Quantifying Workability, Compactability, and Cohesion Gain of Asphalt Emulsion Cold In-place Recycling PDF Download
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Author: Sadie Casillas Publisher: ISBN: Category : Languages : en Pages : 388
Book Description
To maximize the life and quality of a pavement, proper maintenance and rehabilitation are essential. Strategies for pavement rehabilitation with many sustainable benefits are pavement recycling. This dissertation focuses on two types of in-situ pavement recycling: Cold in-place recycling (CIR) stabilized with asphalt emulsion and full depth reclamation (FDR) stabilized with asphalt emulsion or foamed asphalt. One white paper (Chapter 2), two accepted peer reviewed journal articles (Chapters 3 and 4), and one submitted peer reviewed journal article (Chapter 5) are presented in this document to create better understanding of the unique material characterization of asphalt emulsion cold recycled materials, along with factors which influence characterization, pertaining to the measurement of workability, compactability, and cohesion gain. In Chapter 2, a detailed review of the progression of mix design procedures for unbound granular materials (UGM), fully bound hot mix asphalt (HMA), and semi-bound asphalt emulsion CIR is presented to establish the current state of mix design for each material type and identify ways the design of asphalt emulsion CIR could become more engineered rather than empirical. Recommendations included development of additional guidance on use of active and inert fillers, a methodology to account for workability and compactability during mix design, curing procedures which more closely mimic conditions in the field to improve cohesion gain, and a procedure for determination of optimum water content. In Chapter 3, a study was conducted to evaluate different laboratory compaction methods for compaction of asphalt emulsion and foamed asphalt FDR. Both the Proctor hammer, typically used for UGM, and the Superpave Gyratory Compactor (SGC), typically used for HMA, were compared by evaluating densities, tensile strengths, and compaction metrics of FDR samples produced using each method. The modified Proctor hammer produced samples with the highest dry unit weights; however, samples produced using the SGC had higher tensile strengths, indicating compaction method affects material properties. Chapter 4 evaluates different test methods and equipment commonly available in asphalt laboratories for ability to quantify workability, compactability, and cohesion gain of asphalt emulsion CIR by measuring differences in performance due to changes in laboratory curing conditions. Cure temperature was found to have a more significant influence on test results than cure time. SGC metrics were recommended for quantifying workability and compactability. The direct shear test showed promise for quantifying cohesion gain. Finally, Chapter 5 measured effects of various sample fabrication factors on measurement of workability, compactability, and cohesion gain in order to address open questions associated with asphalt emulsion CIR laboratory procedures. Curing temperature most significantly influenced workability and compactability; while cohesion gain was more significantly influenced by mixing temperature and specimen test temperature. The direct shear test again showed promise for measuring cohesion gain of asphalt emulsion CIR. Therefore, a draft specification for this test method was prepared and is included as an appendix of this dissertation. A singular test method for quantifying workability and compactability for asphalt emulsion CIR has not yet been identified due to multiple mechanisms at play during mixing and compaction stages for this material.
Author: Sadie Casillas Publisher: ISBN: Category : Languages : en Pages : 388
Book Description
To maximize the life and quality of a pavement, proper maintenance and rehabilitation are essential. Strategies for pavement rehabilitation with many sustainable benefits are pavement recycling. This dissertation focuses on two types of in-situ pavement recycling: Cold in-place recycling (CIR) stabilized with asphalt emulsion and full depth reclamation (FDR) stabilized with asphalt emulsion or foamed asphalt. One white paper (Chapter 2), two accepted peer reviewed journal articles (Chapters 3 and 4), and one submitted peer reviewed journal article (Chapter 5) are presented in this document to create better understanding of the unique material characterization of asphalt emulsion cold recycled materials, along with factors which influence characterization, pertaining to the measurement of workability, compactability, and cohesion gain. In Chapter 2, a detailed review of the progression of mix design procedures for unbound granular materials (UGM), fully bound hot mix asphalt (HMA), and semi-bound asphalt emulsion CIR is presented to establish the current state of mix design for each material type and identify ways the design of asphalt emulsion CIR could become more engineered rather than empirical. Recommendations included development of additional guidance on use of active and inert fillers, a methodology to account for workability and compactability during mix design, curing procedures which more closely mimic conditions in the field to improve cohesion gain, and a procedure for determination of optimum water content. In Chapter 3, a study was conducted to evaluate different laboratory compaction methods for compaction of asphalt emulsion and foamed asphalt FDR. Both the Proctor hammer, typically used for UGM, and the Superpave Gyratory Compactor (SGC), typically used for HMA, were compared by evaluating densities, tensile strengths, and compaction metrics of FDR samples produced using each method. The modified Proctor hammer produced samples with the highest dry unit weights; however, samples produced using the SGC had higher tensile strengths, indicating compaction method affects material properties. Chapter 4 evaluates different test methods and equipment commonly available in asphalt laboratories for ability to quantify workability, compactability, and cohesion gain of asphalt emulsion CIR by measuring differences in performance due to changes in laboratory curing conditions. Cure temperature was found to have a more significant influence on test results than cure time. SGC metrics were recommended for quantifying workability and compactability. The direct shear test showed promise for quantifying cohesion gain. Finally, Chapter 5 measured effects of various sample fabrication factors on measurement of workability, compactability, and cohesion gain in order to address open questions associated with asphalt emulsion CIR laboratory procedures. Curing temperature most significantly influenced workability and compactability; while cohesion gain was more significantly influenced by mixing temperature and specimen test temperature. The direct shear test again showed promise for measuring cohesion gain of asphalt emulsion CIR. Therefore, a draft specification for this test method was prepared and is included as an appendix of this dissertation. A singular test method for quantifying workability and compactability for asphalt emulsion CIR has not yet been identified due to multiple mechanisms at play during mixing and compaction stages for this material.
Author: Erica Ann Yeung Publisher: ISBN: Category : Asphalt emulsion mixtures Languages : en Pages : 122
Book Description
Cold in-place recycling (CIR) is a process that takes three to four inches of existing pavement surface and reuses 100% of it by milling and crushing it, adding asphalt emulsions and/or additives to it, before placing and re-compacting it. There is currently very little research regarding the interaction between the crushed aggregate and asphalt emulsion during the CIR process. In this study, the interactions between the combinations of crushed aggregates and asphalt emulsions were investigated along with select compaction metrics and a raveling performance test. The three types of aggregates included coated limestone, recycled asphalt pavement (RAP), and coated syenite. The two types of emulsifiers included a commodity and a proprietary one. The compaction metrics explored the compaction behavior of CIR and the raveling test is a standard test that evaluates a mixture's resistance to raveling under initial traffic. The results of this project indicated crushing aggregate and waiting between one hour to one day before mixing can be more optimal for easier compactibility than crushing and mixing immediately or waiting one week later. Not only were the results seen in the compaction metrics, but in the raveling test as well.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Cold in-place asphalt recycling has been shown to be a technically sound, cost-effective, environmentally friendly method of strengthening and maintaining a wide range of deteriorating asphalt pavements. The overall process combines testing and mix design procedures, milling, processing and mixing units with microprocessor control of emulsion addition, compaction, placement of a wearing surface and quality assurance testing. It has been shown, in laboratory work and a number of Ontario projects the past four years, that modification of the cold in-place process to incorporate new aggregate results in an improved recycled binder course with closer voids and stability control, addressing observed conventional cold in-place asphalt recycling problems such as: high residual asphalt cement content (flushing); tine mix (high percent passing 4.75 mm and 75 pm); rutting (low initial stability with emulsion system); and adequacy of in-place material thickness. Structural equivalency factors for cold in-place recycled asphalt compared to conventional binder course hot-mix asphalt have been developed. Resilient properties of laboratory and field samples have been determined with the Nottingham Asphalt Tester (NAT) and used in standard mechanistic design programs such as BISAR. Future applications of modified cold in-place asphalt recycling to improve flexible pavements will undoubtedly include airports, which will require consideration of special features such as operational constraints. For the covering abstract of this conference see IRRD number 872978.
Author: Robert Hill Publisher: ISBN: Category : Asphalt emulsion Languages : en Pages : 10
Book Description
Full depth reclamation (FDR) is a pavement structure rehabilitation technique that uses in-place material to build structural capacity of a roadway. By mixing together 8-12 in. of pavement structure with a binding agent, a higher structural capacity can be achieved. However, there is often a period of time prior to the binding agent fully curing where traffic is released to the FDR before a surface course is applied. In this research, five laboratory testing devices attempted to quantify how asphalt cement based FDR builds resistance to raveling during this traffic. Four in-house designed and built testing devices were compared to the existing cold in-place recycling raveling test. Factors explored during evaluation included curing time (0-48 h), binding agent (asphalt emulsion and asphalt foam), and curing condition (ambient temperature and 40°C). In general, all five testing devices showed a decrease in potential raveling with longer curing times using an asphalt emulsion binding agent at ambient curing temperatures. Asphalt emulsion FDR showed higher resistance to raveling than asphalt foam FDR at ambient curing temperatures, but curing at 40°C did not give conclusive evidence on resistance to raveling versus ambient curing temperatures. Finally, this testing was applied in the laboratory to give a general indication of the performance of each testing device; therefore, the testing devices need to be taken into the field to verify these initial laboratory findings and to begin building correlations between the lab test results and actual raveling susceptibility in the field.
Author: Sadie Casillas
Author: Sadie Casillas
Author: Erica Ann Yeung
Author: Hui Yao
Author: Todd V. Scholz
Author: Charles Warren Schwartz
Author: Mark Richard Lahr
Author: 
Author: Robert Hill
Author: National Research Council (U.S.). Transportation Research Board
Author: Asphalt Institute