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This paper aims to encourage the circular economy and merge the manufacturing and the construction industries, providing waste fibres from the electrical discharge machining of the former as raw material for the latter. The research analyses the effect on the physical, thermal and mechanical properties of mortars reinforced with brass fibres. The m...
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Citations
... In another study, Vidales-Barriguete et al. [83] added plastic cable waste to replace gypsum binder and the results showed that the thermal properties improved slightly with up to 60% of waste incorporation. Some authors studied the incorporation of waste as an additive into mortars [36,55,66]. According to Barreca et al. [36], adding 70% of dry weight of olive stone allowed them to reduce the average thermal conductance of cement lime mortar by over 76% and its density around 30%. ...
... Studies on mortars with the addition of cork waste also showed a reduction in compressive and flexural strengths, despite the good thermal performance [16,59]. Similar results were obtained in studies with the incorporation of biomass fibres from leaves after the pruning and cutting of the trees [40,61], with wood ash and vegetable aggregates, namely sunflower plant bark and pith [65], with wood waste and polyethylene terephthalate waste (PET), with particles and pulverized glass fibre-reinforced plastic (GFRP) [64], with mining residues [56] and with recycled carbon black derived from scrapped off-the-road tires [79], and others residues [39,55,60,66,67,82]. ...
Innovation in construction plays a fundamental role in helping us face current challenges, namely the reduction in energy consumption, the mitigation of the effects of climate change, the depletion of resources, and the generation of waste. Regarding the built environment, improving the thermal properties of the building envelope is one of the growing needs to reduce energy consumption in the building sector. In this context, thermal mortars have been a trend in the construction industry in recent years due to their ability in reducing heat transfer through the building envelope. On the other hand, the addition of waste has been studied as an alternative to improve the thermal properties of mortars and reduce the consumption of primary materials in the construction sector. This work aims to carry out a detailed review regarding the incorporation of waste in thermal mortars through the application of scientometric data analysis and a systematic literature review. To this end, the different residues incorporated into thermal mortars and the various percentages and forms of incorporation were identified throughout the publications gathered in this review. The most studied properties regarding the thermal mortars with the addition of waste were also the subject of study. A comprehensive database of thermal mortars with the incorporation of waste is presented, in which the objectives of the studies, the wastes and forms of incorporation and the measured properties are highlighted. The main results of the analysed researches are deeply discussed and the gaps in this area of the knowledge are identified to point out new directions and possible perspectives for future studies in the field of thermal mortars incorporating waste.
... Fibers are among the most widely studied insulators for use in cementitious materials and have proven to be an excellent solution for mitigating heat loss. In fact, several studies have been carried out in this field of research to study new cement-based composites reinforced with fibers such as wool fiber [20], Acaï [21], palm fiber [22,23], agricultural fiber wastes [24], coconut fiber [25], rice straw fibers [26], recycled brass fibers [27], and basalt fiber [28]. ...
By enhancing the thermal properties of cement-based building materials, energy consumption and carbon dioxide (CO2) emissions related to space conditioning in buildings can be alleviated. This study aims to present cement-based composites reinforced by textile fibers for application in building and construction. Several lightweight coating mortars were produced by partially replacing the sand in the mix with different percentages of textile waste. Mechanical and thermal characterizations of the reinforced cementitious composites were performed. The results showed that the thermal conductivity of cementitious compounds decreased as the proportion of reinforcing material in the mixture increased. In terms of mechanical properties, the textile slightly reduced the compressive strength of cementitious mortar, while it improved the flexural strength. A numerical study was then performed to derive the actual impact of these reinforced materials on the thermal behavior of a building element using COMSOL Multiphysics. Numerous configurations of walls coated with different mortar mixtures were studied. The results showed that coating both sides of a building wall with 20 mm of textile-reinforced mortar reduced the internal temperature by 1.5 °C. Thus, the application of these thermally improved mortars as coating mortars appears to be a relevant solution to enhance the thermal performance of buildings.
... In addition to mechanical properties, experimental results also indicated that the addition of fibres can affect the thermal properties of mortar at various temperatures [20,21]. For instance, Borinaga-Treviño et al. [22] studied the effect of recycled brass fibre on the thermal conductivity of mortar under fibre content of 0.5 to 4.0 vol% and found a maximum of 53% rise in thermal conductivity induced by brass fibre. It was reported that the high-conducting carbon fibres have a promoting effect on the thermal conductivity of mortar, while the low-conducting glass fibres would restrain the effective thermal conductivity over the temperature range of 20-400 o C [23]. ...
The temperature dependency of specific heat capacity is crucial for thermo-mechanical analysis of fibre reinforced cementitious composites. In this study, a combined experimental and theoretical analysis was conducted to characterise the role of micro fibres in tailoring the specific heat capacity of cementitious composites at elevated temperatures. The specific heat capacity of cement mortar reinforced with four types of fibres, including polypropylene, basalt, carbon and glass fibres, was measured by means of a transient method at up to 400 o C. Based on the effective medium theory, a multiscale homogenization model was developed to predict the specific heat capacity evolution of cementitious composite with temperature from micro to macro level. The results indicate that within the measured temperature range, the addition of 2.0 vol% polypropylene and glass fibres lead to the maximum rise or drop in specific heat capacity of mortar by 8.7% and 14.1%, respectively. In addition, the thermal expansion of polymer fibre was proved to effectively enhance the specific heat capacity of mortar due to thermal expansion coupling effect. The parametric analysis suggests that stiffer inclusions with high thermal expansion govern the effective specific heat capacity coupled with thermal expansion, while the composite incorporated with softer inclusions is insensitive to the variation in thermal properties of inclusions.
... Several researches [10][11][12][13][14][15] have focused on studying the effect of adding various types of fibers, especially steel fibers, on the thermal conductivity of concrete. According to Cook and Uher [10], metallic fiber additions improve the thermal conductivity of mortar and concrete. ...
... In fact, the number of fibers f1 and f2 is, respectively, 20 and 14 times the number of fibers f3, which results in a less dense fiber network formed by fibers f3, leaving free spaces between the fibers, which leads to a thermal conductivity decrease. According to Borinaga-Treviño et al. [15], two variables should be considered into account when determining the impact of fibers length: fiber amount and fiberto-fiber connections. ...
... This reduction is probably due to the role played by the length of fibers f2 (lf = 3 cm) which is higher than that of fibers f1 (lf = 2 cm), increasing thus the transfer of heat within the matrix. According to Borinaga-Treviño et al. [15], for the same amount and diameter of fiber, the thermal conductivity increases with the fiber length used. ...
In this paper, the effect of steel fibers recovered from pneumatic waste, dune sand (D), and its granulometric correction on the thermal conductivity of dune sand concrete was studied. Three types of steel fibers were used (f1, f2, and f3) having the lengths of 20 mm, 30 mm, and 40 mm, respectively, and diameters of 0.28 for f1 and f2 and 0.9 mm for f3, incorporated in the concrete with a volume fraction of 1 %. River sand (R) was used for the correction of dune sand granulometry. The proportions of 50 % D mixed with 50 % R and 40 % D mixed with 60 % R were adopted for the mixtures M2 and M3, respectively. The concretes made with only dune sand have a lower thermal conductivity, compared to the mixtures M2 and M3.The results obtained also showed that, when the concrete density decreases, the thermal conductivity decreases. The thermal conductivity of concretes without fibers is lower compared with fiber-reinforced concretes. Other parameters have an influence on this property, namely the diameter, the length, and the aspect ratio (l/d).
... Several researchers [21] identified plastic and metal fibers as the most viable waste material for reinforcing cementitious matrices, promoting circular economy processes. Mortars reinforced with brass fibers obtained from electrical manufacturing process were studied in [22]. Thermal conductivity increases with the amount (0.5%-4% by vol.) and length (10,15, and 25 mm) of the fibers: values in the 1.2-1.8 ...
... Several researchers [21] identified plastic and metal fibers as the most viable waste material for reinforcing cementitious matrices, promoting circular economy processes. Mortars reinforced with brass fibers obtained from electrical manufacturing process were studied in [22]. Thermal conductivity increases with the amount (0.5-4% by vol.) and length (10,15, and 25 mm) of the fibers: values in the 1.2-1.8 ...
This paper investigates the influence of adding vegetal fibers on thermal and acoustic performance based on natural hydraulic lime. Mortar samples with 10% weight of vegetal fibers were fabricated adding water to obtain easily workable mortars with good consistency; their performance was compared to mortar samples without vegetal fibers. The fibers were of different types (rice husk, spelt bran, and Khorasan (turanicum) wheat chaff) and size (as-found and ground form). Thermal performance was measured with the Small Hot Box experimental apparatus. Thermal conductivity was reduced in the 1–11% range (with Khorasan wheat chaff and rice husk); no significant reduction was found with spelled bran in the mixture. When ground, fibers were characterized by both good thermal and acoustic absorption performance; a reduction of 6–22% in thermal conductivity λ was achieved with spelled bran (λ = 0.64 W/mK) and rice husks (λ = 0.53 W/mK), whereas the Khorasan wheat chaff had the highest sound absorption average index (0.38). However, the addition of fibers reduced sound insulation properties due to their low weight densities. This reduction was limited for rice husks (transmission loss value was only 2 dB lower than the reference).
... Several researches [10][11][12][13][14][15] have focused on studying the effect of adding various types of fibers, especially steel fibers, on the thermal conductivity of concrete. According to Cook and Uher [10], metallic fiber additions improve the thermal conductivity of mortar and concrete. ...
... In fact, the number of fibers f1 and f2 is, respectively, 20 and 14 times the number of fibers f3, which results in a less dense fiber network formed by fibers f3, leaving free spaces between the fibers, which leads to a thermal conductivity decrease. According to Borinaga-Treviño et al. [15], two variables should be considered into account when determining the impact of fibers length: fiber amount and fiberto-fiber connections. ...
... This reduction is probably due to the role played by the length of fibers f2 (lf = 3 cm) which is higher than that of fibers f1 (lf = 2 cm), increasing thus the transfer of heat within the matrix. According to Borinaga-Treviño et al. [15], for the same amount and diameter of fiber, the thermal conductivity increases with the fiber length used. ...
The use of Scallion (onion leaf) in cementitious materials can contribute to the improvement of technological properties and environmental issues related to the reuse of agro-industrial waste. In our country Onion production is approximately 31.12 million tons per year, generating large environmental impacts, because the disposal in landfills . The objective of this research was to evaluate the potential of reusing the Scallion as Binding element in eco- friendly mortar for the purpose of recovering building structures committed to coastal environments, in addition to avoiding the disposal of this waste in landfills. The Scallion were characterized physically, morphologically and chemically, in the treated and untreated (natural) condition, for further technological evaluation of mortars in the fresh state, such as consistency, specific mass, incorporated air and water retention. Comprehensive studies of the hardened state were also carried out to study mechanical strength (compressive and tensile), water absorption due to capillarity and immersion, sorptivity as well as durability by evaluating mass loss and mechanical strength after exposure conditions. The results showed that the Scallion treatment process improved its characteristics for application in mortar with addition of 0.25%, 0.5%, 0.75%, 2.5%, 5%, 7.5%, 10%, 15% in cement mass, causing the better in the technological and durability properties, and a proposed new means of disposing of agro-industrial waste, contributing to a circular economy
The development of low-cost and high-efficiency catalysts is of great significance (Sun et al., 2016) [1]. Herein, nanoporous catalysts were synthesized by vapor phase dealloying. Vapor phase dealloying (VPD) is an environmentally friendly method for fabricating nanoporous materials by utilizing the saturated vapor pressure difference of elements to selectively evaporate of one or more components from an alloy (Lu, 2021) [2]. These mechanisms were initially studied for thin films evaporation processes. In the present study we use recycled brass turning chips as starting materials to help the transition from the linear to the circular economy. We combined vacuum dealloying, with a complex characterization from a morphological, structural, and application-oriented point of view to demonstrate the efficacy of the product at the laboratory level. The turning chips were cleaned, dried, and milled in a planetary mill at 400 rpm, 4 cycles of 15 min milling 15 min pause, in air. The milled powders had a diameter of less than 400 µm as presented in Fig. 1. These powders were than subjected to vacuum dealloying at 500–600 °C, for different durations. These samples were be characterized by electron microscopy (SEM-EDS, image analysis and measurements of the photocatalytic activity)
Considering the fact that thermal mass materials enable a significant reduction of 7 - 22% in energy consumption in buildings, it is vital to use cementitious materials with enhanced thermal insulation properties. In this paper, thermal conductivity results of cementitious materials, based on different ASTM & other methods, are reviewed, further discussed, and analysed. The compiled test data are categorized/analysed for thermal conductivity behavioural differences in terms of test methods, assessment models, types of aggregates, mineral admixtures/ additives and fibers used etc. The study also extensively assesses the influence of the microstructure and ambient conditions on the thermal conductivity of cementitious materials. Besides the type and volume of aggregates and cementitious admixtures, density/porosity and moisture content, strongly impact the thermal conductivity of cementitious materials.
