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Book Synopsis Performance Evaluation of Recycled PMA Binders Containing Warm Mix Asphalt Additives by : Hakseo Kim
Download or read book Performance Evaluation of Recycled PMA Binders Containing Warm Mix Asphalt Additives written by Hakseo Kim and published by . This book was released on 2011 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The performance properties of recycled polymer modified asphalt (PMA) binders containing warm mix asphalt (WMA) additives at high, intermediate, and low temperatures were evaluated. First, each combination of two PMA binders (performance grade (PG) 76-22 from two different sources) and two WMA additives (i.e., Aspha-min® and Sasobit®) were blended to produce warm PMA binders. They were then artificially short-term and long-term aged through the rolling thin film oven and pressure aging vessel procedures. Second, long-term aged warm PMA binders were recycled using two virgin binders (PG 76-22 and PG 70-22), and the recycled binders were artificially aged again. Lastly, Superpave binder tests were performed through the rotational viscometer, the dynamic shear rheometer (DSR), and the bending beam rheometer (BBR). In general, the results of this study suggested that (1) the WMA additives and the aged PMA binders were found to have a significant influence on the performance properties of recycled binders (measured by the DSR and the BBR); (2) the use of PG 70-22 as a virgin binder was effective in offsetting the increase of binder stiffness due to the additives and the aged binders; and (3) the recycled warm PMA binders can result in satisfactory binder performance that meets current Superpave binder requirements.
Book Synopsis Performance Evaluation of Warm-Mix Recycled Asphalt Binders After Long-Term Aging by : Qiang Li
Download or read book Performance Evaluation of Warm-Mix Recycled Asphalt Binders After Long-Term Aging written by Qiang Li and published by . This book was released on 2019 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study evaluates the pavement performance evolution of warm-mix recycled asphalt binders during the secondary service period. Warm-mix recycled asphalt binders with various long-term aging levels and recycling plans were produced by the laboratory simulation method. Conventional physical properties tests, the dynamic shear rheometer test, and the bending beam rheometer test were conducted to measure the performance of recycled binders. Effects of the aging level and recycling plan on the resistance to rutting, fatigue cracking, and low temperature cracking were investigated by statistical methods. It was found that after secondary long-term aging, recycled binders are more resistant to rutting, while they are less resistant to fatigue and low temperature cracking. The modified aging kinetic model can be used to accurately characterize the effect of secondary aging time on rutting or fatigue factors for recycled binders. The resistance of aged binders to fatigue and low temperature cracking is obviously improved by adding the warm mix asphalt additive. By comparison, using styrene butadiene rubber latex enhances the binder performance in almost all aspects. The aging level has a more significant effect than the recycling plan for all performance parameters.
Book Synopsis Blending Issues of Hot and Warm Mix Asphalt Containing Recycled Asphalt Pavement and Recycled Asphalt Shingle by : Sheng Zhao (Writer on pavements)
Download or read book Blending Issues of Hot and Warm Mix Asphalt Containing Recycled Asphalt Pavement and Recycled Asphalt Shingle written by Sheng Zhao (Writer on pavements) and published by . This book was released on 2014 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: The current tendency in paving industry is to increase the use of recycled asphalt pavement (RAP) and recycled asphalt shingle (RAS). However, one of the reasons that limit the high recycled amount is the unknown blending between virgin and RAP/RAS binders. A series of studies were conducted in this dissertation to address blending issues in warm mix asphalt (WMA) and hot mix asphalt (HMA) containing RAP and RAS, in terms of evaluation of recycled binder mobilization, binder homogeneity and WMA effects on blending. Partial blending was observed in RAS mixtures and the most efficient blending occurred at approximately 5% RAS by weight. Increasing time led to a better RAS binder mobilization, while aggregate size and temperature in a certain range showed limited effects. A new parameter derived from gel permeation chromatography (GPC), large molecular size percentage [LMS(%)] related to binder molecular weight distribution, was developed to differentiate virgin and RAP/RAS binders as well as their blends, based on which a method was developed to quantify the recycled binder mobilization rate. A two-layer model based on atomic force microscopy (AFM) scanning was developed to evaluate RAS and virgin binder blending. The two binders were found to be “mixing” but not “blending” in a mixing zone of 25 to 30 micrometer. Staged extraction method used to evaluate asphalt binder homogeneity was validated with trichloroethylene (TCE) as the most effective solvent. A non-equal-time staged extraction method was proposed, in conjunction with LMS(%), to quantify binder homogenization after mechanical mixing and diffusion. Different blending scenarios of RAP/RAS mixes were proposed and validated. It was found that diffusion could be accomplished within mixture storage time for both WMA and HMA containing RAP, while blending in RAS mix was limited. WMA additives yielded mixes with higher blending ratios than control mix produced at 135oC, but lower than hot mix produced at 165oC. Laboratory foaming yielded a higher blending ratio, indicating foamed WMA may improve blending. Rutting might still be a concern for WMA-high RAP mixtures while fatigue concern may not exist. WMA-high RAP mixtures showed satisfactory moisture resistance. Blending effects on performance still needs further investigation.
Book Synopsis Recommendations and Guidelines for the Use of WMA Mixtures by : Zelalem Arega
Download or read book Recommendations and Guidelines for the Use of WMA Mixtures written by Zelalem Arega and published by . This book was released on 2012 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main objective of this research study was to evaluate the influence of warm mix additives on the rheology and performance characteristics of asphalt binders with emphasis on the affects of long-term aging and use of recycled asphalt binder. In order to achieve this objective the asphalt binders were first screened based on their chemical makeup. The selected asphalt binders were combined with different warm mix asphalt additives and evaluated for their mechanical properties. Subsets of these binders were also used to evaluate the affect of long-term aging and the affect of using recycled asphalt binder on performance characteristics. Tests were also conducted using a limited number of sand-asphalt mortars and full asphalt mixtures to further corroborate the findings from the binder study.
Book Synopsis Investigating the Rutting and Moisture Sensitivity of Warm Mix Asphalt with Varying Contents of Recycled Asphalt Pavement by : Taha Ahmed Hussien Ahmed
Download or read book Investigating the Rutting and Moisture Sensitivity of Warm Mix Asphalt with Varying Contents of Recycled Asphalt Pavement written by Taha Ahmed Hussien Ahmed and published by . This book was released on 2014 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: To evaluate the performance of Warm Mixture Asphalt (WMA) with varying amounts of recycled asphalt pavement (RAP) in comparison with Hot Mix Asphalt (HMA), comprehensive laboratory and field evaluations were conducted. Mix designs were performed for both WMA with a LEADCAP additive and HMA with large amounts of fractionated RAP materials. Hamburg Wheel Tracking (HWT) test was performed to evaluate the rutting and moisture susceptibility of both HMA and WMA laboratory mixtures. HMA mixtures with up to 50% RAP materials by binder replacement exhibited a better performance than WMA mixtures. However, when RAP materials were increased to 75% both WMA and HMA mixtures showed a superior performance. When a specially designed LEADCAP additive for a mixture with a high RAP content called "RAPCAP" was used, the performance was significantly improved. The existing Asphalt Bond Strength (ABS) test (AASHTO TP91-11) was modified to better evaluate the adhesion bond between asphalt binder and aggregate surface. Based on the modified ABS test results, it was found that the asphalt binder type significantly influenced the adhesion bond. To evaluate the performance of WMA mixtures in the field, test sections were constructed in Iowa, Minnesota and Ohio. The test sections were successfully constructed with less compaction effort than HMA and met the required field densities per each DOT's specification. All HMA and WMA mixtures collected from the test sections passed the HWT and the modified Lottman tests, which indicates high resistance to rutting and moisture damage. The asphalt binders were then extracted and recovered from the field samples then re-graded following AASHTO M320 and AASHTO MP19-10. The recovered asphalt binder grades were found to be higher than the target grades due to the existence of RAP materials in the mixtures except for asphalt binders extracted from WMA mixtures produced using "RAPCAP" additive.
Author :Sandeep Pandey (Researcher in civil and environmental engineering) Publisher : ISBN 13 : Total Pages :180 pages Book Rating :4.:/5 (992 download)
Book Synopsis Performance Characterization of Recycled Asphalt Pavements with Warm Mix Asphalt Technologies by : Sandeep Pandey (Researcher in civil and environmental engineering)
Download or read book Performance Characterization of Recycled Asphalt Pavements with Warm Mix Asphalt Technologies written by Sandeep Pandey (Researcher in civil and environmental engineering) and published by . This book was released on 2016 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study evaluated the laboratory performance characteristics of Recycled Asphalt Pavements (RAP) with Warm Mix Asphalt (WMA) Technologies. RAP was introduced in mixtures at three levels: 0, 15 and 35% of RAP contents. Five WMA technologies were evaluated against all the mentioned levels of RAP content. The study was conducted in two phases, each phase with a separate aggregate and RAP source. Standard Marshall Mix design method was followed for the mix design purpose, with some modification to introduce RAP and WMA. Rheological properties of both the virgin and recovered asphalt binders were determined. Laboratory designed mixtures were evaluated for moisture resistance, dynamic modulus, rutting resistance and thermal resistance behavior. Moisture resistance of the mixtures were evaluated by performing the indirect tensile strength test for 0 and 1 freeze-thaw cycles. Resistance to rutting was evaluated by determining flow number using the Asphalt Mixture Performance Tester (AMPT) machine. Finally, thermal resistance of the mixtures were evaluated by conducting Uniaxial Thermal Stress and Strain Test (UTSST). The study determined that the moisture susceptibility of the mixtures increased with the increase in number of freeze thaw cycles. Dynamic modulus of the mixtures were higher for a higher RAP content. Further, HMA mixtures were determined to have higher dynamic modulus and tensile strengths than the WMA mixtures. Even though, the strength values for WMA mixtures were lower than the HMA mixtures, WMA mixtures satisfied the required criteria defined by agency. HMA mixtures were found to have higher rutting resistance than WMA mixtures, and this resistance increased with the increase in RAP content. Even though HMA mixtures with higher RAP content performed better in terms of rutting, such mixtures exhibited a huge drop in thermal resistance capacity. Varying aggregate source did not significantly influenced the performance of mixtures, except in the case of rutting. Further study is need in order to validate the use of higher RAP content in the mixtures.
Book Synopsis Evaluating the Effects of Recycling Agents on Asphalt Mixtures with High RAS and RAP Binder Ratios by : Amy Epps Martin
Download or read book Evaluating the Effects of Recycling Agents on Asphalt Mixtures with High RAS and RAP Binder Ratios written by Amy Epps Martin and published by . This book was released on 2020 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: "More than 90 percent of highways and roads in the United States are built using hot-mix asphalt (HMA) or warm-mix asphalt (WMA) mixtures, and these mixtures now recycle more than 99 percent of some 76.2 million tons of reclaimed asphalt pavement (RAP) and about 1 million tons of recycled asphalt shingles (RAS) each year. Cost savings in 2017 totaled approximately $2.2 billion with these recycled materials replacing virgin materials. The TRB National Cooperative Highway Research Program's NCHRP Research Report 927: Evaluating the Effects of Recycling Agents on Asphalt Mixtures with High RAS and RAP Binder Ratios presents an evaluation of how commercially available recycling agents affect the performance of asphalt mixtures incorporating RAP and RAS at high recycled binder ratios."--
Book Synopsis Performance Evaluation of Warm Mix Asphalt Mixtures Incorporating Reclaimed Asphalt Pavement by : Brian Hill
Download or read book Performance Evaluation of Warm Mix Asphalt Mixtures Incorporating Reclaimed Asphalt Pavement written by Brian Hill and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Sustainability is a cornerstone of today0́9s engineering world. Warm mix asphalt (WMA) and reclaimed asphalt pavement (RAP) are the most prominent sustainable materials in asphalt concrete pavements. WMA is a not a new concept, however new innovations and increased usage of WMA has been spurred by the increased focus on sustainable infrastructure systems. WMA enables reduced production temperatures through the use of wax, water, or other chemical packages. The effects of reduced production temperatures include fuel use and emissions reductions, improved compaction, and possible RAP concentration increases. RAP is the primary recycled product of the aged asphalt concrete pavements and its use leads to reductions in virgin aggregate and asphalt demand. However, significant performance issues can stem from the individual integration of WMA or RAP materials in asphalt concrete. In particular, WMA technologies can increase moisture and rutting susceptibility while RAP significantly increases the stiffness of the resulting mixture. Consequently, quality performance of sustainable asphalt pavements may require the combined use of WMA and RAP to produce mixtures with sufficient stiffness and moisture and fracture resistance. This study evaluates the potential of WMA technologies and their integration with RAP. Initially, an extensive literature review was completed to understand the advantages, disadvantages, and past field and lab performance of WMA and RAP mixtures. Rotational viscometer and bending beam rheometer tests were then used to evaluate Sasobit, Evotherm M1, and Advera WMA modified and unmodified binders. Finally, virgin and 45% RAP mixtures were designed and tested to examine the rutting, moisture, and fracture resistance of WMA and HMA mixtures. The results of this experiment provided several key observations. First, viscosity reductions may not be the primary cause for the availability of reduced production temperatures for WMA technologies. Second, WMA additive properties have a significant effect upon fracture, moisture, and rutting resistance. Furthermore, the addition of RAP to WMA mixtures improved the rutting and moisture sensitivity performance as characterized in the Hamburg and Tensile Strength Ratio testing procedures.
Book Synopsis Evaluation of Warm Mix Additives for Use in Modified Asphalt Mixtures by : Corina Borroel Wong
Download or read book Evaluation of Warm Mix Additives for Use in Modified Asphalt Mixtures written by Corina Borroel Wong and published by . This book was released on 2011 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: The intention of this research effort is to evaluate the use of warm mix additives with typical polymer-modified and terminal blend tire rubber asphalt mixtures from Nevada and California. The research effort is broken into three phases that are intended to evaluate the impacts of warm mix additives with typical polymer-modified and terminal blend tire rubber asphalt mixtures from Nevada and California: moisture damage, performance characteristics, and mechanistic analysis. In Phase I of this research effort, mixture resistance to moisture damage was evaluated using the indirect tensile test and the dynamic modulus at multiple freeze-thaw cycles. Laboratory testing was conducted to address the following: (1) the impact of warm mix additive and reduced production temperatures on the moisture damage resistance of asphalt mixtures, (2) the impact of residual aggregate moisture on the moisture damage resistance of WMA mixtures, (3) the impact of warm mix additives on the moisture damage resistance of anti-strip treated WMA mixtures, and (3) the impact of long-term aging on strength gain and the moisture damage resistance of WMA mixtures. A total of one aggregate source, four warm mix asphalt technologies (Advera, Sasobit, Revix and Foaming) and three asphalt binder types (neat, polymer-modified and terminal blend tire rubber modified asphalt binders) typically used in both Nevada and California are being evaluated in this study. This thesis will only summarize the test results and findings of the Phase I of the study for two warm-mix additives: Advera and Sasobit. The evaluation of the other two technologies (i.e. Revix and Foaming) as well as the Phase II testing are still in progress and have not been completed.
Book Synopsis Improved Mix Design, Evaluation, and Materials Management Practices for Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content by : Randy Clark West
Download or read book Improved Mix Design, Evaluation, and Materials Management Practices for Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content written by Randy Clark West and published by Transportation Research Board. This book was released on 2013 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: TRB's National Cooperative Highway Research Program (NCHRP) Report 752: Improved Mix Design, Evaluation, and Materials Management Practices for Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content describes proposed revisions to the American Association of State Highway and Transportation Officials (AASHTO) R 35, Superpave Volumetric Design for Hot Mix Asphalt, and AASHTO M 323, Superpave Volumetric Mix Design, to accommodate the design of asphalt mixtures with high reclaimed asphalt pavement contents.
Book Synopsis Performance Properties of Polymer Modified Asphalt Binders (PMA) Containing Wax Additives by : Mithil Mazumder
Download or read book Performance Properties of Polymer Modified Asphalt Binders (PMA) Containing Wax Additives written by Mithil Mazumder and published by . This book was released on 2016 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study presents an experimental evaluation of the rheological properties of control and polymer modified asphalt (PMA) binders containing wax additives and a comprehensive comparison between these two binder types. The control and PMA binders with the additives were produced using two of the available warm asphalt processes (i.e., LEADCAP and Sasobit) and then artificially short-term and long-term aged using the rolling thin film oven (RTFO) and pressure aging vessel (PAV) procedures. Superpave binder tests were carried out on the binders through the rotational viscometer (RV), the dynamic shear rheometer (DSR), and the bending beam rheometer (BBR). In general the results of this study indicated that (1) the addition of wax additives into the control and PMA binders decreases the viscosity, as expected; (2) the reduction in viscosity was quite similar for both the binders with wax additives; (3) the percentage increase of rutting resistance due to the additives was much higher for the control binder, compared to the PMA binder; (4) both the control and PMA binders showed the similar trends in terms of fatigue cracking and low temperature cracking behavior after the addition of wax additives.
Book Synopsis Laboratory Characterization of Asphalt Binders Containing a Chemical-Based Warm Mix Asphalt Additive by : Shivani Rani
Download or read book Laboratory Characterization of Asphalt Binders Containing a Chemical-Based Warm Mix Asphalt Additive written by Shivani Rani and published by . This book was released on 2020 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: Different technologies, namely foamed asphalt, synthetic waxes, zeolites, and chemical additives, are used to produce warm mix asphalt (WMA). This study was undertaken to evaluate the effect of using different amounts of an amine-based chemical WMA additive on the rheology, performance grade (PG), and moisture-induced damage potential of an asphalt binder (PG 58-28). Superpave specifications were used to evaluate the rheological properties and PG of the asphalt binder. Also, a mechanistic approach-based on the surface free energy (SFE) method was used to evaluate the moisture-induced damage potential of the asphalt binder combined with commonly used aggregates in an asphalt mix. It was found that the dynamic viscosity of the asphalt binder was not significantly affected after blending it with the WMA additive. It was also observed that the Superpave high-temperature PG and the rutting factor did not reduce by an increase in the WMA additive content. However, the continuous low-temperature PG of the asphalt binder decreased with an increase in the amount of WMA additive. Furthermore, it was found that the fatigue resistance increased after blending the binder with the WMA additive. The SFE results of the asphalt binder revealed that the WMA additive used in this study reduced the moisture-induced damage potential of the asphalt mixes. However, the extent of this improvement was found to largely depend on the aggregate type. The outcomes of this study are expected to help better understand the influence of amine-based chemical WMA additives on rheological and long-term performance of asphalt mix.
Book Synopsis Evaluation of Warm Mix Asphalt Technologies with Respect to Binder Aging and Emissions by : Faramarz Farshidi
Download or read book Evaluation of Warm Mix Asphalt Technologies with Respect to Binder Aging and Emissions written by Faramarz Farshidi and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years Warm Mix Asphalt (WMA) technologies have been used to modify asphalt binders, with the following objectives: to decrease production and construction temperatures, reduce fumes and emissions, increase haul distance, and improve the workability of the mix. Reduced temperatures at the plant and during laydown and compaction are hypothesized to positively impact long-term oxidative aging behavior due to less oxidation/aging and result in less emissions during production and construction due to reduced production and construction temperatures. The purpose of this investigation was to quantify these improvements with respect to long-term oxidative aging in the field and environmental benefits with respect to volatile organic compounds, semi-volatile organic compounds and poly cyclic aromatic hydrocarbons in order to confirm or deny this hypothesis. This research evaluated the potential durability of WMA and Rubberized Warm Mix Asphalt (R-WMA) binders with respect to long-term aging through characterization of field-aged binders extracted and recovered from field cores. The results were compared to the control conventional Hot Mix Asphalt (HMA) and Rubberized Hot Mix Asphalt (R-HMA) samples. Binders were extracted and recovered from thirteen different test sections and a total of seven different WMA technologies were evaluated in this study. The Dynamic Shear Rheometer (DSR) was used to evaluate the rheological properties of the binders at high temperatures with respect to rutting performance in the field. The Bending Beam Rheometer (BBR) was used to characterize low temperature properties of the binder samples. A new testing procedure was developed to measure and characterize the rheological properties of the R-HMA and R-WMA binders with respect to performance-related properties in the field. The rheological results indicated that depending on the WMA technology used, the addition of WMA technologies and reduced production and compaction temperatures result in increase or decrease rutting resistance performance for WMA and R-WMA binders with respect to permanent deformation at high temperatures in the field. Both WMA and R-WMA binders studied meet the established thermal cracking criteria with respect to low temperature cracking in the field. The aging kinetics curves for WMA-treated binders are parallel to the control binders and the addition of WMA technologies including organic, chemical and mechanical foaming technologies studied in this research did not result in a different aging kinetics trend with respect to long-term aging in the field. A portable "flux" chamber was designed and fabricated to capture and directly measure emissions during paving operations. Emissions were collected in activated charcoal sorbent tubes for characterizing volatile organic compounds and semi-volatile organic compounds. XAD-2 resin tubes and filters were used to capture the gaseous phase and particulate phase of the PAH compounds, respectively. A reliable analytical method was developed to identify and quantify alkane emissions using gas chromatography mass spectrometry (GC/MS) in the laboratory. A separate method was developed for identification and characterization of trace level PAH compounds of the asphalt fumes. The results demonstrated that the warm mix asphalt technology type, plant mixing temperature and level of compaction significantly influence the emission characteristics throughout paving operations. Moreover, the emissions kinetics indicated that the majority of the reactive organic gases are volatilized in the first hour after sampling initiation (immediately after production and before compaction). To better understand and identify any chemical composition changes of the binder due to WMA technologies, nuclear magnetic resonance spectroscopy (NMR) was used for understanding structural complexities of HMA and WMA binder molecules. Qualitative analysis of both carbon and hydrogen atoms with HMA and WMA binders showed that the molecular structures of the binders are not significantly changed by the effect of WMA technologies.
Book Synopsis Effects of Additives for Warm Mix Asphalt on Performance Grades of Asphalt Binders by : Chaofan Wu
Download or read book Effects of Additives for Warm Mix Asphalt on Performance Grades of Asphalt Binders written by Chaofan Wu and published by . This book was released on 2012 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laboratory tests were carried out on a neat asphalt binder and a styrene-butadiene-styrene (SBS) asphalt binder containing Sasobit and Aspha-min as warm mix asphalt (WMA) additives to quantitatively evaluate the effects of the additives on the continuous grading temperatures and grades of asphalt binders in the framework of the performance grading system. Test results and data analyses indicate that the significances of the effects of WMA additives depend on the asphalt binder type, additive type, additive content, and rolling thin film oven (RTFO) aging temperature. The wax-type additive Sasobit has a stiffening effect on the grading temperatures. At typical 3 % content, the upper temperatures can be increased by up to 13.5 °C, the lower temperatures can be increased by up to 6.9 °C, and the intermediate temperatures can be increased by up to 5.0 °C. In the commonly used content range, the zeolite-type additive Aspha-min has little effects on the upper, lower, and intermediate grading temperatures. Although there is a special case, in which the upper grading temperature increase is canceled out by 3.8 °C, the reduction in RTFO aging temperature from 163 °C to 133 °C does not generally result in notable changes in the grading temperatures.
Book Synopsis Laboratory Evaluation of Warm Mix Asphalt Prepared Using Foamed Asphalt Binders by : Ayman W. Ali
Download or read book Laboratory Evaluation of Warm Mix Asphalt Prepared Using Foamed Asphalt Binders written by Ayman W. Ali and published by . This book was released on 2010 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Warm Mix Asphalt (WMA) is a name given to different technologies that have the common purpose of reducing the viscosity of the asphalt binders. This reduction in viscosity offers the advantage of producing asphalt-aggregate mixtures at lower mixing and compaction temperatures, and subsequently reducing energy consumption and pollutant emissions during asphalt mix production and placement. WMA technologies can be classified into two groups. The first group reduces the asphalt binders' viscosity through the addition of organic or chemical additives, while the second group reduces the viscosity of the asphalt binders through the addition of water. The latter has received increased attention in Ohio since it does not require the use of costly additives. In spite of the above-mentioned advantages for WMA mixtures, many concerns have been raised regarding the susceptibility of this material to moisture-induced damage and permanent deformation due to the reduced temperature level used during WMA production. Therefore, this study was conducted to develop a laboratory procedure to produce WMA mixtures prepared using foamed asphalt binders (WMA-FA), and to evaluate their performance in comparison to conventional Hot Mix Asphalt (HMA). This study involved two types of aggregates (natural gravel and crushed limestone) and two types of asphalt binders (PG 64-22 and PG 70-22M). A laboratory scale asphalt binder foaming device called WLB10, produced by Wirtgen, Inc., was used to foam the asphalt binders. The aggregate gradation met the Ohio Department of Transportation (ODOT) Construction and Materials Specification (C&MS) requirements for Item 441 Type 1 Surface Course for Medium Traffic. The resistance of WMA-FA and HMA mixtures to moisture-induced damage was measured using AASHTO T-283, and the resistance to permanent deformation was measured using the Asphalt Pavement Analyzer (APA) and the Simple Performance Test (SPT). Based on the experimental test results and the subsequent analyses findings, the following conclusions were made: [1] WMA-FA mixtures are more workable and easily compacted than HMA mixtures even though they are produced at lower mixing and compaction temperatures; [2] WMA-FA mixtures are slightly more susceptible to moisture damage than HMA mixtures. However, the difference is statistically insignificant. Therefore, if designed properly, both mixtures are expected to meet ODOT's minimum TSR requirement for the proposed traffic level; [3] WMA-FA mixtures, especially those prepared using gravel aggregates and unmodified asphalt binders are more prone to rutting than the corresponding HMA mixtures. Therefore, it is recommended to include the APA test as part of the WMA mix design procedure to ensure satisfactory performance for rutting.
Book Synopsis An Evaluation of the Tensile Strength of Asphalt Binder and Mortar with Recycled Asphalt Additives at Low Temperatures by : Rogelio Gabriel Rodriguez
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.
Book Synopsis Quantifying the Impacts of Warm Mix Asphalt on Constructability and Performance by :
Download or read book Quantifying the Impacts of Warm Mix Asphalt on Constructability and Performance written by and published by . This book was released on 2012 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: Joint efforts by the federal government and HMA industry to minimize cost and the environmental impacts of asphalt pavement construction have resulted in development of warm mix asphalt (WMA). This technology has gained such interest due to the potential to deliver pavements at lower temperatures, allowing for reduced energy consumption and emissions. In order to be effective WMA must meet the specified values of in-place density at reduced temperatures during construction and demonstrate sufficient resistance to pavement distresses while in-service. The overall objective of this research was to promote effective use of WMA through development of a procedure to recommend additive specific mixing and compaction temperature ranges that will provide adequate workability during construction, and an acceptable level of in-service performance. To pursue this objective an experiment was designed to evaluate the effects of various WMA technologies on the workability and performance properties of asphalt binders and mixtures using existing standards and new test methods developed during the study. The new test methods were pursued to better define the role of asphalt binder as a lubricant during compaction and to properly account for the effects of reduced production temperatures on asphalt binder performance and potential for moisture damage. Results found that use of WMA impacts both construction and performance properties. To account for these factors an evaluation framework to select appropriate production temperatures for WMA was introduced that is based on evaluation of mixture volumetrics, compactability, resistance to moisture damage, and rutting performance. Furthermore, to facilitate the mixture design and temperature selection process surrogate test methods to evaluate workability and performance properties of the asphalt binder as well as the integrity of the bond at the asphalt/binder aggregate interface were proposed and verified through relationships with mixture performance.
