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Thermal Insulation with Cork-Based Materials
Abstract
As an eco-friendly and sustainable material, cork, has been adapted to green applications. Cork provides excellent thermal properties for insulation applications as well as lowering the side effects of synthetic engineering materials harmful to environment. Thermal insulation properties of cork are competitive to modern insulation materials that dominate the building and construction sectors. In this study, a cork panel, which is made from cork granules bonded by polyurethane resin, was compared with a conventional synthetic insulator, XPS foam board, by measuring the thermal conductivities. The thermal conductivity measurements exhibited very promising results for cork-based materials in thermal insulation applications. Cork-based panels have a great potential as a thermal insulation material. Moreover, they are more convenient to green applications than the conventional synthetic materials.
... Thermal insulation materials are known to be used to reduce heat losses from heated elements [1][2][3][4][5][6]. In the context of centralized heat supply systems, heat energy losses to the environment occur at the following key points: at the heat source; in the heat carrier transport system (heat network); at the consumer of heat energy, which includes residential and public buildings, industrial enterprises, etc. ...
In the pursuit of conserving non-renewable fuel and energy resources and mitigating harmful emissions into the atmosphere, thermal insulation is commonly employed in practice for heated elements, including but not limited to building exteriors, boilers and furnaces, thermal power equipment, pipelines, and the like. The primary characteristic of any insulation material lies in its thermal conductivity, particularly under operational conditions. The research object is liquid nano-ceramic thermal insulation located on the surface of a round-section pipeline with a circulating heat carrier. The research subject is the thermal conductivity properties of the insulation material under operational conditions. The research aim is to determine the thermal conductivity coefficient of liquid nano-ceramic thermal insulation coating on the surface of the pipeline. The research method involves the laws of steady-state heat conduction and heat transfer for a two-layer cylindrical wall. Research findings indicate that for a steel pipeline measuring 76×3 mm with insulation thickness of 3.5 mm, the thermal conductivity coefficient of the liquid nano-ceramic thermal insulation material amounted to 0.0145 W/(m⋅K). Disregarding the radiative component, the thermal conductivity coefficient equals 0.0135 W/(m⋅K). Conclusions drawn suggest that the obtained value of the operational thermal conductivity coefficient of the liquid nano-ceramic thermal insulation material aligns with the manufacturer's claimed material thermal conductivity of 0.014 W/(m⋅K) and with the findings of other researchers. Minor discrepancies in magnitudes may be attributed to the extended period of insulation usage on the pipeline surface, which at the time of the conducted scientific investigations was approximately 1.5 years.
... Cork-based insulating materials offer numerous advantages but also have limitations because it is a porous material that can absorb moisture, which reduces its insulating capacity and increases the risk of mold growth [5]. ...
Agglomerated cork is a natural cork that has gone through a process of crushing and pressing using heat and binders. One of its applications is thermal insulator in construction. The design of these materials is becoming an essential part of building. The raw materials currently used to make insulators consume a large amount of energy, which has created the need to increase the use of renewable and ecological resources such as plant fibers to reduce the environmental problems generated. The objective of this study was to determine the different properties of experimental particleboard panels made from cork and Canary Island date palms without using any binder at minimum energy consumption. The produced cork–palm boards (density of 850 kg/m³, reached a MOR 8.83 N/mm², MOE 794.5 N/mm², and IB 0.38 N/mm²) are higher values than the traditional cork particleboards with UF made from cork. The thermal conductivity values obtained 0.069 to 0.096 W/m·K are higher than cork boards with UF. Ecological boards that can be used as rigid thermal insulators in the construction industry have been achieved to improve the mechanical properties of the traditional agglomerated cork.
The cork oak (Quercus suber L.) woodlands, known as montados in Portugal, hold significant economic, cultural, social, and environmental value. They are found in the Mediterranean Sea basin, particularly in the Iberian Peninsula, and sustain various activities like silvopastoralism, with cork being a primary product. Despite its economic significance, challenges such as climate change threaten its sustainability. This study aimed to analyze the edaphoclimatic variables affecting cork yield, thickness, price, and gross income in the Alentejo region of Portugal. A total of 35 farmers were selected for the data collection included in this study. Multivariable linear regressions were performed to establish relationships between cork yield, thickness, price, and gross income as dependent variables, various edaphoclimatic factors, and tree densities. A higher tree density correlates with an increased cork yield but a decreased cork thickness. Soil pH affects cork yield and thickness, with a lower pH favoring higher cork yields but thinner cork. A higher clay and silt content in horizon soil C enhances cork thickness and raises the price but reduces the cork yield. Higher accumulated precipitation and temperatures contribute to higher yields and thicknesses of cork. It is concluded that the relationships between the dependent and the independent variables are complex but partially explainable. Understanding these relationships is paramount to ensure sustainable management practices are adopted that are capable of addressing issues raised in the current context of climate change.
Lightweight structures with high energy absorption capacity are in high demand for energy absorption applications in a variety of engineering fields, such as aerospace, automotive, and marine engineering. Anti-impact composites are made of energy-absorbing materials that are incorporated into structures to protect the occupant or sensitive components against strikes or falls. This study deals with an experimental investigation of multi-layer composites consisting of cork and warp-knitted spacer fabrics (WKSF) for anti-impact applications. Composites were designed and created with a laser cutting machine in eight different configurations. To measure the energy absorption of the manufactured composite samples, a low-velocity drop-tower machine was designed, and the maximum reaction force due to the strike of the impactor on the specimens was measured by a dynamometer located under the samples. Moreover, energy absorption and specific energy absorption capacities were calculated for each specimen. In the final part of this study, the Life Cycle Assessment (LCA) of the designed composites was calculated to understand the eco-friendly properties of the composites.
: Rehabilitation of facades may be carried out with the application of External Thermal Insulation Systems (ETICS). Their main contribution is the increase of the energy efficiency of buildings. In the literature, hygrothermal, impact and fire performance studies have been carried out on several systems with different insulation materials, such as expanded polystyrene, mineral wool and extruded polystyrene foam insulation. Due to the growing concern with the environment, systems are being developed with more sustainable and ecological materials, such as ICB (expanded cork). These type of boards are responsible for a negative impact in global warming potential, significantly improving the environmental benefits of their use. As these systems were recently introduced to the market, applications on site are very recent and their behaviour over time still unknown. In this research, the durability and global performance of more sustainable systems (with ICB) were analysed through an experimental campaign and compared with EPS (expanded polystyrene) systems. The results show that the systems with ICB obtained satisfactory global behaviour comparable with the EPS systems. The ICB sustainable systems analysed stood out in acoustic performance.
Novel strategies and technologies to obtain home textiles with thermal insulation properties are increasingly being researched as a strategic approach in the textile industry. The fabric conductivity and heat resistance are two important parameters to take into consideration in order to obtain a structure with improved performance. It is widely accepted that thermal insulation fabrics that resist heat flow possess still air in their structure. The higher is the thickness of the fabric, the bigger is the air entrapped in the structure and thus better is their thermal insulation properties. Nevertheless, these types of textiles face a critical challenge that is obtaining a structure with decreased thickness, without losing the thermal insulation properties required to provide comfort to users. The main objective of this work was to develop different low thickness fibrous structures with improved thermal insulation properties by incorporating cork particles within nonwoven structures. The nonwoven fabrics were produced with wool and hollow polyester fibers and the cork particles were incorporated within the structure in the process of nonwoven fabrication. Nonwoven structures have been prepared in different compositions including 75 % of wool and 25 % of hollow polyester blended with cork granules with sizes ranging from 1-2 and 2-5 mm using as a control an agglomerated cork of 0.8 mm. After production, samples were tested for their thermal behaviour using Alambeta equipment. Results have shown that nonwoven composition comprising cork particles greatly influences the thermal performance, and enables for obtaining a low weight material with improved thermal insulation properties.
This review focuses on cork as a natural, renewable and sustainable construction raw-material. Cork has an unusual combination of properties making it suitable for application in buildings and infrastructures, for example insulation, wear-resistance and durability. The material properties combined with a favourable ecological footprint allow designers, architects and engineers to meet some of the Green Building demands. A summary on cork production, structure, chemistry and properties was made. The processing into cork-based products, for example cork agglomerates and composites, is detailed as well as their properties and applications in construction. The aptitude of cork-based products for compliance with sustainability and energy efficiency criteria is also addressed.
Reducing the energy cost of building has become a necessity, that's why this work was carried out to study the behavior of thermal inertia and thermal properties for walls coated by the sealants: white cement-cork, cement mortar -cork and plaster-cork. For this purpose time of diffusion, total heat capacity and total heat losses were defined for local composed from a layer of those binders. Also an analysis of thermal conductivities, thermal effusivities and thermal diffusivities for composites white cement-cork, mortar cement-cork and plaster-cork were studied.
This review work is an update of a previous work reporting the new cork based materials and new applications of cork based materials. Cork is a material which has been used for multiple applications. The most known uses of cork are in stoppers (natural and agglomerated cork) for alcoholic beverages, classic floor covering with composite cork tiles (made by the binding of cork particles with different binders), and thermal/acoustic/vibration insulation with expanded corkboard in buildings and some other industrial fields. Many recent developments have been made leading to new cork based materials. Most of these newly developed cork materials are not yet on the market, but they represent new possibilities for engineers, architects, designers and other professionals which must be known and considered, potentially leading to their industrialization. This paper is a review covering the last five years of innovative cork materials and applications also mentioning previous work not reported before.
This work is a contribution to understand the thermal behavior of the composite material based on granular cork embedded in plaster. An experimental investigation of its thermal properties was mainly performed using the Flash method and the tiny Hot Plate method in steady state regime. This will allow compare its thermal properties with those of plaster for motivate the proposal that this composite will be used as false ceiling. A comparison of the energy performances of the composite material and plaster was made; it allows deducing a very interesting energy gain. The preliminary findings indicate the composite is better than plaster in term of thermal insulation, energy storage capacity and lightness.
The effects of cork powder loadings on selected physicomechanical, thermal and ablative properties of ethylene propylene diene monomer (EPDM) based thermal insulations were studied in comparison to asbestos filled EPDM thermal insulation. Ethylene propylene diene monomer was compounded with other ingredients, such as fillers, process aid and curing package, and characterised for required properties. It was observed that increasing cork loading up to 33 parts per hundred parts of rubber caused an increase in hardness and tensile strength. Elongation at break, however, decreased with increasing cork percentage in the formulations. Thermal and ablation properties of the thermal insulations were studied by ballistic evaluation motors and oxyacetylene torch. Cork filled vulcanisates had more ablation and better insulative properties than asbestos filled vulcanisates. About 39% reduction in density of the thermal insulation was possible using cork filled insulation instead of asbestos filled insulations.
Cork is a material which has been used for mankind for the last 5,000 years and it is a strategic material used for multiple applications, from wine bottles to aeronautics. Many of current cork materials are composites, in particular cork materials for floor and wall coverings and several other building and industrial applications. Recent developments in cork research have shifted from the classical cork-wine relationship to quality and environmental issues, exploitation of cork industry residues and new cork based materials. In recent years a number of new cork based composite materials were developed.
Nowadays, lightweight and eco-friendly composites with improved mechanical properties are highly interesting. Sandwich-structured composites are a type of high-performance structural composite that is lightweight with a high strength-to-weight ratio and excellent specific energy absorption capabilities. In this study, cork-based sandwich structures resistant to impact and vibrations were designed and produced for the possibility of being used in the protective structures of low-speed aerial vehicles. To identify and match the best combination of different face sheets with a cork core, first, aramid fabric-reinforced polymer (AFRP), carbon fiber-reinforced polymer (CFRP), and glass fiber-reinforced polymer (GFRP) face-sheet composites were produced using the compression molding method (prepreg layup). Then, sandwich structures consisting of AFRP, CFRP, GFRP, and aluminum face sheets with a fixed core layer of cork were designed and assembled. Since the design goal of these structures is to use them in low-speed aerial vehicles, impact deceleration and vibration tests were applied to face sheets and sandwich structures individually, which are the most important factors involved in these structures during flight, particularly in rotary-wing drone applications. A low-energy drop-tower system was used for the calculation of deceleration results. Besides, the vibration properties of the structures were investigated using the modal analysis method and based on the natural frequency responses of the tested face sheets and sandwich structures, damping ratios and structural stiffness were measured. According to the results, compared to other face sheets, CFRP showed better resistance along with the cork core, when the structure was exposed to impact and vibration threats. This study provides useful information on cork core sandwich structures for academic and industrial researchers in choosing the right face sheet.
Impact or sudden accelerations are strictly avoided by sensitive systems such as electronic devices, robotic structures and unmanned aerial vehicles (UAVs). In order to protect these systems, various composites have been developed in recent years. Due to its excellent energy absorbing capabilities as well as eco-friendly and sustainable properties, cork is one of promising materials dedicated to protective applications. In this study, we benefit from cork in multi-layer design considering its advantages such as high flexural stiffnesstoweight ratio and good buckling resistance over monolithic structures. In addition, a non-Newtonian material, namely shear thickening fluid (STF) was incorporated in this design. STF shows rapid increase in its viscosity under loading and thereby enabling a stiffer texture that contributes to protective performance. At rest state, STF exhibit fluidic behavior and provides flexibility for composite. In the experimental stage, deceleration behavior of these composites was investigated. According to the analyses, STF exhibits promising results to lower peak decelerations while extending time period of deceleration under impact loading. STF contribution is pronounced by using this material in a closed medium such as in wrapped foam to avoid spilling out of composite during impact. The designed eco-friendly smart composites are suggested to cover internal parts in sensitive systems. Micro-mobility helmet is another prospective application area for cork/STF structures since they provide light-weight, excellent flexibility and good deceleration behavior.
It is well known that 3D printing has burst onto the scene as a disruptive technology set to revolutionize the way consumer goods are manufactured. This is why the search for new materials that combine the use of natural resources with 3D printing technology has recently become increasingly significant. Finding an alternative use for waste biomass as an additive to develop new materials that can be used in 3D printing is an added benefit to the environmental advantages of 3D printing. For the first time, we report the feasibility of using cork powder to formulate a new photo-curable resin composite that can be used in stereolithography (SLA), a vat photo-polymerization technique. The mechanical and thermal properties of the new composite and the influence of the cork particle size on these properties have been studied. Mechanical and thermal properties improve with the decrease of the particle size; this effect is more pronounced in the thermal stability of the composites. The results obtained in this work open the possibility of designing new photocurable composites using waste biomass as additives.
This work explores the potentialities of combining a multi-layer eco-friendly panel with a phase change material coating. Although the work is based on a numerical approach performed by COMSOL Multiphysics computer program, it can be considered as rigorous, robust, and optimized since the most important parameters added to the model were experimentally evaluated. The scientific soundness was guaranteed by a comparative analysis performed in two different times. The corkcoconut-cork panel was firstly investigated as it was, and secondly it was analysed with a phase change material layer applied on. In the second step, the panel undergone a mechanical process concerning the realization of a subsurface defect simulating a detachment. The aim was based on the conduction of a thermal conductivity analysis to characterize the benefits deriving from the application of the coating, as well as the negative effects introduced by the subsurface defect resembling a potential thermal bridge. The experiments were performed in Italy in a place identified into the manuscript (see ‘‘Testing procedure’’ section) by means of geographical coordinates.
Nowadays, there is a concern in getting buildings with reduced environmental impact and improved thermal and energy performance. The need to use new technologies to comply with the thermal requirements has been driven by the regulation for buildings. With this goal in mind, the use of thermal insulation systems on facades has increased. In this context, renders with high thermal insulation performance have recently emerged on the market. This paper discusses the physical characteristics of four industrial thermal renders, comparing with two experimental render mixtures in which sand is replaced by aggregates with thermal insulating properties (EPS and cork) without any additions or admixtures. It is noticed a need to incorporate high ratios of aggregate with thermal characteristics to achieve thermal insulation renders, affecting other physical properties of the renders at both fresh (workability, air content and bulk density) and hardened (water absorption under low pressure, capillary, dry bulk density, open porosity and drying capacity) states.
Cork is the bark of Quercus suber L. and it differentiates from other barks due to its high content on suberin and cellular structure. Most importantly, the debarking doesn’t damage the tree, and it is currently explored for different industrial applications, of which, stoppers for the wine industry is the most representative and economically significant. During the processing stages, up to 30% of cork is transformed into powder, which presently has no significant economic value. This stream of a low cost and unused natural resource constitutes an opportunity for the development of new products. In this review we discuss cork as a potential source of chemicals for alternative applications. Special emphasis is dedicated to the suberin and extractives fractions. Suberin constitutes a potential source of long chain hydroxyacids which can serve as building blocks for new macromolecules and materials. The structure and composition are briefly addressed, while the advances in suberin depolymerization, extraction methodologies and the proposed applications for this material are thoroughly discussed. The extractives fraction is constituted by lipophilic and phenolic compounds that present strong antioxidant and biological activities. The extractives composition and its properties are addressed. Finally, the use of cork for some recently proposed applications, such as, for the preparation of activated carbons and as templates for the adsorption of pollutants, are also briefly discussed. This review is intended to summarize the current knowledge and technological development state and to push for the progress towards an integrated cork economy.
In recent years, the situation of migrants seeking protection in Europe has grown exponentially since 2013. In Italy, the greatest difficulty is related to landings. Over 170,000 people registered on the coast of southern Italy in 2014. In emergency situations, it is necessary to ensure shelter and medical care to everybody. Many centres are makeshift structures, such as old houses or hotels, which are difficult to manage and entail elevated costs. The shelter prototype can be used for humanitarian emergencies or post-disaster reconstruction projects but also for tourism purposes, in highly naturalistic environments, or for seasonal agricultural workers. The objective of this paper is to propose a prototype of a building module, composed of wood and multilayer agglomerated cork panels, as an environmentally sustainable shelter that can be assembled on any terrain. It takes advantage of the characteristics of cork, such as acoustic and thermal insulation, fire resistance, natural origin, resistance to moulds and microorganisms , and shows high thermal performance. It can be built in different geometries and volumes and not necessarily by skilled workers.
Cork is the bark of the cork oak. It is a light, elastic material that is practically impermeable to liquid and gas, as well as being a thermal and electrical insulator. It also absorbs sound and vibrations and practically impossible to rot. Cork is composed of layers of cells, whose membranes have a certain amount of impermeability and are full of a gas similar to air. When cork is compressed, its cells bend and fold (practically no lateral expansion) and later recover. Cork is also a material that dissipates deformation energy. It has low thermal conductivity and is also remarkably stable and has good fire resistance. The most common cork products for civil construction are: insulators against noise, heat and vibration (walls, ceilings, flooring); false ceilings; coverings for walls, floors and ceilings; skirting boards; linoleums; granulated cork as filler and mixtures for mortar; insulating joints and expansion or compression joints; and anti-vibration devices for machinery and insulation for industrial refrigeration systems. Cork products are also very important from an ecological standpoint, because cork is a renewable product, used in long-life products, helping to boost CO2 sequestration.
The market for insulation material is playing a crucial role in Europe’s energy transformation, due to its influence on energy consumption in buildings. The introduction of renewable materials for thermal insulation is recent, and little is known so far about its environmental implications. This study analyses the environmental performance of a cork insulation board, made of agglomerated cork from forestry cork wastes, by means of cradle-to-gate Life Cycle Assessment methodology. The results indicate that the use of natural insulation materials does not necessarily imply a reduction of environmental impacts due to manufacturing processes with a low technological development. In this case, the most influential stage is the manufacturing stage, in which the board agglomeration and the cork trituration have the highest impacts. The most influential inputs are both the transport used during the life cycle and the large quantities of electricity and diesel in the manufacturing stage. Some strategies have been identified to reduce the environmental impact, such as promote the acquisition of local raw cork to reduce transportation from the manufacturer, improve the efficiency and productivity of manufacturing processes and improve the product design to help increase its market share. Moreover, the inclusion of biogenic carbon contained in forest-based building materials affects the Global Warming Potential results considerably. However, it is very important to consider how this biogenic carbon is calculated and how the product is managed after its lifetime.
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This comprehensive book describes cork as a natural product, as an industrial raw-materials, and as a wine bottle closure. From its formation in the outer bark of the cork oak tree to the properties that are of relevance to its use, cork is presented and explained including its physical and mechanical properties. The industrial processing of cork from post-harvest procedures to the production of cork agglomerates and composites is described. Intended as a reference book, this is the ideal compilation of scientific knowledge on state-of-the-art cork production and use Key Features: *Presents comprehensive coverage from cork formation to post-harvest procedures *Explains the physical properties, mechanical properties and quality of cork *Addresses topics of interest for those in food science, agriculture and forestry.
This study examines the impact of cork used as sand replacement or stone replacement on the plastic, mechanical, transport, microstructural and thermal properties of mortar and concrete. Mix design variables include the percentage of cork, cork size, and the cork blend. Key findings from this study revealed that: (i) The greatest early age (days 3 and 7) cube strengths were achieved by 24 h moisture saturation of the cork followed by draining it prior to use in concrete. Heat exposure of 50 °C or 100 °C resulted in detrimental effects on cube strength gain. (ii) Finer cork sizes were most beneficial to achieve optimum mechanical, and transport properties however high permeability values indicate that concrete-cork composites considered in this study may be vulnerable to poor durability performance. (iii) Greater percentages of cork as sand or stone replacement had the greatest impact on thermal resistance. (iv) Blending multiple cork sizes to achieve a greater size distribution of cork granules used as sand or stone replacement did not yield notable beneficial results.
(eds) Materials for construction and civil engineering
- L Gil