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ABSTRACTApproximately 5% of the global anthropogenic carbon dioxide (CO2) emissions are generated from cement manufacturing. Partial substitution of the clinker in the portland cement with supplementary cementingmaterials (SCM) is a solution to reduce the CO2 emission associated with cement production. Binders containing SCM, specifically designed for road applications, are called hydraulic road binders (HRB). A comparative life cycleassessment (LCA) was conducted to assess the effects of different HRB on the environmental impacts of the full-depth reclamation process. Three different types of HRB and general use cement were used to stabilise reclaimedpavement material containing 60% RAP. The pavement design and performance prediction were done using AASHTOWare Pavement ME. The life cycle impact assessment was performed with Athena software. The results of theanalysis indicated that using HRB, with low clinker content, in the full-depth reclamation implementation could reduce global warming potential by up to 27%.

The structural capacity of using lightweight cellular concrete (LCC) as subbase layer in the flexible pavement structure was investigated. Three different densities of LCC’s mechanical properties were examined. It was determined that LCC has adequate compressive strength for pavement application for all considered densities. It was also found that it exhibited higher stiffness than granular material. Failure criteria analysis found that the LCC sections could allow twice the traffic loadings than the granular material in terms of fatigue cracking at the surface layer for similar thickness. For rutting, it could allow between seven to twenty-four times more traffic. The LCC could reduce subbase thickness by up to 60% to bear the similar traffic loads as the granular material. Although the analysis indicates LCC's benefits as a potential pavement material, it is recommended that further assessment of life cycle costing and environmental impact be performed to further explore its benefits.

Longitudinal joints existing in between the lanes of asphalt pavements may initiate deterioration. Traditionally, core density, deflection, and nuclear density tests are used for the quality control. However, such techniques may not suit to the surface at the joints to assess their condition. Alternatively, the ultrasonic surface wave (USW) methods have the potential to both assess the longitudinal joints and estimate the pavement thickness at the same time. In this study, the USW are investigated on two lab-scale asphalt slabs (one laboratory prepared, and the other is cut from an as-built pavement) and on an in-service asphalt pavement to develop an ultrasound-based assessment methodology. Initially, an empirical compaction model is developed to produce the custom-size slab with the desired air-void profile to mimic a pavement with joint. Then, a variety of coupling systems between the pavement and the ultrasonic transducers are trialed to determine the optimum one. The recorded data are processed to determine the dispersion in velocity and the attenuation, which are then interpreted to estimate the pavement thickness and assess the joint quality, respectively. The dispersion curve is found capable of determining the pavement thickness with a precision of 1 cm, while the attenuation curve is observed to be affected by the transducer configuration excessively. Therefore, a normalisation technique, named the Fourier transmission coefficient (FTC), is implemented to reduce the undesired variability caused by the transducer coupling and type. Finally, it is demonstrated on an as-built pavement that the FTC has promising potential to detect, and hence evaluate the quality of longitudinal joints.

Conventionally it has been presumed that heavy traffic loading is the main driver that causes pavements to reach its limiting performance criteria such as fatigue and permanent deformation, and as a result, pavement designs have primarily only incorporated traffic loading. However, close monitoring of pavements has revealed that in fact, traffic loading alone may not create the conditions that lead to sudden failure of pavements. One aspect that is often not directly included in pavement design is the climatic factors, specifically temperature and moisture variations of the pavement soil. The occurrence of climatic extremes is becoming ever so frequent and there is a pressing need to better understand the effects of these extreme climatic conditions on pavement performance. This study presents the findings of an investigation into the effects of moisture and environmental conditions on the mechanical behaviour of granular pavements. The study was conducted with the aim of determining how seasonal effects from hot and wet climatic conditions impact on the sudden failure of pavements. Data was collected from state-of-the-art instrumentation on two field pavement sites located in Sunshine Coast, Australia. The sites were monitored over three years, and variations in daily temperature, moisture and strain values were analysed. Cyclic strain variations were observed in a cemented pavement basecourse layer where large fatigue tensile strains were present when moisture increased and temperature decreased. The results indicate that as moisture rises and temperature falls, critical fatigue strain increase above the fatigue endurance limit. This occurs when moisture was at or above optimum moisture content and surface layer temperature was between 38°C and 31°C. The data indicated that the change in pore pressure as a result of moisture and temperature variations within the granular basecourse soil were causing the strains in the pavement. Heavy traffic volume only had a minor effect on basecourse strain although the combined effect of soil moisture, temperature and heavy traffic loading was a cause for large fatigue strains in the pavement.

For quality control and quality assurance purposes, it would be desirable to quantify the amount of reclaimed asphalt pavement (RAP) already incorporated in a recycled hot mixture. If RAP is incorporated in higher amounts than approved, without a proper design, it can affect the integrity of the mix and can compromise the performance and lifespan of the pavement. Twelve different laboratory prepared asphalt mixtures with variable virgin asphalt binder grade and RAP content were subjected to multiple testing protocols to determine which variables were most significant for rutting, thermal cracking and mechanical response. Statistical analyses demonstrated that the performance of recycled hot mixtures is the result of the combined effect of the RAP content and the binder grade. It was observed that the quantity of RAP could be strongly related to the results of the indirect tensile strength, flow number, and fracture energy.

The automatic pavement management system has the advantage of providing reliable pavement maintenance and rehabilitation strategies aiming at prolonging existing pavement service life. Therefore, the quality of noise reduction results, which is an unavoidable process of automatic pavement assessment evaluation, has a significant influence on the reliability of pavement maintenance operations suggested. The primary purpose of this paper is to propose an innovative three-dimensional (3D) pavement image-based data filtering protocol, thereby maintaining a highly functional pavement surface. First, a 3D pavement depth data collection system was developed using laser light and a charge-coupled device camera. After that, based on the analysis of Positive Noise and Negative Noise, which are optical instrument-related noises, and tilted pavement model noise, the Primary Surface Profile (PSP)-based raw data filtering approach was proposed which aims at improving the noise reduction quality. Validation experiments were conducted using both the proposed approach and the traditional data filtering method, and the results show that for the not tilted pavement surface model, the PSP-based filter method can achieve the highest noise reduction value (NRV), whereas for the tilted pavement surface model, with a slightly lower NRV than that of biphasic standard deviation average filtering, which demonstrates that the proposed data filtering method has self-adaptive and robust data filter advantages which can be incorporated into a high-performance pavement performance evaluation and management system.

This paper presents the findings from a research conducted to investigate the effects of moisture and environmental conditions on the mechanical behaviour of granular pavements. Analysis was conducted on data collected from state-of-the-art instrumentation on two field pavement sites located in Sunshine Coast, Australia. The sites were monitored over three years, and daily temperature, moisture and strain values were analysed. Large tensile strains in the basecourse occurred when moisture increased and temperature decreased at the end of day. This result indicated that the change in soil pore pressure due to moisture and temperature variations was causing the strains in the pavement. Heavy traffic volume had a minor effect on basecourse strain in comparison to moisture and temperature although, it was concluded that the combined effect of soil moisture, temperature and heavy traffic loading was a cause for large vertical strains in the pavement.

Atomic force microscopy (AFM) is a non-destructive imaging tool, which is capable of qualitative and quantitative surface analysis with sub-nanometer resolution. Simultaneously with the topology at the micro-scale, AFM is capable of acquiring micro-mechanical information such as relative stiffness/Young's modulus, stickiness/adhesion, hardness, energy loss and sample deformation quantitatively. This paper presents an extensive review on the applications of AFM to investigate different physiochemical properties and performances of asphalt binder. AFM techniques and principles, different sample preparation techniques and its effect on observed micro-structures, chemical origin, surface or bulk phenomenon and temperature sensitivity of these micro-structures are also discussed in this paper. All of the studies conducted on this topic clearly indicated that AFM can successfully be utilised as a tool to better understand how the surface morphology and its physicochemical properties are interlinked and related to the binder performances.