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The use of bacteria for the enhancement of construction materials has been a focus of study in the past few years. Microbial cells have been applied to consolidate the surface of different materials. Earthen plasters are eco-efficient building products that can be applied on new buildings but also used to protect cultural heritage structures, with...
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... and following the same trend as surface hardness results, a slight improvement in compactness was observed for bioproducts treatment groups. As Figure 7 presents, an increasing ultrasound propagation velocity was obtained for all tested samples with time. This behavior may be explained due to a higher adsorption of water vapor by the earth mortar samples. ...
Citations
... x xMauffré et al. (2021) xMcGregor et al. (2022) xParracha et al. (2019) xParracha et al. (2021) xx Rescic et al. Permeabilidade ao vapor de água A permeabilidade ao vapor de água foi avaliada por Lagouin et al. (2022), McGregor et al. (2022), Rescic et al. (2021) e Liuzzi et al. (2018). ...
Cientes da necessidade de desenvolver e aplicar materiais de construção que apresentem baixo consumo energético nas etapas de produção, transporte e aplicação, materiais tradicionais são revisitados, como é o caso da terra. Contudo, apesar das diversas vantagens documentadas, este material é altamente suscetível a degradação por ação da água e, buscando contornar essa realidade, algumas pesquisas enfocam na avaliação de propriedades hidráulicas da terra. Assim, o objetivo central deste estudo é apresentar um panorama geral acerca de pesquisas desenvolvidas nos últimos anos, mais especificamente em relação ao comportamento hidráulico de argamassas de terra, buscando identificar tendências de pesquisa. Para tal, 31 artigos científicos disponíveis no Portal de Periódicos da Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) foram sistematicamente selecionados e analisados, dos quais se constatou seis abordagens distintas em relação ao estudo das argamassas de terra, dentre elas a do comportamento hidráulico. Verificou-se que 14 destes trabalhos realizaram campanha experimental avaliando propriedades hidráulicas como, por exemplo, permeabilidade ao vapor de água, absorção e resistência à erosão causada pela água. Ainda, em função de baixa quantidade de normas específicas para argamassas de terra, é comum a adaptação de ensaios desenvolvidos para outros materiais de construção ou até mesmo emprego de procedimentos não padronizados.
... Heteropolysaccharides, on the other hand, are made up of several types of monosaccharide, as is the case with hyaluronic acid (HA), chondroitin and alginate. The latter can be classified according to two main roles: the structural function, observed in polysaccharides such as cellulose and chitin, or the energy storage function, illustrated by examples such as starch [16][17][18]. ...
Sustainable construction has become a global imperative due to the growing awareness of the harmful environmental impacts of the construction industry. The use of cement and lime in traditional methods of stabilizing earth constructions is a significant problem due to their high carbon footprint. This article examines an ecological alternative to stabilizing earth structures with biopolymers. These Bio-based materials can be used to reduce the environmental impact of the construction industry while also ensuring the structure's stability and durability. The purpose of this article is to examine the mechanical properties of biopolymers in the context of stabilizing earth construction. The objective is to guide the decision on which stabilization method to use for earth construction based on the available resources.
... Some scholars tried to apply a surface treatment on earthen elements. Parracha et al. [29] developed a new iron-based bioproduct that has been experimentally validated for its ability to improve the water resistance of earth-based plastering mortars through surface biotreatment. In contrast, hydrophobization offers an effective method to protect the building envelopes from moisture, usually by implementing water-repellent agents to enhance hydrophobicity [30]. ...
... Em relação às dosagens, verificou-se que adição de areia (principalmente de rio) à matriz de terra natural, atuando como estabilizante granulométrico, é comum em nas argamassas de terra, principalmente no intuído de controlar a retração durante o processo de secagem (PEDERGNANA & ELIAS-OZKAN, 2021). Nos estudos analisados, a maioria dos autores definiram a proporção de terra (partículas finas) e areia (material silicioso) com base em estudos prévios, buscando melhorar o desempenho físico ou mecânico das argamassas (CAPPAI et al., 2022;HE et al., 2022;LAGOUIN et al., 2022;MCGREGOR et al., 2022;PEDERGNANA & ELIAS-OZKAN, 2021;LAGOUIN et al., 2021a;LAGOUIN et al., 2021b; 5° Simpósio Científico ICOMOS Brasil e 2° Simpósio Científico ICOMOS/LAC Belo Horizonte/MG -Brasil, 05 a 07 de dezembro de 2022 -Lima-Peru, 08 e 09 de dezembro de 2022 MAUFFRÉ et al., 2021;PARRACHA et al., 2021;QIU et al., 2021;RESCIC et al., 2021;SANTOS et al., 2021;AZEVEDO et al., 2021;SANTOS et al., 2020;CALDAS et al., 2020;SANTOS & FARIA, 2020;GARCÍA-VERA et al., 2020a;GARCÍA-VERA et al., 202b;PARRACHA et al., 2019;LAGOUIN et al., 2019;SOKOLOVÁ & RYPAROVÁ, 2019;SANTOS et al., 2019;GARCÍA-VERA & LANZÓN, 2018;FARIA, 2018;LIUZZI et al., 2018). Em relação a parcela de finos das argamassas, observa-se que esta pode ser obtida tanto da terra em seu estado natural (quando apresentam argila em quantidade adequada) ou de processos industriais que separam os materiais por granulometria (geralmente coletados em lagoas de decantação), como é o caso dos finos de pedreira de processos de lavagem de agregados (LAGOUIN et al., 2022;LAGOUIN et al., 2021a;LAGOUIN et al., 2021b;LIUZZI et al., 2018). ...
Cientes da necessidade de desenvolver e aplicar materiais de construção que apresentem baixo consumo energético nas etapas de produção, transporte e aplicação, pesquisadores vem dando enfoque para materiais alternativos à indústria convencional. Neste sentido, revisitar as técnicas construtivas tradicionais apresenta potencial no desenvolvimento de uma linha de pesquisa que associa conhecimentos de áreas distintas que vão além das ciências dos materiais. Em se tratando de normatização dos revestimentos argamassas de terra, apenas a normativa alemã DIN 18947 aborda este elemento construtivo de forma detalhada em todo planeta. Assim, ciente da existência de campo para explorar a temática apresentada, o objetivo central deste estudo é apresentar pesquisas desenvolvidas, nos últimos anos, acerca das argamassas de terra, buscando verificar enquadramentos e eventuais tendências de pesquisa. Para tal, 31 artigos científicos disponíveis no Portal de Periódicos da Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) foram sistematicamente selecionados e analisados, de onde se constatou seis abordagens distintas em relação ao estudo das argamassas de terra, sendo possível identificar uma tendência bem definida entre elas. Acredita-se que a multidisciplinaridade possa representar uma base sólida para os estudos brasileiros, que ainda são escassos, contribuindo para melhoria do desempenho deste componente frente as suscetibilidades ambientais e fomentando as discussões acerca da normatização.
... In the laboratory, the rigid piece has a defined weight [67]; for in situ tests, the person performing the test can be placed with an inclination of 30°to the wall, with his/her arm perpendicular to it and the hand pressing the rigid piece, that can be of wood. ...
Renders and plasters have significant functions in buildings. Their functionality is closely related to their properties, which depend on the mortar itself, the application technology, the interaction with the environment and the substrate. There are many basic characteristics that influence the performance of renders and plasters; however, many of them are interrelated, thus the set of characteristics to be determined in each case is different, depending on the specific at each time use. These characteristics, their interrelations and the grouping of them are discussed and schematically described in the first and introductory section. Three groups are considered for renders and plasters: properties of fresh mortars; properties related to the hygric behaviour; and the mechanical behaviour. The properties of lime-based mortars measured in laboratory are highly affected by factors, such as: need of long time for development of representative values for prediction of their life-time behaviour, proper climatic conditions adequate for carbonation or/and hydration, sensitivity to the suction of water by the substrate. The last two factors—environment and substrate—have an important role for rendering and plastering with lime-based mortars, since both their exposed surfaces and the substrate areas they cover are large. Due to those specificities, the current test methods that have been mainly developed for cement-based mortars are not always fitted to characterize lime-based mortars, and in particular to assess lime-based renders and plasters. In section two the main characteristics and current standardized test methods are discussed based on experience in using them. Furthermore, needs of improvement are identified and changes are proposed, or, in some cases, new methods are outlined. Some of the most significant changes proposed are the possibility, as an option, to apply the mortar on a porous substrate, instead of moulding specimens in metallic moulds, together with modifications on curing conditions and times of mixing and testing. Additionally, test methods developed at laboratory to evaluate the cracking tendency due to restrained shrinkage and to determine the modulus of elasticity of under checking mortars are proposed, as well as alternative test methods for adhesion. In the case of testing other properties, smaller changes are proposed, in order for the standardized test methods to be adapted to the particularities of lime-based renders and plasters. As conclusions, in the third section, a synthesis of the proposed changes and complementary tests has been made in formulated tables, that could be considered as a first approach of adapted requirements for better performance of lime-based mortars for renders and plasters.
... Adhesion -Adhesion to the substrate is a very important characteristic of ETICS, renders and plasters, because lack of adhesion results in total loss of functionality and, even worth, may become a safety risk, as the fall of render fragments from the façades or of plaster pieces from ceilings and higher zones of walls can seriously hurt the users of those spaces. The assessment of this characteristic is standardized for example in the European system [35,36], using pull-off tests. However, for low strength coatings, such as those based in lime or in earth, this method can be too aggressive, because the vibration of the drilling machine may be enough to detach weak mortars, or to significantly interfere with their adhesion. ...
... In Santos et al. [37] the results of the method are compared with the results of bond strength by the method of EN 1015-12 [35]. It is found that the average values obtained are rather similar; however, with the direct tensile method the variation coefficient is much lower (29% versus 73%) and null values are eliminated. ...
Coatings are an important part of buildings in terms of performance, costs and time needed to be applied, repaired and replaced. They are requested to perform several functions, starting with the protection of the substrates and, therefore, durability of the coated building elements. With the increased concern on ecological performance, energy conservation and economic efficiency, the durability of the coatings themselves and several innovative requirements, such as contributing to lightning, comfort, health (indoors and outdoors) and safety, are also very important nowadays. Therefore, innovative tests have recently been defined, usually designed to reproduce the real actions while other tests have been adapted from tests designed for other materials. The new tests have to be optimized and validated before being formally adopted. This chapter addresses several building coating requirements, namely some which only recently are attracting research. Many innovative tests to assess new requirements and tests that were adapted to properly assess coatings performance are described and are briefly discussed to contribute to advances in research and to the identification of gaps.KeywordsDurabilityHygroscopicityPollutant release and captureSelf-cleaningVisual comfortWeathering
... The wet sponge mass is registered before the test and results can be assessed by the difference in mass of the sponge, which corresponds to the water absorbed by the earthen surface. An advantage of this test is that, by registering the mass of water [23] added to the sponge and containing the wet sponge in closed Petri dishes after the test until weighing, the simple test can also be applied in situ. ...
... Another simple test that can be used with a similar aim is the contact angle test. This test can be performed with standardized equipment [22] but, when it is not available, it can be performed in a simplified way using a video camera to record the time a drop of water takes to be absorbed ( Fig. 3.5) [23]. ...
Innovation in structures and construction materials demands a more accurate performance analysis during the life cycle. In addition, climatic changes pose new challenges to civil infrastructures that were not so relevant in the past. In most cases, the traditional test methods cannot accurately assess the complex phenomena involved in durability. The modern and complex factors require a different approach to durability analysis. The purpose of this chapter is to present innovative durability tests on construction materials: wood; rammed earth, cob and unfired blocks; natural stone; bituminous binders and mixtures; and Fibre Reinforced Polymers (FRP) to concrete bonded connections. Most of these tests concern the accelerated simulation of the main phenomena involved in durability performance – ageing – of the materials and structures, such as wet-dry cycles, UV exposure, salt water immersion, salt fog cycles, and action of biological agents The demonstration and validation of the new durability test methods on construction materials are supported by the description of some case studies based on experimental research.KeywordsAgeing techniquesAccelerated durability testsConstruction materialsDurabilityInnovationPerformance
... Some scholars tried to apply a surface treatment on earthen elements. Parracha et al. [29] developed a new iron-based bioproduct that has been experimentally validated for its ability to improve the water resistance of earth-based plastering mortars through surface biotreatment. In contrast, hydrophobization offers an effective method to protect the building envelopes from moisture, usually by implementing water-repellent agents to enhance hydrophobicity [30]. ...
The moisture performance of building envelopes largely depends on the building materials, construction techniques, and exposure loads from the indoor and outdoor regions. A ventilated air interlayer placed in a wall can help dehumidify the wall and indoor air. This paper presents an experimental study of the heat, air, and moisture variations within the envelope wall of a chamber featuring different air interlayer settings under real outdoor air conditions during the summer of 2020 in Shanghai, China. Self-developed humidity-controlling building materials were applied to the inner building envelope. Temperature, humidity, wind velocity, and heat-flow sensors were placed at different positions in the middle of the wall. These parameters were measured and recorded in real-time under three working conditions: humidification, dehumidification, and ventilation. The experimental results show that under the ventilation working conditions, moisture content of 0.52 kg can be removed after a 2-h air layer ventilation, which can benefit the design strategy for the humidification and ventilation of dehumidification walls.
... The water droplet absorption time was determined based on standard RILEM Test N ∘ II. 8a [31], using the protocol described by Parracha et al. [34]. The assay was video recorded to optimize the accuracy of the measured time (seconds) required for the sample surface to completely absorb a drop of water, defined in terms of loss of sheen. ...
This article examined the effect of a bioproduct suspension obtained from fermentation of biodiesel’s crude glycerol when used to formulate natural hydraulic lime mortars, as a fluid replacing the mixing water. The bioproduct was used either sonicated or non-sonicated and two volumes of mixing fluid were tested. The aim was to assess the advantages and drawbacks that could be achieved with a waste-based bioproduct, instead of petrochemical-based additions. The investigation revealed a positive effect on workability, producing mortars with a lower mixing fluid content, improving the mechanical performance. Finally, the bioproducts reduced the mortar water absorption by gravity and capillary.
... The absorption rates for 9 drops of water (50 µL/drop) applied on the treated surfaces were measured, except for the reference specimens, where only 4 drops of water were applied to avoid contact with each other. The test was applied based on the RILEM procedure and schematized by Parracha et al. [60]. To accurately determine the absorption time, the difference between the exact moment in which the drop was applied until the moment of its complete absorption was calculated from video-recorded images. ...
... The results for both conditions were in line with the ones obtained by García-González et al. [82] when applying the two MMC bioproducts made with pinewood bio-oil and crude glycerol as substrates on recycled concrete. The results obtained in the present work were much higher than those reported by Parracha et al. [60] when utilizing iron-based bioproducts on clay plastering mortars. For these authors, the most effective treatment at 4 days resulted in absorption times approximately 18 times higher than those of the control. ...
Two eco-friendly healing bioproducts generated from microbial mixed cultures (MMC) for the production of polyhydroxyalkanoates (PHA) were used as surface treatments, with two residual materials used as the substrates, namely crude glycerol and pinewood bio-oil. Their ability to improve the durability of concrete samples containing recycled aggregates was assessed. To determine this protective capacity, 180 samples were analyzed using different tests, such as water penetration under pressure, capillary absorption, freeze–thaw and water droplet absorption test. Three types of conditions were used: outdoor–indoor exposure, re-application of biopolymers and application in vertical exposure conditions. The results showed reductions of up to 50% in the water penetration test and a delay in the water droplet absorption test of up to 150 times relative to the reference. The surface application of these bioproducts significantly reduced the degree of water penetration in recycled concrete, increasing its useful lifespan and proving to be a promising treatment for protecting concrete surfaces.
