Colin Leek

Evaluation and validation of characterization methods for fatigue performance of asphalt mixes for Western Australia

The determination of appropriate pavement thickness using laboratory determined parameters is one of the key issues facing the road manager. Five different types of asphalt mixes were produced in laboratory to modify pavement performance mixture. The main objective of this study is to evaluate the characterization methods for fatigue performance of asphalt mixes to Western Australia road. In this study, laboratory test for indirect tensile modulus, dynamic creep, wheel tracking and aggregate gradation tests were taken to analyze each asphalt mixtures for a design traffic road. The results and analysis showed that AC20-75 asphalt mix blow is the most effective and efficient in pavement performance than the other asphalt mixes. AC14-75 was the second in rank to strengthen and durability of asphalt pavement. All asphalt mixes in this study can be used to strength and stable the overall stiffness of pavement, and modification rank can be described as AC20-75 Blow > AC14-75 Blow > AC14-50 Blow > AC7-50 Blow > SMA7-50 Blow in this research.

Effects of Geometrical parameters on Numerical Modeling of Pavement Granular Material

Numerical modeling of the granular pavement materials is one of the modeling approaches which can be used to predict material response to specific loading conditions. This modeling is dependent on many factors and variables and includes assumptions for material behavior, loading conditions, geomechanical properties and geometrical parameters. In this study in-depth research has been undertaken to determine the sensitivity of geometrical parameters on pavement numerical modeling. Geometrical parameters are all those parameters that can be used to define a numerical model including layer thickness, meshing system and nature of the model (2D or 3D). In this study a layered granular pavement has been modeled through ABAQUS which is a general finite element program. The results have been compared with layered elastic theory by CIRCLY and KENLAYER. This study will deal with three kinds of modeling being 2D axisymmetric, 2D plain strain and a complete 3D model. In each of these three models, the influence of layer thickness, elements type and mesh density has been investigated. The results have been presented, compared and discussed in order to identify the most influential parameters.

Engineering Characterization of Hot-Mix Asphalt in Western Australia

The use of full depth asphalt pavement to construct and rehabilitate heavily loaded urban roads that has grown rapidly in Western Australia over the past 3 years. Five different types of asphalt mixes were produced in the laboratory according to the Australian Standard methods of sampling and testing asphalt to modify payment performance mixture. The main role of this research is to evaluate and assess the hotmix asphalt pavement performance characteristic for Western Australia road. In this study, laboratory test for tensile strength, resilient modulus, wheel tracking, asphalt binder content and Marshall Compaction test were taken and analyzed to each asphalt mixtures. Results showed that AC20-75 and AC14-75 Blow asphalt mixes were more efficient and effective in pavement performance as compared to the other mixes. In general, all the asphalt mixes that are used in this study can strength and stable the mixture stiffness of asphalt that is notable. The modification effect rank can be described as AC20-75 Blow > AC14-75 Blow > AC14-50 Blow > AC7-50 Blow > SMA7-50 Blow in this research.

Pavement Materials Characterization of Hot-Mix Asphalt Mixes in Western Australia

The use of deep strength asphalt materials characterization to construct and restore the heavily urban roads where damage has been induced is rapidly grown in Western Australia. Five different types of asphalt mixes were produced in laboratory to modify pavement performance mixture. The main role of this research is to evaluate the pavement materials characterization for Western Australia road. In this study, laboratory test for tensile strength, resilient modulus, wheel tracking, binder contents, Marshall Compaction, and air voids contents test were taken to analyze each asphalt mixtures. The results indicated that AC20-75 and AC14-75 asphalt mixes blow were in a good pavement performance as compared to other asphalt mixes. For a mix design purposed, all the asphalt mixes that are used in this study can strength and stable the stiffness of pavement that is notable, and the modification effect rank can be described as AC20-75 Blow > AC14-75 Blow > AC14-50 Blow > AC7-50 Blow > SMA7-50 Blow in this research.

A comparison between effects of linear and non-linear mechanistic behaviour of materials on the layered flexible pavement response

Modelling granular pavement materials has a significant role in the pavement design procedure. Modelling can be through an experimental or numerical approach to predict the granular behaviour during cyclic loading. The current design process in Australia is based on linear elastic analysis of layers. The analysis is performed through a well-known program CIRCLY which is applied to model bound pavement material behaviour. The KENLAYER is one of the common pavement software models used for pavement design in the United States which performs non-linear analysis for granular materials. Alternatively, a general Finite Element program such as ABAQUS can be used to model the complicated behaviour of multilayer granular materials. This study is to compare results of numerical modelling with these three programs on two sample pavement models.

Cracking and flexural behaviors on cement treated crushed rock for thin flexible pavement

Fatigue cracking is considered to be one of the most important types of distress affecting the performance of flexible pavements on major highways. This report analyses the results of a laboratory study of the static and fatigue response of a typical Western Australia Cement Treated Base (CTB) to evaluate its mechanical parameters i.e. flexural strength, flexural stiffness and tensile strains. Five different series of cement content were evaluated in the mix of 1%, 2%, 3%, 4% and 5%. Two major types of testing were conducted for the purpose of this study, i.e. Flexural Fatigue Tests (dynamic loading) and Flexural Beam Tests (static loading). The flexural fatigue tests were carried out with strain control mode. From the tests, the flexural stiffness for each specimen was calculated. The flexural stiffness was obtained from maximum tensile strains on the bottom of the specimens. The outcomes of the paper are as summarized as follow: First, 1% to 3% CTB was found out to be classified as modified material while 4% and 5% TB are categorized as stabilized materials. Second, fatigue cracking phenomenon can be seen in stabilized materials (4% and 5% CTB) while other types of distress may affect the behavior of modified materials (1 to 3% CTB). Third, 4% cemented material is observed to be the most suitable material to perform under fatigue loading conditions. Fourth, a series of recommendations are presented for further research i.e. the Flexural Fatigue Test be conducted at a suitable (lower) strain value instead of the 400 μe magnitude used in this research.

Haul road rolling resistance and pavement condition

Abstract An understanding of haul road rolling resistance and the impact of pavement surface and structural parameters will create an opportunity for energy and cost savings within mining operations. A search of previous studies provides limited understanding of the pavement characteristics that influence rolling resistance, or have excluded consideration of pavement stiffness. An investigation has been completed to define the impact of pavement texture, roughness and deflection on the rolling resistance experienced by off-highway, rigid dump trucks which are often referred to as ‘haul trucks’ within the mining industry. To allow such analysis, rolling resistance was calculated through data-logging of wheel motor torque. Measurement of pavement properties was completed utilising terrestrial laser scanning. Pavement roughness and deflection were found to be the pavement parameters most significantly influencing rolling resistance.

A comparison between austroads pavement structural design and AASHTO design in flexible pavement

This study deals with the Austroads (2008) Guide to Pavement Technology Part 2: Pavement Structural Design on which most road pavement designs in Australia are based. Flexible pavement designs and performance predictions for pavements containing one of more bound layers derived from the mechanistic Austroads pavement design methodology and the AASHTO-2004 approach are compared for Australian conditions, with consideration of subgrade and other material properties and local design preferences. The comparison has been made through two well-known programs namely CIRCLY (5.0) and KENLAYER. The study shows that each guide has its own advantages and disadvantages in predicting stress and strain in pavement layers under different conditions. The study recommends that modifications are necessary resulting in more realistic and longer lasting pavements in Australia.