Thermal and Acoustic Building Insulations from Agricultural Wastes

Balador, Zahra; Gjerde, Morten; Isaacs, Nigel; Imani, Marzieh

doi:10.1007/978-3-319-48281-1_190-1

Cited by 9 publications

(20 citation statements)

References 61 publications

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“…Still, with different natural processes, the physical properties can be modified to better meet the requirements. In many cases, there arises the problem that natural-based thermal insulators are not fire-resistant, and do not simultaneously have the lowest possible thermal conductivity and high load-bearing capability, but they have homogeneity problems or contain hazardous additives [ 44 ].…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer in Straw-Based Thermal Insulating Materials

2021

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An analytic-empirical model was developed to describe the heat transfer process in raw straw bulks based on laboratory experiments for calculating the thermal performance of straw-based walls and thermal insulations. During the tests, two different types of straw were investigated. The first was barley, which we used to compose our model and identify the influencing model parameters, and the second was wheat straw, which was used only for validation. Both straws were tested in their raw, natural bulks without any modification except drying. We tested the thermal conductivity of the materials in a bulk density range between 80 and 180 kg/m3 as well as the stem density, material density, cellulose content, and porosity. The proposed model considers the raw straw stems as natural composites that contain different solids and gas phases that are connected in parallel to each other. We identified and separated the following thermal conductivity factors: solid conduction, gas conduction in stem bulks with conduction factors for pore gas, void gas, and gaps among stems, as well as radiation. These factors are affected by the type of straw and their bulk density. Therefore, we introduced empirical flatness and reverse flatness factors to our model, describing the relationship between heat conduction in stems and voids to bulk density using the geometric parameters of undisturbed and compressed stems. After the validation, our model achieved good agreement with the measured thermal conductivities. As an additional outcome of our research, the optimal bulk densities of two different straw types were found to be similar at 120 kg/m3.

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Section: Introductionmentioning

confidence: 99%

Heat Transfer in Straw-Based Thermal Insulating Materials

2021

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“…The most common natural raw materials for thermal insulation are flax, hemp, sheep wool, corn husk, cotton, coconut husk [8][9][10][11]. Some sustainable insulation reaches the thermal insulation performance [12], durability, usability, or mechanical properties of artificial insulations, but these properties usually not combined in one product [13]. This fact hinders the spread of these environmentally conscious materials.…”

Section: Research Motivationmentioning

confidence: 99%

Effect of drying method on compressive strength of straw-based thermal insulations

Fenyvesi¹,

Csanády²

2021

MST

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Most of the thermal insulations in the construction industry market based on fossil raw material or need a huge amount of production energy. Nowadays, sustainable thermal insulation products are more popular, and the demand for these products on the market is increasing. Some of them reach the main material properties of artificial ones but usually not all. Today the reaction to fire is another big challenge in this field. In many cases, producers use chemicals that can increase fire resistance, but on the other hand, increase the environmental impact of insulations too. It is also hard to find a binder which provides proper mechanical parameters and durability and is environmentally friendly too. During our scientific research on environmentally friendly thermal insulation materials, which is running for 4 years, we found that silicate-based adhesives meet many of these criteria mentioned above. In this article, the mechanical properties of straw-based insulation bonded with silicate binder were investigated. The effect of conventional and microwave drying on compressive strength were compared to found the optimal hardening process of binders. During the experiments, straw was applied in a natural state, natural stem length distribution and without microstructure and surface modification. The used binder is a simple silicate-based binder (potassium silicate) without any modification agent. Conventional drying needs a longer time, and during it, many cracks form in the early age of the hardened binder. It is because of shrinkage and the differences in the rigidity of the binder along its cross-section. Besides, the straw stems swell when exposed to moisture (from binder), and after drying they shrink, which decreases the quality of the bond between stems and binder. The microwave drying evenly heats the various points of the specimen, so it is not generated such big differences in shrinkage. The contact between stems and binder are also better. Due to these effects, the microwave dried specimens reached the limit required for step resistance, and they had three-time higher average compressive strength than we got by the conventional drying of the same raw material.

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“…In particular, for the building economic sector, the interest in new alternative materials with low environmental impact and energy efficiency has grown. Materials based on natural fibers are becoming increasingly popular, due to some common features such as their high availability and environmental sustainability benefits [2,3].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Colombian Crops Fibrous Byproducts for Potential Applications in Sustainable Building Acoustics

et al. 2020

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Local production of construction materials is a valuable tool for improving the building sector sustainability. In this sense, the use of lignocellulosic fibers from local species becomes an interesting alternative to the development of such materials. As it is thought that the properties of fiber-based materials are dependent on the fibers properties, the knowledge of such properties is fundamental to promote materials development. This study compares the physical, morphological, acoustic, and mechanical characteristics of coir (Cocos nucifera) and fique (Furcraea Agavaceae) fibers and panels. The chemical composition appears to be associated with the general behavior of the fibers and panels, regarding higher tensile strength, thermal degradation behavior, and water absorption. In most tests, fique had the upper hand, showing superior performance; however, on thermal degradation and water absorption, both materials had similar behavior. The sound absorption measurement showed that the fiber diameter affects the sound absorption at high frequencies, where fique panels showed better performance than coir panels.

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Thermal and Acoustic Building Insulations from Agricultural Wastes

Cited by 9 publications

References 61 publications

Heat Transfer in Straw-Based Thermal Insulating Materials

Heat Transfer in Straw-Based Thermal Insulating Materials

Effect of drying method on compressive strength of straw-based thermal insulations

Evaluation of Colombian Crops Fibrous Byproducts for Potential Applications in Sustainable Building Acoustics

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