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

Rheological Behavior of Warm Mix Asphalt Modified with Foaming Process and Surfactant Additive

Surfactants are frequently used to improve the engineering performances of foamed bitumen. Additionally, the foaming process can also perform a significant influence on the foam characteristics and rheological properties of foamed bitumen. However, rare research investigates the synergistic effect of both surfactant and foaming process on the engineering properties of foamed bitumen. To fill the gap, this research investigated the synergistic effect of surfactant and foaming process on the foaming characteristics and rheological properties of foamed bitumen. Based on the experimental results, the synergistic effect shows a significant effect on improving the half-life of foamed bitumen, which reached up to 69 s when 6% foaming Evotherm-DAT content was used. In addition, the foaming temperature also has a significant effect on the foaming characteristics. This study shows that the best foaming conditions can be achieved when the foaming temperature and Evotherm-DAT content are 170 °C and 8%, respectively. Based on the study of synergistic effect, the engineering performances of surfactant foamed bitumen were further characterized in this research, for instance, the enhancement in high-temperature performance and fatigue resistance, and the improvement in workability. Generally, the results of this study have greatly promoted the application of surfactant foam bitumen in the engineering practice

Permeable pavements : hydraulic and mechanical investigations

Conventionally, pavements are designed as sealed structures to inhibit the penetration of water into the structure, where it may cause damage. However, with the rapid increase of sealed areas due to urban development and industrial activity, the natural retention capacity of urban areas has exhibited a significant decrease. To recover the natural hydrological cycle and to mitigate risk of urban flooding, permeable pavements can be implemented. During a rainfall event, water can quickly infiltrate through the pavement structure into the subsoil; this relieves the requirements to urban drainage facilities and replenishes the natural water cycle. A void-rich pavement structure, such as Porous Asphalt (PA) and Pervious Concrete (PC) pavements based on open-graded aggregate distribution, is currently the most feasible and effective way to ensure a high permeability. Apart from the high hydraulic conductivity, porous structures also contribute to a reduction of traffic noise emissions by acting as an acoustic absorber. However, the open porous design results in a weakened pavement structure; the low shear-stress resistance of the porous structure can be identified as a main cause of the high susceptibility to grain ravelling. The durability as well as adhesion failure of porous pavement mixtures represent the most prominent obstacles restricting a more widespread application of permeable pavements. Based on the recent development of novel polyurethane-bound pervious mixtures (PUPM), the widespread application of fully permeable pavement (FPP) structures has become viable, which entails significant environmental benefits for the transport infrastructure. However, the saturation state has a major influence on the performance and durability of FPP. Due to the open porous structural design of pervious pavement material (PPM), surface runoff is allowed to infiltrate through pavement surface into the subsoil. In this case, moisture-induced damage is one of the most significant contributors to the premature deterioration of such permeable pavement mixtures. The pore-water pressures generated by intermittent dynamic vehicle loading can decrease the material strength significantly. The build-up and dissipation of pore-water pressure is recognized as a critical factor influencing the bearing capacity of FPP structures. The majority of research on the deterioration of permeable pavements has focused on phenomenological approaches, while the underlying mechanisms are still mostly unclear. To fully understand the moisture induced deterioration mechanisms of permeable pavements, comprehensive studies of the material characteristics, the hydraulic properties, the mechanical response and numerical investigations of FPP are required. The main objective of this thesis is to characterize the mechanical and functional properties of PUPM by combining applicable standards and modified testing methods. The water distribution and the flow characteristics in the vertical and the horizontal directions in PUPM will be quantitatively studied. The effect of the hydraulic gradient and mixture design on the flow will be characterized. Both laboratory and in-situ testing will be conducted to evaluate the response of permeable pavements to various loading states. Lastly, a numerical investigation will be conducted to explain the fundamental deterioration mechanism of FPP based on the novel PUPM material. This thesis provides an important reference for the facilitation of a wider application of PU binder in permeable pavements by providing an extensive understanding of the functionality of PUPM. Research on the hydraulic properties of PPM illustrates the inapplicability of Darcy’s law in the analysis of directional water transport in PPMs. Modified flow models are developed based on the pore microstructures, which exhibit more consistent results compared to the experimental data. Based on laboratory and in-situ measurements, it is found that the accumulated pore water pressure increases with the number of load cycles and also increases for each layer as the saturation increases. These findings support the quest for an in-depth understanding of stress states in FPP and the corresponding degradation mechanisms. During the numerical investigation, a modified stress-dependent moisture-sensitive cross-anisotropic elastic (SMAE) model was successfully applied as a constitutive law to characterize the coupled hydro-mechanical interaction in the unbound granular base (UGB) material. Based on the predictions for the stress state of the UGB layer, an optimized design of FPP with a PUPM surface layer is proposed. Further FEM analyses were performed based on the coupled stress-dependent moisture-sensitive cross-anisotropic elastoplastic (SMAEP) model. The results obtained by the SMAEP model predict a reduction of the tensile stress along the depth of the base course, and an increase of the compressive stress from the centre of the UGB layer to the top of the UGB layer, which is more suitable for the FPP system. To further understand the material characteristics and the deterioration mechanism of the FPP system, prospect researches are addressed. The constitutive model for the PUPM and the fracture behaviour are suggested for further in-depth studies. The analysis of the hydraulic properties, based on the characteristics of the three-dimensional (3D) pore structure is highly recommended. To further consider the dilation effect within the base course of FPP, a more comprehensive theoretical model based on hypoplasticity should be explored for the UGB layer. Moreover, it is suggested that the life cycle analysis (LCA) method is to be modified in a theoretical and experimental manner

Desarrollo de las Propiedades Hidráulicas del Asfalto con Poliuretano

To investigate the development of hydraulic and filtration property of Polyurethane bound porous pavement, by define the particles clogging behaviour within the porous structure subjected to the urban runoff. In the present study, it is hard to quantify the particles concentration of runoff. The test method and equipment for evaluating the clogging and filtration behaviour need to be re-designed and manufactured respectively

Performance characterisation of asphalt mixture modified with one-component polyurethane

The use of polyurethane (PU)-modified asphalt for paving purposes has recently gained increasing interest in both academia and industry. This study aimed to characterise the engineering performance of an asphalt mixture modified with one-component PU and explore its adhesive mechanism. To achieve these objectives, PU-modified bitumen and asphalt mixtures with two different PU contents (10% and 30%) were prepared. Various laboratory material property tests, such as rotational viscosity test of the binder, Marshall test, indirect tensile strength (ITS) test, Hamburg wheel-tracking test, moisture susceptibility and indirect tensile fatigue test of the PU-modified mixture, were carried out. Fourier transform infrared spectroscopy was carried out to explore the adhesive mechanism between PU-modified binders and aggregates. The results indicated that the overall performance of the asphalt mixture increased significantly with the PU prepolymer, with increased Marshall stability, ITS and resistance to moisture damage, rutting and fatigue damage. It was found that the PU prepolymer reacted with hydroxyl groups on the surface of the aggregate, which contributed to the improved performance of the asphalt mixture. The findings of this study may facilitate further practical applications of bituminous materials modified with one-component PU in the pavement industry