Assessing photocatalytic asphalt mixtures: practical and laboratory methods for measuring air quality

Air pollution in urban areas has become a major global concern, leading to a series of programs and regulations to be implemented to reduce it. Among the various pollutants that affect air quality is nitrogen monoxide (NO), which, once in the atmosphere, oxidizes into nitrogen dioxide (NO2). The combination of NO and NO2 refer to the nitrogen oxides (NOx), which, besides being harmful to health, have a negative impact on the environment with acid rain and intensify the greenhouse effect. This issue is exacerbated in large cities due to the high concentration of pollutant-emitting vehicles. To mitigate this problem by cleaning the air, researchers are investing in photocatalytic capability that can be applied to the surface of various substrates. Titanium dioxide (TiO2) is a highly utilized material, especially when aiming to attain both photocatalytic and self-cleaning abilities. The application of TiO2 over asphalt pavements has become an important topic in Transportation Engineering as a way of functionalized conventional pavement into a substrate where it becomes feasible to alleviate the environmental damage related to pollutant emissions, mainly NOx. The application of photocatalytic materials on asphalt pavements has the necessary conditions to increase the success of reducing pollutant levels. Pavements present a large area and are closer to vehicle exhausts. In addition, a major part of asphalt pavements is exposed to sunlight, which can activate the photocatalytic reaction. Due to these benefits, researchers have conducted studies that evaluate photocatalytic efficiency on surfaces of asphalt pavements.When evaluating photocatalytic efficiency, the literature describes a series of methods based on laboratory and field tests. In the laboratory, efficiency can be evaluated by degrading different organic dyes and degradation gas tests. For the first method, some dyes are widely used, such as methylene orange (MO), methylene blue (MB) and rhodamine B (RhB). For testing, samples of asphalt mixtures are immersed in an initial dye solution and exposed to light irradiation. Over time, changes in the solution absorbance (and, consequently, concentration) are monitored using spectrophotometry. The photocatalytic efficiency is calculated as a function of the maximum absorbance of the dye and the time. The second test follows the ISO 22197-1 standard, which specifies a test method for determining the air purification performance of materials with photocatalysis on the surface. To simulate and ensure the photocatalytic reactions occur, the experimental setup must contain an air compressor, pollutant source, humidifier, photoreactor, light source and pollutant analyzer. The photocatalytic asphalt mixture sample is placed inside the photoreactor and exposed to a controlled amount of pollutants, light and humidity. The gas flow is continuously injected into the photoreactor and subjected to light irradiation, and gas concentration is monitored over a period of time. The photocatalytic efficiency can be assessed by the net amount of pollutants that the sample removes.In field applications, one method that can be used to evaluate the efficiency is the air quality monitoring stations by conducting a comparative analysis of pollutant concentrations in a specific area before and after installing photocatalytic asphalt pavements. Those stations have sensors that collect outdoor air and distribute it through analyzers. These analyzers continuously and automatically measure various atmospheric pollutants, determining their concentrations in the ambient air "in real-time". Typically, they are fixed at strategic points in large cities, limiting assessment in more remote locations. Usually, these stations can measure several types of pollutants, such as NOx, SO2, CO2, particulate matter, among others, and the meteorological conditions, for example temperature, relative humidity, wind speed and direction , etc. Another method to evaluate the performance in field studies is to use passive sampling. The passive sampling approach is a low-cost, non-electrical, and simplified solution for the distribution of samples. The principle of the passive sampler involves gas collection through the diffusion of atmospheric air, which enters the device through one of its ends, travels through the body of the sampler (in the form of a tube) until it reaches its other end, which is sealed and contains a filter paper previously impregnated with a specific absorbent solution designed to react with the targeted pollutant to be collected. Measurement of photocatalytic efficiency is crucial in determining the performance of photocatalytic pavements and their impact on air quality. Thus, this study aims to provide a comprehensive elucidation of how to evaluate the photocatalytic efficiency of photocatalytic asphalt pavements functionalized with TiO2 nanoparticles through various methods, encompassing laboratory approaches and field studies.This research was funded by FCT: NanoAir PTDC/FISMAC/6606/2020, MicroCoolPav EXPL/EQU-EQU/1110/2021, UIDB/04650/2020, UIDB/04029/2020, 2022.00763.CEECIND and 2023.02795.BD. Also, it was funded by FUNCAP: MLC-0191-00144.01.00/22 and CNPq: 404978/2021-5 – Chamada CNPq/MCTI/FNDCT Nº 18/2021.

Smart asphalt mixtures: a bibliometric analysis of the research trends

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.This research was funded by the Portuguese Foundation for Science and Technology (FCT), NanoAir PTDC/FIS-MAC/6606/2020, MicroCoolPav EXPL/EQU-EQU/1110/2021, UIDB/04650/2020, and UIDB/04029/2020. This research was also supported by the doctoral grant 2023.02795.BD, funded by FCT, as well as and bydoctoral grant PRT/BD/154269/2022 financed by the FCT and with funds from POR Norte-Portugal 2020 and State Budget, under MIT Portugal Program. The first author would like to acknowledge the FCT for funding (2022.00763.CEECIND)

Evaluation of air cleaning using functionalized asphalt mixture sprayed with TiO 2 nanoparticles

[Excerto] Photocatalytic asphalt mixtures have gained attention as a possible alternative to mitigate the air pollution in urban areas. The asphalt surface when functionalized with nano-TiO2 can reduce nitrogen oxides (NOx), a harmful pollutant emitted by vehicles that contributes to problems such as acid rain and public health concernsCT/MCTES sponsored this research by the projects NanoAir PTDC/FISMAC/6606/2020, MicroCoolPav EXPL/EQU-EQU/1110/2021 and UIDB/04650/2020, under the R&D from ISISE (UIDB/04029/2020) and the ARISE (LA/P/0112/2020). Also, the second and third authors would like to acknowledge the FCT for funding PRT/BD/154269/2022, 2022.00763.CEECIND, respectively

Passive sampling for air quality assessment: proposal of an in-situ method to measure the efficiency of photocatalytic pavements

Currently, air pollution is a matter of great relevance due to its significant impact on human health. Semiconductor photocatalysis technology, known for its high efficiency and low environmental degradation, is considered a highly promising means to improve air quality. Asphalt pavements are commonly used in urban areas with high population concentrations. During the production cycle of these pavements, various air pollutants are emitted, primarily due to the high temperatures required for asphalt pavement. Photocatalysis using the semiconductor TiO2 has the capacity to degrade atmospheric NO under sunlight, which has sparked significant interest in photocatalysis technology and its applications.The bandgap, enduring physicochemical properties of the element, and its nontoxicity, along with its NO degradation capabilities, make TiO2 a highly viable option for photocatalysis. This study aims to elucidate how air quality is controlled through passive sampling for the quantification of nitrogen dioxide (NO2) in the atmosphere. Through this technique, it is possible to quantify the level of pollutants, in this case, NO2, present in the atmosphere at a selected location over a certain period of time.MicroCoolPav EXPL/EQU-EQU/1110/2021, UIDB/04650/2020, UIDB/04029/2020, 2022.00763.CEECIND and 2023.02795.BD. Also, it was funded by FUNCAP: MLC-0191-00144.01.00/22 and CNPq: 404978/2021-5 – Chamada CNPq/MCTI/FNDCT Nº 18/2021

Use of scenarios as a means of assessing leadership competencies in project management

Dissertação de mestrado em Gestão de Projetos de EngenhariaO objetivo deste estudo é a criação de um modelo de avaliação, baseado em cenários, para avaliar competências de liderança em profissionais de gestão de projetos. O desenvolvimento do modelo de avaliação teve como base o Manual de Entrevista da Universidade de McMaster desenvolvido por Michael G. DeGroote. O modelo desenvolvido neste projeto de mestrado foca na avaliação da competência de liderança, através do conjunto de indicadores de competência apresentados pelo Referencial do International Project Management Association (IPMA, 2015) de Competências Individuais para Gestão de Projetos, Programas e Portefólios. Para construir e avaliar este processo de avaliação, utilizaram-se dois elementos fundamentais: (1) desenvolveu-se uma rúbrica para avaliação da competência de liderança; (2) adaptou-se um processo de avaliação inspirado no modelo de McMaster, utilizando um cenário de liderança. Uma rubrica de avaliação é concebida como ferramenta para auxiliar o processo e compor os indicadores e medidas de desempenho a serem avaliados pelo modelo. Esta rúbrica passou por processos de validação interna e externa e por testes estatísticos de fiabilidade. Os resultados demonstraram as evidencias necessárias referidas na literatura para sua aplicabilidade. Além disso, um cenário simulado específico foi utilizado para permitir a aplicação do modelo de avaliação concebido. O modelo de avaliação foi aplicado através de entrevista com 13 participantes, sendo 10 profissionais, 2 avaliadores e 1 observador. O processo de recolha de dados foi realizado em três momentos: o primeiro momento na etapa de validação da rubrica de avaliação, o segundo momento durante a experiência quando os participantes responderam ao cenário e foram avaliados pelos avaliadores e o terceiro momento quando os participantes desenvolveram narrativas sobre a experiência vivida. Os dados foram analisados de forma quantitativa, para validação e fiabilidade, e qualitativa, para análise de narrativas sobre o processo de avaliação. Os resultados evidenciam que a utilização de cenários, como meio de avaliar competências, tem potencial de aplicação na gestão de projetos, e pode ser um modelo utilizado por organizações. A título de exemplo, pode utilizar-se na contratação profissional, na identificação de perfis dentro da organização, também em processos de certificação e na acreditação profissional. A utilização da rubrica de avaliação é de fundamental importância para que os avaliadores sejam orientados e consigam pontuar.The purpose of this study is the creation of a scenario-based assessment model to evaluate leadership competencies in project management professionals. The development of the assessment model was based on the McMaster University Interview Manual developed by Michael G. DeGroote. The model developed in this master's project focuses on assessing leadership competency through the set of competency indicators presented by the International Project Management Association (IPMA, 2015) Benchmark of Individual Competencies for Project, Program and Portfolio Management. Two key elements were used to construct and evaluate this assessment process: (1) a rubric was developed for assessing the leadership competency; (2) an assessment process inspired by McMaster's model was adapted using a leadership scenario. An evaluation rubric is designed as a tool to assist the process and compose the indicators and performance measures to be evaluated by the model. This rubric went through internal and external validation processes and statistical reliability testing. The results demonstrated the necessary evidence referred to in the literature for its applicability. In addition, a specific simulated scenario was used to allow the application of the designed evaluation model. The evaluation model was applied through interview with 13 participants, being 10 professionals, 2 evaluators, and 1 observer. The data collection process was carried out in two moments: the first moment in the validation stage of the evaluation rubric, and the second moment during the experience when the participants responded to the scenario and were evaluated by the evaluators and the third moment when the participants developed narratives about their lived experience. Data were analyzed quantitatively, for validation and reliability, and qualitatively, for analysis of narratives about the evaluation process. The results show that the use of scenarios as a means of assessing competencies has potential application in project management, and can be a model used by organizations. As an example, it can be used in professional hiring, in identifying profiles within the organization, also in certification processes and professional accreditation. The use of the assessment rubric is of fundamental importance for the assessors to be guided and able to score