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)

Review on the incorporation of phase change materials (PCM) into asphalt mixtures to mitigate urban heat Island

Serious environmental problems are attributed to the uncontrolled growth of cities. Usually, highly populated areas suffer from soil sealing caused by the construction of infrastructure, such as road pavements and buildings. Regarding the Transportation Engineering, the most common material applied in road pavements is bitumen as binder constituent. Usually dark-coloured, the surface temperature of asphalt pavements may reach values higher than 60 °C during summer. This fact can significantly contribute to the formation of thermal cracks and deformations in asphalt binders and, in large urban centres, promote the formation of warmer microclimates since all the accumulated heat is released to the surrounding environment. The formation of Urban Heat Islands (UHI), a type of microclimate that arises from the increase in temperature of a location that does not match the region, caused by anthropic changes, for some time now, is a problem that has attracted a range of research to minimise harmful effects caused to the environment. Some of the most promising studies to decrease the temperature of pavements are using Phase Change Materials (PCM). PCM are materials that can accumulate a large amount of thermal energy and are widely used in the textile industry, smart tissues, and construction, improving thermal comfort. PCM can minimise the problems arising from seasonal temperature variations when used in conjunction with asphalt materials. In this work, a review was made about which types of PCM are mainly used to achieve a significant decrease in pavement temperature—evaluating the material's thermal performance and the most used strategies to avoid its leakage. A systematic review of recent papers published in peer-reviewed journals (available in the Scopus database) involving asphalt mixtures with phase change materials revealed that the most used type of PCM is polyethylene glycol (PEG). Asphalt mixtures containing PCM generally have lower mechanical performance than conventional asphalt mixtures. There are problems related to leaking the material into the asphalt, sometimes reaching the soil and possibly causing contamination. On average, the temperature values decrease 4 °C, in some cases reaching 9 °C of difference, compared to conventional asphalt-based binders. To avoid leaking of this material, the most applied strategy is the PCM encapsulation within particles composed of silicon dioxide (SiO2) or polyacrylamide (PAM). According to the literature surveyed, it can be concluded that incorporating PCM into asphalt pavements can mitigate the formation of UHI acting as a thermoregulation factor, with acceptable mechanical and improved environmental performance

Study of the composition of coaxial microfibers with phase change materials under thermal analysis

Asphalt pavements cover a large area of urban centers and are directly related to Urban Heat Islands (UHI). These materials heat up by absorbing a large amount of solar energy and then slowly release it, generating environmental, economic and social impacts that directly harm the well-being of citizens. The use of Phase Change Materials (PCM) in asphalt mixtures is indicated in the literature as an efficient thermoregulation method to mitigate UHI. However, their direct incorporation in asphalt mixtures presents some disadvantages related to modifying the asphalt structure after PCM melting. The development of Coaxial Polymeric Fibers (CPF) emerges as an innovative alternative to incorporate PCM in asphalt mixtures. Thus, the research herein reported aims to produce and select the best composition of coaxial fibers composed of Polyethylene glycol (PEG) as PCM and core and cellulose acetate (Mn: 30,000 and 50,000) as sheath. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used for thermal characterization. TGA was used to analyse whether the materials could tolerate the mixing and compaction temperatures of the asphalt mixtures (up to about 200°C) without any mass loss, and DSC to assess the melting point for the CPF. Thereby it is possible to determine the effect of cellulose acetate molecular weight on the phase change temperature of PEG inside the CPF. This information will aid in deciding on suitable materials for asphalt concrete mixtures capable of withstanding asphalt mixing temperatures

Reducing the effects of Low Albedo of asphalt materials incorporating Polyethylene Glycol (PEG) 1000, 2000 and 4000 as Phase Change Materials (PCM)

Albedo plays a vital role in urban microclimates. Civil engineering structures usually absorb a high amount of energy in form of heat, for example asphalt pavements, which have a low albedo, thus contributing to the Urban Heat Island (UHI) effects. Modifying the physical characteristics of asphalt pavements, including reflectance and thermal properties, can help mitigate UHI. The literature points out that one alternative to thermoregulating asphalt materials is the incorporation of phase change materials. Thus, the main goal of this research is to present a systematic review regarding the effectiveness of the incorporation of polyethylene glycol (PEG) 1000, 2000 and 4000 as Phase Change Material (PCM) in asphalt materials. The results showed that incorporating PEG into asphalt materials can regulate heat storage, promoting stability and reducing UHI effects. PEG2000 was more frequently used. PEGs can reduce between of 3.5 and 4.2ºC of the asphalt materials when compared to the conventional ones.This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UIDB/04650/2020 and the projectsMicroCoolPav project EXPL/EQU-EQU/1110/2021, and NanoAir project PTDC/FISMAC/6606/2020

Coaxial fibres incorporated with phase change materials for thermoregulation applications

Nowadays, the growing concern about improving thermal comfort in different structures (textiles, buildings, and pavements, among others) has stimulated research into phase change materials (PCMs). The direct incorporation of PCMs into composite materials can cause mechanical impacts. Therefore, this study focuses on the design of phase change coaxial fibres (PCFs), using commercial cellulose acetate (CA) or recycled CA obtained from cotton fabrics (CAt) as the sheath and polyethylene glycol (PEG) 2000 as the core, via the wet spinning method; the fibres vary in molecular weight, concentration and ejection velocity. The fibres were assessed for their optical, chemical, thermal, and mechanical properties. The presence of PEG2000 is confirmed in the core of the fibres. Thermal analyses revealed a mass loss at high temperatures, attributable to the presence of PEG2000. Notably, the fibres with CA (Mn 30,000) showed superior thermal and mechanical performance. The melting point of PEG2000 incorporated into these PCFs coincided with the melting point of pure PEG2000 (about 55 °C), with a slight deviation, indicating that PCFs were obtained. Finally, the results point to the application of the fibres in civil engineering materials requiring a phase change between 50 and 60 °C, providing promising prospects for their use in applications requiring thermoregulatory properties.This research was funded by the Portuguese Foundation for Science and Technology (FCT) under the projects MicroCoolPav EXPL/EQUEQU/1110/2021 and NanoAir PTDC/FISMAC/6606/2020 (https://doi.org/10.54499/PTDC/FIS-MAC/6606/2020) and within the framework of Strategic Funding UIDB/04650/2020, UIDB/04029/2020 (https://doi.org/10.54499/UIDB/04029/2020) and UID/QUI/0686/2020. I.R.S. and H.P.F. would like to thank FCT for their funding contracts 2022.00763.CEECIND (https://doi.org/10.54499/2022.00763.CEECIND/CP1718/CT0006) and 2021.02720.CEECIND (https://doi.org/10.54499/DL57/2016/CP1377/CT0098)

Advancements in phase change materials in asphalt pavements for mitigation of urban heat island effect: bibliometric analysis and systematic review

This research presents a dual-pronged bibliometric and systematic review of the integration of phase change materials (PCMs) in asphalt pavements to counteract the urban heat island (UHI) effect. The bibliometric approach discerns the evolution of PCM-inclusion asphalt research, highlighting a marked rise in the number of publications between 2019 and 2022. Notably, Chang’an University in China has emerged as a leading contributor. The systematic review addresses key questions like optimal PCM types for UHI effect mitigation, strategies for PCM leakage prevention in asphalt, and effects on mechanical properties. The findings identify polyethylene glycols (PEGs), especially PEG2000 and PEG4000, as prevailing PCMs due to their wide phase-change temperature range and significant enthalpy during phase transitions. While including PCMs can modify asphalt’s mechanical attributes, such mixtures typically stay within performance norms. This review emphasises the potential of PCMs in urban heat management and the need for further research to achieve optimal thermal and mechanical balanceThis research was partially funded by the Portuguese Foundation for Science and Technology (FCT) under the framework of the projects MicroCoolPav EXPL/EQU-EQU/1110/2021, NanoAir PTDC/FIS-MAC/6606/2020, UIDB/04650/2020, and UIDB/04029/2020. This research was also supported by the doctoral Grant PRT/BD/154269/2022 financed by the FCT, and with funds from POR Norte-Portugal 2020 and State Budget, under MIT Portugal Program. I.R.S. would like to acknowledge the FCT for funding (2022.00763.CEECIND). V.C.B. acknowledges the Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico (Funcap), MLC-0191- 00144.01.00/22 (Edital Mulheres na Ciência), and the National Council for Scientific and Technological Development (CNPq), Process 404978/2021-5—Call CNPq/MCTI/FNDCT N° 18/2021—Faixa B—Consolidated Groups

Dez anos da Revista Multiface e o Incentivo à Pesquisa na Graduação

A Revista Multiface Online é um periódico organizado por alunos de graduação da UFMG e que publica exclusivamente trabalhos produzidos por graduandos, nas áreas de Economia, Administração e Relações Econômicas Internacionais. Contando com 10 anos de existência e sendo uma revista disponibilizada no formato digital, a Multiface tem recebido trabalhos de alunos das mais diversas universidades do país. Nesse sentido, este trabalho tem como objetivo apresentar o periódico e as características particulares que o tornam um espaço de incentivo à pesquisa na graduação. Entre estes está o processo de avaliação, que busca sempre produzir pareceres construtivos, a fim de contribuir para a formação de novos pesquisadores desde a graduação. Além disso, a existência de uma revista editorada por alunos de graduação também possibilita a formação de membros de comitês editoriais desde a graduação