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Experimental tests to measure the photocatalytic activity: (a) NOx degradation efficiency (1: lamp for light irradiation, 2: quartz window, 3: test specimen, and 4: temperature stabilizer); (b) degradation of an organic dye; (c) aqueous solution of an organic dye of different color intensity over time, thus indicating its degradation.
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Nowadays, there is increasing concern in transportation engineering about the use of techniques less harmful to the environment and also about road safety. Heterogeneous photocatalysis based on the application of semiconductor materials onto asphalt mixtures is a promising technology because it can mitigate air pollution and road accidents. The fun...
Contexts in source publication
Context 1
... order to evaluate the photocatalytic ability, the literature presents gas degradation tests, such as NOx and VOCs, most of them according to the standards ISO 22197-1 and JIS TR Z 0018 [60,67,70], and tests of photocatalytic efficiency via the degradation of different organic dyes, such as methylene orange (MO) [61], methylene blue (MB) [6,67] and rhodamine B (RhB) [7,8], which use spectrophotometric techniques (Figure 4). Both tests can be used to evaluate the photocatalytic gas degradation, considering both air depollution and dye degradation for self-cleaning applications. ...
Context 2
... the first test, some gases have been used: some VOCs: HC [84], benzene, toluene, xylene and trimethylbenzene [59], SO2 [9] and mainly NO, NO2 or NOx [68,71,83]. Briefly, the gas flow with a controlled concentration passes into a chamber where the sample containing the semiconductor material resides inside and is subjected to light irradiation (Figure 4a). The gas concentration is monitored at the outlet of the system and the photocatalytic efficiency can be further evaluated. ...
Context 3
... the second test, that is, the organic dye degradation, the asphalt mixture samples under study are dipped into a dye's aqueous solution of known initial concentration. Subsequently, the sample already immersed in the dye's aqueous solution is exposed to light irradiation and, over time, the variation in solution concentration is monitored by spectrophotometry (Figure 4b,c). The photocatalytic efficiency can be calculated from detected variations (decrease) in the maximum absorbance values recorded on the absorption spectrum by using visible spectroscopy. ...
Citations
... Photocatalytic asphalt mixtures that use semiconductors can also mitigate air quality problems and degrade oils. Studies tested these materials in terms of physicochemical and rheological characterization and skid resistance finding them to be of high-quality with few differences in comparison to conventional pavements (Segundo et al. 2019b(Segundo et al. , 2019c. Asphalt mixtures can be augmented with microcapsules, glass fibers, nanoparticles, and other materials that enable the surface layers to autonomously repair microcracks, thus enhanc-ing resistance to wear and tear and extending the pavement's lifespan (Qiu et al. 2009). ...
This article explores the connection between Smart City advancements and the development of materials and strategies for asphalt pavements. It highlights the synergy between Smart Cities and Industry 4.0 through current technological advancements using connectivity, artificial intelligence, and big data analysis. The relationships between Smart Cities and Industry 4.0 are examined with an emphasis on five major areas: (i) Internet of Things and integrated systems; (ii) robotics and additive manufacturing; (iii) augmented reality for modeling and simulations; (iv) data-driven analysis: big data, artificial intelligence; and (v) citizen participation. We also point to the importance of smart infrastructure, with the integration of nanomaterials and materials into the structure to reduce energy consumption, optimize resources, and assist automation in construction and maintenance strategies, contributing to the efficiency and longevity of pavement infrastructure. We conclude by envisioning how generative artificial intelligence is integrated into pavement research, opening new avenues for innovation.
... There is a wide range of studies that present Smart City frameworks and indicators, but there is a shortage of studies that compile how smart city advancements can further demand new materials, asphalt in speci c. In certain instances, the term "smart" is used but with no clear connection to established smart concepts and technologies [3]. As stated by Berglund et al., "gaps have been identi ed where the civil engineering profession can apply creativity to improve de ciencies in urban infrastructure" ( [2], p. 21). ...
... This category pertains to the use of intelligent infrastructure that incorporates technology that seeks to produce more sustainable. Within pavement research, there are studies on the so-called smart materials, which can produce certain reactions that are independent of human intervention due to their chemical composition [3]. Through the precise engineering and integration of nanomaterials and nanocoatings, road surfaces can be endowed with enhanced mechanical strength, improved resistance, and advanced functionalities such as self-healing capabilities and sensor-based monitoring systems [15]. ...
... Considering the extensive coverage of road pavements supporting traffic and their proximity to populated areas, highways and parking lots often make up over 35% of metropolitan areas. Recognizing these factors, scientists in Transportation Engineering have been enhancing asphalt mixtures to equip them with additional capabilities, yielding various social, environmental, and financial benefits [8,9]. This functionalization process has given rise to smart materials, which are defined as intelligent substances capable of responding to stimuli like temperature and stress. ...
... When exposed to ultraviolet (UV) light and humidity, semiconductor oxides like TiO 2 and ZnO engage in a process that oxidizes pollutants such as NOx and SO 2 while simultaneously breaking down organic molecules [4, 22,31]. Researchers are actively exploring the incorporation of semiconductor nano/ microparticles in a coating on asphalt mixes to harness their photocatalytic capabilities, effectively reducing air pollution levels [8,33]. This innovative approach shows promise in advancing environmental sustainability within civil engineering practices. ...
... In the past decade, there has been a noticeable increase in research efforts dedicated to advancing the functionalities of asphalt mixtures, often referred to as smart asphalt. This category encompasses a range of features, including but not limited to photocatalytic, self-cleaning, self-healing, superhydrophobic, thermochromic, deicing/anti-icing, and latent heat thermal energy storage characteristics [4,8,12,42,43]. It is crucial to highlight emerging trends in materials, technologies, and processes that require thorough examination. These trends include the comparative analysis between asphalt pavement and asphalt bitumen materials [44], the nuances of pavement management [45], the intricate systems of permeable pavement [46], and a comprehensive exploration of pavement distress [47,48]. ...
Asphalt pavements are essential to our transportation infrastructure, but they have a significant drawback: they require frequent maintenance. However, innovation is revolutionizing the field of materials engineering and could change the way we think about road construction and maintenance. Incorporating self-healing technology into the road design phase holds the promise of extending the durability of roads, eliminating the need for frequent maintenance, leading to significant time and cost savings. Past research has shown that asphalt pavement can restore its stiffness and strength during periods of rest due to the closure of micro-cracks that naturally occur under the stress of traffic loads. Recently, interest in utilizing induction heating to improve the self-healing characteristics of asphalt pavements is revived. Integrating self-healing technology into the road design process holds the promise of revolutionizing road construction and maintenance procedures. Self-healing asphalt technology harnesses asphalt’s natural ability to repair itself. By delaying the need for traditional replacement of heavily damaged roads, this technology reduces the production of asphalt mixtures and also cuts down on energy usage during replacement reducing the environmental impact of waste disposal. This chapter provides and insight to the three most promising options and outlines the future development in self-healing asphalt technology.
... As research and development continue, someone can expect to see these innovative paints play a bigger role in keeping roads safer and more sustainable. [19][20][21][22] Acrylic resins constitute a diverse class of polymers with versatile properties and applications. 23 These resins are formed through the addition polymerization of acrylic acid (CH₂ = CHCOOH) or its derivatives, such as methacrylic acid (CH₂ = C(CH₃)COOH) or acrylates/methacrylates (esters of these acids). ...
Traffic paints hold paramount importance in road markings and ensuring efficient traffic flow. Self-cleaning marking traffic paints are a type of paint which recently developed to keep traffic lines clean with high visibility. Several paints were formulated with acrylic resin and self-cleaning agents, titanium dioxide (TiO2), silicon dioxide (SiO2), and zinc oxide (ZnO) individually and or in combination. All agents were treated in a furnace at 800°C for 2 hours before incorporating into the paint formulation. The effect of untreated and treated agents on several crucial properties of the formulated paints was assessed and compared. It revealed that heat treatment was effective on the crystallinity and impurity content of the agents evidenced by traditional characteristic techniques. The SEM-EDX analysis confirmed the presence and distribution of self-cleaning agents in the paint matrix. Water contact angles ranged from 68° to 97° for paints with self-cleaning agents, indicating improved hydrophilicity. Oil contact angles ranged from 27° to 42° for most paints with self-cleaning agents, showing some improvement in hydrophobicity. The qualitative assessment confirmed superior self-cleaning performance for paints with self-cleaning agents compared to the reference paint, especially for treated agents. Overall, the type and amount of self-cleaning agents significantly affect the hydrophilicity, hydrophobicity, and self-cleaning performance of paints.
... The photocatalysis process takes place on semiconducting oxide materials such as titanium dioxide (TiO2) and zinc oxides (ZnO). Light energy triggers chemical reactions which lead to the formation of carbon dioxide and water in the last phase, resulting in the decomposition of organic compounds on the surfaces of the materials [6] [7] (Equation 1). * + ( ...
Building façades are affected by atmospheric pollution and other external agents that can impact aesthetic aspects and lead to the appearance of anomalies with impacts on the durability and performance of materials. The reduction in maintenance costs and the preservation of the original characteristics of coatings make the use of photocatalytic semiconductor materials highly attractive, particularly for the conservation of historical heritage. These materials can maintain the cleanliness of building surfaces, promote the degradation of pollutants, and have decontamination and antibacterial effects. Thus, the objective of this study was to develop and evaluate the self-cleaning properties of cementitious panels for façades, aiming to obtain a coating with characteristics to contribute to the preservation of built heritage through the incorporation of titanium dioxide (TiO2) nanoparticles and zinc oxide (ZnO) microparticles. To evaluate the self-cleaning, a Rhodamine B (RhB) solution was deposited on the surfaces of concrete samples, which were subjected to 5 irradiation phases by a lamp simulating sunlight totalling 720 minutes. Visual analysis and colour characterisation tests were carried out to evaluate the self-cleaning capacity. The results showed that the treatment improved surface cleanliness after exposure to light while preserving the original aesthetics of the surfaces.
... Researchers worldwide have studied this application using different functionalization techniques, with the spray coating method usually being selected to apply TiO2 nanoparticles over the surface of the asphalt mixture Carneiro et al., 2013;Tang et al., 2017). The advantages of this technique are that it is simple and presents a high efficiency, as most of the nanoparticles are exposed to light (Rocha Segundo et al., 2019). ...
... When organic molecules react with hydroxyl radicals, they can be destroyed to carbon dioxide (CO 2 ) and water (H 2 O) (Rocha Segundo et al. 2019). Different organic compounds, such as oil and grease and biological microbes, can be used in the process described in Eq. 5 (Bogutyn et al. 2015). ...
Air pollution, driven by nitric oxide (NOx) and sulphur oxide (SOx) emissions from heavy traffic and industries, poses global environmental and public health challenges. Titanium dioxide (TiO2) in concrete, harnessing its photocatalytic action under ultraviolet (UV) radiation, emerges as a promising solution for addressing air pollution and achieving sustainable construction practices. It is imperative to comprehend the efficiency factors to ensure the effective implementation of photocatalytic concrete in real-world applications. This review provides a comprehensive analysis of the factors influencing the efficiency of photocatalytic concrete including environmental conditions, TiO2 characteristics, and operational parameters. Additionally, challenges related to long-term performance, environmental impact, and economic viability are discussed. Future research directions and potential solutions to overcome these challenges are also highlighted. Overall, this review offers valuable insights into the current state of photocatalytic concrete technology, its limitations, and the opportunities for its advancement in sustainable construction practices.
... Table 1 presents various research studies that have investigated the absorption capacity of asphalt mixtures using different additives and techniques. Regarding former studies, there are four techniques for adding air pollution absorbing semiconductor additives to asphalt mixture (Rocha Segundo et al., 2019a): adding to bitumen Zhang et al., 2018;Mohammad et al., 2012), volume incorporation (Zhang et al., 2019;Ji 2005;Rehman et al., 2009), spraying coating (Li & Haneda, 2003;Chen & Liu, 2010;Brovelli & Crispino, 2013), and spreading (Wang et al., 2016;Cao et al., 2017;Wang et al., 2018). Materials are only combined with bitumen in the addition technique (Zhang et al., 2019), whereas additives are introduced directly to the aggregates and fillers combination in the volume incorporation approach (Zhang et al., 2018). ...
This paper aimed to investigate the effect of Nano-TiO2 as a semi-conductor additive on the pollutant’s absorption of a micro-surfacing layer. In this research, micro-surfacing samples with Nano-TiO2 values of 5, 7, 9, 11, and 13% (by weight of bitumen) and two types of aggregates (immersed and non-immersed aggregates in Nano-TiO2) were tested to determine contaminant absorption and evaluate rutting performance at two temperatures of 20 and 40°C. The results revealed that NOX absorption improved with increasing Nano-TiO2, reaching 40% in samples with the optimal amount of Nano-TiO2 (11% by weight of bitumen). Wheel track test results showed that the optimum sample had a better performance compared to the control sample. Also, it was observed that the absorption of pollutants decreased after conducting the wheel track test.
... However, there are several functions that can be used on concrete pavements, such as energy-harvesting function, smartness function, conductivity, and shielding [11,[26][27][28][29][30][31]. For asphalt pavements, functions including thermochromic, photocatalytic, wettability control, and self-healing also attracted numerous attentions [32][33][34][35][36][37][38][39]. This review mainly focuses on the photocatalytic, thermochromic, self-healing, and self-sensing functions to analyse the functional improvements of concrete and asphalt pavements. ...
Cement-asphalt pavements are widely used in transport infrastructure. Multifunctional pavement is a novel concept that can improve the functionalities, durability, and serviceability of the pavement for smart transport. The self-healing, self-sensing, photocatalytic, and thermochromic capacities of cement-asphalt concrete are significant components of multifunctional pavements. The self-healing function can extend the service life of pavements with improved durability. The concept of self-sensing concrete has been proposed and widely investigated for structural health monitoring. The photocatalytic function helps reduce pollution caused by vehicle gas emission. The thermochromic function can be used to detect the temperature of asphalt concrete pavements. Previous studies mainly focused on the individual components and performance of these functionalities in cement-asphalt concrete. To achieve these multifunctionalities, various carbon nanomaterials can be added to the cementitious-asphalt concrete, such as carbon black (CB), carbon nanofiber (CNF), carbon nanotubes (CNTs), graphene nanoplate (GNP), and others. However, more and more attentions have been paid to the pavements with integrated multifunctionalities. The functional concrete has been applied to the smart transport system, such as pavement, railway, bridge, and tunnel for infrastructure health monitoring and traffic-flow monitoring. This paper comprehensively reviews the recent developments of multifunctional technologies as well as the potential applications of these novel technologies. The related findings will be useful for future research on multifunctional pavements and their applications for smart transport.
... Photocatalysts, semiconductor oxides such as TiO 2 and ZnO, can oxidize pollutants, including, for instance, NO x and SO 2 , and degrade organic compounds in the presence of ultraviolet (UV) light and humidity [1,22,33]. To mitigate air pollution levels, researchers are concerned about the application of photocatalytic capability on asphalt mixtures by coating with semiconductor nano/microparticles [6,35]. In the literature, some strategies can be highlighted when it comes to the immobilization of particles. ...
... Given that road pavements are close to people and cover a large area, accounting for more than 50% of the urban area comprising roads and parking lots, researchers in Transportation Engineering have started functionalizing asphalt mixtures. This approach provides them with new capabilities, consequently offering several social, environmental, and financial benefits [6][7][8][9]. ...
... Snow and ice in winter are known to cause many traffic accidents due to the reduced friction between tires and pavement [10][11][12]. Current practices to mitigate this problem rely on deicing agents [13], and conductive materials in asphalt superhydrophobic, thermochromic, deicing/anti-icing, and latent heat thermal energy storage [1,6,12,47,48]. ...
A smart asphalt mixture holds new capabilities different from the original ones or can react to a stimulus. These capabilities can be categorized based on smartness or function: smartness, mechanical, electrical, optical, energy harvesting, electromagnetic wave/radiation shielding/absorbing, and water related. The most important capabilities applied to asphalt mixtures are the photocatalytic, self-cleaning, self-healing, superhydrophobic, thermochromic, deicing/anti-icing, and latent heat thermal energy storage abilities. This research deals with a bibliometric review of the peer-reviewed journal articles published on the Scopus database, with the strings of terms related to these capabilities and asphalt or bitum in their titles, abstracts, and keywords. The review analysis highlighted the increasing number of accumulated publications, confirming the relevance of this research topic in recent years. The capability most often referred to was self-healing. The study showed that China was the most productive country. Research articles were mostly published in the journal Construction and Building Materials. Several techniques and methods are being developed regarding smart asphalt mixtures; for that reason, this research work aims to evaluate the literature under a bibliometric analysis.
