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Author: Justin D. Warner
Publisher:
ISBN:
Category : Asphalt
Languages : en
Pages : 16
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Book Description
A large-scale recycling and reuse application of scrap shingles would utilize an otherwise wasted resource while clearing landfill space and creating new business opportunities. One potential reuse application is the use of reclaimed asphalt shingles (RAS) as an additive or substitute for the earth materials typically used in the aggregate base (AB) and subbase (ASB) layers of roadway pavements. The purpose of this study was to determine the technical specifications of RAS, the effect of fly ash stabilization on RAS strength, and the practicality of the widespread implementation of RAS in the AB and ASB layers of roadway pavements. RAS, fly ash stabilized RAS (S-RAS), RAS-aggregate mixtures, and RAS-silt mixtures were evaluated for particle size characteristics, compaction characteristics, CA Bearing Ratio (CBR), unconfined compressive strength, and resilient modulus. According to the results of the testing protocol, unstabilized RAS is unsuitable as base material although RAS could potentially be used as subbase or general fill material. RAS-aggregate mixtures are suitable for use as subbase and are potentially suitable as base course in an unstabilized state; however, RAS-aggregate mixtures exhibited decreasing resilient modulus with increasing RAS content. Fly ash stabilized RAS (S-RAS) was less susceptible to penetrative deformation than unstabilized RAS, however, S-RAS was still highly susceptible to penetrative deformation when unpaved. Fly ash stabilization of RAS generally provided less improvement in resilient modulus compared to fly ash stabilized low-plasticity clays. This may be due to the high asphalt content of RAS particles and resulting diminishment in pozzolanic activity and/or the diminished particle interconnectedness for cementation. Other forms of stabilization, such as cold asphalt emulsion, may be more effective in strengthening RAS. Further evaluation of alternative stabilization methods and additional studies to evaluate the practicality of RAS in other geotechnical applications such as embankment fill, filter, and/or drainage material are recommended.
Author: Justin D. Warner
Publisher:
ISBN:
Category : Asphalt
Languages : en
Pages : 16
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Book Description
A large-scale recycling and reuse application of scrap shingles would utilize an otherwise wasted resource while clearing landfill space and creating new business opportunities. One potential reuse application is the use of reclaimed asphalt shingles (RAS) as an additive or substitute for the earth materials typically used in the aggregate base (AB) and subbase (ASB) layers of roadway pavements. The purpose of this study was to determine the technical specifications of RAS, the effect of fly ash stabilization on RAS strength, and the practicality of the widespread implementation of RAS in the AB and ASB layers of roadway pavements. RAS, fly ash stabilized RAS (S-RAS), RAS-aggregate mixtures, and RAS-silt mixtures were evaluated for particle size characteristics, compaction characteristics, CA Bearing Ratio (CBR), unconfined compressive strength, and resilient modulus. According to the results of the testing protocol, unstabilized RAS is unsuitable as base material although RAS could potentially be used as subbase or general fill material. RAS-aggregate mixtures are suitable for use as subbase and are potentially suitable as base course in an unstabilized state; however, RAS-aggregate mixtures exhibited decreasing resilient modulus with increasing RAS content. Fly ash stabilized RAS (S-RAS) was less susceptible to penetrative deformation than unstabilized RAS, however, S-RAS was still highly susceptible to penetrative deformation when unpaved. Fly ash stabilization of RAS generally provided less improvement in resilient modulus compared to fly ash stabilized low-plasticity clays. This may be due to the high asphalt content of RAS particles and resulting diminishment in pozzolanic activity and/or the diminished particle interconnectedness for cementation. Other forms of stabilization, such as cold asphalt emulsion, may be more effective in strengthening RAS. Further evaluation of alternative stabilization methods and additional studies to evaluate the practicality of RAS in other geotechnical applications such as embankment fill, filter, and/or drainage material are recommended.
Author: Justin D. Warner
Publisher:
ISBN:
Category :
Languages : en
Pages : 296
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Book Description
Author: Shirley Jacqueline Ddamba
Publisher:
ISBN:
Category :
Languages : en
Pages : 204
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Book Description
Due to the 15-20 year life span of roofing shingles, 1.5 million tonnes of asphalt roofing shingles are being demolished and replaced annually in Canada from both residential and commercial facilities. These roofing shingles are manufactured from very high quality materials which are considered a valuable by-product. Recycled Asphalt Shingles (RAS), a product containing approximately 30% asphalt cement by mass, is a valuable additive to Hot Mix Asphalt (HMA) pavements and a potential savings for the construction industry. Recycling of demolished asphalt shingles is a significant new step forward in abating the need to put the waste into landfills. This re-use creates a great opportunity in reducing materials being dumped at landfills while providing an additive to HMA mixtures for paving. Therefore, this leads to economic, environmental, and social benefits for all the stakeholders and road users such as reduced need for landfill space, conservation of virgin materials and environment, and financial saving.
Author: Riyad-UL. Islam
Publisher:
ISBN:
Category :
Languages : en
Pages : 103
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Book Description
Today, a large quantity of waste is generated from the replacement of residential and commercial roofs. Many of the roofs being upgraded with previously constructed from asphalt shingles. Recycled Asphalt Shingles (RAS) contain nearly 30% of asphalt cement by mass, which can be a useful additive to asphalt pavements. In addition, shingles can offer significant potential savings through recycling and recovery as a construction material in flexible pavement. Currently, one and a half million tons of roofing shingle waste is generated each year in Canada related to the replacement of residential and commercial roofs and 90% of this valuable material is sent to landfills. If engineered properly, the addition of RAS into Hot Mix Asphalt (HMA) can provide significant benefits. The University of Waterloo's Centre for Pavement and Transportation Technology (CPATT) is committed to working with public and private sector partners to develop sustainable technologies for the pavement industry. Using RAS in HMA can lead to economical, environmental and social benefits. Examples of which are reduced waste going to landfills and a reduction in the quantity of virgin material required. This research has involved the Ontario Centres of Excellence (OCE) and Miller Paving Limited. It was conducted to evaluate the performance of HMA containing RAS in both field and laboratory tests.
Author: Hemanta Hazarika
Publisher: Springer Nature
ISBN: 9819992273
Category :
Languages : en
Pages : 530
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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In this research, geotechnical properties of recycled asphalt shingles (RAS) were evaluated at constant and varying temperatures for use in high volume structural fill applications. Since compressibility of RAS is significantly higher than that of natural soils, addition of less compressible granular materials such as bottom ash (BA) or foundry slag (FS) to RAS, or stabilization of RAS using self cementing fly ash (FA) were considered to reduce the compressibility. To evaluate the effect of seasonal temperature on engineering properties of RAS mixtures, a thermo-mechanical system and the related testing procedures were developed. Systematic tests including hydraulic conductivity, one-dimensional compression, triaxial compression and deviatoric creep tests were conducted at constant and varying temperatures. Results show that at room temperature, RAS mixtures have sufficient shear strength and drainage capacity for use in structural fills. Up to 50% RAS in granular materials and between 10 and 20% FA in the stabilized RAS reduced the compressibility to meet the settlement criteria for roadway design. The secondary compression index increased as a power function with stress level. As the temperature increases the shear strength decreased due to reduction in viscosity of the asphalt binder in RAS particles. However the shear strength of the mixture with RAS content up to 50% remained higher than 30 degrees. The hydraulic conductivity increased with increasing temperature due to reduction of viscosity of permeating water. The compressibility of the compacted RAS mixtures exponentially increased with temperature. If the embankment containing RAS mixture is constructed during warm season of the year, the majority of the compression occurs during construction and the RAS embankment settlement during the rest of the year will be negligible. RAS mixtures were also susceptible to creep rupture under the applied deviatoric stress. When designing side slopes of the embankments containing RAS, the applied stress should be reduced to 80% of the maximum deviatoric stress to ensure no creep rupture will occur. Design graphs and analytical models were developed to predict shear strength and compressibility of RAS mixtures at constant and varying temperatures under temperature and stress levels typical to highway embankments.
Author: M. Z. Alavi
Publisher:
ISBN:
Category : Asphalt
Languages : en
Pages : 45
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Author: Faisal Ahmed Samoo
Publisher:
ISBN:
Category :
Languages : en
Pages : 181
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Book Description
This thesis documents the evaluation of the initial performance of pavement containing recycled asphalt shingles (RAS) in Oregon. The research was funded by the Oregon Department of Transportation (ODOT) and the Federal Highway Administration and was conducted at Oregon State University. The key objectives of this thesis are to document the state-of-the-practice for implementation of recycled asphalt shingles in hot mix asphalt (HMA) mixtures, and to evaluate the initial field and laboratory performance of mixtures containing RAS. Recent oil price increases, coupled with environmental impacts has encouraged industry to use materials containing asphalt binder, such as asphalt shingles as a partial replacement of virgin materials in the construction of bituminous pavement. Residential home reroofing projects generate RAS as does the asphalt shingle manufacturing industry as a waste product at a rate of approximately 11 million tons per year nationwide. Disposal of these materials ordinarily involves discarding the materials in landfills. However, since these shingles contain asphalt binder, many states and asphalt pavement contractors have made efforts to incorporate these materials into asphalt pavements. Asphalt shingles are produced with asphalt binders that have substantially higher stiffness than paving grade asphalt binders. With increased stiffness comes increased brittleness. Consequently, incorporating RAS into hot mix asphalt may expose the pavement to an increased likelihood of low temperature cracking and fatigue cracking unless modifications are made to the mixtures to compensate for increased stiffness due to the RAS binder. House Bill 2733, proposed before the Oregon Legislative Assembly in 2009, would have required ODOT to use up to 5% RAS in HMA. However, inclusion of RAS in HMA raised concerns within the agency with regard to the potential for reduction in pavement performance ultimately leading to increased costs due to early failures. Consequently, considering these concerns the legislation on this bill was postponed pending completion of research to investigate the performance of pavement containing RAS in Oregon pavements. As a result, ODOT sponsored preliminary research on use of RAS in HMA in 2009 and subsequently through the research project described herein. The research work described herein was separated into three distinct but interconnected tasks. The first involved conducting a detailed literature review to gain an understanding of the state-of-the-practice for successful implementation of RAS in pavements. Emphasis during this effort was placed on selection of the virgin binder grade to offset the effects of increased stiffness due to incorporation of RAS binder, batching and mixing procedures for inclusion of RAS in HMA mixtures, ignition oven calibration factors for mixtures containing RAS, and quality control/quality assurance procedures for pavements built with RAS mixtures. There exists a substantial body of literature covering use of recycled asphalt pavement (RAP) as a partial replacement of virgin materials in HMA pavements. Due to many similarities of RAP and RAS, many of the documents reviewed covered only RAP, but with the aim of extending the technologies used for RAP mixtures to those containing RAS or RAS and RAP. The second task involved conducting laboratory investigations to verify the practicality and effectiveness of procedures found in the literature for batching and mixing materials containing RAS and/or RAP and RAS. Finally, the third task involved investigations of performance of two pavements containing RAP and RAS constructed as pilot projects. The investigations involved an assessment of field performance and laboratory tests on samples obtained from the two pavements. For comparison purposes, the same investigations were performed on pavements and samples from pavements that contained RAP but no RAS. These were constructed adjacent to, and at the same time as, the pavements with RAP and RAS. Based on the findings from the literature review, this thesis contains recommendations for: 1) selection of a virgin binder grade when RAP and/or RAS is used in an HMA mixture; 2) a procedure for effectively and efficiently extracting and recovering asphalt binder from RAS; 3) batching and mixing procedures for manufacturing laboratory test specimens containing RAS; 4) a method for determining ignition over calibration factors for mixtures containing RAS; and 5) quality control/quality assurance procedures for pavements built with RAS mixtures. The recommended batching and mixing procedure was verified through laboratory investigations while ongoing research is in the process of verifying the remaining procedures. Laboratory investigations involving dynamic modulus testing and comparative analyses of RAP-only mixtures (control mixtures) versus RAP and RAS mixtures indicated a trend of reduced dynamic modulus due to the addition of RAS in the mixture on both pilot projects. However, when the mixtures were compared at a 95 percent confidence level, a significant difference was found for only one of the two projects. This reduction in dynamic modulus was likely due to the softening of blended binder and the increased air voids in the mixtures containing RAS. In addition, fatigue testing and comparative analyses using phenomenological and dissipated energy approaches indicated that there was no significant difference in fatigue resistance of the RAP-only mixture versus the RAP and RAS mixture at a 95 percent confidence level. Assessment of field performance through visual inspections of the pavements built with mixtures containing RAS revealed no low temperature cracking following the first winter season in service. Nor did the inspections reveal any fatigue cracking. Although these inspections occurred within 8 months of construction of the pavements, the findings provide encouraging early-life performance of the mixtures.
Author: Reza Saeedzadeh
Publisher:
ISBN:
Category : Life cycle costing
Languages : en
Pages : 197
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Book Description
The pavement practitioners use more recycled materials in asphalt mixtures in order to compensate for the high price of petroleum products and save the limited resources of virgin materials. Reclaimed Asphalt Pavement (RAP) and Recycled Asphalt Shingles (RAS) have been in wide use in asphalt mixtures for several decades. Public perception on the utilization of recycled materials is that the mixtures become more cost effective and more environmental friendly. This is true when the initial stage of construction of pavements is assessed. However, a mixture that costs less and/or burdens the environment less at the beginning may require more frequent rehabilitation because of poor performance. Therefore, in order to have a comprehensive idea of the sustainability of a mixture, its entire life cycle should be evaluated. The objective of this research was to assess the sustainability of three recycled asphalt mixtures and of a mix not containing recycled materials. The recycled mixtures were labeled as "High RAP", "RAP&RAS-WMA" and "BMD". The "High RAP" mixture had 19 percent fractionated RAP. The "RAP&RAS-WMA" had 15 percent RAP and 3 percent RAS while the production technology was WMA. The "BMD" mixture had 15 percent RAP, 3 percent RAS and slightly higher binder content. The virgin mixture was "Type D" which is a common dense-graded mixture in Texas. Twelve pavement sections were constructed from these four mixtures to evaluate their resistance to rutting, fatigue cracking and reflection cracking. The Accelerated Pavement Testing machine of the University of Texas at Arlington was employed to perform the full-scale testing. The results of field sections were then utilized to determine the service life of the mixtures for initial construction and subsequent required overlays. The life cycle environmental burden and cost of each mixture were also calculated. Field results suggested that rutting is not a concern for these mixtures. The virgin control mixture had the second best performance in resistance to both fatigue cracking and reflection cracking. The life cycle environmental assessment of mixtures showed that the "BMD" mixture had the least environmental impacts and was followed by the "Type D", the "RAP&RAS-WMA" and the "High RAP" mixtures. The same ranking of mixtures was observed in life cycle cost analysis. Among different construction phases, the "Materials Production" phase had the highest energy consumption and carbon dioxide emission, mainly due to the bitumen production process.
Author: Matthew A. MacEachern
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
The province of Prince Edward Island (PEI) among other provinces is trying not only to save money, but also help the environment by recycling materials for construction applications that would otherwise end up in a landfill. Reclaimed asphalt shingles (RAS) were investigated to see if the material would be a suitable partial replacement for the base course in roadway construction and backfilling materials. Mixtures of RAS and the natural aggregate (currently used for this type of construction by PEI) were tested for characteristics (e.g. density, strength, permeability, etc.) to validate the potential to replace up to 30% of natural aggregates with RAS.The laboratory test results such as standard Proctor and California Bearing Ratio (CBR) demonstrated that the addition of RAS to the natural aggregates can significantly decrease its performance. This indicates that only a small amount (
