Juan Gallego - Academia.edu (original) (raw)
Papers by Juan Gallego
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](La innovación docente como misión del profesorado : Congreso Internacional Sobre Aprendizaje, Innovación y Competitividad, 2017
Resumen-Las prácticas de laboratorio en enseñanza universitaria están siendo sustituidas en mucho... more Resumen-Las prácticas de laboratorio en enseñanza universitaria están siendo sustituidas en muchos casos por laboratorios virtuales o entornos Web que permiten trabajar a distancia. Sin embargo, parece ser que el mejor modelo docente en este ámbito está constituido por una combinación de las tradicionales prácticas presenciales en el laboratorio y laboratorios virtuales o entornos Web que complementen las prácticas reales. Esta comunicación técnica presenta el Proyecto LCweb. Se trata de un entorno Web que no sustituye sino complementa las prácticas
Materiales de Construcción, 2017
This study examines the potential of adding electric arc furnace slag to bituminous mixtures to b... more This study examines the potential of adding electric arc furnace slag to bituminous mixtures to be heated by microwaves. The susceptibility of bituminous mixtures to microwave energy is limited and so, in order to improve the energy performance of the heating process, it is necessary to incorporate additives or components to the mixture so as to improve the capacity for microwave heating. The article presents the results of adding various components, (steel wool, scrap tire wire, silicon carbide, iron filings) and an alternative aggregate: electric arc furnace slag. According to the results obtained in the laboratory, slag addition of at least 5% by weight of the bituminous mixture represents the best option for both technical and economic reasons. The results may promote the valorization of this steel industry residue in bituminous mixtures by improving microwave heating response.
Construction and Building Materials, 2013
Over the last ten years the concept of self-healing in asphalt mixtures for road pavements has be... more Over the last ten years the concept of self-healing in asphalt mixtures for road pavements has been reaching great importance due to the fact that this capability allows a material to recuperate original properties after failure. This new generation of asphalt paving materials would allow road agencies to save no renewable resources as aggregates and bitumen, making the road investments more efficient. Probably the most promising method for the in-situ heating of the pavements is the radiation by microwaves. By heating the pavement, the asphalt binder gets melt and refills the cracks in the material, recuperating a part of its initial structural parameters. Unfortunately, asphalt mixture components (aggregates and binder) are low sensitive to microwave energy. This is why it may be advantageous to incorporate in the mixture additives to improve the sensibility to the radiation with microwaves. In this investigation two additives were studied: graphene and electric arc furnace (EAF) slag coming from the steel industry. These additives were incorporated at several contents and the efficiency of the heating process was evaluated by the ratio ºC/kwh/kg in order to optimize the content of the additive in the asphalt mixture. Additionally, an evaluation of the electrical conductivity of the asphalt mixture at different contents of additives were carried out to study the possible relation between the conductivity of the mixture and its sensibility to microwave radiation. As a result of the investigation, it seems that microwave radiation can be a real option to promote in situ self-healing of asphalt pavements.
Materials, 2021
Compaction of cold asphalt mixtures is a subject that has not been thoroughly studied, and, for t... more Compaction of cold asphalt mixtures is a subject that has not been thoroughly studied, and, for this reason, requires new efforts from researchers to have a better understanding. Unlike hot mixtures, cold mixtures and mainly recycled mixtures require specific considerations for compaction. There is a lack of consensus about the methodology to select the optimum premix water and emulsion contents. In the absence of specific regulations, the use of soil tests or hot mixtures procedures is common. For these reasons, this investigation’s main goal was to evaluate two compaction methods used to design cold recycled mixtures with emulsion: the modified Proctor procedure and the gyratory compaction. It was concluded that both methods could be useful to study compactability since consistent results were obtained by applying the maximum bulk density criterion. However, the higher bulk densities achieved, the smaller specimens used, and the suitability of the gyratory specimens to be later te...
Road and Rail Infrastructure V
This work evaluates resistance to plastic deformation and cracking of two hot asphalt mixtures ma... more This work evaluates resistance to plastic deformation and cracking of two hot asphalt mixtures made with recycled aggregates from construction and demolition debris. On the basis of this study it was inferred that the samples designed with recycled aggregates result in a stiffer mixture and are more resistant to plastic deformation. From the standpoint of fatigue behaviour, however, they present a lower fatigue life for a given deformation amplitude. Finally, a multi-layered elastic-linear model was used to determine the variation in the service life of a section of pavement earmarked for roads with low traffic volumes when layers containing recycled aggregates are added. The viability of the use of construction and demolition debris in hot asphalt mixtures was verified, since the number of standard axles that the section can carry is greater than the predicted number of standard axles that will be carried during the service life of the pavement.
Asphalt mixes with asphalt rubber have been widely employed in highway pavements. However, their ... more Asphalt mixes with asphalt rubber have been widely employed in highway pavements. However, their use is much less common in airport runways. This paper proposes a design method for rehabilitation of PCC airport pavements with asphalt rubber overlays. In the case of the Foronda Airport in Vitoria, Spain, the runway is 3.5 km long and its pavement is constructed from PCC slabs. There are partial breaks in some of the slabs and signs of fatigue have appeared around the contact points. The region has a intermediate climate, with temperatures as low as -1 oC in the winter. Several alternatives were suggested for use as the overlay. In the end, 10 cm of bituminous mixes with asphalt rubber were added. This article presents an overlay design procedure 2 Asphalt Rubber 2012 based on the FAARFIELD (Federal Aviation Administration Rigid and Flexible Iterative Elastic Layered Design) program, combined with a method of thickness reduction previously applied only to highways. The application of ...
Construction and Building Materials
Construction and Building Materials
Materials
Nowadays, the self-healing of asphalt pavements promoted by microwave radiation heating energy is... more Nowadays, the self-healing of asphalt pavements promoted by microwave radiation heating energy is gaining attention and strength in the scientific community. However, most of these studies are only conceptual and, thus, remain shrouded in uncertainty regarding technology development, economy, and application effect. Therefore, there are several efforts underway to offer more effective assisted healing treatments that are capable of overcoming such uncertainties. This paper aims to assess and quantify the healing performance rates (HR) of half-warm recycled asphalt (HWRA) mixtures containing electric arc furnace (EAF) slag and total recycled asphalt pavement (RAP) rates. To this end, a novel assisted thermomechanical healing treatment (i.e., a recompaction-based technique and microwave heating energy) was put forward to promote the potential healing effect of this treatment on the mechanical properties of the asphalt mixtures. In order to do this, three microwave heating temperatures...
Proceedings 17th International Conference on Microwave and High Frequency Heating, Sep 9, 2019
Over the last ten years the concept of self-healing in asphalt mixtures for road pavements has be... more Over the last ten years the concept of self-healing in asphalt mixtures for road pavements has been reaching great importance due to the fact that this capability allows a material to recuperate original properties after failure. This new generation of asphalt paving materials would allow road agencies to save no renewable resources as aggregates and bitumen, making the road investments more efficient. Probably the most promising method for the in-situ heating of the pavements is the radiation by microwaves. By heating the pavement, the asphalt binder gets melt and refills the cracks in the material, recuperating a part of its initial structural parameters. Unfortunately, asphalt mixture components (aggregates and binder) are low sensitive to microwave energy. This is why it may be advantageous to incorporate in the mixture additives to improve the sensibility to the radiation with microwaves. In this investigation two additives were studied: graphene and electric arc furnace (EAF) slag coming from the steel industry. These additives were incorporated at several contents and the efficiency of the heating process was evaluated by the ratio ºC/kwh/kg in order to optimize the content of the additive in the asphalt mixture. Additionally, an evaluation of the electrical conductivity of the asphalt mixture at different contents of additives were carried out to study the possible relation between the conductivity of the mixture and its sensibility to microwave radiation. As a result of the investigation, it seems that microwave radiation can be a real option to promote in situ self-healing of asphalt pavements.
Construction and Building Materials
Applied Sciences
Pavement preventive maintenance is an important tool for extending the service life of the road p... more Pavement preventive maintenance is an important tool for extending the service life of the road pavements. Microwave heating seems to be a promising technology for this application, as bituminous materials have the potential to self-repair above a certain temperature. As ordinary asphalt mixture has low microwave absorbing properties, some additives should be used to improve the heating efficiency. In this paper, the effect of adding Electric Arc Furnace (EAF) slag and Graphene Nanoplatelets (GNPs) on the microwave heating and healing efficiency of asphalt mixtures was evaluated. Microwave heating efficiency was assessed by heating the specimens using several heating times. In addition, the electrical resistivity of the mixtures was measured to understand its possible relationship with the microwave heating process. Furthermore, the healing rates of the asphalt mixtures were assessed by repeated Indirect Tensile Strength (ITS) tests. The results obtained indicate that the additions ...
Materials and Structures, 2017
The growing concern regarding global warming has led to the recent development of warm mix asphal... more The growing concern regarding global warming has led to the recent development of warm mix asphalt (WMA) technology in the field of pavement materials. Production and compaction temperatures can be reduced by lowering the binder viscosity and in turn reduce greenhouse gas emissions (GHG) and energy consumption without significantly changing the mechanical characteristics of the mixtures. There are different additives and technologies which reduce production temperatures, but not all of them have been studied, especially regarding asphalt rubber (AR) mixtures with a high content of rubber (20% over the weight of bitumen). These mixtures, with a high viscosity binder, must be produced at higher temperatures compared to a conventional mixture. This study contrasted and assessed AR mixtures with waxes as WMA additives in order to test: water sensitivity, resistance to permanent deformation and fatigue as well as stiffness. The study demonstrated that the waxes used enhance resistance to permanent deformation without compromising fatigue resistance. Water resistance is slightly inferior and the stiffness modulus depends on production temperature.
Proceedings of 6th Eurasphalt & Eurobitume Congress, 2016
Energy consumption and the corresponding greenhouse gas (GHG) emissions can be reduced with techn... more Energy consumption and the corresponding greenhouse gas (GHG) emissions can be reduced with technology recently developed in the field of road pavement materials: warm mix asphalt (WMA). This technology is being incorporated to improve workability and, consequently, production and compaction temperatures of asphalt mixtures can be lowered without significantly affecting their mechanical properties. However, since this technology is relatively new, the influence of WMA additives on the properties of crumb rubber modified (CRM) binders has not yet been investigated in depth and clearly identified. The main objective of this study is to investigate the effect of different types and quantities of WMA additives on the high and intermediate temperature properties of a 20%CRM binder. For this purpose, binder´s properties are determined using a dynamic shear rheometer (DSR) which allows elastic, viscoelastic and viscous properties of bitumen to be defined over a wide range of temperatures and frequencies. The results of this study indicate that there are significant improvements produced by the additives concerning the mechanical behaviour and the elasticity for the whole temperature range; the complex modulus (stiffness) is increased at the high temperatures avoiding permanent deformation and the phase angle curve is shifted on lower values over a wide range of frequencies. However, the increased content of additives slightly shifted the complex modulus master curves in high frequency regions, increasing the stiffness at low temperatures.
Materials and Structures, 2016
Pavements containing crumb-rubber modified (CRM) binders present one major drawback: larger amoun... more Pavements containing crumb-rubber modified (CRM) binders present one major drawback: larger amounts of greenhouse gas emissions are produced as there is an increase in the energy consumption at the asphalt plant due to the greater viscosity of these type of binders compared with a conventional mixture. One possible solution to this problem could be the Warm Mix Asphalt (WMA) technology, which has been developed recently to reduce the manufacturing and paving temperatures of asphalt mixtures. The WMA additives may improve the mixture’s workability without significantly affecting the mechanical properties of the pavement materials. However, most of the existing research has been focused on conventional asphalt pavements while asphalt rubber mixtures with WMA additives have yet to be studied in detail. The present study includes the results of tests performed using a dynamic shear rheometer of 15 and 20 % CRM binders that incorporate two different types of organic WMA additives (waxes) to provide information about the trend of the complex modulus and the phase angle in function of frequency sweeps. The master curves have highlighted the significant change produced by the additives regarding their rheological behaviour and the non-applicability of the time–temperature superposition principle. The results suggest that these binders might be appropriate for countries with warm climates although further tests should be made to evaluate the behaviour of the mixtures that contain these binders at low temperatures.
Materiales de Construcción, 2007
En este trabajo se dosificaron mezclas bituminosas fabricadas con áridos reciclados de residuos d... more En este trabajo se dosificaron mezclas bituminosas fabricadas con áridos reciclados de residuos de construcción y demolición. Se realizaron una serie de ensayos que permitieron caracterizar el comportamiento mecánico de estas mezclas. Los parámetros mecánicos de las mezclas con áridos reciclados son similares a los de las mezclas fabricadas únicamente con áridos naturales de cantera. Sin embargo, las mezclas bituminosas con áridos reciclados tuvieron un mal comportamiento frente a la disminución de la resistencia por pérdida de cohesión por la acción del agua. No obstante, mediante la selección de materiales de mejor calidad y corrección de este mal comportamiento, existen posibilidades de utilizar áridos reciclados en mezclas bituminosas. Para ello será necesario ampliar la primera aproximación realizada en este artículo.
Sustainability
The extent of rubber-bitumen interaction in crumb rubber modified (CRM) binders depends on the co... more The extent of rubber-bitumen interaction in crumb rubber modified (CRM) binders depends on the contact time of rubber-bitumen as well as the temperature and mixing energy. However, this can vary depending on the composition of the base binders as well as the characteristics of the rubber particles (composition, method of grinding, and size). The present study aims to determine the influence of the composition of the base binders and the type of rubber on the properties of the crumb-rubber modified (CRM) binders and the performance of the asphalt mixtures produced with them. To carry out this project, two different base binders were chosen with the same penetration grade but different naphthenic-aromatic content (56.7 versus 46.0%). Additionally, different types of ambient ground rubber powder were evaluated: two different sources (70% of truck tyres +30% of passenger car tyres and 100% of truck tyres) and two different maximum particle sizes (0.8 and 1.25 mm). According to the main ...
Materials
Stone mastic asphalt (SMA) mixtures exhibit excellent behaviour; they are highly resistant to ref... more Stone mastic asphalt (SMA) mixtures exhibit excellent behaviour; they are highly resistant to reflective cracking and permanent deformation, as well as providing the wearing surface with an optimal texture. However, the production and compaction temperatures are similar to conventional mixtures, which means that there is a significant consumption of energy, as well as greenhouse gas emissions. Warm mix asphalt (WMA) technology, which has been developed over the last few years, might allow lower temperatures without compromising the mechanical behaviour of the mixtures. Also, over the last few decades, rubberized asphalt has proved to be effective in improving the performance and being environmentally suitable, but it requires higher production temperatures than conventional mixtures. In this study, several tests were performed to evaluate the effect of a chemical WMA additive on the compactability and water sensitivity of rubberized SMA mixtures with both the Marshall and the gyrato...
Environmental Research Letters
La innovación docente como misión del profesorado : Congreso Internacional Sobre Aprendizaje, Innovación y Competitividad, 2017
Resumen-Las prácticas de laboratorio en enseñanza universitaria están siendo sustituidas en mucho... more Resumen-Las prácticas de laboratorio en enseñanza universitaria están siendo sustituidas en muchos casos por laboratorios virtuales o entornos Web que permiten trabajar a distancia. Sin embargo, parece ser que el mejor modelo docente en este ámbito está constituido por una combinación de las tradicionales prácticas presenciales en el laboratorio y laboratorios virtuales o entornos Web que complementen las prácticas reales. Esta comunicación técnica presenta el Proyecto LCweb. Se trata de un entorno Web que no sustituye sino complementa las prácticas
Materiales de Construcción, 2017
This study examines the potential of adding electric arc furnace slag to bituminous mixtures to b... more This study examines the potential of adding electric arc furnace slag to bituminous mixtures to be heated by microwaves. The susceptibility of bituminous mixtures to microwave energy is limited and so, in order to improve the energy performance of the heating process, it is necessary to incorporate additives or components to the mixture so as to improve the capacity for microwave heating. The article presents the results of adding various components, (steel wool, scrap tire wire, silicon carbide, iron filings) and an alternative aggregate: electric arc furnace slag. According to the results obtained in the laboratory, slag addition of at least 5% by weight of the bituminous mixture represents the best option for both technical and economic reasons. The results may promote the valorization of this steel industry residue in bituminous mixtures by improving microwave heating response.
Construction and Building Materials, 2013
Over the last ten years the concept of self-healing in asphalt mixtures for road pavements has be... more Over the last ten years the concept of self-healing in asphalt mixtures for road pavements has been reaching great importance due to the fact that this capability allows a material to recuperate original properties after failure. This new generation of asphalt paving materials would allow road agencies to save no renewable resources as aggregates and bitumen, making the road investments more efficient. Probably the most promising method for the in-situ heating of the pavements is the radiation by microwaves. By heating the pavement, the asphalt binder gets melt and refills the cracks in the material, recuperating a part of its initial structural parameters. Unfortunately, asphalt mixture components (aggregates and binder) are low sensitive to microwave energy. This is why it may be advantageous to incorporate in the mixture additives to improve the sensibility to the radiation with microwaves. In this investigation two additives were studied: graphene and electric arc furnace (EAF) slag coming from the steel industry. These additives were incorporated at several contents and the efficiency of the heating process was evaluated by the ratio ºC/kwh/kg in order to optimize the content of the additive in the asphalt mixture. Additionally, an evaluation of the electrical conductivity of the asphalt mixture at different contents of additives were carried out to study the possible relation between the conductivity of the mixture and its sensibility to microwave radiation. As a result of the investigation, it seems that microwave radiation can be a real option to promote in situ self-healing of asphalt pavements.
Materials, 2021
Compaction of cold asphalt mixtures is a subject that has not been thoroughly studied, and, for t... more Compaction of cold asphalt mixtures is a subject that has not been thoroughly studied, and, for this reason, requires new efforts from researchers to have a better understanding. Unlike hot mixtures, cold mixtures and mainly recycled mixtures require specific considerations for compaction. There is a lack of consensus about the methodology to select the optimum premix water and emulsion contents. In the absence of specific regulations, the use of soil tests or hot mixtures procedures is common. For these reasons, this investigation’s main goal was to evaluate two compaction methods used to design cold recycled mixtures with emulsion: the modified Proctor procedure and the gyratory compaction. It was concluded that both methods could be useful to study compactability since consistent results were obtained by applying the maximum bulk density criterion. However, the higher bulk densities achieved, the smaller specimens used, and the suitability of the gyratory specimens to be later te...
Road and Rail Infrastructure V
This work evaluates resistance to plastic deformation and cracking of two hot asphalt mixtures ma... more This work evaluates resistance to plastic deformation and cracking of two hot asphalt mixtures made with recycled aggregates from construction and demolition debris. On the basis of this study it was inferred that the samples designed with recycled aggregates result in a stiffer mixture and are more resistant to plastic deformation. From the standpoint of fatigue behaviour, however, they present a lower fatigue life for a given deformation amplitude. Finally, a multi-layered elastic-linear model was used to determine the variation in the service life of a section of pavement earmarked for roads with low traffic volumes when layers containing recycled aggregates are added. The viability of the use of construction and demolition debris in hot asphalt mixtures was verified, since the number of standard axles that the section can carry is greater than the predicted number of standard axles that will be carried during the service life of the pavement.
Asphalt mixes with asphalt rubber have been widely employed in highway pavements. However, their ... more Asphalt mixes with asphalt rubber have been widely employed in highway pavements. However, their use is much less common in airport runways. This paper proposes a design method for rehabilitation of PCC airport pavements with asphalt rubber overlays. In the case of the Foronda Airport in Vitoria, Spain, the runway is 3.5 km long and its pavement is constructed from PCC slabs. There are partial breaks in some of the slabs and signs of fatigue have appeared around the contact points. The region has a intermediate climate, with temperatures as low as -1 oC in the winter. Several alternatives were suggested for use as the overlay. In the end, 10 cm of bituminous mixes with asphalt rubber were added. This article presents an overlay design procedure 2 Asphalt Rubber 2012 based on the FAARFIELD (Federal Aviation Administration Rigid and Flexible Iterative Elastic Layered Design) program, combined with a method of thickness reduction previously applied only to highways. The application of ...
Construction and Building Materials
Construction and Building Materials
Materials
Nowadays, the self-healing of asphalt pavements promoted by microwave radiation heating energy is... more Nowadays, the self-healing of asphalt pavements promoted by microwave radiation heating energy is gaining attention and strength in the scientific community. However, most of these studies are only conceptual and, thus, remain shrouded in uncertainty regarding technology development, economy, and application effect. Therefore, there are several efforts underway to offer more effective assisted healing treatments that are capable of overcoming such uncertainties. This paper aims to assess and quantify the healing performance rates (HR) of half-warm recycled asphalt (HWRA) mixtures containing electric arc furnace (EAF) slag and total recycled asphalt pavement (RAP) rates. To this end, a novel assisted thermomechanical healing treatment (i.e., a recompaction-based technique and microwave heating energy) was put forward to promote the potential healing effect of this treatment on the mechanical properties of the asphalt mixtures. In order to do this, three microwave heating temperatures...
Proceedings 17th International Conference on Microwave and High Frequency Heating, Sep 9, 2019
Over the last ten years the concept of self-healing in asphalt mixtures for road pavements has be... more Over the last ten years the concept of self-healing in asphalt mixtures for road pavements has been reaching great importance due to the fact that this capability allows a material to recuperate original properties after failure. This new generation of asphalt paving materials would allow road agencies to save no renewable resources as aggregates and bitumen, making the road investments more efficient. Probably the most promising method for the in-situ heating of the pavements is the radiation by microwaves. By heating the pavement, the asphalt binder gets melt and refills the cracks in the material, recuperating a part of its initial structural parameters. Unfortunately, asphalt mixture components (aggregates and binder) are low sensitive to microwave energy. This is why it may be advantageous to incorporate in the mixture additives to improve the sensibility to the radiation with microwaves. In this investigation two additives were studied: graphene and electric arc furnace (EAF) slag coming from the steel industry. These additives were incorporated at several contents and the efficiency of the heating process was evaluated by the ratio ºC/kwh/kg in order to optimize the content of the additive in the asphalt mixture. Additionally, an evaluation of the electrical conductivity of the asphalt mixture at different contents of additives were carried out to study the possible relation between the conductivity of the mixture and its sensibility to microwave radiation. As a result of the investigation, it seems that microwave radiation can be a real option to promote in situ self-healing of asphalt pavements.
Construction and Building Materials
Applied Sciences
Pavement preventive maintenance is an important tool for extending the service life of the road p... more Pavement preventive maintenance is an important tool for extending the service life of the road pavements. Microwave heating seems to be a promising technology for this application, as bituminous materials have the potential to self-repair above a certain temperature. As ordinary asphalt mixture has low microwave absorbing properties, some additives should be used to improve the heating efficiency. In this paper, the effect of adding Electric Arc Furnace (EAF) slag and Graphene Nanoplatelets (GNPs) on the microwave heating and healing efficiency of asphalt mixtures was evaluated. Microwave heating efficiency was assessed by heating the specimens using several heating times. In addition, the electrical resistivity of the mixtures was measured to understand its possible relationship with the microwave heating process. Furthermore, the healing rates of the asphalt mixtures were assessed by repeated Indirect Tensile Strength (ITS) tests. The results obtained indicate that the additions ...
Materials and Structures, 2017
The growing concern regarding global warming has led to the recent development of warm mix asphal... more The growing concern regarding global warming has led to the recent development of warm mix asphalt (WMA) technology in the field of pavement materials. Production and compaction temperatures can be reduced by lowering the binder viscosity and in turn reduce greenhouse gas emissions (GHG) and energy consumption without significantly changing the mechanical characteristics of the mixtures. There are different additives and technologies which reduce production temperatures, but not all of them have been studied, especially regarding asphalt rubber (AR) mixtures with a high content of rubber (20% over the weight of bitumen). These mixtures, with a high viscosity binder, must be produced at higher temperatures compared to a conventional mixture. This study contrasted and assessed AR mixtures with waxes as WMA additives in order to test: water sensitivity, resistance to permanent deformation and fatigue as well as stiffness. The study demonstrated that the waxes used enhance resistance to permanent deformation without compromising fatigue resistance. Water resistance is slightly inferior and the stiffness modulus depends on production temperature.
Proceedings of 6th Eurasphalt & Eurobitume Congress, 2016
Energy consumption and the corresponding greenhouse gas (GHG) emissions can be reduced with techn... more Energy consumption and the corresponding greenhouse gas (GHG) emissions can be reduced with technology recently developed in the field of road pavement materials: warm mix asphalt (WMA). This technology is being incorporated to improve workability and, consequently, production and compaction temperatures of asphalt mixtures can be lowered without significantly affecting their mechanical properties. However, since this technology is relatively new, the influence of WMA additives on the properties of crumb rubber modified (CRM) binders has not yet been investigated in depth and clearly identified. The main objective of this study is to investigate the effect of different types and quantities of WMA additives on the high and intermediate temperature properties of a 20%CRM binder. For this purpose, binder´s properties are determined using a dynamic shear rheometer (DSR) which allows elastic, viscoelastic and viscous properties of bitumen to be defined over a wide range of temperatures and frequencies. The results of this study indicate that there are significant improvements produced by the additives concerning the mechanical behaviour and the elasticity for the whole temperature range; the complex modulus (stiffness) is increased at the high temperatures avoiding permanent deformation and the phase angle curve is shifted on lower values over a wide range of frequencies. However, the increased content of additives slightly shifted the complex modulus master curves in high frequency regions, increasing the stiffness at low temperatures.
Materials and Structures, 2016
Pavements containing crumb-rubber modified (CRM) binders present one major drawback: larger amoun... more Pavements containing crumb-rubber modified (CRM) binders present one major drawback: larger amounts of greenhouse gas emissions are produced as there is an increase in the energy consumption at the asphalt plant due to the greater viscosity of these type of binders compared with a conventional mixture. One possible solution to this problem could be the Warm Mix Asphalt (WMA) technology, which has been developed recently to reduce the manufacturing and paving temperatures of asphalt mixtures. The WMA additives may improve the mixture’s workability without significantly affecting the mechanical properties of the pavement materials. However, most of the existing research has been focused on conventional asphalt pavements while asphalt rubber mixtures with WMA additives have yet to be studied in detail. The present study includes the results of tests performed using a dynamic shear rheometer of 15 and 20 % CRM binders that incorporate two different types of organic WMA additives (waxes) to provide information about the trend of the complex modulus and the phase angle in function of frequency sweeps. The master curves have highlighted the significant change produced by the additives regarding their rheological behaviour and the non-applicability of the time–temperature superposition principle. The results suggest that these binders might be appropriate for countries with warm climates although further tests should be made to evaluate the behaviour of the mixtures that contain these binders at low temperatures.
Materiales de Construcción, 2007
En este trabajo se dosificaron mezclas bituminosas fabricadas con áridos reciclados de residuos d... more En este trabajo se dosificaron mezclas bituminosas fabricadas con áridos reciclados de residuos de construcción y demolición. Se realizaron una serie de ensayos que permitieron caracterizar el comportamiento mecánico de estas mezclas. Los parámetros mecánicos de las mezclas con áridos reciclados son similares a los de las mezclas fabricadas únicamente con áridos naturales de cantera. Sin embargo, las mezclas bituminosas con áridos reciclados tuvieron un mal comportamiento frente a la disminución de la resistencia por pérdida de cohesión por la acción del agua. No obstante, mediante la selección de materiales de mejor calidad y corrección de este mal comportamiento, existen posibilidades de utilizar áridos reciclados en mezclas bituminosas. Para ello será necesario ampliar la primera aproximación realizada en este artículo.
Sustainability
The extent of rubber-bitumen interaction in crumb rubber modified (CRM) binders depends on the co... more The extent of rubber-bitumen interaction in crumb rubber modified (CRM) binders depends on the contact time of rubber-bitumen as well as the temperature and mixing energy. However, this can vary depending on the composition of the base binders as well as the characteristics of the rubber particles (composition, method of grinding, and size). The present study aims to determine the influence of the composition of the base binders and the type of rubber on the properties of the crumb-rubber modified (CRM) binders and the performance of the asphalt mixtures produced with them. To carry out this project, two different base binders were chosen with the same penetration grade but different naphthenic-aromatic content (56.7 versus 46.0%). Additionally, different types of ambient ground rubber powder were evaluated: two different sources (70% of truck tyres +30% of passenger car tyres and 100% of truck tyres) and two different maximum particle sizes (0.8 and 1.25 mm). According to the main ...
Materials
Stone mastic asphalt (SMA) mixtures exhibit excellent behaviour; they are highly resistant to ref... more Stone mastic asphalt (SMA) mixtures exhibit excellent behaviour; they are highly resistant to reflective cracking and permanent deformation, as well as providing the wearing surface with an optimal texture. However, the production and compaction temperatures are similar to conventional mixtures, which means that there is a significant consumption of energy, as well as greenhouse gas emissions. Warm mix asphalt (WMA) technology, which has been developed over the last few years, might allow lower temperatures without compromising the mechanical behaviour of the mixtures. Also, over the last few decades, rubberized asphalt has proved to be effective in improving the performance and being environmentally suitable, but it requires higher production temperatures than conventional mixtures. In this study, several tests were performed to evaluate the effect of a chemical WMA additive on the compactability and water sensitivity of rubberized SMA mixtures with both the Marshall and the gyrato...
Environmental Research Letters