International Journal of Pavement Engineering, 2009
As warm asphalt has been gaining increasing popularity in recent years, there are still several c... more As warm asphalt has been gaining increasing popularity in recent years, there are still several characteristics of warm asphalt, which are unknown. While several studies have been conducted to analyse the performance of warm asphalt mixtures, aging characteristics of warm-mix asphalt (WMA) binders are not known in great detail. This paper presents the results of a study to evaluate the
ABSTRACT The main objective of using warm mix asphalt (WMA) is to reduce emissions and improve th... more ABSTRACT The main objective of using warm mix asphalt (WMA) is to reduce emissions and improve the workability by lowering the mixing and compaction temperatures of asphalt mixes through different mechanisms. Since warm asphalt is a relatively new technology, not much research has been conducted on various mix compositions. While some of the concerns about WMA have been addressed, the interaction of warm mix additives with modified binders, especially crumb rubber modified (CRM) binder, is not known in great detail. This paper presents the data on rheological tests conducted on rubberized binders containing warm asphalt additives. Binders from five different sources were modified using 10% crumb rubber by weight of the virgin binders. Two of the available warm asphalt technologies, Aspha-min® and Sasobit®, were used to produce the warm asphalt binders. From the tests, it was observed that the addition of the warm asphalt additives significantly reduce the permanent deformation of the binders, increase the viscosity at 60 °C and the complex modulus, G*, and decrease the phase angle, δ, at high frequencies and low temperatures compared with the CRM binders.
International Journal of Pavement Engineering, 2010
Since warm asphalt technology is relatively new, there are no old pavements to study the ageing b... more Since warm asphalt technology is relatively new, there are no old pavements to study the ageing behaviour of warm mix asphalt (WMA). While several studies have been conducted to study the properties of WMA, its ageing characteristics are yet to be evaluated in detail. This paper presents the results of a laboratory study conducted to evaluate the ageing characteristics of
In recent years, warm mix asphalt (WMA) is widely used for reducing energy requirements and emiss... more In recent years, warm mix asphalt (WMA) is widely used for reducing energy requirements and emissions in hot mix asphalt (HMA) industry. In addition, the use of rubberized asphalt in the past has proven to be economical, environmentally sound and effective in improving the performance of pavements across the US and the world. The objective of this research was to investigate the mixture performance characteristics of rubberized warm asphalt mixtures, and their correlation with binder properties, through a series of laboratory tests (e.g., viscosity, dynamic shear rheometer (DSR), and bending beam rheometer (BBR)) conducted on the binders, and obtaining the indirect tensile strength, rutting resistance, and resilient modulus of various mixtures. The results of the experiments indicated that the use of crumb rubber and WMA additive in HMA can effectively improve the engineering properties of these mixes at lower mixing and compacting temperatures and some statistical correlations between rheological and/or engineering properties were developed successfully.
The use of hydrated lime or other liquid anti-stripping agents (ASA) is the most common method to... more The use of hydrated lime or other liquid anti-stripping agents (ASA) is the most common method to improve the moisture susceptibility of asphalt mixes. However, most laboratory test conditions used to evaluate the moisture susceptibility of the mixes are only for a short duration of time. This might not be a good representation of the field conditions (i.e., several months or years of service). Thus, a study to evaluate the effects of conditioning the mixes for longer duration was initiated. Also, another problem with the use of the liquid anti-stripping agents is their heat storage capability. This paper addresses these two issues, by preparing and testing mixtures made with fresh binder for indirect tensile strengths after conditioning the samples for 1, 7, 28, 90 and 180 days, and samples prepared from binder stored for 3 days at 163˚C after conditioning them for 1, 28 and 90 days. The results of this limited study indicated that hydrated lime and the liquid anti-stripping agents were equally effective for the mixes used in this research when conditioned beyond 1 day. In case of samples prepared from stored binder, there was no significant difference in the effectiveness of hydrated lime and the liquid anti-stripping agents even after conditioning for 1 day. Though it was observed that none of the ASA treatments performed better than others in case of samples prepared with stored binder, it was also observed that almost all mixes gave significantly similar wet ITS and TSR values as samples prepared from fresh binder.
International Journal of Pavement Engineering - INT J PAVEMENT ENG, 2012
Moisture damage in flexible pavements might cause stripping in asphalt pavements and ultimately r... more Moisture damage in flexible pavements might cause stripping in asphalt pavements and ultimately result in premature failure. Warm mix asphalt (WMA) technology as a means to decrease the energy consumption and emissions associated with conventional hot mix asphalt production is broadly being used recently. However, the utilisation of the hydrated lime and liquid anti-strip additives in WMA mixtures makes these issues more complicated. The objective of this study was to investigate and evaluate the moisture susceptibility of mixtures containing anti-stripping agents (ASAs) and WMA additives after long-term saturated durations. The experimental design for this study included the utilisations of one binder source (PG 64-22), three ASA additives and control, two WMA additives and hot mix, and three aggregate sources. A total of 36 types of mixtures and 540 specimens were fabricated and tested in this study. The performed properties included indirect tensile strength (ITS), tensile streng...
International Journal of Pavement Engineering, 2009
As warm asphalt has been gaining increasing popularity in recent years, there are still several c... more As warm asphalt has been gaining increasing popularity in recent years, there are still several characteristics of warm asphalt, which are unknown. While several studies have been conducted to analyse the performance of warm asphalt mixtures, aging characteristics of warm-mix asphalt (WMA) binders are not known in great detail. This paper presents the results of a study to evaluate the
Rising energy prices, global warming, and more stringent environmental regulations have resulted ... more Rising energy prices, global warming, and more stringent environmental regulations have resulted in an interest in warm mix asphalt ͑WMA͒ technologies as a means to decrease the energy consumption and emissions associated with conventional hot mix asphalt production. However, the utilization of the hydrated lime and liquid antistripping agents ͑ASA͒ in WMA mixture makes these issues more complicated. The objective of this study was to investigate and evaluate the moisture susceptibility of the mixtures containing ASA and WMA additives. The experimental design for this study included the utilizations of one binder source ͑PG 64-22͒, three ASA additives and control, two WMA additives and virgin, and three aggregate sources. A total of 36 types of mixtures and 216 specimens were fabricated and tested in this study. The performed properties include indirect tensile strength ͑ITS͒, tensile strength ratio ͑TSR͒, flow, and toughness. The results indicated that the hydrate lime exhibits the best moisture resistance for WMA mixtures, the liquid ASA additives can increase the ITS values of the mixtures but the liquid ASA generally exhibits a weak moisture resistance compared to the hydrate lime regardless of WMA and aggregate types in this study. In addition, the wet ITS values of mixtures containing WMA additives were lower than that of the mixtures without WMA additives.
ABSTRACT The main objective of using warm mix asphalt (WMA) is to reduce emissions and improve th... more ABSTRACT The main objective of using warm mix asphalt (WMA) is to reduce emissions and improve the workability by lowering the mixing and compaction temperatures of asphalt mixes through different mechanisms. Since warm asphalt is a relatively new technology, not much research has been conducted on various mix compositions. While some of the concerns about WMA have been addressed, the interaction of warm mix additives with modified binders, especially crumb rubber modified (CRM) binder, is not known in great detail. This paper presents the data on rheological tests conducted on rubberized binders containing warm asphalt additives. Binders from five different sources were modified using 10% crumb rubber by weight of the virgin binders. Two of the available warm asphalt technologies, Aspha-min® and Sasobit®, were used to produce the warm asphalt binders. From the tests, it was observed that the addition of the warm asphalt additives significantly reduce the permanent deformation of the binders, increase the viscosity at 60 °C and the complex modulus, G*, and decrease the phase angle, δ, at high frequencies and low temperatures compared with the CRM binders.
International Journal of Pavement Engineering, 2009
As warm asphalt has been gaining increasing popularity in recent years, there are still several c... more As warm asphalt has been gaining increasing popularity in recent years, there are still several characteristics of warm asphalt, which are unknown. While several studies have been conducted to analyse the performance of warm asphalt mixtures, aging characteristics of warm-mix asphalt (WMA) binders are not known in great detail. This paper presents the results of a study to evaluate the
With the increasing awareness of the warm asphalt technology, it is imperative to study the prope... more With the increasing awareness of the warm asphalt technology, it is imperative to study the properties of the binders containing the warm asphalt additives thoroughly, especially since not much research has been conducted on warm asphalt binder properties to date. Also, in the recent years, researchers have observed that the SHRP rutting parameter G * /sin d is not very effective in predicting the rutting performance of binders, especially in case of modified binders. Zero shear viscosity (ZSV) has been evaluated to determine its effectiveness in predicting the rutting behavior of asphalt binders. Thus, in this paper, the ZSV of five asphalt binders with and without the warm asphalt additives, Asphamin Ò and Sasobit Ò , were calculated using the different models and test methods available in literature. From the test results, it was observed that the addition of the warm asphalt additives increased the ZSV of all the five binders used in this study. It was also observed that the different test methods gave different ZSV values, and that the selection of the test methods and the testing parameters are crucial parameters.
International Journal of Pavement Engineering, 2009
As warm asphalt has been gaining increasing popularity in recent years, there are still several c... more As warm asphalt has been gaining increasing popularity in recent years, there are still several characteristics of warm asphalt, which are unknown. While several studies have been conducted to analyse the performance of warm asphalt mixtures, aging characteristics of warm-mix asphalt (WMA) binders are not known in great detail. This paper presents the results of a study to evaluate the
ABSTRACT The main objective of using warm mix asphalt (WMA) is to reduce emissions and improve th... more ABSTRACT The main objective of using warm mix asphalt (WMA) is to reduce emissions and improve the workability by lowering the mixing and compaction temperatures of asphalt mixes through different mechanisms. Since warm asphalt is a relatively new technology, not much research has been conducted on various mix compositions. While some of the concerns about WMA have been addressed, the interaction of warm mix additives with modified binders, especially crumb rubber modified (CRM) binder, is not known in great detail. This paper presents the data on rheological tests conducted on rubberized binders containing warm asphalt additives. Binders from five different sources were modified using 10% crumb rubber by weight of the virgin binders. Two of the available warm asphalt technologies, Aspha-min® and Sasobit®, were used to produce the warm asphalt binders. From the tests, it was observed that the addition of the warm asphalt additives significantly reduce the permanent deformation of the binders, increase the viscosity at 60 °C and the complex modulus, G*, and decrease the phase angle, δ, at high frequencies and low temperatures compared with the CRM binders.
International Journal of Pavement Engineering, 2010
Since warm asphalt technology is relatively new, there are no old pavements to study the ageing b... more Since warm asphalt technology is relatively new, there are no old pavements to study the ageing behaviour of warm mix asphalt (WMA). While several studies have been conducted to study the properties of WMA, its ageing characteristics are yet to be evaluated in detail. This paper presents the results of a laboratory study conducted to evaluate the ageing characteristics of
In recent years, warm mix asphalt (WMA) is widely used for reducing energy requirements and emiss... more In recent years, warm mix asphalt (WMA) is widely used for reducing energy requirements and emissions in hot mix asphalt (HMA) industry. In addition, the use of rubberized asphalt in the past has proven to be economical, environmentally sound and effective in improving the performance of pavements across the US and the world. The objective of this research was to investigate the mixture performance characteristics of rubberized warm asphalt mixtures, and their correlation with binder properties, through a series of laboratory tests (e.g., viscosity, dynamic shear rheometer (DSR), and bending beam rheometer (BBR)) conducted on the binders, and obtaining the indirect tensile strength, rutting resistance, and resilient modulus of various mixtures. The results of the experiments indicated that the use of crumb rubber and WMA additive in HMA can effectively improve the engineering properties of these mixes at lower mixing and compacting temperatures and some statistical correlations between rheological and/or engineering properties were developed successfully.
The use of hydrated lime or other liquid anti-stripping agents (ASA) is the most common method to... more The use of hydrated lime or other liquid anti-stripping agents (ASA) is the most common method to improve the moisture susceptibility of asphalt mixes. However, most laboratory test conditions used to evaluate the moisture susceptibility of the mixes are only for a short duration of time. This might not be a good representation of the field conditions (i.e., several months or years of service). Thus, a study to evaluate the effects of conditioning the mixes for longer duration was initiated. Also, another problem with the use of the liquid anti-stripping agents is their heat storage capability. This paper addresses these two issues, by preparing and testing mixtures made with fresh binder for indirect tensile strengths after conditioning the samples for 1, 7, 28, 90 and 180 days, and samples prepared from binder stored for 3 days at 163˚C after conditioning them for 1, 28 and 90 days. The results of this limited study indicated that hydrated lime and the liquid anti-stripping agents were equally effective for the mixes used in this research when conditioned beyond 1 day. In case of samples prepared from stored binder, there was no significant difference in the effectiveness of hydrated lime and the liquid anti-stripping agents even after conditioning for 1 day. Though it was observed that none of the ASA treatments performed better than others in case of samples prepared with stored binder, it was also observed that almost all mixes gave significantly similar wet ITS and TSR values as samples prepared from fresh binder.
International Journal of Pavement Engineering - INT J PAVEMENT ENG, 2012
Moisture damage in flexible pavements might cause stripping in asphalt pavements and ultimately r... more Moisture damage in flexible pavements might cause stripping in asphalt pavements and ultimately result in premature failure. Warm mix asphalt (WMA) technology as a means to decrease the energy consumption and emissions associated with conventional hot mix asphalt production is broadly being used recently. However, the utilisation of the hydrated lime and liquid anti-strip additives in WMA mixtures makes these issues more complicated. The objective of this study was to investigate and evaluate the moisture susceptibility of mixtures containing anti-stripping agents (ASAs) and WMA additives after long-term saturated durations. The experimental design for this study included the utilisations of one binder source (PG 64-22), three ASA additives and control, two WMA additives and hot mix, and three aggregate sources. A total of 36 types of mixtures and 540 specimens were fabricated and tested in this study. The performed properties included indirect tensile strength (ITS), tensile streng...
International Journal of Pavement Engineering, 2009
As warm asphalt has been gaining increasing popularity in recent years, there are still several c... more As warm asphalt has been gaining increasing popularity in recent years, there are still several characteristics of warm asphalt, which are unknown. While several studies have been conducted to analyse the performance of warm asphalt mixtures, aging characteristics of warm-mix asphalt (WMA) binders are not known in great detail. This paper presents the results of a study to evaluate the
Rising energy prices, global warming, and more stringent environmental regulations have resulted ... more Rising energy prices, global warming, and more stringent environmental regulations have resulted in an interest in warm mix asphalt ͑WMA͒ technologies as a means to decrease the energy consumption and emissions associated with conventional hot mix asphalt production. However, the utilization of the hydrated lime and liquid antistripping agents ͑ASA͒ in WMA mixture makes these issues more complicated. The objective of this study was to investigate and evaluate the moisture susceptibility of the mixtures containing ASA and WMA additives. The experimental design for this study included the utilizations of one binder source ͑PG 64-22͒, three ASA additives and control, two WMA additives and virgin, and three aggregate sources. A total of 36 types of mixtures and 216 specimens were fabricated and tested in this study. The performed properties include indirect tensile strength ͑ITS͒, tensile strength ratio ͑TSR͒, flow, and toughness. The results indicated that the hydrate lime exhibits the best moisture resistance for WMA mixtures, the liquid ASA additives can increase the ITS values of the mixtures but the liquid ASA generally exhibits a weak moisture resistance compared to the hydrate lime regardless of WMA and aggregate types in this study. In addition, the wet ITS values of mixtures containing WMA additives were lower than that of the mixtures without WMA additives.
ABSTRACT The main objective of using warm mix asphalt (WMA) is to reduce emissions and improve th... more ABSTRACT The main objective of using warm mix asphalt (WMA) is to reduce emissions and improve the workability by lowering the mixing and compaction temperatures of asphalt mixes through different mechanisms. Since warm asphalt is a relatively new technology, not much research has been conducted on various mix compositions. While some of the concerns about WMA have been addressed, the interaction of warm mix additives with modified binders, especially crumb rubber modified (CRM) binder, is not known in great detail. This paper presents the data on rheological tests conducted on rubberized binders containing warm asphalt additives. Binders from five different sources were modified using 10% crumb rubber by weight of the virgin binders. Two of the available warm asphalt technologies, Aspha-min® and Sasobit®, were used to produce the warm asphalt binders. From the tests, it was observed that the addition of the warm asphalt additives significantly reduce the permanent deformation of the binders, increase the viscosity at 60 °C and the complex modulus, G*, and decrease the phase angle, δ, at high frequencies and low temperatures compared with the CRM binders.
International Journal of Pavement Engineering, 2009
As warm asphalt has been gaining increasing popularity in recent years, there are still several c... more As warm asphalt has been gaining increasing popularity in recent years, there are still several characteristics of warm asphalt, which are unknown. While several studies have been conducted to analyse the performance of warm asphalt mixtures, aging characteristics of warm-mix asphalt (WMA) binders are not known in great detail. This paper presents the results of a study to evaluate the
With the increasing awareness of the warm asphalt technology, it is imperative to study the prope... more With the increasing awareness of the warm asphalt technology, it is imperative to study the properties of the binders containing the warm asphalt additives thoroughly, especially since not much research has been conducted on warm asphalt binder properties to date. Also, in the recent years, researchers have observed that the SHRP rutting parameter G * /sin d is not very effective in predicting the rutting performance of binders, especially in case of modified binders. Zero shear viscosity (ZSV) has been evaluated to determine its effectiveness in predicting the rutting behavior of asphalt binders. Thus, in this paper, the ZSV of five asphalt binders with and without the warm asphalt additives, Asphamin Ò and Sasobit Ò , were calculated using the different models and test methods available in literature. From the test results, it was observed that the addition of the warm asphalt additives increased the ZSV of all the five binders used in this study. It was also observed that the different test methods gave different ZSV values, and that the selection of the test methods and the testing parameters are crucial parameters.
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Papers by Tejash Gandhi