Comprehensive Performance Evaluation of In-place Recycled Hot Mix Asphalt as Unbound Granular Material PDF Download
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Author:
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ISBN:
Category :
Languages : en
Pages :
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Book Description
A promising pavement rehabilitation strategy that is of interest to state highway agencies and local governments involves the in-place pulverization of failed hot mix asphalt (HMA) pavements and re-use of the pulverized material as a granular base material. Advantages of this technique include a reduction in the use of virgin aggregate, a reduction in the amount of construction traffic, and removal of the potential for reflective cracking from the existing cracked pavement layers through the new HMA surface. However, the performance of this technique has not been comprehensively evaluated, and, in particular, permanent deformation characteristics. In this thesis, four pilot projects in northeastern California were used to evaluate the pulverized material and this rehabilitation strategy. The characteristics and performance of the pulverized material were evaluated by comprehensive laboratory and field testing, and analyses. Based on the multistage repeated load triaxial test results, the shakedown limits of the pulverized material were estimated and compared with the stress states calculated from the cross-anisotropic finite element analyses based on real traffic and climate data. A recursive-incremental damage model was used to predict permanent deformation of the pulverized base layer over the long term and to compare it with that of typical aggregate base material. Based on the comprehensive laboratory testing, field testing, and analyses, the pulverized material was found to be generally stiffer than typical aggregate base material, possibly due to better aggregate shape than that found in typical aggregate base material. The pulverized mateiral has less permanent deformation resistance at low stress levels but greater resistance at higher stress levels than typical granular material used in California. Possible reasons for the lower permanent deformation resistance at low stress levels might be the laboratory compaction method and that the recycled HMA in the pulverized material undergoes additional breakdown under initial loading since coarse fractions of the pulverized materials are greater than that of the comparison virgin aggregate base. Overall, the performance benefits of this rehabilitation strategy make it a viable option for flexible pavement rehabilitation.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
A promising pavement rehabilitation strategy that is of interest to state highway agencies and local governments involves the in-place pulverization of failed hot mix asphalt (HMA) pavements and re-use of the pulverized material as a granular base material. Advantages of this technique include a reduction in the use of virgin aggregate, a reduction in the amount of construction traffic, and removal of the potential for reflective cracking from the existing cracked pavement layers through the new HMA surface. However, the performance of this technique has not been comprehensively evaluated, and, in particular, permanent deformation characteristics. In this thesis, four pilot projects in northeastern California were used to evaluate the pulverized material and this rehabilitation strategy. The characteristics and performance of the pulverized material were evaluated by comprehensive laboratory and field testing, and analyses. Based on the multistage repeated load triaxial test results, the shakedown limits of the pulverized material were estimated and compared with the stress states calculated from the cross-anisotropic finite element analyses based on real traffic and climate data. A recursive-incremental damage model was used to predict permanent deformation of the pulverized base layer over the long term and to compare it with that of typical aggregate base material. Based on the comprehensive laboratory testing, field testing, and analyses, the pulverized material was found to be generally stiffer than typical aggregate base material, possibly due to better aggregate shape than that found in typical aggregate base material. The pulverized mateiral has less permanent deformation resistance at low stress levels but greater resistance at higher stress levels than typical granular material used in California. Possible reasons for the lower permanent deformation resistance at low stress levels might be the laboratory compaction method and that the recycled HMA in the pulverized material undergoes additional breakdown under initial loading since coarse fractions of the pulverized materials are greater than that of the comparison virgin aggregate base. Overall, the performance benefits of this rehabilitation strategy make it a viable option for flexible pavement rehabilitation.
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: Bin Yu
Publisher:
ISBN:
Category : Asphalt mortar
Languages : en
Pages : 11
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Book Description
Despite increasing application, limited knowledge is known of in situ and laboratory properties of asphalt mixes placed through hot in-place recycling (HIR). This study conducted a preliminary investigation to inspect the individual and joint effects of binder (aged or rejuvenated) and gradation (decayed or normal) on respective performance indicators. Three mixes were designed and the properties were determined, including mix A collected from aged asphalt pavement, mix B designed with the same gradation of mix A but using virgin materials, and mix C designed with the initial construction aggregate gradation of the aged pavement section using virgin materials. The experimental program was carried out at the binder/aggregate, mortar and mix levels. The binder property, aggregate quality, and gradation of mix A were changed compared to the initial design, and the proper dosage of rejuvenator is able to restore the binder properties largely except for ductility. Asphalt mortars of mixes A and B were prepared and submitted for repeated shear at constant height (RSCH) and frequency sweep at constant height (FSCH) tests and found that the former has a better rutting resistance in terms of the Gv (viscous component of creep stiffness) and complex shear modulus G*, whereas poorer low-temperature and fatigue performances in terms of the glassy modulus G*g and NP20. At the mix level, master curves of the three mixes were developed by dynamic modulus tests and revealed disparate viscoelastic properties, of which mix C is mostly desired. Binder aging and gradation decay work contradictorily, determining flow number test results so that mixes A and C have close and higher flow number values than mix B. Fatigue and low-temperature fracture properties were evaluated by semi-circular bending tests and indicated the poorest performance for mix A because of binder aging and gradation decay.
Author: Asphalt Institute
Publisher:
ISBN: 9781934154175
Category : Asphalt
Languages : en
Pages : 102
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Book Description
Author: Randy Clark West
Publisher: Transportation Research Board
ISBN: 0309259134
Category : Pavements, Asphalt
Languages : en
Pages : 162
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Book Description
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.
Author: Athar Saeed
Publisher: Transportation Research Board National Research
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 66
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Book Description
Explores performance-related procedures to test and select recycled hot-mix asphalt and portland cement concrete materials for use in unbound layers of highway pavements. Appendixes A through C of NCHRP Report 598, which cover the literature review and background information, new aggregate tests, and surface dielectric measurements, were published as NCHRP Web-Only Document 119.
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: P. E. Larsen
Publisher:
ISBN:
Category : Asphalt-rubber
Languages : en
Pages : 40
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Book Description
Author: Brian Hill
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
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.
Author: Joe W. Button
Publisher:
ISBN:
Category : Pavements, Asphalt concrete
Languages : en
Pages : 80
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Book Description
This synthesis will be of interest to administrators, pavement designers, highway, material, research, and specification engineers, and others interested in economical methods for reconstructing or rehabilitating asphalt concrete pavements. It describes the processes and equipment used for hot in-place recycling of asphalt concrete and provides information on mix designs, performance, and guidelines for its effective use. A significant amount of the information provided is based on the current practices of state highway agencies. As such, numerous case histories are included in the report.
