beads with a specified gradation. Four asphalt binders with similar true temperature grades but different modifiers were used in this study. The viscoelastic and fatigue cracking characteristics of the binders were measured using the glass bead-binder composite specimens in a dynamic shear rheometer at an intermediate temperature. The results demonstrate that the four asphalt binders modified using different methods had different damage characteristics despite the fact that these four binders were rated to have a similar performance grade based on the Superpave specifications. Fatigue cracking characteristics of the glass bead-binder test specimens used in this study were qualitatively very similar to the fatigue cracking characteristics of full asphalt mixtures using the same binders. The rank order of fatigue cracking resistance for the four glass bead-binder mixtures compared reasonably well to the rank order of fatigue cracking resistance for the full asphalt mixtures that incorporated these asphalt binders.

Download or read book Impact of Additives on Low Temperature Cracking Properties of Soft Binders Used in Cold Regions written by Wade A. Lein and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Low-temperature cracking is the main distress in asphalt pavement in cold regions (such as the arctic and subarctic regions) as the climate in these areas is severe in winter. While soft asphalt binders (such as PG 52-34 and PG 52-28) are used in the cold regions, asphalt pavements can still exhibit premature cracking failures. One of the approaches to solve this issue is to modify binders using additives. However, it is not clear which additives can significantly improve the thermal cracking resistance of binders. Therefore, there is a need to find potential additives resulting in improved resistance to thermal cracking because of extreme low temperatures experienced in cold regions. In this study, five additives [nano TiO2, nano SiO2, styrene-butadiene-styrene (SBS), ground tire rubber (GTR), and corn oil-based softening agent (SA)] were applied at various dosages with two soft base binders (PG 52-28 and PG 64E-40). Performance properties of modified binders were evaluated using the dynamic shear rheometer (DSR), standard bending beam rheometer (BBR), and modified BBR. The testing results indicated that the combination of a 7% softening agent and 7.5% SBS exhibited the highest improvement in the resistance to thermal cracking. Meanwhile, this combination also resulted in two performance grade bumps at high temperatures. Based on the laboratory testing results, the combination of a softening agent and high SBS could be potential additives to create high-performance binders for cold regions.

Download or read book Understanding the Performance of Modified Asphalt Binders in Mixtures written by Kevin D. Stuart and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall objective of this study was to determine if the Superpave high-temperature rheological properties of polymer-modified asphalt binders correlate to asphalt mixture rutting resistance. An emphasis was placed on evaluating polymer-modified asphalt binders with identical (or close) high-temperature performance grades (PG's), but varied polymer chemistries. Eleven asphalt binders were obtained for this study: two unmodified asphalt binders, an air-blown asphalt binder, and eight polymer-modified asphalt binders. High-temperature asphalt binder properties were measured by a dynamic shear rheometer (DSR). Mixture rutting resistance was measured by repeated shear at constant height (RSCH), and the French Pavement Rutting Tester (French PRT). The first objective was to verify the findings of a previous study using a different aggregate. In the previous study, it was found that the Superpave high-temperature asphalt binder properties correlated to mixture rutting resistance with few outliers, and a change in high-temperature PG from 70 to 76 increased rutting resistance. However, the correlation between RSCH and asphalt binder G*/sind (delta) depended on DSR frequency. The data suggested that a low DSR frequency, such as 0.1 rad/s, might provide a better grading system than the standard DSR frequency of 10.0 rad/s. This would require a change in the current asphalt binder specification. A diabase aggregate was used in a previous study. The data using a second aggregate, a limestone aggregate, in combination with four of the asphalt binders, agreed with the findings from the diabase mixtures. The second objective was to retest the diabase mixtures at 70 degrees Celsius using RSCH. The test temperatures used in the previous study were 50 degrees Celsius for RSCH and 70 degrees Celsius for the French PRT. The polymer-modified asphalt binders had continuous high-temperature PG's ranging from 71 to 77. Therefore, it was recommended that the test temperature for RSCH be increased to 70 degrees Celsius. Again, the correlation between RSCH and G*/sind was dependent on DSR frequency. The data suggested that a low DSR frequency, such as 0.1 rad/s, might provide a better grading system. However, it is not known whether this finding applies to pavements, or is related to the accelerated nature of the RSCH test. Furthermore, G*/sind (delta) at 0.1 rad/s did not clearly provide a better correlation to RSCH than the high-temperature PG's of the asphalt binders. The degree of correlation between the French PRT and G*/sind at 70 degrees Celsius did not depend on DSR frequency, and there was only one outlier. A correlation between the French PRT and high-temperature PG provided no obvious outliers. No changes to the specification are recommended based on the French PRT results.

Download or read book Guideline for Asphalt Refiners and Suppliers written by Jack S. Youtcheff and published by . This book was released on 1994 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: