Recent research has shown that fatigue life in non strain-crystallising rubber increases if the m... more Recent research has shown that fatigue life in non strain-crystallising rubber increases if the material is subjected to pre-loading. The central research question posed in this project is ‘whether preloading and surface treatments improve the surface finish of rubber components, reduce stress concentration and can this reduction partially account for greater fatigue resistance’. The specific objectives of the research are:-
ABSTRACT There is a need for a method for assessing the results from changes in the potential dur... more ABSTRACT There is a need for a method for assessing the results from changes in the potential durability of road materials due to the inclusion of reclaimed and secondary component materials in the manufacture of new road materials. Such changes will have an effect on the cost of the construction maintenance, both financially to the client and environmentally to society in general, and any savings may be transitory. A site trial has been laid of mixtures with and without reclaimed asphalt and work started to assess their durability from early-life properties. The trials are being monitored for their initial performance whilst laboratory trials are concentrating on the combined effect of ageing and moisture damage on the performance of asphalt mixtures on the trial. All three strands are being used to develop life-cycle analysis models to customize them for the effect of using alternative component materials on the availability of the network and their overall financial and environmental cost, both initial and whole-life. The costs will be identified as being direct (of the construction and maintenance) and indirect (on society in general, such as congestion).
This paper investigates the applicability of a cohesive zone model for simulating the performance... more This paper investigates the applicability of a cohesive zone model for simulating the performance of bituminous material subjected to quasi-static loading. The Dugdale traction law was implemented within a finite volume code in order to simulate the binder course mortar material response when subjected to indirect tensile loading. A uniaxial tensile test and a three-point bend test were employed to determine initial stress-strain curves at different test rates and the cohesive zone parameters (specifically, fracture energy and cohesive strength). Numerical results agree well with the experimental data up to the peak load and onset of fracture, demonstrating the value of the cohesive zone modelling technique in successfully predicting fracture initiation and maximum material strength.
ABSTRACT Non-destructive testing of rubber by optical means presents a challenge because rubber h... more ABSTRACT Non-destructive testing of rubber by optical means presents a challenge because rubber has different mechanical properties from conventional solids when subjected to stress. The size of flaws introduced in rubber during the manufacturing process is an important characteristic as they increase the stress in the specimen when it is in use. The use of electronic speckle pattern interferometry, electronic speckle pattern shearing interferometry and white light interferometry for non-destructive material characterization of rubber is presented. It is shown that electronic speckle pattern shearing interferometry can be of some use for visualization of flaws on the rubber surface under thermal stress. White light interferometry gives a complete profiling of the elastomer surface and it is only one of the three interferometric techniques for measuring flaws on the rubber surface.
This paper presents the physical properties of recycled asphalt pavement ͑RAP͒ and its influence ... more This paper presents the physical properties of recycled asphalt pavement ͑RAP͒ and its influence on the mechanical performance of a binder course asphalt pavement mix. A series of binder course mixes were designed containing varying percentages of RAP. A mix made from only virgin material was selected as the control mix for the investigation. The effect of introducing RAP into the binder course mix was evaluated through a series of laboratory tests including the Marshall test, the indirect tensile stiffness modulus test, the indirect tensile fatigue test and the water sensitivity test. A circular wheel track ͑CWT͒ was developed in order to study the dynamic effects of a rolling wheel traveling over an asphalt pavement. The CWT was commissioned within a temperature controlled room along with a customized data acquisition system. The system involves the testing of rectangular slabs and allows for the investigation of dynamic tensile strain. The laboratory tests have shown that the introduction of RAP to the binder course mix resulted in an improvement in all mechanical properties. In particular, it was found that the mix containing up to 30% RAP, displayed improved fatigue resistance relative to the control mix manufactured from virgin materials.
This paper investigates the applicability of a cohesive zone model for simulating the performance... more This paper investigates the applicability of a cohesive zone model for simulating the performance of bituminous material subjected to quasi-static loading. The Dugdale traction law was implemented within a finite volume code in order to simulate the binder course mortar material response when subjected to indirect tensile loading. A uniaxial tensile test and a three-point bend test were employed to determine initial stress-strain curves at different test rates and the cohesive zone parameters (specifically, fracture energy and cohesive strength). Numerical results agree well with the experimental data up to the peak load and onset of fracture, demonstrating the value of the cohesive zone modelling technique in successfully predicting fracture initiation and maximum material strength.
ABSTRACT Cold-mix bituminous materials offer a sustainable, cost effective alternative to traditi... more ABSTRACT Cold-mix bituminous materials offer a sustainable, cost effective alternative to traditional hot-mixes. Difficulties however can be encountered when specifying cold-mix materials due to the strong influence of time and temperature on material performance. In the field of concrete technology maturity methods are routinely used for assessing materials of known curing history. This research presents the development of a maturity approach for the assessment of cold-mix bituminous materials and its application for predicting the effect of climatic variations on in situ mixture performance. A strong correlation was observed between the calculated maturity and the measured stiffness for a range of conditioning temperatures and durations thus enabling the prediction of long and short-term material performance in situ where ambient conditions are known.
ABSTRACT: This paper presents the results of ongoing research on the mechanical performance of a ... more ABSTRACT: This paper presents the results of ongoing research on the mechanical performance of a 20mm binder course asphalt pavement mix incorporating recycled asphalt pavement (RAP). A series of binder course mixes were designed containing varying percentages of ...
Page 1. Abstract for COMPTEST conference, Porto, April 2006 DEVELOPMENT OF A COMBINED MICROMECHAN... more Page 1. Abstract for COMPTEST conference, Porto, April 2006 DEVELOPMENT OF A COMBINED MICROMECHANICS & DAMAGE MECHANICS MODEL FOR THE DESIGN OF ASPHALT PAVEMENTS A. Tabaković1,2, C. McNally1, LG Sorelli1, A. Gibney1, MD Gilchrist2* ...
Self-healing technology is a new field within material technology. It represents a revolution in ... more Self-healing technology is a new field within material technology. It represents a revolution in materials engineering and is changing the way that materials behave. Incorporating self-healing technology into the road design process has the potential to transform road construction and maintenance processes by increasing the lifespan of roads and eliminating the need for road maintenance. By decreasing the unnecessary premature ageing of asphalt pavements, self-healing asphalt can reduce the amount of natural resources used to maintain road networks, decrease the traffic disruption caused by road maintenance processes, decrease CO 2 emissions during the road maintenance process and increase road safety. In addition to environmental savings, self-healing materials have the potential to deliver significant cost savings for road network maintenance across the EU. There are three main self-healing technologies available for asphalt pavement design: nanoparticles, induction heating and rejuvenation. This chapter reviews all three options and outlines the future development of self-healing asphalt technology.
Recent research has shown that fatigue life in non strain-crystallising rubber increases if the m... more Recent research has shown that fatigue life in non strain-crystallising rubber increases if the material is subjected to pre-loading. The central research question posed in this project is ‘whether preloading and surface treatments improve the surface finish of rubber components, reduce stress concentration and can this reduction partially account for greater fatigue resistance’. The specific objectives of the research are:-
ABSTRACT There is a need for a method for assessing the results from changes in the potential dur... more ABSTRACT There is a need for a method for assessing the results from changes in the potential durability of road materials due to the inclusion of reclaimed and secondary component materials in the manufacture of new road materials. Such changes will have an effect on the cost of the construction maintenance, both financially to the client and environmentally to society in general, and any savings may be transitory. A site trial has been laid of mixtures with and without reclaimed asphalt and work started to assess their durability from early-life properties. The trials are being monitored for their initial performance whilst laboratory trials are concentrating on the combined effect of ageing and moisture damage on the performance of asphalt mixtures on the trial. All three strands are being used to develop life-cycle analysis models to customize them for the effect of using alternative component materials on the availability of the network and their overall financial and environmental cost, both initial and whole-life. The costs will be identified as being direct (of the construction and maintenance) and indirect (on society in general, such as congestion).
This paper investigates the applicability of a cohesive zone model for simulating the performance... more This paper investigates the applicability of a cohesive zone model for simulating the performance of bituminous material subjected to quasi-static loading. The Dugdale traction law was implemented within a finite volume code in order to simulate the binder course mortar material response when subjected to indirect tensile loading. A uniaxial tensile test and a three-point bend test were employed to determine initial stress-strain curves at different test rates and the cohesive zone parameters (specifically, fracture energy and cohesive strength). Numerical results agree well with the experimental data up to the peak load and onset of fracture, demonstrating the value of the cohesive zone modelling technique in successfully predicting fracture initiation and maximum material strength.
ABSTRACT Non-destructive testing of rubber by optical means presents a challenge because rubber h... more ABSTRACT Non-destructive testing of rubber by optical means presents a challenge because rubber has different mechanical properties from conventional solids when subjected to stress. The size of flaws introduced in rubber during the manufacturing process is an important characteristic as they increase the stress in the specimen when it is in use. The use of electronic speckle pattern interferometry, electronic speckle pattern shearing interferometry and white light interferometry for non-destructive material characterization of rubber is presented. It is shown that electronic speckle pattern shearing interferometry can be of some use for visualization of flaws on the rubber surface under thermal stress. White light interferometry gives a complete profiling of the elastomer surface and it is only one of the three interferometric techniques for measuring flaws on the rubber surface.
This paper presents the physical properties of recycled asphalt pavement ͑RAP͒ and its influence ... more This paper presents the physical properties of recycled asphalt pavement ͑RAP͒ and its influence on the mechanical performance of a binder course asphalt pavement mix. A series of binder course mixes were designed containing varying percentages of RAP. A mix made from only virgin material was selected as the control mix for the investigation. The effect of introducing RAP into the binder course mix was evaluated through a series of laboratory tests including the Marshall test, the indirect tensile stiffness modulus test, the indirect tensile fatigue test and the water sensitivity test. A circular wheel track ͑CWT͒ was developed in order to study the dynamic effects of a rolling wheel traveling over an asphalt pavement. The CWT was commissioned within a temperature controlled room along with a customized data acquisition system. The system involves the testing of rectangular slabs and allows for the investigation of dynamic tensile strain. The laboratory tests have shown that the introduction of RAP to the binder course mix resulted in an improvement in all mechanical properties. In particular, it was found that the mix containing up to 30% RAP, displayed improved fatigue resistance relative to the control mix manufactured from virgin materials.
This paper investigates the applicability of a cohesive zone model for simulating the performance... more This paper investigates the applicability of a cohesive zone model for simulating the performance of bituminous material subjected to quasi-static loading. The Dugdale traction law was implemented within a finite volume code in order to simulate the binder course mortar material response when subjected to indirect tensile loading. A uniaxial tensile test and a three-point bend test were employed to determine initial stress-strain curves at different test rates and the cohesive zone parameters (specifically, fracture energy and cohesive strength). Numerical results agree well with the experimental data up to the peak load and onset of fracture, demonstrating the value of the cohesive zone modelling technique in successfully predicting fracture initiation and maximum material strength.
ABSTRACT Cold-mix bituminous materials offer a sustainable, cost effective alternative to traditi... more ABSTRACT Cold-mix bituminous materials offer a sustainable, cost effective alternative to traditional hot-mixes. Difficulties however can be encountered when specifying cold-mix materials due to the strong influence of time and temperature on material performance. In the field of concrete technology maturity methods are routinely used for assessing materials of known curing history. This research presents the development of a maturity approach for the assessment of cold-mix bituminous materials and its application for predicting the effect of climatic variations on in situ mixture performance. A strong correlation was observed between the calculated maturity and the measured stiffness for a range of conditioning temperatures and durations thus enabling the prediction of long and short-term material performance in situ where ambient conditions are known.
ABSTRACT: This paper presents the results of ongoing research on the mechanical performance of a ... more ABSTRACT: This paper presents the results of ongoing research on the mechanical performance of a 20mm binder course asphalt pavement mix incorporating recycled asphalt pavement (RAP). A series of binder course mixes were designed containing varying percentages of ...
Page 1. Abstract for COMPTEST conference, Porto, April 2006 DEVELOPMENT OF A COMBINED MICROMECHAN... more Page 1. Abstract for COMPTEST conference, Porto, April 2006 DEVELOPMENT OF A COMBINED MICROMECHANICS & DAMAGE MECHANICS MODEL FOR THE DESIGN OF ASPHALT PAVEMENTS A. Tabaković1,2, C. McNally1, LG Sorelli1, A. Gibney1, MD Gilchrist2* ...
Self-healing technology is a new field within material technology. It represents a revolution in ... more Self-healing technology is a new field within material technology. It represents a revolution in materials engineering and is changing the way that materials behave. Incorporating self-healing technology into the road design process has the potential to transform road construction and maintenance processes by increasing the lifespan of roads and eliminating the need for road maintenance. By decreasing the unnecessary premature ageing of asphalt pavements, self-healing asphalt can reduce the amount of natural resources used to maintain road networks, decrease the traffic disruption caused by road maintenance processes, decrease CO 2 emissions during the road maintenance process and increase road safety. In addition to environmental savings, self-healing materials have the potential to deliver significant cost savings for road network maintenance across the EU. There are three main self-healing technologies available for asphalt pavement design: nanoparticles, induction heating and rejuvenation. This chapter reviews all three options and outlines the future development of self-healing asphalt technology.
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Papers by Amir Tabakovic