The Experts below are selected from a list of 159598638 Experts worldwide ranked by ideXlab platform
Feipeng Xiao - One of the best experts on this subject based on the ideXlab platform.
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superpave evaluation of higher rap contents using wma technologies
Construction and Building Materials, 2016Co-Authors: Feipeng Xiao, Xiangdao Hou, Serji N Amirkhanian, Kwang W KimAbstract:Abstract In this study, the objective was to conduct an investigation of Superpave mix design characteristics of WMA technologies in terms of various high percentages of reclaimed asphalt pavements (RAPs). One PG 58-28 binder, two PG 64-22 binders, and two RAP sources were selected from South Carolina. In addition, three mix technologies (e.g. hot mix asphalt (HMA), foaming technology, and Evotherm additive) were employed to produce the mixtures. Meanwhile, four RAP contents of 20%, 30%, 40%, and 50% (by weight of total mixture) were utilized to blend with virgin materials. 36 Superpave mix designs were conducted to explore the volumetric characteristics of various mixtures. In this study, the results indicated that, all mixtures have an optimum asphalt content (OAC) less than 5.0%, and most of these values are close to a minimum OAC value of 4.5% set by South Carolina Department of Transportation (SCDOT). No noticeable increases at the mixing and compaction temperatures for these mixtures containing a higher percentage of RAP (i.e., over 40%) were found in this study. In addition, the voids in mineral aggregate (VMA), voids filled with asphalt (VFA), dust/asphalt ratios, and moisture susceptibility meet the requirements of SCDOT’s specifications. Therefore, these specific mix designs could be used as the guidelines for developing a set of specifications for a higher percentage of RAP in terms of warm mix asphalt technology.
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influences of crumb rubber size and type on reclaimed asphalt pavement rap mixtures
Construction and Building Materials, 2009Co-Authors: Feipeng Xiao, Serji N Amirkhanian, Junan Shen, Bradley J PutmanAbstract:Over the years, recycling has become one of the most attractive pavement rehabilitation alternatives, and different recycling methods are now available to address specific pavement distresses and structural needs. The objective of this study was to investigate and evaluate the engineering properties of crumb rubber size and type influences on reclaimed asphalt pavement (RAP) mixtures. The experimental design for this study included the use of three rubber sizes and two rubber types (ambient or cryogenic) in the mixture containing 25% RAP mixtures. In this study, the results of the experiments indicated that the addition of crumb rubber was helpful in increasing the voids in mineral aggregate (VMA) in Superpave mix design and improving rutting resistance of mixture regardless of rubber size and type. On the other hand, indirect tensile strength (ITS) values show no significant difference for mixtures made with three type rubber sizes. However, the increase of rubber size, regardless of rubber type, reduced the resilient modulus values but extended the fatigue life of the modified mixtures.
Serji N Amirkhanian - One of the best experts on this subject based on the ideXlab platform.
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superpave evaluation of higher rap contents using wma technologies
Construction and Building Materials, 2016Co-Authors: Feipeng Xiao, Xiangdao Hou, Serji N Amirkhanian, Kwang W KimAbstract:Abstract In this study, the objective was to conduct an investigation of Superpave mix design characteristics of WMA technologies in terms of various high percentages of reclaimed asphalt pavements (RAPs). One PG 58-28 binder, two PG 64-22 binders, and two RAP sources were selected from South Carolina. In addition, three mix technologies (e.g. hot mix asphalt (HMA), foaming technology, and Evotherm additive) were employed to produce the mixtures. Meanwhile, four RAP contents of 20%, 30%, 40%, and 50% (by weight of total mixture) were utilized to blend with virgin materials. 36 Superpave mix designs were conducted to explore the volumetric characteristics of various mixtures. In this study, the results indicated that, all mixtures have an optimum asphalt content (OAC) less than 5.0%, and most of these values are close to a minimum OAC value of 4.5% set by South Carolina Department of Transportation (SCDOT). No noticeable increases at the mixing and compaction temperatures for these mixtures containing a higher percentage of RAP (i.e., over 40%) were found in this study. In addition, the voids in mineral aggregate (VMA), voids filled with asphalt (VFA), dust/asphalt ratios, and moisture susceptibility meet the requirements of SCDOT’s specifications. Therefore, these specific mix designs could be used as the guidelines for developing a set of specifications for a higher percentage of RAP in terms of warm mix asphalt technology.
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influences of crumb rubber size and type on reclaimed asphalt pavement rap mixtures
Construction and Building Materials, 2009Co-Authors: Feipeng Xiao, Serji N Amirkhanian, Junan Shen, Bradley J PutmanAbstract:Over the years, recycling has become one of the most attractive pavement rehabilitation alternatives, and different recycling methods are now available to address specific pavement distresses and structural needs. The objective of this study was to investigate and evaluate the engineering properties of crumb rubber size and type influences on reclaimed asphalt pavement (RAP) mixtures. The experimental design for this study included the use of three rubber sizes and two rubber types (ambient or cryogenic) in the mixture containing 25% RAP mixtures. In this study, the results of the experiments indicated that the addition of crumb rubber was helpful in increasing the voids in mineral aggregate (VMA) in Superpave mix design and improving rutting resistance of mixture regardless of rubber size and type. On the other hand, indirect tensile strength (ITS) values show no significant difference for mixtures made with three type rubber sizes. However, the increase of rubber size, regardless of rubber type, reduced the resilient modulus values but extended the fatigue life of the modified mixtures.
Ali Topal - One of the best experts on this subject based on the ideXlab platform.
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minimum voids in mineral aggregate in hot mix asphalt based on asphalt film thickness
Building and Environment, 2007Co-Authors: Burak Sengoz, Ali TopalAbstract:Abstract This study is aimed at determining the relationship between asphalt film thickness and aging characteristics of various hot-mix asphalt (HMA) mixtures. Resilient modulus and indirect tensile strength tests were conducted on the Superpave Gyratory-compacted specimens with five different asphalt film thicknesses in order to determine an optimum asphalt film thickness. From the relationships between the asphalt film thickness and resilient modulus and indirect tensile strength test values of the short and long-term aged samples, optimum asphalt film thickness has been determined about 9–10 μm. The minimum void content of mineral aggregate (VMA) to obtain this optimum asphalt film thickness can be calculated as 15.2%.
Rajib B Mallick - One of the best experts on this subject based on the ideXlab platform.
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critical review of voids in mineral aggregate requirements in superpave
Transportation Research Record, 1998Co-Authors: Prithvi S Kandhal, Kee Y Foo, Rajib B MallickAbstract:Reports of increased difficulties in meeting the minimum voids in mineral aggregate (VMA) requirements have surfaced with the recent use of Superpave volumetric mix design. The low VMA of Superpave mixes generally can be contributed to the increased compactive effort by the Superpave gyratory compactor. This has led to the increased use of coarser asphalt mixes (gradations near the lower control points). However, the minimum VMA requirements in Superpave volumetric mix design for these coarse mixes are the same as those developed for the dense mixes designed by the Marshall method. Literature review has indicated that the rationale behind the minimum VMA requirement was to incorporate at least a minimum permissible asphalt content into the mix to ensure its durability. Studies have shown that asphalt mix durability is directly related to asphalt film thickness. Therefore, the minimum VMA should be based on the minimum desirable asphalt film thickness instead of on a minimum asphalt content because the lat...
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a critical review of vma requirements in superpave
1998Co-Authors: Prithvi S Kandhal, Kee Y Foo, Rajib B MallickAbstract:Reports of increased difficulties in meeting the minimum voids in mineral aggregate (VMA) requirements have surfaced with the recent use of Superpave volumetric mix design. The low VMA of Superpave mixes can generally be contributed to the increased compactive effort by Superpave gyratory compactor. This has led to the increased use of coarser asphalt mixes (gradations near the lower control points). However, the minimum VMA requirements in Superpave volumetric mix design for these coarse mixes are the same as those developed for the dense mixes designed by the Marshall method. Literature review has indicated that the rationale behind the minimum VMA requirement was to incorporate at least a minimum permissible asphalt content into the mix in order to ensure its durability. Studies have shown that asphalt mix durability is directly related to asphalt film thickness. Therefore, the minimum VMA should be based on the minimum desirable asphalt film thickness rather than a minimum asphalt content because the latter will be different for mixes with different gradations. Mixes with coarse gradation (and, therefore, low surface area) have difficulty meeting the minimum VMA requirement based on minimum asphalt content in spite of thick asphalt films. A rational approach based on a minimum asphalt film thickness has been proposed and validated. The film thickness approach represents a more direct, equitable, and appropriate method of ensuring asphalt mix durability and encompasses various mix gradations.
Mohammadreza Mirzahosseini - One of the best experts on this subject based on the ideXlab platform.
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permanent deformation analysis of asphalt mixtures using soft computing techniques
Expert Systems With Applications, 2011Co-Authors: Mohammadreza Mirzahosseini, Amir H Gandomi, Amir H Alavi, Alireza Aghaeifar, Reza SeyednourAbstract:Research highlights? New prediction models derived by means of multi expression programming (MEP) and multilayer perceptron (MLP) of artificial neural networks give reliable estimates of the flow number of dense asphalt-aggregate mixtures. The MEP-based straightforward formulas are much more practical for the engineering applications compared with the complicated equations provided by MLP. ? The proposed models correlate the flow number of Marshall specimens with the coarse and fine aggregate contents, percentage of bitumen, percentage of voids in mineral aggregate, Marshall stability, and Marshall flow. ? Sensitivity and parametric analyses were performed to verify the validity of the derived models. The obtained results were confirmed with the experimental study results and those of previous studies. ? The proposed MEP and MLP-based models perform superior than the developed regression models. ? The derived design equations can reliably be used as a quick check on solutions developed by more time consuming and in-depth deterministic analyses. This study presents two branches of soft computing techniques, namely multi expression programming (MEP) and multilayer perceptron (MLP) of artificial neural networks for the evaluation of rutting potential of dense asphalt-aggregate mixtures. Constitutive MEP and MLP-based relationships were obtained correlating the flow number of Marshall specimens to the coarse and fine aggregate contents, percentage of bitumen, percentage of voids in mineral aggregate, Marshall stability, and Marshall flow. Different correlations were developed using different combinations of the influencing parameters. The comprehensive experimental database used for the development of the correlations was established upon a series of uniaxial dynamic creep tests conducted in this study. Relative importance values of various predictor variables of the models were calculated to determine the significance of each of the variables to the flow number. A multiple least squares regression (MLSR) analysis was performed to benchmark the MEP and MLP models. For more verification, a subsequent parametric study was also carried out and the trends of the results were confirmed with the experimental study results and those of previous studies. The observed agreement between the predicted and measured flow number values validates the efficiency of the proposed correlations for the assessment of the rutting potential of asphalt mixtures. The MEP-based straightforward formulas are much more practical for the engineering applications compared with the complicated equations provided by MLP.
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nonlinear genetic based models for prediction of flow number of asphalt mixtures
Journal of Materials in Civil Engineering, 2011Co-Authors: Amir H Gandomi, Amir H Alavi, Mohammadreza Mirzahosseini, Fereidoon Moghadas NejadAbstract:Rutting has been considered the most serious distress in flexible pavements for many years. Flow number is an explanatory index for the evaluation of the rutting potential of asphalt mixtures. In this study, a promising variant of genetic programming, namely, gene expression programming (GEP), is utilized to predict the flow number of dense asphalt-aggregate mixtures. The proposed constitutive models relate the flow number of Marshall specimens to the coarse and fine aggregate contents, percentage of air voids, percentage of voids in mineral aggregate, Marshall stability, and Marshall flow. Different correlations were developed using different combinations of the influencing parameters. The comprehensive experimental database used for the development of the correlations was established on the basis of a series of uniaxial dynamic-creep tests conducted in this study. Relative importance values of various predictor variables were calculated to determine their contributions to the flow number prediction. A multiple-least-squares-regression (MLSR) analysis was performed to benchmark the GEP models. For more verification, a subsequent parametric study was carried out, and the trends of the results were confirmed with the results of previous studies. The results indicate that the proposed correlations are effectively capable of evaluating the flow number of asphalt mixtures. The GEP-based formulas are simple, straightforward, and particularly valuable for providing an analysis tool accessible to practicing engineers.
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formulation of flow number of asphalt mixes using a hybrid computational method
Construction and Building Materials, 2011Co-Authors: Amir H Alavi, Amir H Gandomi, Mahmoud Ameri, Mohammadreza MirzahosseiniAbstract:Abstract A high-precision model was derived to predict the flow number of dense asphalt mixtures using a novel hybrid method coupling genetic programming and simulated annealing, called GP/SA. The proposed constitutive model correlates the flow number of Marshall specimens with the percentages of filler, bitumen, voids in mineral aggregate, Marshall stability, and Marshall flow. The comprehensive experimental database used for the development of the model was established upon a series of uniaxial dynamic creep tests conducted in this study. Generalized regression neural network and multiple regression-based analyses were performed to benchmark the GP/SA model. The contributions of the variables affecting the flow number were evaluated through a sensitivity analysis. A subsequent parametric study was carried out and the trends of the results were confirmed with the results of the experimental study. The results indicate that the proposed GP/SA model is effectively capable of evaluating the flow number of asphalt mixtures. The derived model is remarkably straightforward and provides an analysis tool accessible to practicing engineers.
