Gradation Modification Effects on Engineering Performance of Reclaimed Asphalt Pavement for Use as Roadway Base PDF Download

Author: Babacar Sedikh Diouf
Publisher:
ISBN:
Category : Pavements, Asphalt
Languages : en
Pages : 504

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Author: American Association of State Highway and Transportation Officials
Publisher: AASHTO
ISBN: 1560510552
Category : Pavements
Languages : en
Pages : 622

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Book Description
Design related project level pavement management - Economic evaluation of alternative pavement design strategies - Reliability / - Pavement design procedures for new construction or reconstruction : Design requirements - Highway pavement structural design - Low-volume road design / - Pavement design procedures for rehabilitation of existing pavements : Rehabilitation concepts - Guides for field data collection - Rehabilitation methods other than overlay - Rehabilitation methods with overlays / - Mechanistic-empirical design procedures.

Author:
Publisher:
ISBN:
Category : Pavements, Asphalt
Languages : en
Pages : 561

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The objective of this study was to improve Reclaimed Asphalt Pavement (RAP) strength in base course applications while reducing creep to an acceptable level using compaction techniques, fractionating, blending with high quality base course aggregate, and/or by chemical stabilization with asphalt emulsion, Portland cement, or lime. RAP/limerock blends with and without chemical stabilization were compacted by modified Proctor, Marshall, or gyratory methods, cured, and tested for strength and creep. Strength tests included limerock bearing ratio (LBR), unconfined compression, Marshall compression, and indirect tensile tests. Strength specimens were tested dry and soaked to evaluate retained strength. Seven-day one-dimensional creep testing was performed. Gyratory compaction produced higher densities than modified Proctor or Marshall compaction. At the same density, gyratory compaction improved RAP strength by a factor of two to three over modified Proctor but had less effect on creep. Modified Proctor moisture-density plots followed an S-shape without a clear optimum; modified Proctor may not be the best method to predict RAP compaction behavior. Fractionating RAP did not improve strength or creep unless RAP was remixed to match a maximum density curve. Fractionating did not produce acceptable LBRs or creep. RAP blended with limerock, cemented coquina, or reclaimed concrete aggregates showed improved LBR and creep performance. RAP/aggregate blends have the potential to be used as Florida base course. As the amount of aggregate blended with RAP increased, LBR increased and creep decreased. Creep behavior of blends with 75 percent aggregate was similar to 100 percent aggregate. Unstabilized blends with 50 percent aggregate did not produce LBR values over 100. Blends of 50 percent RAP/50 percent limerock stabilized with 1 percent of either asphalt emulsion or cement attained soaked LBRs over 100 and acceptable creep. Blends of RAP with 75 percent limerock attained soaked LBRs close to 100 and low creep without any chemical stabilizer. Adding RAP to limerock blends generally increased the soaked retained strength and improved permeability compared to 100 percent limerock.

Author: Ken Skorseth
Publisher:
ISBN:
Category : Gravel roads
Languages : en
Pages : 112

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The purpose of this manual is to provide clear and helpful information for maintaining gravel roads. Very little technical help is available to small agencies that are responsible for managing these roads. Gravel road maintenance has traditionally been "more of an art than a science" and very few formal standards exist. This manual contains guidelines to help answer the questions that arise concerning gravel road maintenance such as: What is enough surface crown? What is too much? What causes corrugation? The information is as nontechnical as possible without sacrificing clear guidelines and instructions on how to do the job right.

Author: Bora Cetin
Publisher:
ISBN:
Category : Aggregates (Building materials)
Languages : en
Pages : 154

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Book Description
The use of recycled materials promotes sustainability in roadway construction by reducing the consumption of energy and emission of greenhouse gases associated with mining and the production of virgin aggregate (VA). Recycled asphalt pavement (RAP) and recycled concrete aggregate (RCA) have comparable characteristics to VA that have been used in roadway base course applications. This study develops a database for RAP and RCA material characteristics, including gradation, compaction, resilient modulus (Mr), California bearing ratio (CBR), and saturated hydraulic conductivity (Ksat). In addition, this study summarizes construction specifications provided by several departments of transportation (DOTs) regarding the use of recycled aggregates in pavement systems. The effects of the presence of RAP and RCA in aggregate matrices on the engineering and index properties of aggregates are investigated and some trends are observed. For example, the study finds a higher RAP content reveals a higher summary Mr (SMr), and a higher RCA content causes an increase in optimum moisture content (OMC) and a decrease in maximum dry unit weight (MDU). In addition, a series of AASHTOWare Pavement Mechanistic-Empirical (ME) Design (PMED) analyses are conducted for three traffic volumes [low (1,000 AADTT), medium (7,500 AADTT), and high (25,000 AADTT)] with the material inputs collected for the database to determine whether different values of different characteristics of RCA and RAP can be used in flexible/rigid pavement designs. Results show that Mr has a higher effect on pavement distress predictions compared to gradation and saturated hydraulic conductivity (Ksat).

Author: Asphalt Institute
Publisher:
ISBN: 9781934154175
Category : Asphalt
Languages : en
Pages : 102

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 192

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Author: Imtiaz Ahmed
Publisher:
ISBN:
Category : Waste products as road materials
Languages : en
Pages : 26

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Author: Albert Marshall Bleakley
Publisher:
ISBN:
Category :
Languages : en
Pages : 668

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Book Description
Reclaimed Asphalt Pavement (RAP) is produced by milling during resurfacing operations. Finding innovative ways to incorporate RAP into highway base course applications will provide both environmental and economic benefits by allowing in situ recycling of material for projects such as widening or shoulder addition. RAP is a well-drained granular material which is already on site, however 100% RAP is low bearing strength and creeps under load. The objective of this research was to develop methods to improve RAP's strength while reducing creep to an acceptable level through blending with high quality crushed limestone aggregate and/or by chemical stabilization with asphalt emulsion, Portland cement, or lime. RAP/aggregate blends with and without chemical stabilization were compacted by modified Proctor, Marshall, or gyratory methods, cured, and tested for strength and creep. Strength tests included limerock bearing ratio (LBR), a variant of the CBR test, unconfined compression, Marshall compression, and indirect tensile tests. Strength specimens were tested dry and soaked to evaluate retained strength. One dimensional creep testing was performed using seven day oedometer tests. RAP/aggregate blends have the potential to be used successfully as a base course material. Blends of RAP with 50% limerock base material attained a soaked LBR strength of 100 and acceptable levels of creep with the addition of 1% of either asphalt emulsion or cement. Blends of RAP with 75% or more limerock attained a soaked LBR close to 100 and low levels of creep without any chemical stabilizer. In general adding RAP to limerock blends increased the soaked retained strength and improved permeability compared to 100% limerock. Gyratory compaction achieved higher densities than modified Proctor or Marshall compaction and improved RAP's strength by a factor of two to three compared to modified Proctor compaction at the same density but had less effect on creep. Field testing is required to determine whether it is feasible to reproduce the gyratory compaction results on an actual construction site. Significant variability was noted between results with different blends, compaction methods, and stabilizing agents. Site specific performance testing should be conducted to establish the viability of blending RAP into a base or subbase.

Author: National Research Council (U.S.). Transportation Research Board
Publisher: Transportation Research Board National Research
ISBN:
Category : Nature
Languages : en
Pages : 64

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"This synthesis will be of special interest and usefulness to design engineers, materials technologists, and others seeking information on the potential use of recycled materials in design, construction, rehabilitation, and maintenance of pavements, bases, and other components of the highway system. Detailed information is presented on procedures for pavement recycling."--Avant-propos.