2024-04-23 13:00:23
Scientists have managed to develop a type of porous brick that is more durable against salt crystallization, by using carbon fiber waste from discarded wind turbine blades, used as additives in its manufacture.
The achievement is the work of researchers from the Department of Mineralogy and Petrology of the University of Granada (UGR) in Spain.
The team, led by Laura Crespo López from the UGR, set out to create an environmentally friendly brick that uses fewer raw materials and meets the standards required for use in construction.
In the field of construction, there is a need to move towards a more sustainable economic model and in recent years alternatives have been explored aimed at reducing the consumption of natural resources and minimizing the accumulation of waste.
The discovery made by the group of UGR researchers not only allows us to reduce dependence on non-renewable resources such as clay, but also offers very significant economic and environmental benefits.
A less polluting process with many benefits
The bricks made in the framework of this study have been manufactured manually, following the traditional methodology. In an effort to maximize the use of waste without compromising the consistency of the clay mixture, 5% and 10% by weight of carbon fiber powder has been incorporated, since a greater addition would make correct mixing difficult taking into account the lightness of the waste in relation to its volume. Once dry, the bricks were fired at 800, 950 and 1100 degrees Celsius.
Different analytical techniques were used to determine the influence of carbon fiber on the quality of the bricks, from determining the importance of the particle sizes of the fibers and the clay material, to microtextural analysis using high-resolution electron microscopy. , showing very relevant results.
Among them, research has revealed, for example, that the carbon fiber from wind turbine blades also contains resins and thermoplastic compounds. During the brick firing process, these elements and part of the fibers are consumed, generating micropores and significantly improving the thermal conductivity of the ceramic pieces. The use of carbon fiber as an additive in the production of bricks is also a less harmful alternative in terms of atmospheric pollution compared to other “waste reduction” methods used in the wind industry, such as incineration, pyrolysis or chemical recycling.
In terms of durability, the research has allowed us to observe that bricks fired at 950 and 1100 degrees Celsius with carbon fiber experience the least material loss compared to bricks made only from clay, thus demonstrating greater resistance to salt attack. and greater durability. This finding further reveals the ability of carbon fiber to improve the structural resistance of bricks in aggressive environmental conditions, cementing its position as a durable option in sustainable construction.
Detail of the carbon fibers. (Photo: Laura Crespo-López et al. / UGR)
The process of adding carbon fiber to the clay mixture also determines partial changes in the mineralogy of the bricks. In particular, a significant decrease in hematite concentration is observed as the firing temperature increases in samples containing carbon fiber. This phenomenon is attributed to favoring the development of a reducing environment in the furnace.
Regarding the analysis of the porous texture, it is observed that the carbon fibers tend to orient themselves in the brick structure. This phenomenon can be influenced both by the process of kneading and molding the raw bricks, and by the firing temperature, since the change in orientation varies depending on the temperature and within the same sample from the outside to the inside.
After the cooking process, the degradation of the carbon fibers begins. With increasing temperature, these tend to fade, leaving a distinctive cylindrical imprint in the clay matrix.
The color changes derived from the addition of carbon fiber do not compromise the aesthetic properties of the bricks. This aspect highlights the possibility that these bricks, while incorporating carbon fibers to improve their sustainability, maintain their visual appeal. This duality makes carbon fiber bricks a valuable contribution as alternative building materials, promoting sustainability without sacrificing aesthetics, a key consideration in the evolution of modern construction.
The results obtained by the research group of the Department of Mineralogy and Petrology of the University of Granada show that the integration of carbon fiber in the production of bricks represents a great opportunity to address two crucial aspects in the construction industry, in the context of the so-called “circular economy”. Firstly, because of the possibility of significantly reducing the consumption of a non-renewable raw material such as clay, and secondly, because it is presented as an effective way to reuse carbon fiber from wind turbine blades that, Currently, they accumulate in wind blade “landfills.”
The research team presents the technical details of their progress in the academic journal Ceramics International. (Source: UGR)
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