Infrastructures

The generalized Maxwell (GM) constitutive model has been widely applied to characterize the viscoelastic properties of asphalt mixtures. The parameters (Prony series) of the GM are usually obtained via interconversion between a dynamic modulus and relaxation modulus, and they are then input to a finite element model (FEM) as viscoelastic parameters. However, the dynamic modulus obtained with the common loading mode only provides the compressive and tensile properties of materials. Whether the compression or tensile modulus can represent the shear properties of materials related to flow rutting is still open to discussion. Therefore, this study introduced a novel method that integrates the Kriging model into the genetic algorithm as a surrogate model to determine the viscoelastic parameters of an asphalt mixture in rutting research. Firstly, a wheel tracking test (WTT) for AC-13 was conducted to clarify the flow rutting development mechanism. Secondly, two sets of the AC-13 viscoelastic parameters obtained through the optimization method and the dynamic modulus were used as inputs into the FEM simulation of the WTT to compare the simulation results. Finally, a sensitivity analysis of viscoelastic parameters was performed to improve the efficiency of parameter optimization. The results indicating the viscoelastic parameters obtained by this method could precisely characterize the development law of flow rutting in asphalt mixtures. Full article

There are many existing buildings for which seismic rehabilitation interventions are required, especially in earthquake-prone areas like Italy. At the same time, the deep energy crisis that Europe is facing highlights the need for sustainable techniques that are able to increase the energy efficiency of buildings. In order to mitigate the social and cultural obstacles for deep renovations of buildings, effective techniques and methods are required to avoid relocating users, which often discourages such interventions. To this purpose and as the main novelty, this research is aimed at presenting a new strengthening technique for reinforced concrete buildings that is able to integrate structural seismic strengthening and energy efficiency improvements. It is made up of new framed structures connected from the outside to the existing building, thus reducing the intrusiveness and relocation needs of users. At the same time, the seismic strengthening technique is conceived for an optimal coupling with energy saving interventions like high-performance external insulation finishing systems. In this study, these techniques are described and applied to a reinforced concrete (RC) school building designed only for gravity loads, according to outdated standards. The results show that the considered strengthening technique increases the seismic performance of the building with respect to both life safety and damage limitation requirements, avoiding any further local interventions to the building’s interior. On the other hand, the energy renovation allows for significant savings, since the resulting reduction in the total non-renewable energy consumption is larger than 80%. Full article

Today, everything is connected, including the exchange of data and the generation of new information. As a result, large amounts of data are being collected at an ever-increasing rate and in a variety of forms, a phenomenon now known as Big Data. Recent developments in information and communication technologies are driving the generation of significant amounts of data from multiple sources, namely sensors. In response to these technological advances and data challenges, this paper proposes a Big Data system architecture for paved road monitoring and implements part of this architecture on a section of road in Portugal as a case study. The challenge in the case study architecture is to collect and process sensor data in real time, at a rate of 500 records per second, producing 15 GBytes of data per day, using a real-time data stream for real-time monitoring and a batch data stream for deeper analysis. This allows users to obtain instant updates on road conditions such as the number of vehicles, loads, weather, and pavement temperatures on the road. They can monitor what is happening on the road in real time, receive alerts, and even gain insight into historical data, such as analysing the condition of structures or identifying traffic patterns. Full article

The Mexican asphalt paving industry is increasingly interested in using reclaimed asphalt pavement (RAP) to produce hot mix asphalt (HMA) due to its economic and environmental advantages. However, an ill-defined methodology for integrating RAP into the HMA mix design has hindered its use. This paper investigates how compaction energy affects both rejuvenated and non-rejuvenated recycled HMA mixtures. A Superpave gyratory compactor was used to determine the optimal binder content and find a balance between flexibility and stiffness that meets cracking and rutting resistance requirements. Various recycled HMA mixtures were subjected to different compaction energy levels (75, 100, and 125 gyros), different RAP contents (15%, 30%, and 45%), and various dosages (10%, 15%, and 36%) of the rejuvenating additive Maro-1000^®, following the blending chart. Performance was evaluated using the Hamburg wheel tracking test (HWTT) and the fracture energy flexibility index test (I-FIT). The results demonstrate that mixtures with RAP, a rejuvenating admixture, and varying compaction energies exhibit favorable mechanical behavior. However, both rejuvenated and non-rejuvenated mixes with 15% RAP showed performance comparable to conventional mixtures. They improved stiffness by up to 46% while reducing the flexibility index to 25%, striking a balanced equilibrium between rutting resistance and cracking susceptibility. Full article

Microtransit is a shared mobility service that operates between fixed-route transit and ride-hailing. It operates with a fleet of vans or minibuses within a service zone that is usually located in a rural or suburban car-oriented area with a transport demand that is temporally and spatially dispersed. Microtransit often expects customers to walk a short distance to pick-up/drop-off (PUDO) locations. The PUDO points need to be quickly, easily, and safely reachable by pedestrians. Thus, PUDO locations must be chosen after analyzing the walkability of the suburban area served by microtransit. This paper presents a comparison of macroscale and microscale indicators to assess the walkability of suburban neighborhoods where microtransit has to be introduced. We chose three suburban neighborhoods (Partanna Mondello, Tommaso Natale, and Mondello) in Palermo, Italy, as a study area, aiming to identify the best places to locate PUDO stops for a microtransit service. A GIS database has been built associating each link with a series of qualitative and quantitative attributes. Finally, we developed a walkability index that indicates the attractiveness of specific locations in terms of intermodal walkability. We also identified the critical pedestrian links that need actions to improve their walkability. Full article

Over the last two decades, many researchers have focused on providing new ideas and frameworks to help improve conventional bridge inspection planning approaches, however, little guidance is provided for implementing these new ideas in practice, resulting in limited change. Accordingly, this qualitative study aims to identify the factors that can help improve research products and accelerate research transfer to bridge inspection departments with the goal of enhancing bridge inspection practice. This study used semi-structured interviews, written interviews, and questionnaires for data collection to provide rich results. Responses from twenty-six bridge personnel from state Departments of Transportation (DOTs) across the United States (U.S.) were included in this study. The study found that most participants support a fixed inspection interval over a variable interval since fixed intervals are easier in scheduling and budget planning. Also, participants indicated that the barriers hindering the use of nondestructive techniques are the training required by inspectors, traffic control, and the required access equipment. The study presents the factors change leaders should focus on to facilitate organizational change in DOTs such as enhancing the capacity of DOT staff members and gaining support from the Federal Highway Administration (FHWA) Full article

Asphalt binder is a crucial component of asphalt pavements that undergoes ageing over time, which can result in the reduced performance and deterioration of pavements. Consequently, artificial ageing methods play a significant role in providing valuable insights into the ageing behaviour and long-term performance of asphalt binders. However, a consensus on the most effective method for simulating ageing behaviour remains elusive, leading to disparities in the outcomes across different research studies. To address this issue, the study utilises two thermo-oxidative ageing approaches, one focusing on the binder itself and another on the loose asphalt mixture. The study investigates the effect of these ageing methods on the behaviour of asphalt binder using physical, rheological, and chemical characterisation. For the binder ageing method, a rolling thin film oven (RTFO) and a pressure ageing vessel (PAV) were utilised, whereas the loose asphalt mixture ageing was performed in an oven at 95 °C for various durations. The results indicated that the ageing trend differed between the two oxidative ageing approaches as the ageing duration increased. However, by employing an ageing sensitivity index, comparable rheological properties were observed between the binders aged using the PAV for 20 h and the loose asphalt mixture for 5 days. The Fourier Transform Infrared (FTIR) spectroscopy analysis revealed that the ageing methods influenced the functional groups associated with ageing in distinct ways, even though they exhibited similar rheological behaviour. Overall, this study provides a comprehensive understanding of different thermo-oxidative ageing approaches, their correlation, and their relevance to the studied field-aged binders. Full article

Railway noise barrier constructions are subjected to high aerodynamic loads during the train passages, and the knowledge of their actual structural condition is relevant to assure safety for railway users and to create a basis for forecasting. This paper deals with deterministic and probabilistic approaches for the condition assessment and prediction of the remaining lifetime of railway noise barriers that are embedded in a safety concept that takes into account the damage consequence classes. These approaches are combined into a holistic assessment concept, in other words, a progressive four-stage model in which the information content increases with each model stage and thus successively increases the accuracy of the determined structural conditions at the time of observation and the forecast of the remaining service life of the structure. The analytical methods used in the first stage of the developed holistic framework are based on common static calculations used in engineering practice and, together with expert knowledge and large-scale fatigue test results of noise barrier constructions, form the basis for the subsequent stages. In the second stage of the data-driven condition assessment and life cycle analysis approach, linking routines are implemented that combine the condition assessments from the visual inspections with the additional information from temporary or permanent monitoring systems with the analytical methods. With the application of numerical finite element methods for the development of a digital twin of the noise barrier in the third stage and the probabilistic approaches in the fourth stage, a maximum determination accuracy of the noise barrier condition at the time of observation and prediction accuracy of the remaining service life is achieved. The data-driven condition assessment and life cycle analysis approach enables infrastructure operators to plan their future investments more economically regarding the maintenance, retrofitting, or new construction of railway noise barriers. Ultimately, the aim is to integrate the presented four-stage holistic assessment concept into the specific maintenance and repair planning of infrastructure operators for aerodynamically loaded railway noise barrier constructions. Full article

The incorporation of biomaterials into concrete for engineering applications has gained significant attention in recent years due to its potential to enhance both the mechanical properties and sustainability of construction materials. This study conducts a comprehensive bibliometric analysis (BA) to examine the state of the research on utilizing biomaterials in concrete through the analysis of scientific production considering the information in the Scopus database. The BA provides insights into this interdisciplinary field’s evolution, trends, and global research landscape. Key aspects explored include the types of biomaterials employed, their impacts on concrete properties, and the environmental benefits associated with their masonry use. R-Software was used to analyze the scientific growth and topics (BA) in the field of biomaterials in concrete for industrial applications. The results exposed that biomaterials in concrete related to scientific production represent a total amount of 1558 documents published by 489 journals and 4521 authors, which represents an annual rate of 20.81% higher than other related topics, with India, the United Kingdom, and China being the most representative countries. Finally, this work exposes the growing interest in sustainable construction practices and the promising future of biomaterial-infused concrete in the engineering sector, seeking to advance the knowledge and application of biomaterials in concrete technology. Full article

Crosslinking agents, notably sulfur, are used in asphalt binder modification to facilitate chemical bonding between polymer chains and the asphalt binder. Despite some prior research indicating the benefits of sulfur crosslinking in enhancing polymer-modified asphalt’s (PMA) stability, there is a lack of comprehensive understanding regarding its impact on rheological properties and its anti-aging potential. This study addresses these gaps by thoroughly investigating the effects of varying the sulfur content (ranging from 0.03% to 0.5% by total weight of binder) on PMA’s rheological properties. The research assesses the effectiveness of sulfur in enhancing PMA’s resistance to aging using various methods, including the Glover-Rowe parameter, FTIR analysis, and the examination of the dynamic modulus and phase angle master curves. The results indicated that the addition of sulfur, particularly up to 0.3%, bumps the high-temperature performance grade by one level, and significantly improves elasticity, allowing the PMA to support heavier traffic without experiencing rutting, all while maintaining resistance to low-temperature cracking. Furthermore, PMA with sulfur demonstrated an increase in resistance to aging, reducing the aging potential by approximately 15% with the best sulfur formulation. This enhanced durability can reduce the frequency of maintenance activities, leading to cost savings, reduced roadwork emissions, and prolonged pavement life. Full article

The past decade has seen a rise in the availability of modern information and communication technologies (ICTs) for developing smart societies and communities. However, the smart divide, characterized by inequalities in ICT infrastructures, software access, and individual capabilities, remains a significant barrier for rural communities. Limited empirical studies exist that explore what and how ICT infrastructures can be developed to bridge the smart divide. The paper aimed to address rural broadband access in the context of infrastructural dimensions of smart divide (i.e., smart infrastructural divide) in the United States, focusing on the wireless network infrastructure’s role in narrowing the gap. It examined the broadband specifications needed for smart applications like smart education and telehealth, emphasizing the importance of wireless network capabilities. While fixed broadband offers higher speeds, wireless networks can support many smart applications with decent flexibility and ease of access. To further understand the implications of wireless broadband to rural communities, we conducted a case study in Carbondale and Cairo, two rural towns in Southern Illinois, using on-site user-inspired speed testing. An Android application was developed to measure download/upload speeds and Reference Signal Received Power (RSRP) for broadband quality. Results suggest both Carbondale and Cairo experienced below-average speeds with high variability among census blocks, which highlights the need for improved wireless network infrastructure. The paper culminated in the technological and policy recommendations to narrow down the smart infrastructural divide. Full article

A key goal of structural health monitoring (SHM) systems applied to infrastructure is to improve asset management. SHM systems yield benefits by providing information that allows improved asset management decisions. Often, improvement is measured in monetary terms, whereby lower expenses are sought. The value of information (VoI) is often evaluated through the quantification of the incremental benefit, resulting from the information provided by the SHM system. The VoI can be considered as having two components: value derived from the improved operation of the infrastructure and value derived from increased useful life. This work focuses on the latter source of value in the context of concrete decks in US highway bridges. To estimate the lifecycle extension potential and the connected VoI, we need to simulate bridge deck condition degradation over time to support a discounted cash flow analysis of bridge replacement cost. We accomplish this by utilizing a neural network-based survival analysis combined with Monte Carlo simulation. We present a case study using the developed methods. We have chosen to study the southbound portion of the bridge on the US Highway 202, located in Wayne, NJ. The selected bridge is a representative concrete highway overpass, the type of which there are large numbers in the US. The case study demonstrates the applicability of the methods developed for the general evaluation of the VoI obtained via SHM. The results are encouraging for the widespread use of SHM for lifecycle extension purposes; the potential value in such applications is large. Full article

This research undertook an extensive examination of the ramifications of integrating steel dust as a partial substitute for cement within reinforced concrete beams. The investigation encompassed an assessment of various facets, encompassing the workability of the concrete mixture, alongside crucial mechanical properties such as compressive strength, split tensile strength, flexural strength, ultrasonic pulse velocity (UPV), and elasticity modulus. The findings unveiled a notable reduction in workability as the proportion of steel dust increased within the mixture, with a consequential substantial impact on the elasticity modulus. Notably, compressive strength exhibited an enhancement at a 10% replacement of cement yet exhibited a decline with higher degrees of cement substitution. The inclusion of steel dust led to the formulation of adjusted equations pertaining to split tensile and flexural strength characteristics within the mixture. Remarkably, the incorporation of 10% steel dust yielded an increase in ductility. Conversely, at a 30% steel dust inclusion level, ductility diminished alongside a reduction in the maximum load-bearing capacity. In light of these findings, it is imperative to exercise prudence when considering the utilization of steel dust as a cement substitute, particularly when approaching or exceeding the 10% replacement level threshold. Further comprehensive research is imperative to acquire a comprehensive understanding of its implications and its susceptibility to potential corrosion concerns. Full article

Accurate detection and prediction of the lane-change (LC) processes can help autonomous vehicles better understand their surrounding environment, recognize potential safety hazards, and improve traffic safety. This study focuses on the LC process, using vehicle trajectory data to select a model for identifying vehicle LC intentions. Considering longitudinal and lateral dimensions, the information extracted from vehicle trajectory data includes the interactive effects among target and adjacent vehicles (54 indicators) as input parameters. The LC intention of the target vehicle serves as the output metric. This study compares three widely recognized machine-learning models: support vector machines (SVM), ensemble methods (EM), and long short-term memory (LSTM) networks. The ten-fold cross-validated method was used for model training and evaluation. Classification accuracy and training complexity were used as critical metrics for evaluating model performance. A total of 1023 vehicle trajectories were extracted from the CitySim dataset. The results indicate that, with an input length of 150 frames, the XGBoost and LightGBM models achieve an impressive overall classification performance of 98.4% and 98.3%, respectively. Compared to the LSTM and SVM models, the results show that the two ensemble models reduce the impact of Types I and III errors, with an improved accuracy of approximately 3.0%. Without sacrificing recognition accuracy, the LightGBM model exhibits a sixfold improvement in training efficiency compared to the XGBoost model. Full article

The research presented here demonstrates the practical aspects of the numerical correlation of the results of the compressive strength test. The destructive test (DT) in a hydraulic press and the non-destructive test (NDT) using a Schmidt hammer in several process variations were evaluated. The aim was to evaluate the real differences between the tool supplier’s curve and testing. Therefore, 150 concrete cube specimens with an edge length of 150 mm were produced using a mixture of three types of concrete classes: C30, C35, and C40. The test was carried out 7 and 28 days of age of the concrete. The Schmidt hammer test was carried out in horizontal (θ = 0) and vertical (θ = 90) directions and using a series of 10 measurements. Furthermore, the tests were performed in two sets: first, the sample was placed on the ground, and second, under a hydraulic jack with a load of 50% of the maximum bearing capacity of specific concrete. Then, regression analysis was performed on the data sets to establish linear mathematical relationships between compressive strength and number of bounces. The results showed that the correlation between the DT and NDT tests has a high value for each group, but the correlation equations are different and must be taken into account. Full article

Cement with fly ash has rarely been used in Japan, mainly because its strength development is slower than ordinary Portland cement. In this research, the effect of the new type of fly ash (which was modified by the electrostatic belt separation method) with high alite (C₃S) cement on cracking resistance of precast concrete prepared by steam curing was studied. The mechanical and shrinkage properties of the proposed fly ash concrete were compared with those of concrete made using OPC cement without fly ash. In order to study the cracking tendency of precast concrete with the proposed cement with fly ash, thermal stress analysis was conducted, taking into consideration the experimental data of concrete properties with the different concrete mix proportions. A standard precast concrete box culvert model was used in this 3D FEM analysis, and the distribution of temperature and relative humidity in the cross-section and induced restraint stress during and after steam curing were discussed. Steam-cured concrete with fly ash and high alite cement developed higher compressive strength on the first day of age than concrete with OPC. The proposed fly ash concrete developed high cracking resistance in the early days. On the other hand, the results showed that the drying shrinkage at later ages was the main cause of cracking. Full article

The demand for preserving existing roadway infrastructure has been increasing to regulate expensive reconstruction activities. The maintenance of homogeneous road sections is one of the approaches to economize the overall management of pavement systems. The existing homogeneous delineation methods consider one or two parameters for segmenting the pavements based on similar characteristics, which are found to be a repetitive process. Also, there is a need to consider multiple parameters that represent the functional, structural, and traffic characteristics in segmentation process. Therefore, the objective of this study was to develop a multi-parameter-based delineation approach (MPDA) to segment the pavements into subsections with similar features considering functional, structural, and traffic characteristics. Deflection bowl parameters, unified pavement health index (functional performance metric), surface layer modulus, and traffic reported in terms of AADT were employed for developing a multi-parametric delineation index (MPDI). A total of 1781 datapoints covering 26 road sections in the State of Andhra Pradesh, India, were used. The C-charts method-based segmentation for MPDI was applied to obtain the homogeneous sections. The devised approach was found to be efficient in segmenting the pavements as well as robust in selecting suitable maintenance strategies for each group of the homogeneous sections. Further, the segmentation processes were automated for easier implementation by the agencies. Full article

Video processing for structural monitoring has attracted much attention in recent years thanks to the possibility of measuring displacement time histories in the absence of stationary points close to the structure, using hardware that is simple to operate and with accessible costs. Experimental studies show a unanimous consensus on the potentialities of vision-based monitoring to provide accurate results that can be equivalent to those obtained from accelerometers and displacement transducers. However, past studies mostly involved steel bridges and footbridges while very few applications can be found for concrete bridges, characterised by a stiffer response with lower displacement magnitudes and different frequency contents of their dynamic behaviour. Accordingly, the attention of this experimental study is focused on the application of a vision-based structural monitoring system to a medium-span, post-tensioned, simply supported concrete bridge, a very common typology in many road networks. The objective is to provide evidence on the quality of the results that could be obtained using vision-based monitoring, understanding the role and influence on the accuracy of the measurements of various parameters relevant to the hardware settings and target geometry, highlighting possible difficulties, and providing practical recommendations to achieve optimal results. Full article

The aim of this study is to compare the properties of refractory concrete made with thermally treated and untreated steel slag. Five concrete compositions were prepared and investigated in the present work. The first mixture, referred to as the reference, was formulated using dolomite aggregates, whereas the second and third mixtures were developed by replacing natural coarse aggregate with 50 and 100% by weight of thermally untreated steel slag, respectively. The same replacement ratio (50% and 100%) of thermally treated steel slag was used to produce the fourth and fifth mixtures. Specimens of each specimen were placed in a furnace and heated to 400 °C and 800 °C. The mass loss for all the specimens heated to 400 °C was about 8%, while the reference suffered the maximum mass loss at 800 °C, which was 21.6%. The mixture with a 100% substitution of thermally treated steel slag produced the maximum compressive strength when compared to other mixtures at a temperature of 800 °C. The compressive strength of the M5 mixture was 18 MPa versus 10.87 MPa for the reference mixture. Additionally, optical microscope examination of specimens containing thermally treated steel slag revealed less damage than that observed in mixtures with dolomite. Full article