Gordon Airey - Academia.edu (original) (raw)

Papers by Gordon Airey

Research paper thumbnail of High Temperature Viscosity of Polymer and Filler Modified Binder Systems

PROCEEDINGS OF THE 3RD EURASPHALT AND EUROBITUME CONGRESS HELD VIENNA, MAY 2004, 2004

This paper describes the influence of polymer type as well as filler type and content on the high... more This paper describes the influence of polymer type as well as filler type and content on the high temperature viscosity and shear rate dependency of a number of modified binder systems. The viscosity testing was undertaken using a Brookfield (rotational) viscometer and the viscosity data analysed in terms of the material's strain dependency and increased high temperature viscosity as related to the practical usage of the material. The results clearly indicate the increased strain rate dependency (non-Newtonian) behaviour of the filler modified systems compared to the strain independent (Newtonian) behaviour of both the conventional bituminous binders and polymer modified systems. Out of five fillers, hydrated lime was found to cause the largest increase in viscosity although all the fillers had a similar effect in terms of increasing the strain rate dependency of the system. The viscosity versus testing time relationship of the bitumen-filler systems was also studied and showed a sharp reduction in initial viscosity with time with the viscosity finally stabilising after approximately ten minutes. The cause of this shear thinning was attributed to a combination of factors including filler sedimentation, localised heating and the addition torque (force) required initially to mobilise and accelerate the suspended and transported filler particles to a uniform shear rate. For the covering abstract see ITRD E121480.

Research paper thumbnail of Viscosity, stiffness and deformation of bituminous materials

Research paper thumbnail of Linear and non-linear rheological properties of asphalt mixtures

Research paper thumbnail of Development of a combined ageing / moisture sensitivity laboratory test

PROCEEDINGS OF THE 3RD EURASPHALT AND EUROBITUME CONGRESS HELD VIENNA, MAY 2004, 2004

This paper describes the development of a combined ageing/moisture sensitivity laboratory test to... more This paper describes the development of a combined ageing/moisture sensitivity laboratory test to evaluate the performance of coated macadam binder course and base mixtures with relatively low binder contents and relatively high air void contents. The test is known as the Saturation Ageing Tensile Stiffness (SATS) test and consists of placing compacted asphalt core samples in a high temperature and pressure environment in the presence of moisture for an extended period of time. The stiffness modulus measured after the test divided by the stiffness modulus measured before the test (retained stiffness modulus), and the specimen saturation after the test (retained saturation), are used as an indication of the sensitivity of the compacted mixture to combined ageing/moisture effects. The test was used to reproduce in the laboratory the loss of stiffness modulus observed on a trial site where High Modulus Base (HMB) had been used. Two different aggregate types (basic and acidic) and four different binders were tested. For the mixtures containing the acidic aggregate, the general trend is for the retained stiffness modulus to reduce from approximately 0.6 at a retained saturation level of 10% to 0.2 at a retained saturation level of between 80% and 100%. At a retained saturation level of 40%, the retained stiffness modulus is approximately 0.4, which compares favourably with the 60% reduction in stiffness modulus observed from the HMB trial site (for nominally identical mixtures). For the mixtures containing the basic aggregate, the retained stiffness modulus remains at an approximately constant value of 0.7 over a wide range of retained saturation levels (between 15% and 80%) indicating a lower sensitivity to moisture. For the low binder content, high air void content mixtures investigated, the effect of changing the binder (source and grade) was small compared to the effect of the aggregate types. The additive of 2% Hydrated Lime Filler (HLF) to mixtures containing the acidic aggregate significantly improved performance showing retained stiffness moduli slightly in excess of those obtained from mixtures containing the basic aggregate. For the covering abstract see ITRD E121480.

Research paper thumbnail of Determination of viscoelastic properties from the indirect tensile stiffness modulus (ITSM) test

This paper describes a method for determining viscoelastic material properties from the Indirect ... more This paper describes a method for determining viscoelastic material properties from the Indirect Tensile Stiffness Modulus (ITSM) test undertaken using the Nottingham Asphalt Tester (NAT). A number of viscoelastic material idealizations have been fitted to ITSM results and the effects of the order of the viscoelastic model (i.e. the number of elements), and the details of the load pulse (rise time, number of load pulses utilized in the fit) have been investigated. Results indicate that the use of a model comprising a Maxwell element in series with two Voigt elements can yield unrealistic and more variable fitted viscoelastic parameters from the simpler model comprising a Maxwell element in series with one Voigt element. The fitted viscoelastic parameters for the model comprising a Maxwell element in series with one Voigt element have been found to show a slight dependence on the rise time in the ITSM test. Results also indicate that the fitted elastic bulk and shear moduli tend to be slightly lower and the shear viscosity and time constants tend to be slightly higher in the case where 5 consecutive load and deflection pulses have been used in the fitting procedure rather than single load and deflection pulses. For the covering abstract see ITRD E117423.

Research paper thumbnail of Sample Preparation Methods, Geometry and Temperature Control for Dynamic Shear Rheometers

CRC Press eBooks, Dec 17, 2020

The dynamic shear rheometer (DSR) can be considered to be one of the most complex and powerful in... more The dynamic shear rheometer (DSR) can be considered to be one of the most complex and powerful instruments for characterising the flow properties of bitumen. This paper describes an investigation into the influence of three sample preparation methods (hot pour, silicone mould and weighing), different sample geometries and the importance of temperature control on the rheological parameters measured during DSR testing. The effect of the different sample preparation methods and sample geometry have been evaluated for a series of unmodified (penetration grade bitumen), process modified and polymer modified bitumens. The results indicate that a method involving the pouring of hot bitumen onto one of the plates of the DSR and then trimming the edge of the sample is the most consistent means of sample preparation. In addition, the magnitude of the measured rheological parameters are influenced by the sample preparation method with the silicone mould and weighing methods producing consistently higher and lower values of complex modulus compared to the hot pour method. For the covering abstract see ITRD E118503.

Research paper thumbnail of Optimisation of the preparation procedure of crumb rubber modified bitumen with wax-based additives

Road Materials and Pavement Design, Mar 24, 2023

Research paper thumbnail of Rheological investigation on the ageing performance of bio-recycled asphalt binders and mixtures

Road Materials and Pavement Design, Feb 27, 2023

Research paper thumbnail of Durability of bituminous mixtures

Research paper thumbnail of Recycling of bituminous materials

Research paper thumbnail of The influence of geometry and sample preparation on dynamic shear rheometer testing

... The Black diagram for the EVA PMB, in Figure 13, and the Dobson plot in Figure 14 ... Black d... more ... The Black diagram for the EVA PMB, in Figure 13, and the Dobson plot in Figure 14 ... Black diagrams in order to determine the actual rheological characteristics of the bituminous binder. ... method of test for determining the rheological properties of asphalt binder using a dynamic ...

Research paper thumbnail of Toward Non-Petroleum-Derived Asphalt Mixes: Using Biobinders for High-Modulus Asphalt Mixes with High Reclaimed Asphalt Content

Transportation Research Board 96th Annual MeetingTransportation Research Board, 2017

Research paper thumbnail of Developments in Bituminous Binders

Research paper thumbnail of Three-Dimensional Truck Tire Contact Pressures and Key Pavement Strains for a Thin Pavement

Transportation Research Board 95th Annual MeetingTransportation Research Board, 2016

There is 3 dimensional (3-D) contact pressure behaviour under a tire in contact with a pavement; ... more There is 3 dimensional (3-D) contact pressure behaviour under a tire in contact with a pavement; these contact pressures are vertical, transverse and longitudinal. This research used measured 3-D contact pressures for truck tires in conjunction with finite element analysis to simulate the effect of this 3-D contact pressure on pavement behaviour. There were three truck tires included in the analysis with three inflation pressures and three axle loadings. The loading combinations these created were also modelled for different combinations of the components of contact pressure. The key strains for pavement surface distress, asphalt (50-80 mm from the surface) distress, bottom-up cracking and subgrade rutting were recorded and analysed. The effect of the 3-D contact pressure varied for the different tires, inflation pressure and axle loading. All the components of 3-D contact pressure were found to be important for the behaviour of the pavement surface. The value and geometry of the vertical contact pressure was found to be important for all pavement behaviour. The components of 3-D contact pressure should be incorporated into pavement design if higher performance and more predictable pavements are to be designed and operated in the future.

Research paper thumbnail of An Investigation Into the Deterioration Mechanisms of Lightly Trafficked Roads

Identification of pavement deterioration mechanisms is an essential area in road maintenance. If ... more Identification of pavement deterioration mechanisms is an essential area in road maintenance. If the mechanisms by which lightly trafficked roads deteriorate can be quantified and understood, improved pavement design procedures can be formulated, with the aim of improving pavement performance and reducing maintenance costs. This paper presents an investigation undertaken to identify the distress mechanisms prevalent in a group of sixteen typical UK lightly trafficked roads. The results indicate a relationship firstly between inadequate unbound granular sub-base thickness and wheel track rutting and longitudinal cracking and, secondly between inflexible, thin, high stiffness bituminous layers and shoulder collapse, particularly if there is a lack of edge support or inadequate drainage. For the covering abstract see ITRD E107185.

Research paper thumbnail of Evaluating the ageing degrees of bitumen by rheological and chemical indices

Road Materials and Pavement Design, Feb 22, 2023

Research paper thumbnail of Evaluation of the Linear and Non-Linear Viscoelastic Behaviour of Bituminous Binders and Asphalt Mixtures

CRC Press eBooks, Dec 17, 2020

Research paper thumbnail of Residual bitumen characteristics following dry process rubber-bitumen interaction

Research paper thumbnail of High and Low Temperature Rheological Characteristics of Low Penetration Grade Bitumen

PROCEEDINGS OF THE 3RD EURASPHALT AND EUROBITUME CONGRESS HELD VIENNA, MAY 2004, 2004

There has been a general trend in the UK to use progressively stiffer roadbase materials, due to ... more There has been a general trend in the UK to use progressively stiffer roadbase materials, due to their expected "long life" performance. However, recent concerns over the durability of these High Modulus Base (HMB) materials containing hard low penetration grade bitumens has questioned the use of these "brittle" binders especially at low temperatures and after ageing. This paper investigates both the high and low temperature rheological characteristics of a semi-blown and straight-run low penetration grade bitumen using a Brookfield (rotational) viscometer, Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR) and Direct Tension Tester (DTT) in order to provide a practical means of selecting an optimum low penetration grade bitumen. The binders have been tested in their virgin condition and after short-term, Rolling Thin Film Oven Test (RTFOT) and long-term, High Pressure Ageing Test (HiPAT) ageing. The results show considerable differences in the high and low temperature rheological properties of the 15 penetration grade bitumens as a function of their production method especially after ageing. In general the semi-blown 15 pen bitumen showed a higher susceptibility to ageing than the polymer modified and direct distillation 15 pen bitumens and an increased elastic "brittle" response to loading in terms of DSR, BBR and DTT test data. For the covering abstract see ITRD E121480.

Research paper thumbnail of Bitumen: Current Situation and Future Challenges

Research paper thumbnail of High Temperature Viscosity of Polymer and Filler Modified Binder Systems

PROCEEDINGS OF THE 3RD EURASPHALT AND EUROBITUME CONGRESS HELD VIENNA, MAY 2004, 2004

This paper describes the influence of polymer type as well as filler type and content on the high... more This paper describes the influence of polymer type as well as filler type and content on the high temperature viscosity and shear rate dependency of a number of modified binder systems. The viscosity testing was undertaken using a Brookfield (rotational) viscometer and the viscosity data analysed in terms of the material's strain dependency and increased high temperature viscosity as related to the practical usage of the material. The results clearly indicate the increased strain rate dependency (non-Newtonian) behaviour of the filler modified systems compared to the strain independent (Newtonian) behaviour of both the conventional bituminous binders and polymer modified systems. Out of five fillers, hydrated lime was found to cause the largest increase in viscosity although all the fillers had a similar effect in terms of increasing the strain rate dependency of the system. The viscosity versus testing time relationship of the bitumen-filler systems was also studied and showed a sharp reduction in initial viscosity with time with the viscosity finally stabilising after approximately ten minutes. The cause of this shear thinning was attributed to a combination of factors including filler sedimentation, localised heating and the addition torque (force) required initially to mobilise and accelerate the suspended and transported filler particles to a uniform shear rate. For the covering abstract see ITRD E121480.

Research paper thumbnail of Viscosity, stiffness and deformation of bituminous materials

Research paper thumbnail of Linear and non-linear rheological properties of asphalt mixtures

Research paper thumbnail of Development of a combined ageing / moisture sensitivity laboratory test

PROCEEDINGS OF THE 3RD EURASPHALT AND EUROBITUME CONGRESS HELD VIENNA, MAY 2004, 2004

This paper describes the development of a combined ageing/moisture sensitivity laboratory test to... more This paper describes the development of a combined ageing/moisture sensitivity laboratory test to evaluate the performance of coated macadam binder course and base mixtures with relatively low binder contents and relatively high air void contents. The test is known as the Saturation Ageing Tensile Stiffness (SATS) test and consists of placing compacted asphalt core samples in a high temperature and pressure environment in the presence of moisture for an extended period of time. The stiffness modulus measured after the test divided by the stiffness modulus measured before the test (retained stiffness modulus), and the specimen saturation after the test (retained saturation), are used as an indication of the sensitivity of the compacted mixture to combined ageing/moisture effects. The test was used to reproduce in the laboratory the loss of stiffness modulus observed on a trial site where High Modulus Base (HMB) had been used. Two different aggregate types (basic and acidic) and four different binders were tested. For the mixtures containing the acidic aggregate, the general trend is for the retained stiffness modulus to reduce from approximately 0.6 at a retained saturation level of 10% to 0.2 at a retained saturation level of between 80% and 100%. At a retained saturation level of 40%, the retained stiffness modulus is approximately 0.4, which compares favourably with the 60% reduction in stiffness modulus observed from the HMB trial site (for nominally identical mixtures). For the mixtures containing the basic aggregate, the retained stiffness modulus remains at an approximately constant value of 0.7 over a wide range of retained saturation levels (between 15% and 80%) indicating a lower sensitivity to moisture. For the low binder content, high air void content mixtures investigated, the effect of changing the binder (source and grade) was small compared to the effect of the aggregate types. The additive of 2% Hydrated Lime Filler (HLF) to mixtures containing the acidic aggregate significantly improved performance showing retained stiffness moduli slightly in excess of those obtained from mixtures containing the basic aggregate. For the covering abstract see ITRD E121480.

Research paper thumbnail of Determination of viscoelastic properties from the indirect tensile stiffness modulus (ITSM) test

This paper describes a method for determining viscoelastic material properties from the Indirect ... more This paper describes a method for determining viscoelastic material properties from the Indirect Tensile Stiffness Modulus (ITSM) test undertaken using the Nottingham Asphalt Tester (NAT). A number of viscoelastic material idealizations have been fitted to ITSM results and the effects of the order of the viscoelastic model (i.e. the number of elements), and the details of the load pulse (rise time, number of load pulses utilized in the fit) have been investigated. Results indicate that the use of a model comprising a Maxwell element in series with two Voigt elements can yield unrealistic and more variable fitted viscoelastic parameters from the simpler model comprising a Maxwell element in series with one Voigt element. The fitted viscoelastic parameters for the model comprising a Maxwell element in series with one Voigt element have been found to show a slight dependence on the rise time in the ITSM test. Results also indicate that the fitted elastic bulk and shear moduli tend to be slightly lower and the shear viscosity and time constants tend to be slightly higher in the case where 5 consecutive load and deflection pulses have been used in the fitting procedure rather than single load and deflection pulses. For the covering abstract see ITRD E117423.

Research paper thumbnail of Sample Preparation Methods, Geometry and Temperature Control for Dynamic Shear Rheometers

CRC Press eBooks, Dec 17, 2020

The dynamic shear rheometer (DSR) can be considered to be one of the most complex and powerful in... more The dynamic shear rheometer (DSR) can be considered to be one of the most complex and powerful instruments for characterising the flow properties of bitumen. This paper describes an investigation into the influence of three sample preparation methods (hot pour, silicone mould and weighing), different sample geometries and the importance of temperature control on the rheological parameters measured during DSR testing. The effect of the different sample preparation methods and sample geometry have been evaluated for a series of unmodified (penetration grade bitumen), process modified and polymer modified bitumens. The results indicate that a method involving the pouring of hot bitumen onto one of the plates of the DSR and then trimming the edge of the sample is the most consistent means of sample preparation. In addition, the magnitude of the measured rheological parameters are influenced by the sample preparation method with the silicone mould and weighing methods producing consistently higher and lower values of complex modulus compared to the hot pour method. For the covering abstract see ITRD E118503.

Research paper thumbnail of Optimisation of the preparation procedure of crumb rubber modified bitumen with wax-based additives

Road Materials and Pavement Design, Mar 24, 2023

Research paper thumbnail of Rheological investigation on the ageing performance of bio-recycled asphalt binders and mixtures

Road Materials and Pavement Design, Feb 27, 2023

Research paper thumbnail of Durability of bituminous mixtures

Research paper thumbnail of Recycling of bituminous materials

Research paper thumbnail of The influence of geometry and sample preparation on dynamic shear rheometer testing

... The Black diagram for the EVA PMB, in Figure 13, and the Dobson plot in Figure 14 ... Black d... more ... The Black diagram for the EVA PMB, in Figure 13, and the Dobson plot in Figure 14 ... Black diagrams in order to determine the actual rheological characteristics of the bituminous binder. ... method of test for determining the rheological properties of asphalt binder using a dynamic ...

Research paper thumbnail of Toward Non-Petroleum-Derived Asphalt Mixes: Using Biobinders for High-Modulus Asphalt Mixes with High Reclaimed Asphalt Content

Transportation Research Board 96th Annual MeetingTransportation Research Board, 2017

Research paper thumbnail of Developments in Bituminous Binders

Research paper thumbnail of Three-Dimensional Truck Tire Contact Pressures and Key Pavement Strains for a Thin Pavement

Transportation Research Board 95th Annual MeetingTransportation Research Board, 2016

There is 3 dimensional (3-D) contact pressure behaviour under a tire in contact with a pavement; ... more There is 3 dimensional (3-D) contact pressure behaviour under a tire in contact with a pavement; these contact pressures are vertical, transverse and longitudinal. This research used measured 3-D contact pressures for truck tires in conjunction with finite element analysis to simulate the effect of this 3-D contact pressure on pavement behaviour. There were three truck tires included in the analysis with three inflation pressures and three axle loadings. The loading combinations these created were also modelled for different combinations of the components of contact pressure. The key strains for pavement surface distress, asphalt (50-80 mm from the surface) distress, bottom-up cracking and subgrade rutting were recorded and analysed. The effect of the 3-D contact pressure varied for the different tires, inflation pressure and axle loading. All the components of 3-D contact pressure were found to be important for the behaviour of the pavement surface. The value and geometry of the vertical contact pressure was found to be important for all pavement behaviour. The components of 3-D contact pressure should be incorporated into pavement design if higher performance and more predictable pavements are to be designed and operated in the future.

Research paper thumbnail of An Investigation Into the Deterioration Mechanisms of Lightly Trafficked Roads

Identification of pavement deterioration mechanisms is an essential area in road maintenance. If ... more Identification of pavement deterioration mechanisms is an essential area in road maintenance. If the mechanisms by which lightly trafficked roads deteriorate can be quantified and understood, improved pavement design procedures can be formulated, with the aim of improving pavement performance and reducing maintenance costs. This paper presents an investigation undertaken to identify the distress mechanisms prevalent in a group of sixteen typical UK lightly trafficked roads. The results indicate a relationship firstly between inadequate unbound granular sub-base thickness and wheel track rutting and longitudinal cracking and, secondly between inflexible, thin, high stiffness bituminous layers and shoulder collapse, particularly if there is a lack of edge support or inadequate drainage. For the covering abstract see ITRD E107185.

Research paper thumbnail of Evaluating the ageing degrees of bitumen by rheological and chemical indices

Road Materials and Pavement Design, Feb 22, 2023

Research paper thumbnail of Evaluation of the Linear and Non-Linear Viscoelastic Behaviour of Bituminous Binders and Asphalt Mixtures

CRC Press eBooks, Dec 17, 2020

Research paper thumbnail of Residual bitumen characteristics following dry process rubber-bitumen interaction

Research paper thumbnail of High and Low Temperature Rheological Characteristics of Low Penetration Grade Bitumen

PROCEEDINGS OF THE 3RD EURASPHALT AND EUROBITUME CONGRESS HELD VIENNA, MAY 2004, 2004

There has been a general trend in the UK to use progressively stiffer roadbase materials, due to ... more There has been a general trend in the UK to use progressively stiffer roadbase materials, due to their expected "long life" performance. However, recent concerns over the durability of these High Modulus Base (HMB) materials containing hard low penetration grade bitumens has questioned the use of these "brittle" binders especially at low temperatures and after ageing. This paper investigates both the high and low temperature rheological characteristics of a semi-blown and straight-run low penetration grade bitumen using a Brookfield (rotational) viscometer, Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR) and Direct Tension Tester (DTT) in order to provide a practical means of selecting an optimum low penetration grade bitumen. The binders have been tested in their virgin condition and after short-term, Rolling Thin Film Oven Test (RTFOT) and long-term, High Pressure Ageing Test (HiPAT) ageing. The results show considerable differences in the high and low temperature rheological properties of the 15 penetration grade bitumens as a function of their production method especially after ageing. In general the semi-blown 15 pen bitumen showed a higher susceptibility to ageing than the polymer modified and direct distillation 15 pen bitumens and an increased elastic "brittle" response to loading in terms of DSR, BBR and DTT test data. For the covering abstract see ITRD E121480.

Research paper thumbnail of Bitumen: Current Situation and Future Challenges