Assessment of hygrothermal characteristics of earthen materials

The author was invited to present orally the research performed in this thesis at a meeting of the RILEM TC 274 that was held in Université de Pau et Pays de l’Adour at Anglet, France, in October 2019. Gomes, R. (2019). Assessment of hygrothermal characteristics of earthen materials. RILEM TC 274 meeting.One of the biggest challenges currently faced by society is the fight against climatic change. The building sector is an important part of the total emissions of carbon dioxide. Hence, there has been a rising interest on the building sector to reduce its impact on the environment. Earth is used as a construction material since ancient times and its known for its sustainability, hygroscopic and thermal behaviour, making it a natural moisture buffer, helping in the regulation and control of the indoor air quality, maintaining the levels of relative humidity inside the buildings, providing a healthier environment for their occupants. Despite being an ancient building material, its use is not disseminated across the world, mainly due to the lack of appropriate and specified standards for assessing its characteristics. Therefore, studies must be performed with the aim to establishing technical guides and standards for earthen building materials. The aim of this dissertation is to elaborate accurate, repeatable and reproducible test protocols in order to measure the dry mass and the water vapour permeability for earthen materials. Furthermore, there is the need to confirm the reliability of the different methods assessed, mainly through round robin tests performed in different laboratories. Samples manufactured with a chosen reference earth at two laboratories are tested at both laboratories. Firstly, it is evaluated the similarity of samples fabricated at different laboratories with the same protocol, and finally, the assessment of the hygrothermal characteristics is studied. Results show that samples manufactured with the same earth at different laboratories with the same protocol can be considered similar regarding their apparent and dry densities and thermal conductivity, however with slightly differences. Samples manufactured at ENTPE present lower apparent and dry densities as well as lower thermal conductivity values than the ones manufactured at NOVA. Therefore, the assessment of the water vapour permeability is studied based on three different methods, showing similar results by the experimental data collected. The wet cup test performed through the gloves box obtained the lowest variations of the water vapour resistance factor. Several drying-methods were studied mainly through sorption isotherms and cycles of drying-wetting, with one outcoming drying-method. Oven-drying at 105ºC prove to be an accurate and repeatable dry-method and able to allow the material to return to its initial state from a hygroscopic point of view

Fernandina Wall of Lisbon: Mineralogical and Chemical Characterization of Rammed Earth and Masonry Mortars

PTDC/EPH-PAT/4684/2014 UIDB/04625/2020This paper aims to provide information on rammed earth and masonry mortars of the Fernandina defensive Wall of Lisbon, Portugal, which was built in the second half of the 14th century. No previous information exists concerning the materials and construction techniques used in this defensive structure, which is essential to increase knowledge and to define requirements for a reliable conservation. An experimental campaign was carried out on samples extracted in nine different sections of this structure, which were analyzed by X-ray diffraction, thermogravimetry and wet chemical analysis. Calcitic lime was employed as a binder in the stone masonry bedding mortars and was also identified in the rammed earth samples. The results obtained allowed us to verify the use of different binders and aggregates, with heterogeneous binder/aggregate ratios, in different sections of the Wall. To reduce time for lime preparation and to achieve a durable lime matrix, most probably quicklime was used and hydrated together with the moistened earth to produce rammed earth and masonry bedding mortars.publishersversionpublishe

Algorithm for automatic fatigue crack growth simulation on welded high strength steels

Nowadays the demand for high strength steels is increasing. In order to design and develop high performance products, it is essential to understand the fatigue behavior of these materials. When considering welded components, the fatigue behavior is even more complex. The material parameters may change along the crack growth and mixed mode crack propagation may also occur. To assess welded high strength steel fatigue behavior, different welded CT specimens were tested. The Paris law material constants were obtained for the heat affected zone material. Fatigue crack growth life predictions were made using the obtained parameters and different automatic techniques. Previous work showed that the ABAQUS extended finite element method can predict fatigue crack growth, but as the implementation of the Paris law is not straight forward, to many conversions must be made and the results are too computer intensive. A simpler and more intuitive Python algorithm was developed, to enable the use of the experimental material parameters, to predict the crack propagation path. The obtain results show a good agreement with both the experimental Paris curves, and the analytical solution

Carbonation potential of recycled aggregates from construction and demolition waste

One of the biggest challenges currently faced by Society is climate change, leading to the need of mitigation of carbon dioxide (CO2) emissions, among other consequences. The construction sector is responsible for a large part of these emissions. In addition, this sector is also responsible for a significant part of all waste globally produced, about one third in the European Union. The use of construction and demolition wastes (CDW) as aggregates in mortars and concrete has been the objective of several studies. This incorporation reduces the volume of natural aggregates used in these construction products, decreasing the depletion of natural resources, while increasing the life cycle of the incorporated by-products. It thus contributes to the reduction of the environmental impacts of the construction sector. Nevertheless, recycled aggregates are not often incorporated in mortars and concrete due to their higher porosity and lower strength compared to natural aggregates. Jointly with the Portuguese cement industry, this research intends to produce more sustainable mortars and concrete by using CDW aggregates as a carbon capture and storage source. This not only reduces the global greenhouse emissions of concrete but also potentially improves the CDW aggregates’ properties. To this extent, different types of CDW aggregates will be subjected to forced and accelerated sequestration of CO2, contributing to the capture of part of the CO2 emissions of the Portuguese cement industry, providing it with more sustainable processes. As a result, this study intends to contribute to the reduction of non-renewable natural resources, in the form of natural aggregates, while reusing CDW and capturing part of the CO2 released by the production of cement. This article presents the characterization of three CDW from different origin and treatments, regarding the analysis of their carbonation potential.publishersversionpublishe

Mortars with cdw recycled aggregates submitted to high levels of co2

Funding Information: Funding: This research was funded within the research project WP10B by c5Lab (CoLab 4/2018-CemLab).Construction and demolition wastes (CDW) are generated at a large scale and have a diversified potential in the construction sector. The replacement of natural aggregates (NA) with CDW recycled aggregates (RA) in construction materials, such as mortars, has several environmental benefits, such as the reduction in the natural resources used in these products and simultaneous prevention of waste landfill. Complementarily, CDW have the potential to capture CO2 since some of their components may carbonate, which also contributes to a decrease in global warming potential. The main objective of this research is to evaluate the influence of the exposure of CDW RA to CO2 produced in cement factories and its effect on mortars. Several mortars were developed with a volumetric ratio of 1:4 (cement: aggregate), with NA (reference mortar), CDW RA and CDW RA exposed to high levels of CO2 (CRA). The two types of waste aggregate were incorporated, replacing NA at 50% and 100% (in volume). The mortars with NA and non-carbonated RA and CRA from CDW were analysed, accounting for their performance in the fresh and hardened states in terms of workability, mechanical behaviour and water absorption by capillarity. It was concluded that mortars with CDW (both CRA and non-carbonated RA) generally present a good performance for non-structural purposes, although they suffer a moderate decrease in mechanical performance when NA is replaced with RA. Additionally, small improvements were found in the performance of the aggregates and mortars with CRA subjected to a CO2 curing for a short period (5 h), while a long carbonation period (5 d) led to a decrease in performance, contrary to the results obtained in the literature that indicate a significant increase in such characteristics. This difference could be because the literature focused on made-in-laboratory CDW aggregates, while, in this research, the wastes came from real demolition activities, and were thus older and more heterogeneous.publishersversionpublishe

MAMMALS IN PORTUGAL : A data set of terrestrial, volant, and marine mammal occurrences in P ortugal

Mammals are threatened worldwide, with 26% of all species being includedin the IUCN threatened categories. This overall pattern is primarily associatedwith habitat loss or degradation, and human persecution for terrestrial mam-mals, and pollution, open net fishing, climate change, and prey depletion formarine mammals. Mammals play a key role in maintaining ecosystems func-tionality and resilience, and therefore information on their distribution is cru-cial to delineate and support conservation actions. MAMMALS INPORTUGAL is a publicly available data set compiling unpublishedgeoreferenced occurrence records of 92 terrestrial, volant, and marine mam-mals in mainland Portugal and archipelagos of the Azores and Madeira thatincludes 105,026 data entries between 1873 and 2021 (72% of the data occur-ring in 2000 and 2021). The methods used to collect the data were: live obser-vations/captures (43%), sign surveys (35%), camera trapping (16%),bioacoustics surveys (4%) and radiotracking, and inquiries that represent lessthan 1% of the records. The data set includes 13 types of records: (1) burrowsjsoil moundsjtunnel, (2) capture, (3) colony, (4) dead animaljhairjskullsjjaws, (5) genetic confirmation, (6) inquiries, (7) observation of live animal (8),observation in shelters, (9) photo trappingjvideo, (10) predators dietjpelletsjpine cones/nuts, (11) scatjtrackjditch, (12) telemetry and (13) vocalizationjecholocation. The spatial uncertainty of most records ranges between 0 and100 m (76%). Rodentia (n=31,573) has the highest number of records followedby Chiroptera (n=18,857), Carnivora (n=18,594), Lagomorpha (n=17,496),Cetartiodactyla (n=11,568) and Eulipotyphla (n=7008). The data setincludes records of species classified by the IUCN as threatened(e.g.,Oryctolagus cuniculus[n=12,159],Monachus monachus[n=1,512],andLynx pardinus[n=197]). We believe that this data set may stimulate thepublication of other European countries data sets that would certainly contrib-ute to ecology and conservation-related research, and therefore assisting onthe development of more accurate and tailored conservation managementstrategies for each species. There are no copyright restrictions; please cite thisdata paper when the data are used in publications.info:eu-repo/semantics/publishedVersio

Mammals in Portugal: a data set of terrestrial, volant, and marine mammal occurrences in Portugal

Mammals are threatened worldwide, with ~26% of all species being included in the IUCN threatened categories. This overall pattern is primarily associated with habitat loss or degradation, and human persecution for terrestrial mammals, and pollution, open net fishing, climate change, and prey depletion for marine mammals. Mammals play a key role in maintaining ecosystems functionality and resilience, and therefore information on their distribution is crucial to delineate and support conservation actions. MAMMALS IN PORTUGAL is a publicly available data set compiling unpublished georeferenced occurrence records of 92 terrestrial, volant, and marine mammals in mainland Portugal and archipelagos of the Azores and Madeira that includes 105,026 data entries between 1873 and 2021 (72% of the data occurring in 2000 and 2021). The methods used to collect the data were: live observations/captures (43%), sign surveys (35%), camera trapping (16%), bioacoustics surveys (4%) and radiotracking, and inquiries that represent less than 1% of the records. The data set includes 13 types of records: (1) burrows | soil mounds | tunnel, (2) capture, (3) colony, (4) dead animal | hair | skulls | jaws, (5) genetic confirmation, (6) inquiries, (7) observation of live animal (8), observation in shelters, (9) photo trapping | video, (10) predators diet | pellets | pine cones/nuts, (11) scat | track | ditch, (12) telemetry and (13) vocalization | echolocation. The spatial uncertainty of most records ranges between 0 and 100 m (76%). Rodentia (n =31,573) has the highest number of records followed by Chiroptera (n = 18,857), Carnivora (n = 18,594), Lagomorpha (n = 17,496), Cetartiodactyla (n = 11,568) and Eulipotyphla (n = 7008). The data set includes records of species classified by the IUCN as threatened (e.g., Oryctolagus cuniculus [n = 12,159], Monachus monachus [n = 1,512], and Lynx pardinus [n = 197]). We believe that this data set may stimulate the publication of other European countries data sets that would certainly contribute to ecology and conservation-related research, and therefore assisting on the development of more accurate and tailored conservation management strategies for each species. There are no copyright restrictions; please cite this data paper when the data are used in publications

Mortars with construction and demolition waste recycled aggregates after CO2 exposure

CoLAB 4/2018-CemLabO aquecimento global é causado pela quantidade crescente de gases com efeito de estufa na atmosfera, assumindo-se como uma das maiores ameaças ambientais a nível mundial. Assim, têm surgido esforços globais para a sua mitigação, nomeadamente através da redução das emissões de gases, particularmente do dióxido de carbono (CO2). Diversas estratégias de captura e armazenamento do CO2 emitido têm sido estudadas e vindo a ser implementadas. Os resíduos de construção e demolição (RCD) são gerados em grande abundância e têm um potencial diversificado no sector da construção, que é a indústria que os gera e tem maior responsabilidade na sua gestão. Não obstante os estudos já desenvolvidos, a sua utilização em materiais de construção, como argamassas, é ainda limitada. Esta incorporação reduz o volume de matéria-prima natural utilizada nestes produtos, abrandando assim o esgotamento de recursos naturais, ao mesmo tempo que reduz a energia que incorporam e aumenta o seu ciclo de vida. Complementarmente, muitos RCD têm potencial para captação de CO2 produzido pela indústria, por processos químicos ou físicos. Este artigo visa apresentar os primeiros resultados de um estudo de avaliação de desempenho de agregados reciclados após submissão a carbonatação forçada e acelerada, com o objectivo de contribuir para a captação de CO2. São estudadas argamassas cimentícias fabricadas com agregados naturais (argamassas de referência) e com agregados reciclados antes e após carbonatação, com um traço volumétrico de 1: 4 (cimento: agregado). Pretende-se, desta forma, contribuir para a captação de parte das emissões de CO2 da indústria cimentícia Portuguesa, dotando-a de mecanismos que permitam torná-la mais sustentável em termos energéticos e ambientais. Adicionalmente, pretende-se contribuir para a diminuição da extracção de recursos naturais não renováveis, na forma de agregados naturais, por parte do sector de construção.authorsversionunpublishe

CO2 sequestration by construction and demolition waste aggregates and effect on mortars and concrete performance - An overview

WP10B (CoLAB 4/2018-CemLabGlobal warming is one of the greatest environmental threats worldwide. It is mainly caused by the growing amount of greenhouse gases in the atmosphere, such as argon and carbon dioxide (CO2), among others. Hence, the need to reduce these gases’ emissions, in particular CO2, is imperative. This reduction may be achieved through strategies that allow capturing and storing emitted CO2 (CCS - carbon capture and storage). Construction and demolition waste (CDW) is found in great abundance with diverse potential in the building sector. However, its incorporation as recycled aggregates (RA) in construction materials, such as mortars and concrete, is still limited. This is mainly due to its higher heterogeneity, porosity and lower strength compared to natural aggregates (NA). Several studies have been carried out focusing on the reduction of CO2 emissions and of NA exploitation, as well as improving these RA's characteristics. This article intends to provide a review of the performance of mortars and concrete with RA from CDW after undergoing a CO2 curing treatment, thus contributing to CCS. Overall, CO2 curing of RA has a positive effect on their physical and mechanical characteristics. By increasing the apparent density, their porosity and water absorption consequently decrease. Also, these treatments considerably reduce the crushing index of RA, increasing their strength. Mortars and concrete produced with carbonated recycled aggregates (CRA) show increase in workability and decrease in shrinkage in comparison to those with uncarbonated RA. The mechanical performance of these construction materials is also positively influenced. Therefore, the levels of confidence in its use should increase.authorsversionpublishe

Pathway to Carbon Neutrality in the Cement Industry: CO₂ Uptake by Recycled Aggregates from Construction and Demolition Waste

Cementitious materials can capture CO2 through carbonation reaction during their service life and post-demolition. Indeed, construction and demolition waste (CDW) still have some potential for carbonation as they contain concrete and cement-based mortars. This research consists of an experimental programme to evaluate the CO2 capture of recycling aggregates (RAs) from CDW. Two types of CDW were studied, namely mixed recycled aggregates (MRAs) and recycled concrete aggregates (RCAs). The recycled aggregates were submitted to forced and accelerated carbonation at 23 °C, 60% relative humidity and 25% of CO2 concentration. This study contributes to the existing literature by investigating more realistic RA sources that have already absorbed atmospheric CO2 during their service life. From the experimental campaign, the results show that RCAs have higher carbonation potential when compared to MRAs due to the higher cementitious material content (Rc) and to the degree of natural carbonation. The recycled aggregates’ maximum CO2 capture was assessed by thermogravimetric analysis (TGA) at different CO2 exposure times. It was verified that the maximum CO2 capture, respectively, for MRAs and RCAs, occurred after 5 h and 12 h of exposition. In short, CDW captured from 5 wt.% to 35 wt.% of CO2 per tonne of cement paste, which corresponds to 0.6% to 4.1% per tonne of aggregate. It was concluded that the carbonation process of CDW has the potential to sequester from 123 kg to 225 kg of CO2 per tonne of cement paste for MRAs and 52 up to 491 kg of CO2 per tonne of cement paste for RCAs