Thermal Insulation Materials Research Articles

New Eco-Friendly Thermal Insulation and Sound Absorption Composite Materials Derived from Waste Black Tea Bags and Date Palm Tree Surface Fibers

A tremendous amount of waste black tea bags (BTBs) and date palm surface fibers (DPSFs), at the end of their life cycle, end up in landfills, leading to increased pollution and an increase in the negative impact on the environment. Therefore, this study aims to utilize these normally wasted materials efficiently by developing new composite materials for thermal insulation and sound absorption. Five insulation composite boards were developed, two were bound (BTB or DPSF with polyvinyl Acetate resin (PVA)) and three were hybrids (BTB, DPSF, and resin). In addition, the loose raw waste materials (BTB and DPSF) were tested separately with no binder. Thermal conductivity and sound absorption coefficients were determined for all boards. Thermal stability analysis was reported for the components of the tea bag (string, label, and bag) and one of the composite hybrid boards. Mechanical properties of the boards such as flexural strain, flexural stress, and flexural elastic modulus were determined for the bound and hybrid composites. The results showed that the thermal conductivity coefficients for all the hybrid composite sample boards are less than 0.07 at the ambient temperature of 24 °C and they were enhanced as the BTB ratio was reduced in the hybrid composite boards. The noise reduction coefficient for bound and all hybrid composite samples is greater than 0.37. The composite samples are thermally stable up to 291 °C. Most composite samples have a high flexure modulus between 4.3 MPa and 10.5 MPa. The tea bag raw materials and the composite samples have a low moisture content below 2.25%. These output results seem promising and encouraging using such developed sample boards as eco-friendly thermal insulation and sound absorption and competing with the synthetic ones developed from petrochemicals in building insulation. Moreover, returning these waste materials to circulation and producing new eco-friendly composites can reduce the number of landfills, the level of environmental pollution, and the use of synthetic materials made from fossil resources.

Construction and Properties of Ultralow Thermal Conductivity and High Strength Zirconia Aerogel Composites by Freeze-Drying.

Zirconia aerogels possess significant applications, including their use catalyst carriers, thermal insulation materials, and thermal barrier coatings. This is due to their ultrahigh temperature resistance, high porosity, and low thermal conductivity. Nonetheless, the inherent challenges associated with ZrO2 aerogels, such as high brittleness, low compressive strength, and inadequate formability, restrict their potential applications. In this paper, with ultralow thermal conductivity and high strength zirconia aerogel composites with inorganic zirconium salt zirconium carbonate as the raw material, acetic acid as the solvent, polyvinylpyrrolidone (PVP) as the viscosity builder to stabilize the structure of the aerogel during the freeze-drying process. Additionally, yttrium nitrate hexahydrate (Y(NO3)3·6H2O) is employed as a phase stabilizer. The sol-gel method, in conjunction with the freeze-drying process, is utilized to fabricate ZrO2 aerogel composites with an optimized microstructure. The findings indicate that optimal process parameters are achieved with a PVP solution concentration of 2.0 wt % and a zirconium carbonate concentration of 20 wt %. The mechanical properties of the resulting composites reach up to 550 kPa, while the thermal insulation performance exhibits a temperature difference of 207 °C/cm and a thermal conductivity of 0.0504 W/(m·K). This advancement addresses the mechanical stability issues commonly associated with traditional ceramic aerogels and widely used elastic insulating materials, thereby enhancing their applicability as thermal insulation and heat preservation materials.

Harmonizing lightweight and ablation resistance: Design and performance of multilayer composite insulation materials for solid rocket motors

AbstractThe realization of lightweight insulation materials is often accompanied by a decrease in ablation performance. Coordinating the contradiction between lightweight and ablation resistance is the key to the development of thermal protection technology. Addressing the need for high‐performance insulation materials within solid rocket motors (SRMs) combustion chambers, we designed three multilayer composite structural insulation materials and studied their properties. The results show that among these constructed multilayer composites, the bilayer structure exhibited the lowest density at a mere 0.72 g/cm3, marking a 27% reduction compared to the basic structure. Remarkably, the bilayer configuration demonstrated superior ablation resistance, showcasing a 25% decrease in the line ablation rate in contrast to the basic structure after oxygen‐acetylene test. This achievement embodies the successful harmonization of lightweight properties with ablation resistance. Furthermore, based on the performance and microstructure of the char layer, a further analysis revealed the enhancement mechanism of ablative performance by the multilayer composite structure. It was found that the synergistic effect of the compact/porous structure of the char layer grants the bilayer structure thermal insulation material optimal ablative performance. This work provides strong support for improving the performance of SRMs.Highlights Insulation materials with multilayer composite structures are designed. The materials exhibit both lightweight and superior ablation resistance. Compact/porous char layers enhance material ablation performance.

Interfacial assembly of nanocellulose microgels enhances thermal insulation of Pickering foam

Nanocellulose has attracted extensive attention in the preparation of thermal insulation materials because of its high Young's modulus, high strength and low thermal expansion coefficient. In this study, nanocellulose microgels prepared by self-assembly of 2,2,6,6-Tetramethylpiperidoxyl oxidized nanocellulose (TOCNC) and Nisin were used as particle stabilizers, and acrylated epoxidized soybean oil (AESO) was used as oil phase to prepare Pickering emulsion, which was cured by heating to obtain biomass-based Pickering thermal insulation foam. Pickering foams prepared based on microgels with different Nisin contents have significant differences in thermal insulation performance. The results show that the addition of microgel particles can improve the thermal stability, increase the roughness of pore wall and reduce the thermal conductivity of AESO polymer foam. Among them, the Pickering foam prepared by microgel containing 0.06 wt% Nisin has the best thermal insulation performance and rougher pore wall surface, and its thermal conductivity is 0.040 W/(m·K), which is obviously lower than that of the foam prepared by TOCNC (0.083 W/(m·K)). Based on the structural design of nanocellulose microgel particles, this work innovatively realized the assembly of microgels at the oil-water interface and the regulation of thermal insulation performance through Pickering technology, and developed a biomass-based foam with improved thermal insulation effect, which provides a new idea for expanding the advanced application of nanocellulose in the field of thermal insulation materials.

Analytical and numerical calculation and simulation of heat transfer in a composite wall made of polyethylene terephthalate bottle

The dynamics of heat transfer in composite walls made of Polyethylene Terephthalate (PET) bottles is studied using the energy conservation model. Ten walls of different structures were studied, including two control walls made of compressed earth brick (CEB) and cementitious material, cement-sand brick (CSB) and eight composite walls made of PET bottles filled with thermal insulation and/or mechanical stabilisation materials. The model equation is solved analytically using the separation of variables method and numerically using the finite difference method, and they are confirmed using CASTEM finite element software. As boundary conditions, a constant temperature (Text) is applied at one end of the wall, and the constant temperature (T0) is applied at any other point at the initial time. The effect of PET bottles filling on the thermal behaviour of the wall was then carried out to determine the optimum design that would give the wall better thermal inertia. The results obtained with CASTEM is fairly in agreement with the results obtained analytically and numerically, with a maximum relative error closed to that of the spatial evolution and 3.310−2 for the temporal one. It is found that heterogeneous filling of PET bottles provides better thermal inertia at the wall.

Bio-Templated Aerogel Fibers: Heterogeneous Spinodal Architecting and In Situ Fibrillation of Thermoplastic Polyurethane-Silica on Nanostructured Cellulose Nanofiber Scaffold for Enhanced Thermomechanical Performance.

This study addresses the inherent fragility and fractal limitations of traditional silica aerogels by developing a bio-templated aerogel fiber. Integrating cellulose nanofibers (CNFs), thermoplastic polyurethane (TPU), and silica aerogel (SA) in a dimethyl sulfoxide (DMSO) dispersion, a gel-spinning technique was employed to create aerogel fibers with superior thermomechanical performance. CNF also provided excellent rheological modification for successful spinnability, fast gelation, and fiber formation. The unique hierarchical structure of these fibers, formed through hot-stretching and surface modification, combined the superior mechanical strength and flexibility of TPU with the exceptional insulation properties of CNF and SA. The CNF network, encapsulated within the SA particles, formed a core-shell structure, axially aligned, that significantly enhances the thermal stability and mechanical performance of the fibers while maintaining a lightweight and porous architecture. Comprehensive morphological, thermal, and mechanical analyses were conducted to evaluate the properties of the developed aerogel fibers. Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy verified the successful surface modification and grafting reactions on CNF, contributing to improved hydrophobicity and thermal insulation. Adjusting the CNF content allowed for tailoring of the thermomechanical characteristics, with a notable 294% increase in tensile strength from 5.3 to 15.6 MPa and an enhanced crystallization temperature from 106 to 119.97 °C. Furthermore, cyclic tensile and compression tests validated the durability and shape recovery capabilities of the aerogel fibers, making them promising candidates for high-performance applications in extreme environments. The thermal conductivity validated by experimental data further highlights the potential of CNF-based aerogel fibers as sustainable and multifunctional materials for advanced thermal insulation, mechanical reinforcement, and flexible structural applications.

A Comprehensive Review and Recent Trends in Thermal Insulation Materials for Energy Conservation in Buildings

In recent years, energy conservation became a strategic goal to preserve the environment, foster sustainability, and preserve valuable natural resources. The building sector is considered one of the largest energy consumers globally. Therefore, insulation plays a vital role in mitigating the energy consumption of the building sector. This study provides an overview of various organic and inorganic insulation materials, recent trends in insulation systems, and their applications, advantages, and disadvantages, particularly those suitable for extreme climates. Moreover, natural and composite materials that can be used as a low-cost, thermally efficient, and sustainable option for thermal insulation are discussed along with their thermal properties-associated problems, and potential solutions that could be adopted to utilize natural and sustainable options. Finally, the paper highlights factors affecting thermal performance and essential considerations for choosing a particular insulation system for a particular region. It is concluded that the most commonly used insulation materials are found to have several associated problems and there is a strong need to utilize sustainable materials along with advanced materials such as aerogels to develop novel composite insulation materials to overcome these deficiencies.

Application of Experimental Studies of Humidity and Temperature in the Time Domain to Determine the Physical Characteristics of a Perlite Concrete Partition

These days, the use of natural materials is required for sustainable and consequently plus-, zero- and low-energy construction. One of the main objectives of this research was to demonstrate that pelite concrete block masonry can be a structural and thermal insulation material. In order to determine the actual thermal insulation parameters of the building partition, in situ experimental research was carried out in real conditions, taking into account the temperature distribution at different heights of the partition. Empirical measurements were made at five designated heights of the partition with temperature and humidity parameters varying over time. The described experiment was intended to verify the technical parameters of perlite concrete in terms of its thermal insulation properties as a construction material used for vertical partitions. It was shown on the basis of the results obtained that the masonry made of perlite concrete blocks with dimensions of 24 × 24.5 × 37.5 cm laid on the mounting foam can be treated as a building element that meets both the structural and thermal insulation requirements of vertical single-layer partitions. However, it is important for the material to work in a dry environment, since, as shown, a wet perlite block has twice the thermal conductivity coefficient. The results of the measurements were confirmed, for they were known from the physics of buildings, the general principles of the formation of heat and the moisture flow in the analysed masonry of a perlite block. Illustrating this regularity is shown from the course of temperature and moisture in the walls. The proposed new building material is an alternative to walls with a layer of thermal insulation made of materials such as polystyrene or wool and fits into the concept of sustainable construction, acting against climate change, reducing building operating costs, improving living and working conditions as well as fulfilling international obligations regarding environmental goals.

Requirements of the Vapour Barrier in Wood-Frame Walls

This paper examines the water-vapour diffusion resistance (Z-value) of vapour versus wind barriers by determining their Z-value ratio in exterior wood-frame walls thermally insulated with six different materials to prevent mould growth. Using WUFI Pro, the water-vapour diffusion resistance requirements were determined for thermal insulation using mineral wool and biogenic materials: wood fibre, straw, flax, grass, and hemp. Hygrothermal simulations determine the minimum Z-value ratio between these materials with vapour versus wind barriers in temperate and cold climates. Wind barriers with Z-values between 1 and 8 GPa s m2/kg were used in walls with U-values of 0.15 and 0.10 W/m2 K. The indoor moisture load was defined from classes of 1 to 5 with a U-value of 0.15 W/m2 K and classes of 2 and 3 were used for a U-value of 0.10 W/m2 K. The Z-value ratio depends on the Z-values of the wind barrier and thermal insulation material, moisture load class, and U-value. The required Z-value ratio declines with an increased wind-barrier Z-value. The vapour-barrier Z-value approaches a fixed threshold for wind-barrier Z-values approaching lower values (1 GPa s m2/kg) and those approaching higher values (8 GPa s m2/kg), depending on the thermal insulation material. This parameter study examines wind barriers with a Z-value ranging between 1 and 8 GPa s m2/kg, which characterises typical wind barriers used in Denmark For the water-vapour diffusion resistance requirement of the vapour barrier, the Z-value increases for increased moisture load classes and thermally insulated walls with lower U-values. The conversion between the Z-value, the Sd-value, and the water-vapour resistance factor µ can be found in DS/EN ISO 12572:2016.

Kinetics of moisture exchange during convection drying of thin flat wet materials

The kinetics of convective drying of thin wet thermal insulation materials based on the relative drying rate and relative moisture contents has been studied. Processing of experimental data on drying of various wet materials has established that the relative drying rate is related to the relative moisture contents, which are the ratios of the current moisture content to its critical and initial values. Based on the functional dependence of the relative drying rate on the relative moisture contents using the processing of the experiment on drying of ceramics, felt, and asbestos, equations for calculating the drying time are obtained. The dependence of the relative drying rate on the ratio of the current moisture content to the critical one is given. Zonal methods for calculating the drying time are given, based on the drying rate curve. An expression for determining the drying coefficient is developed. Based on the analysis of experimental data on drying porous ceramics, sheet asbestos, and wool felt, graphs of the dependence of the relative drying rate on the ratio of the current moisture content to the initial one are constructed. Dependencies for determining the critical moisture content of the material are given. The considered method of processing experimental data allows obtaining all the main equations for calculating the kinetics of the drying process. A variant of estimating the drying time based on one experiment with a short time interval is given. A comparison of the calculated values according to the equations with the experiment is performed. The spread of the calculated values is in the range of experimental error. The formulas for calculating the drying time obtained without plotting the drying rate curve allow significantly reducing the time of processing the experimental data and can be applied to other materials.

Characterization, modeling and prediction of foam-formed softwood fiber sound absorption

The transition towards building materials with low or negative carbon-dioxide footprint is a pressing topic in nowadays society. Materials for thermal and acoustic insulation are among those attracting a growing number of research publications. Commonly used materials in the building sector are mostly mineral wools which demand huge amounts of energy during production by melting sand or stone. Cellulose-based materials are a promising substitute for the current market leaders. These materials are able to reach negative carbon footprints due to low embodied energy and their ability to store carbon dioxide in buildings for decades. Predicting the sound absorption behavior prior to manufacturing can further improve their usability. This study delves into the prediction and characterization of wood-based pulp fiber foams and their acoustic properties. By comparing analytical models, semi-phenomenological models and experimental measurements the prediction of sound absorption based on fiber diameter and bulk density is evaluated. The findings reveal that refining a recent analytical model for natural fibers through parameter fitting to non-acoustic parameters yields improved accuracy in predicting sound absorption curves. While the accuracy declines towards higher densities, this work lays the groundwork to create environmentally sustainable sound absorbers with carefully tailored sound absorption properties.

Double cross-linked biomass aerogels with enhanced mechanical strength and flame retardancy for construction thermal insulation

Biomass aerogels are expected to be a popular material in construction field due to their sustainability, eco-friendliness and excellent thermal insulation properties. In this paper, high modulus biomass aerogels based on the principle of double cross-linking of physics and chemistry were synthesized by freeze-drying technique using gelatin, sodium carboxymethyl cellulose, glutaraldehyde, phytic acid and diatomite as raw materials. The presence of a double cross-linked network structure endowed the prepared aerogels with a low thermal conductivity (0.021–0.029 W·m−1·k−1). The density of only 0.0865 g·cm−3 biomass aerogel exhibited an extrastrong compression modulus of 31.5 MPa, which was superior to common biomass aerogels. Biomass intumescent flame retardant system composed of sodium carboxymethyl cellulose (carbon source), gelatin (gas source) and phytic acid (acid source) was used in combination with diatomite to enhance flame retardancy (limit oxygen index value up to 36.5 %, UL-94 V-0 rating and total smoke production reduced from 0.31 m2 to 0.18 m2) and thermal stability (the residue up to 48.91 %). Remarkably, the modified aerogel showed incredible hydrophobicity (hydrophobic angle of 137°). In summary, the results indicated this study proposed a novel green idea for the preparation of construction thermal insulation materials with a combination of high modulus, flame retardancy and hydrophobicity.

Enhancing Fire Resistance of Geopolymers Modified with Thermal Insulation Additives

This study aims to improve the fire resistance of geopolymers by adding thermal insulation materials. These additives help the material perform better at high temperatures. Previous research focused on using fly ash, metakaolin, and zeolite in geopolymer composites. This study looks at how porous additives affect compressive strength and whether non-destructive testing can measure damage after heat exposure. Four temperature tests were set: 400 °C for 60 min, 400 °C for 120 min, 800 °C for 60 min, and a maximum of 658 °C for 120 min. The results showed that the compressive strength and ultrasonic pulse velocity (UPV) dropped as the temperature increased, with a sharp decrease at 800 °C. Unmodified samples broke apart at high temperatures, while modified samples lost 40% to 70% of their strength. The study confirmed that a dense, amorphous matrix improves heat resistance, even with porous additives like fly ash. A link between UPV and compressive strength was found, suggesting non-destructive testing could be useful for checking structural integrity after a fire.

Lightweight, ultrahigh-strength and flame-retardant cellulose aerogel crosslinked with a reactive P/N-rich curdlan derivative.

Cellulose aerogel, recognized for its eco-friendliness, bio-sustainability and excellent thermal insulation property, holds immense potential as an insulation material. However, the application of cellulose aerogel has been hindered by its inherent drawbacks, particularly its low strength and flammability. In this study, a reactive P/N-rich curdlan derivative (NT) was synthesized and characterized. Lightweight, ultrahigh-strength and flame-retardant composite aerogels were then prepared by slow freezing, freeze-drying and chemical crosslinking methods. Composite aerogel crosslinked with 30% NT exhibited exceptional thermal insulation property with a low thermal conductivity of 33.9mW/(m·K), which rivaled the value of petroleum-based thermal insulation materials. It possessed an ultrahigh compressive modulus (0.786MPa) at low density (21.6mg/cm3), which supported >12,000 times its weight. It also displayed superior flame-retardant property, with a limiting oxygen index of up to 33.1% and a V-0 rating in the UL-94 test. This study provides a new insight into the high-value utilization of natural polysaccharide and an innovative solution to the problem of low strength and flammability of cellulose aerogel. Cellulose aerogels with ultrahigh strength, superior flame retardancy and thermal insulation property possess a promising application in the fields of construction, aerospace and thermal protective clothing as high-performance thermal insulation materials.

Thermal insulation materials based on eucalyptus bark fibres

The civil construction industry significantly contributes to global energy consumption, prompting a shift towards sustainable practices to mitigate environmental impacts throughout the building lifecycle. Traditional thermal insulation materials, such as polyurethane foam and mineral wool, are cost-effective but fail to meet environmental safety standards. In this context, plant-based materials have emerged as an eco-friendly alternative for thermal insulation, with agroforestry waste offering a sustainable raw material source. This waste is abundant and often improperly disposed of, thus utilizing it can reduce the environmental footprint of the agroforestry sector. This study focuses on developing thermal insulation plates using eucalyptus bark fibres, with some samples incorporating wheat straw. Various methods were employed: sodium silicate as a binder in some samples, while others used a binder-free method involving pulping bark in lye, and some included carbonised eucalyptus bark. The primary goal was to evaluate properties like thermal conductivity and moisture sorption. The electron microscope analysis provided insights into the microstructure of the fibres, explaining their insulation mechanisms. The thermal conductivity of the plates ranged from 0.036 to 0.059 W/(m·K) at a density of 80–220 kg/m3, influenced by the preparation processes (mechanical grinding, lye pulping, carbonization) and binder use. Eucalyptus bark fibre samples demonstrated low moisture sorption for plant-based materials, with 9.4–14.5 % at 60 % relative humidity and 21.6–38.5 % at 97 % relative humidity. Additionally, the samples showed high resistance to fungal growth when wet, suggesting good durability for thermal insulation applications. Overall, the study's results indicate that eucalyptus bark fibres hold significant promise as a sustainable raw material for producing thermal insulation, offering an environmentally friendly alternative to traditional materials while enhancing the durability and effectiveness of insulation in construction.

Construction of ZrC@SiC shell-core structure in SiBCN aerogel for enhanced thermal stability and thermal insulation

SiBCN aerogels have drawn increased attention as thermal insulation material, but they still suffer from precipitation and phase transition causing the microstructural collapse and performance deterioration under high-temperature environments. Here, ZrC/SiBCN aerogels were prepared using zirconium (IV) butoxide modified polyborosilazane as precursor through solvothermal reaction, frozen casting followed by frozen drying and pyrolysis. Benefiting from its unique hierarchical cellular structure, ZrC/SiBCN aerogel exhibits super-low density (0.042 g/cm3), high specific surface area (287.9 m2/g) as well as low thermal conductivity (24 mW/(m·K)). Shell-core ZrC@SiC nanocrystals are in-situ formed in amorphous SiBCN matrix through step-by-step carbothermal reduction of oxygen-containing phases and free carbon phase during the pyrolysis process, which effectively inhibits the crystallization and growth of SiC crystals, further enhancing the thermal stability under high-temperature environments. It could maintain a high specific surface area (163 m2/g) and low thermal conductivity (29 mW/(m·K)) after thermal treatment at 1800 °C for 2 h. The excellent structural and performance stability of the SiBCN-based aerogels will expand their applications under high-temperature extreme environments.

Low-impact thermal insulation materials for sustainable retrofitting: potentialities and barriers from a literature review

Abstract The present study provides both an updated overview of the most recent studies about low environmental impact materials for building retrofitting and meta-analyses of the most important features, such as the thermal conductivity, allowing to evaluate their insulation potential against the diffused and recurrent conventional competitors. Specifically, 466 case studies about materials derived by co-production, wastes of other products and recycled ones have been selected and their thermal performances have been analysed. The materials have been clustered into homogeneous classes: lose materials and foams; structural materials; panels; finishing materials. The results show that some low environmental impact materials are characterized by thermal performances which can position them as materials able to contribute to building decarbonization, but little information can be found about other characteristics which can be crucial when the built environment is considered, such as durability, fire resistance, costs, and load resistance. Yet, these latter aspects may be investigated further when the material is considered to enter the prototyping phase whether in the academic or market context. The present study provides a base for discussion about the use of more environmentally friendly thermal insulation materials which in the coming years might represent a valid option for sustainable building renovation.

The effect of the isocyanate trimerisation catalyst on the chemical composition and strength characteristics of polyurethane-polyisocyanate foams

Nowadays polyurethane-polyisocyanurate (PIR) foams are in a wide use as structural and thermal insulation materials. Isocyanate trimerisation catalysts for foams synthesis have low selectivity in terms of isocyanurate formation. As a consequence, a significant number of target (primary) and (secondary) chemical processes occur during the synthesis of PIR foams. We estimated the dependence of isocyanate group consumption for the formation of the main primary and secondary products on composition isocyanate index by methods based on the internal standard. Indeed, with an increase in the isocyanate index, the conversion of isocyanate to isocyanurate decreases significantly. The paper examines the influence of trimerisation catalyst type on chemical composition and strength characteristics of PIR foams. Hence, catalysts based on organic salts of alkali metals are more selective to the isocyanate trimerisation process than tertiary amines and derivatives of quaternary ammonium bases.

Lightweight and hydrophobic silica aerogel/glass fiber composites with hierarchical networks for outstanding thermal and acoustic insulation

Silica aerogels are regarded as potential thermal and acoustic insulation materials with low density and porous structure. However, the hydrophilicity due to surface hydroxyl groups and the low mechanical intensity have limited its further application. Generally, it can be achieved by adjusting the process parameters of the sol-gel to refine the structure of silica aerogels and optimize performance. In this study, we adopted an appropriate modification strategy of incorporating glass fiber felts as the reinforcing phase and trimethylchlorosilane (TMCS) as the hydrophobic modifier. By adjusting the solvent exchange time, the micro-nano structure, i.e. hierarchical networks, was optimized. The TMCS-modified silica aerogel/glass fiber/hot-melt fiber composites (TSGMs) exhibited great sound insulation, and the maximum sound transmission loss (STL) was up to 34 dB at 6300 Hz. Compared to unmodified, STL improved by 8 dB in simulated practical applications. In addition, TSGMs also exhibited high hydrophobicity with a water contact angle of 147° and excellent thermal insulation with a thermal conductivity of 0.0345 W (m k)-1. The results could contribute to the refinement in the preparation process of silica aerogel composites and use in the fields of thermal and acoustic insulation.

3DP for sustainable built environment – synthesis and thermomechanical characterization of composite materials based on local soil and date palm fiber waste

There is an increasing demand for sustainable construction materials to address the challenges posed by the environmental impact of the built environment (BE), which is driven by climate change, population growth, and urbanization. Conventional construction materials like cement contribute significantly to carbon emissions during production, transport, use, and disposal phases, and their poor thermal conductivity hinders efforts to maintain comfortable indoor environments. To address these challenges, there is an urgent need for innovative, locally sourced thermal insulation materials specifically designed for regions with extreme climates and high energy demands to maintain building comfort. This research explores synthesizing novel, environmentally friendly building materials using locally sourced date palm fiber waste and clay. The study also investigates the developed material's 3D printing (3DP) capabilities and optimizes its printing parameters with lab-scale prototypes. Additionally, thermo-mechanical characterization is conducted to assess its suitability for built environment applications. Different concentrations, from 1 to 5 wt% of date palm fiber to clay ratio (Dpf/C), were studied regarding microstructural, thermal, and mechanical properties, dimensional accuracy, and feasibility for 3DP of BE structures. Results demonstrated a significant reduction in thermal conductivity by 73%, achieving 0.244 W/mK, and an increase in compressive strength by 106%, reaching 10.9 MPa at 5 wt% Dpf/C. The promising thermomechanical properties of these composites and their suitability for 3DP support their use in real-world applications in the future’s sustainable built environment. This scalable methodology can be adapted to regions with similar sustainable local and waste resources, advancing the circular economy.