The Experts below are selected from a list of 5046 Experts worldwide ranked by ideXlab platform
Alireza Azarhoosh - One of the best experts on this subject based on the ideXlab platform.
-
Evaluate the mechanism of the effect of hydrated lime on moisture damage of Warm Mix Asphalt
Construction and Building Materials, 2013Co-Authors: Saeid Hesami, Hossein Roshani, Gholam Hossein Hamedi, Alireza AzarhooshAbstract:Abstract With increasing interest in the use of Warm Mix Asphalt in the paving industry, more studies in this field for improvement of Warm Mix Asphalt properties seem to be necessary. In spite of many Warm Mix Asphalt advantages, moisture susceptibility is one of the potential disadvantages of Warm Mix Asphalt Mixtures. In this study, the effects of using hydrated lime as a common anti-strip additive on moisture susceptibility of Asphalt Mixtures has been evaluated by determining the mechanism that affects the adhesive bond between the aggregate and Asphalt binder using the surface free energy method. Two types of aggregates, limestone and granite, and two types of Warm Mix Asphalt additives, namely sasobit and asphamin, as well as hydrated lime as anti-strip additives were evaluated in this study. The results of the surface free energy method indicate that hydrated lime increases the wettability of Asphalt binder on the aggregate and improves the adhesion between the Asphalt binder and aggregate. Also, the difference between surface free energies of Asphalt-aggregate and water-aggregate is higher in samples made with untreated aggregates, as using hydrated lime caused these values to decrease. This implies that more energy is needed for stripping phenomena to occur, and the rate of moisture damage decreases.
C. Fonseca - One of the best experts on this subject based on the ideXlab platform.
-
Highway trial sections: Performance evaluation of Warm Mix Asphalt and recycled Warm Mix Asphalt
Construction and Building Materials, 2020Co-Authors: G. Valdes-vidal, Alejandra Calabi-floody, Elsa Sanchez-alonso, C. Díaz, C. FonsecaAbstract:Abstract The present article presents the construction and evaluation of an experimental stretch of highway with environmentally sustainable Mixes; Warm Mixes Asphalt and recycled Warm Mixes Asphalt. Six trial sections of an urban highway were constructed with different structural characteristics. Each section was 15 cm thick and 90 m long. The Asphalt Mixes used for construction of the experimental sections were: reference hot Mix Asphalt (HMA), Warm Mix Asphalt with natural zeolite (WAMz), Warm Mix Asphalt with Evotherm (WMAe), recycled Warm Mix Asphalt with 20% reclaimed Asphalt pavement (RAP) and natural zeolite (WMA R20z), recycled Warm Mix Asphalt with 20% RAP and Evotherm (WMA R20e), and recycled Warm Mix Asphalt with 30% RAP and natural zeolite (WMA R30z). All the Asphalt Mixes were designed to comply with the design properties required by Chilean specifications, and were fabricated in an Asphalt batch plant. The following performance properties were evaluated: stiffness modulus, water susceptibility, permanent deformation, cracking resistance and fatigue behaviour. The ageing of the Asphalt binder in each of these Asphalt Mixes fabricated in the plant was also evaluated by physical and rheological assays of the binder extracted from the Mixes. One month after construction of the trial sections, the structural capacity of each section of the experimental stretch was evaluated by falling weight deflectometer (FWD), and the pavement indicators of rutting and the International Roughness Index (IRI) were determined by laser profilometer. Finally, field cores were extracted and tested for stiffness modulus and cracking resistance. The results obtained indicate that the Asphalt Mixes used presented no major differences in the mechanical properties evaluated, nor in their structural capacity parameters and pavement indices, compared to the control HMA. These Mixes present a suitable behaviour, similar to that of a conventional Mix, in both their technical and constructive properties, while offering important environmental advantages.
David Jones - One of the best experts on this subject based on the ideXlab platform.
-
Warm-Mix Asphalt Study: Summary Report on Warm-Mix Asphalt Research in California
2014Co-Authors: David JonesAbstract:Author(s): Jones, D. | Abstract: Warm Mix Asphalt (WMA) is a relatively new technology. It was developed in response to needs for reduced energy consumption and stack emissions during the production of Asphalt concrete, improved workability and compaction after long hauls and when using lower placement temperatures, and better working conditions for plant and paving crews. Studies in the United States and Europe indicate that significant reductions in production and placement temperatures, and, potentially, in related emissions are possible. However, concerns exist about how these lower production and placement temperatures could influence Asphalt binder aging and, consequently, short- and longterm performance, specifically rutting. The overall objective of this Warm Mix Asphalt study was to determine whether the use of technologies that reduce the production and construction temperatures of Asphalt concrete Mixes influences performance of the Mix. The testing completed in this Warm Mix Asphalt study provided no results to suggest that Warm Mix technologies should not be used in conventional, gap-graded Asphalt rubber, and open-graded friction course Mixes in California, provided that standard specified Mix design, construction, and performance limits for hot Mix Asphalt are met. The use of Warm Mix Asphalt has clear benefits when compared to hot Mixes. These include significant reductions in, or even elimination of, smoke and odors, lower emissions, improved workability, better working conditions, and better performance on projects with long hauls or where Mixes are placed under cool conditions. The slightly higher costs of using Warm Mix technologies are outweighed by these benefits. Based on the findings of this study, the use of Warm Mix Asphalt technologies in Asphalt Mixes is encouraged, especially on Asphalt rubber projects, projects in urban areas, and on projects with long hauls and/or where Mixes are placed under cool conditions. Given that Warm Mix Asphalt may be produced at significantly lower temperatures than hot Mix Asphalt (with associated lower aggregate heating temperatures), moisture sensitivity, especially on water-based Warm Mix Asphalt technologies, should be closely monitored in Mix design and quality control/quality assurance testing.
-
Warm-Mix Asphalt Study: Summary Report on Rubberized Warm-Mix Asphalt Research
2013Co-Authors: David Jones, Frank Farshidi, John T HarveyAbstract:Warm-Mix Asphalt (WMA) is a relatively new technology. Concerns exist about how lower production and placement temperatures could influence Asphalt binder aging and short- and long-term performance, specifically rutting. The objective of this study was to identify limitations and benefits of using Warm-Mix Asphalt technologies in rubberized Asphalt Mixes. Results suggest that Warm-Mix technologies can be used in rubberized Mixes in California, provided that standard specified Mix design, construction, and performance limits for hot-Mix Asphalt are met. The use of Warm-Mix Asphalt technologies in rubberized Asphalt Mixes has clear benefits when compared to hot Mixes including significant reductions in smoke and odors, lower emissions, improved workability, better working conditions, and better performance on projects with long hauls or where Mixes are placed under cool conditions. The slightly higher costs of using Warm-Mix technologies are outweighed by these benefits. Based on the findings of this study, the use of Warm-Mix Asphalt technologies in rubberized Asphalt Mixes is encouraged.
-
Warm-Mix Asphalt Study: Evaluation of Rubberized Hot- and Warm-Mix Asphalt with Respect to Emissions
2013Co-Authors: Frank Farshidi, David Jones, John T HarveyAbstract:Author(s): Farshidi, F.; Jones, D.; Harvey, J. T. | Abstract: In recent years, Warm Mix Asphalt (WMA) technologies have been used to modify Asphalt binders, with the aims of decreasing production and construction temperatures, reducing fumes and emissions, retaining the properties of the Mix during long haul distances, and improving workability. Reduced production temperatures at the plant and during paving and compaction are believed to reduce emissions from the Asphalt. The objective of this research study was to quantify the potential environmental benefits during paving operations with respect to the reduction of volatile and semi-volatile organic compounds and polycyclic aromatic hydrocarbons to confirm or refute this hypothesis. Asphalt plant stack emissions were not assessed as part of this study. A portable “flux” chamber was designed and fabricated to capture and directly measure emissions during paving operations. An analytical method was developed to identify and quantify alkane emissions using gas chromatography mass spectrometry (GC-MS). A separate method was developed for identification and characterization of trace level polycyclic aromatic hydrocarbon compounds in the Asphalt fumes. The results demonstrated that the Warm-Mix Asphalt technology type, plant Mixing temperature, and level of compaction significantly influence emissions characteristics throughout paving operations. Depending on these variables, most Warm-Mix technologies appear to have potential for reducing emissions during transport and paving operations. Key findings from the study include: The majority of the reactive organic gases are volatilized in the first hour after sampling initiation. There is a significant difference between emissions concentrations from loose Mix and those recorded immediately after compaction. Gaseous phase PAH compounds in Asphalt fumes are mainly low molecular weight compounds and are present at trace levels. The concentrations vary depending on the temperature of the Mix at the time of sampling. Particulate phase PAHs were below the detection limit of this study for all the Mixes. The results confirmed that typical Asphalt production temperatures are not high enough to initiate significant PAH formation. The total alkane emissions from the Warm-Mixes were, in most instances, significantly lower than those measured from the hot-Mixes (e.g., 117 µg/m3 from one of the Warm-Mixes compared to 2,516 µg/m3 from the hot-Mix control). In some instances, specific Warm-Mixes had higher alkane concentrations than the hot-Mix controls. Consequently, any generalization with regard to emissions reduction through the use of Warm-Mix Asphalt is inappropriate. PAH concentrations correlated with initial Mix production temperature, with those Warm-Mixes produced at the lowest temperatures showing the lowest PAH concentrations.
Hamzeh F. Haghshenas - One of the best experts on this subject based on the ideXlab platform.
-
Hydrated lime effect on moisture susceptibility of Warm Mix Asphalt
Construction and Building Materials, 2012Co-Authors: Ali Khodaii, H. Kazemi Tehrani, Hamzeh F. HaghshenasAbstract:Abstract Beneficial effects of using hydrated lime to reduce moisture susceptibility of Hot Mix Asphalts are well recognized and widely used in industry. In present study, the effect of varying percentages of hydrated lime (from 0% to 2%) on the moisture susceptibility of Warm Mix Asphalt was evaluated. Based on the obtained results it was shown that increasing hydrated lime content reduces the moisture susceptibility of dense graded Warm Mix Asphalt. However, 80% of tensile strength ratio was reached without utilization of hydrated lime in some prepared samples with gap grading, using polymer modified bitumen.
Saeid Hesami - One of the best experts on this subject based on the ideXlab platform.
-
Evaluate the mechanism of the effect of hydrated lime on moisture damage of Warm Mix Asphalt
Construction and Building Materials, 2013Co-Authors: Saeid Hesami, Hossein Roshani, Gholam Hossein Hamedi, Alireza AzarhooshAbstract:Abstract With increasing interest in the use of Warm Mix Asphalt in the paving industry, more studies in this field for improvement of Warm Mix Asphalt properties seem to be necessary. In spite of many Warm Mix Asphalt advantages, moisture susceptibility is one of the potential disadvantages of Warm Mix Asphalt Mixtures. In this study, the effects of using hydrated lime as a common anti-strip additive on moisture susceptibility of Asphalt Mixtures has been evaluated by determining the mechanism that affects the adhesive bond between the aggregate and Asphalt binder using the surface free energy method. Two types of aggregates, limestone and granite, and two types of Warm Mix Asphalt additives, namely sasobit and asphamin, as well as hydrated lime as anti-strip additives were evaluated in this study. The results of the surface free energy method indicate that hydrated lime increases the wettability of Asphalt binder on the aggregate and improves the adhesion between the Asphalt binder and aggregate. Also, the difference between surface free energies of Asphalt-aggregate and water-aggregate is higher in samples made with untreated aggregates, as using hydrated lime caused these values to decrease. This implies that more energy is needed for stripping phenomena to occur, and the rate of moisture damage decreases.
