Advances in Asphalt Pavement Technologies and Practices

Unlike other construction materials, road materials have developed minimally over the past 100 years. However, since the 1970s, the focus has been on more sustainable road construction materials such as recycled asphalt pavements. Recycling asphalt involves removing old asphalt and mixing it with new (fresh) aggregates, binders, and/or rejuvenators. Similarly, there are various efforts to use alternative modifiers and technical solutions such as crumb rubber, plastics, or various types of fibres. For the past two decades, researchers have been developing novel materials and technologies, such as self-healing materials, in order to improve road design, construction, and maintenance efficiency and reduce the financial and environmental burden of road construction. This Special Issue on “Advances in Asphalt Pavement Technologies and Practices” curates advanced/novel work on asphalt pavement design, construction, and maintenance. The Special Issue comprises 19 papers describing unique works that address the current challenges that the asphalt industry and road owners face

A New Generation of Open-Graded Friction Course for Enhanced Durability and Functionality

This study aims at (1) enhancing Open Graded Friction Course (OGFC) mixes durability using additives and other by-products; (2) investigating the impacts of selected factors on OGFC pavements seepage characteristics; (3) developing a quantitative tool to model the deterioration in OGFC pavements functional performance; and (4) developing new guidelines of Air Void (AV) content for OGFC for optimum functionality and durability. For the durability objective, eight mixes were prepared with a PG 76-22 binder and two sources of aggregate (i.e., # 78 limestone and # 67 sandstone). Three Warm Mix Additives (WMA), one by-product (i.e., crumb rubber [CR]), and two fillers (i.e., F1 and F2) were evaluated. Results concluded that OGFC durability can be enhanced using WMA, CR, and fillers. For the second and third objectives, a 3-D Finite Element (FE) model was developed and calibrated based on field measurements. The transient analyses were used to evaluate the impacts of OGFC layer thickness, OGFC permeability, underlying layer permeability, rain intensity, and traffic volume on the seepage characteristics of OGFC. The impacts of these factors were evaluated by calculating the time at which a critical location on OGFC surface reaches overflow condition (TC). The statistical analysis showed that all these factors had a significant impact on the seepage characteristics of OGFC, except OGFC permeability. Furthermore, an Artificial Neural Network (ANN) model was developed for the prediction of TC without the need for FE modeling. Results indicated that the ANN model predicted TC accurately with R2 of 99 % and 98% in the training and validation stages, respectively. Moreover, this model accurately predicted the deterioration rate of OGFC functionality over time when compared to the results of the FE model. Therefore, this model can be used to determine the time at which routine maintenance should be applied for OGFC pavements. Lastly, simulation runs were conducted using the developed FE model under different AV content conditions ranging from (10 to 24 %) under varying rain intensity conditions. Results revealed that an OGFC layer with an AV content of 16% would provide adequate drainage performance of rainwater while minimizing OGFC durability issues

Recent Advances and Future Trends in Pavement Engineering

This Special Issue “Recent Advances and Future Trends in Pavement Engineering” was proposed and organized to present recent developments in the field of innovative pavement materials and engineering. The 12 articles and state-of-the-art reviews highlighted in this editorial are related to different aspects of pavement engineering, from recycled asphalt pavements to alkali-activated materials, from hot mix asphalt concrete to porous asphalt concrete, from interface bonding to modal analysis, and from destructive testing to non-destructive pavement monitoring by using fiber optics sensors. This Special Issue partly provides an overview of current innovative pavement engineering ideas that have the potential to be implemented in industry in the future, covering some recent developments

MODELING AND ANALYSIS OF THE INTERACTION BETWEEN ROLLER DRUM AND PAVEMENT MATERIAL DURING COMPACTION

The problem of ensuring real time control of compaction quality during pavement construction is considered in this dissertation. Asphalt pavements are complex, multilayer, heterogeneous structures where different layers of asphalt mixes are often placed on top of and supported by a base subgrade layer. In order to ensure long term performance of these pavements, it is imperative to ensure proper quality in both the subgrade and the asphalt layer during their construction. Compaction is one of the important steps in pavement construction that significantly affects the quality and long term performance of the pavement. Proper and uniform compaction of the subgrade and asphalt layers during construction is necessary for the pavement to support the expected traffic load over its lifetime. Inadequate compaction of asphalt layers could result in a pavement with insufficient stiffness leading to problems such as reduced fatigue life, accelerated aging/decreased durability, rutting, raveling, and moisture damage. The underlying subgrade also needs sufficient compaction to ensure adequate load bearing capacity of the pavement and reduce its susceptibility to moisture and other weather-related distresses. Although the impact of compaction on the performance and longevity of pavements is well understood, addressing compaction issues during construction is not easy given the limitations in the available quality control tools. The traditional QC methods rely on in situ measurement devices that provide an estimate of compaction quality at discrete test locations and generally cover less than 1% of the entire pavement area. Therefore, it is not possible to address under-compaction in areas other than those identified at the test locations. Besides, the tests are time consuming, expensive, and often destructive in nature. In order to overcome these limitations, ‘Intelligent Compaction (IC)’ methods have been proposed to provide 100% coverage of the pavement surface during compaction. These methods analyze the vibrations of roller drum and provide an estimate of the stiffness of the compacted pavement material. Further, these systems have integrated Global Position Sensors (GPS) and computational devices that record the spatial location of the roller and the stiffness values continuously during compaction. One major limitation in the available IC technologies is that they provide the estimation of pavement quality in terms of vendor specific values and do not provide estimates in terms of any of the parameters used in the design of the pavement. The relationship between these measurement values and accepted measures such as modulus or pavement density is also not well established. Limitations in the understanding on the coupled dynamics between a vibratory roller and lack of mathematical framework hamper the research and validation of the IC technologies. In this dissertation, the limitations of the IC technologies in quality control of asphalt compaction are addressed through the development of a mathematical model to study and analyze the interaction between a moving vibratory roller and the underlying asphalt pavement. A lumped element modelling approach is adopted and the vibration of the roller drum, its movement along and interaction with the pavement are formulated by mathematical equations. The asphalt pavement is represented by a collection of blocks of mechanical elements arranged in a grid wise manner with each block exhibiting visco-elastic and plastic properties. The asphalt model parameters are estimated from the results of standard laboratory complex modulus test. These parameters account for the effect of pavement temperature, layer thickness, loading frequency and volumetric properties of asphalt mix. Numerical simulations are performed to study the ability of the model to replicate the results of field compaction. Comparison of the model simulation results with field compaction data shows that the model can emulate the salient characteristic vibratory response of the drum observed during field compaction. The results also indicate that the model is able to replicate the pass by pass densification process during field compaction. Analyses of the results show that the model can be used to account for the asphalt-roller interaction in both the vertical and the horizontal directions. The development of an intelligent compaction technology for real time control of subgrade quality is also addressed in this dissertation. An Artificial Neural Network (ANN) based intelligent compaction system is developed to estimate the stiffness of the subgrade during compaction. The ANN classifies the vibrations of the roller drum during compaction into known patterns. Details of the pavement under compaction and the classified patterns are then used together to estimate the stiffness of the layer. A calibration procedure is developed that can adjust the IC parameters to minimize the error between the IC estimated stiffness values and in-situ measurements taken after the pavement is fully compacted. The system was tested and validated during four different construction projects. The results indicate that the system is capable of real time estimation of subgrade stiffness with accuracy suitable for contractor’s quality control operations. Field investigations also indicate that the system can be used for detecting under-compacted regions of subgrade in real time, thereby allowing remedial actions to be performed. Improving the overall quality of pavement during construction will improve its performance and service life and reduce the cost to maintain it over its lifetime. It will help to improve driver safety by providing a smooth, stable and skid resistant surface for the vehicle. Sustainable pavements will also reduce the impact of road construction on the environment

INCORPORATION OF FUNCTIONAL CONSIDERATIONS IN HIGHWAY PAVEMENT DESIGN AND OPERATIONS

Ph.DDOCTOR OF PHILOSOPH

Eleventh International Conference on the Bearing Capacity of Roads, Railways and Airfields

Innovations in Road, Railway and Airfield Bearing Capacity – Volume 3 comprises the third part of contributions to the 11th International Conference on Bearing Capacity of Roads, Railways and Airfields (2022). In anticipation of the event, it unveils state-of-the-art information and research on the latest policies, traffic loading measurements, in-situ measurements and condition surveys, functional testing, deflection measurement evaluation, structural performance prediction for pavements and tracks, new construction and rehabilitation design systems, frost affected areas, drainage and environmental effects, reinforcement, traditional and recycled materials, full scale testing and on case histories of road, railways and airfields. This edited work is intended for a global audience of road, railway and airfield engineers, researchers and consultants, as well as building and maintenance companies looking to further upgrade their practices in the field

Review of advanced road materials, structures, equipment, and detection technologies

As a vital and integral component of transportation infrastructure, pavement has a direct and tangible impact on socio-economic sustainability. In recent years, an influx of groundbreaking and state-of-the-art materials, structures, equipment, and detection technologies related to road engineering have continually and progressively emerged, reshaping the landscape of pavement systems. There is a pressing and growing need for a timely summarization of the current research status and a clear identification of future research directions in these advanced and evolving technologies. Therefore, Journal of Road Engineering has undertaken the significant initiative of introducing a comprehensive review paper with the overarching theme of “advanced road materials, structures, equipment, and detection technologies”. This extensive and insightful review meticulously gathers and synthesizes research findings from 39 distinguished scholars, all of whom are affiliated with 19 renowned universities or research institutions specializing in the diverse and multidimensional field of highway engineering. It covers the current state and anticipates future development directions in the four major and interconnected domains of road engineering: advanced road materials, advanced road structures and performance evaluation, advanced road construction equipment and technology, and advanced road detection and assessment technologies

Advanced Testing and Characterization of Bituminous Materials, Two Volume Set

Bituminous materials are used to build durable roads that sustain diverse environmental conditions. However, due to their complexity and a global shortage of these materials, their design and technical development present several challenges. Advanced Testing and Characterisation of Bituminous Materials focuses on fundamental and performance testin