Search Results (19)

This study investigates a comprehensive study on the mechanical and microstructural behavior of cementitious mortars modified with a combination of internal carbonation (via solid CO₂), calcined clay as a ceramic pozzolanic additive, and bio-based sheep wool fibers. The investigation aimed to explore sustainable routes for enhancing mortar performance while reducing the environmental impact of cement production. A series of mortars incorporating various combinations of dry ice, calcined clay, and wool fibers was prepared and tested to evaluate compressive and flexural strength, porosity, pore size distribution, phase composition, and microstructural morphology. Results demonstrated that internal carbonation significantly promoted matrix densification and compressive strength, increasing fc by approximately 8% compared to the reference. The addition of calcined clay further improved microstructural compactness, reducing total pore volume by 12%, while the incorporation of wool fibers enhanced post-cracking toughness by over 40% despite a 15–30% decrease in compressive strength. SEM and TGA confirmed the formation of calcite and reduced portlandite content, consistent with carbonation and pozzolanic reactions. The findings underscore the potential and limitations of multicomponent eco-modified cement mortars. Optimizing the balance between internal carbonation, pozzolanic reaction, and fiber stability is a key to developing next-generation low-carbon composites suitable for durable and resilient construction applications. Full article

Rammed earth (RE), a traditional material aligned with circular economy (CE) principles, has been gaining renewed interest in contemporary construction due to its low environmental impact and compatibility with sustainable building strategies. Though not a modern invention, it is being reintroduced in response to the increasingly strict European Union (EU) regulations on carbon footprint, life cycle performance, and thermal efficiency. RE walls offer multiple benefits, including humidity regulation, thermal mass, plasticity, and structural strength. This study also draws attention to their often-overlooked ability to mitigate indoor overheating. To preserve these advantages while enhancing thermal performance, this study explores insulation strategies that maintain the vapor-permeable nature of RE walls. A parametric analysis using Delphin 6.1 software was conducted to simulate heat and moisture transfer in two main configurations: (a) a ventilated system insulated with mineral wool (MW), wood wool (WW), hemp shives (HS), and cellulose fiber (CF), protected by a jute mat wind barrier and finished with wooden cladding; (b) a closed system using MW and WW panels finished with lime plaster. In both cases, clay plaster was applied on the interior side. The results reveal distinct hygrothermal behavior among the insulation types and confirm the potential of natural, low-processed materials to support thermal comfort, moisture buffering, and the alignment with CE objectives in energy-efficient construction. Full article

In a global context where sustainability is becoming a priority in construction, this paper analyzes the use of composite materials based on clay and plant waste, offering an ecological alternative to conventional materials. This article analyzes the mechanical properties of composite materials made from clay with walnut shell inserts, shredded biomass from corn stalks, wheat straw, and wool waste. These materials are developed for sustainable rural construction. The study evaluates flexural and compressive strength based on measurements at varying insert concentrations. The results indicate that mechanical strength decreases as insert concentration increases. The materials are suitable for partitions and insulating walls, and in lightweight buildings without floors, they can be used as load-bearing walls if reinforced with wood or metal. Future research directions include improving the estimation of mechanical behavior, studying rheological characteristics under environmental conditions, and expanding the application of clay and plant waste composites. Full article

The European Climate Law mandates a 55% reduction in CO₂ emissions by 2030, intending to achieve climate neutrality by 2050. To meet these targets, there is a strong focus on reducing energy consumption in buildings, particularly for heating and cooling, which are the primary drivers of energy use and greenhouse gas emissions. As a result, the demand for energy-efficient and sustainable buildings is increasing, and thermal insulation plays a crucial role in minimizing energy consumption for both winter heating and summer cooling. This review explores the historical development of thermal insulation materials, beginning with natural options such as straw, wool, and clay, progressing to materials like cork, asbestos, and mineral wool, and culminating in synthetic insulators such as fiberglass and polystyrene. The review also examines innovative materials like polyurethane foam, vacuum insulation panels, and cement foams enhanced with phase change materials. Additionally, it highlights the renewed interest in environmentally friendly materials like cellulose, hemp, and sheep wool. The current challenges in developing sustainable, high-performance building solutions are discussed, including the implementation of the 6R principles for insulating materials. Finally, the review not only traces the historical evolution of insulation materials but also provides various classifications and summarizes emerging aspects in the field. Full article

This case study focuses on twelve compacted clay soil samples to understand their fundamental physical and thermal properties. For each sample, the density, thermal conductivity, thermal diffusivity, specific heat, and drying shrinkage were assessed. The identification and characterisation of the materials were also carried out by positioning them into the ternary diagram based on the percentage of sand, silt, and clay. These properties are definitive for the performance characteristics of materials used in rammed earth wall construction. The aim is to provide information for better knowledge and prediction regarding the dynamic heat flow in rammed earth walls. Experimental results show a relatively wide range of values for each property, reflecting the diverse properties of the sampled clays. The thermophysical characteristics of the 12 types of earth analysed showed correlations with reports in the literature in terms of density (1490–2150 kg/m³), porosity (23.22–39.99%), specific heat capacity (701–999 J/kgK), and thermal conductivity (0.523–1.209 W/mK), which indicates them as materials suitable for use in the construction of rammed earth walls. Using test data, a dynamic assessment of heat flow through simulated rammed earth walls was performed. For a better understanding of the results obtained, they were compared with results obtained for simulations where the building element would be made of concrete, i.e., a mineral wool core composite. Thus, heat flux at the wall surface and mass flux, respectively, during the 16 years of operation showed similar evolution for all 12 types of clay material analysed, with small variations explained by differences in thermophysical characteristics specific to each type of S1–S12 earth. In the case of walls made from clay material, there is a stabilisation in the evolution of the water content phenomenon by the 5th year of simulation. This contrasts with walls made of concrete, where the characteristic water content appears to evolve continuously over the 16-year period. Therefore, it can be said that in the case of the construction elements of existing buildings, which have already gone through a sufficient period for the maturation of the materials in their construction elements, the rammed earth wall quickly develops a moisture buffer function. In the case of simulating a mineral wool core composite wall, it cannot perform as a temperature or humidity buffer, exhibiting an enthalpy exchange with indoor air that is only 4% of that of the rammed earth walls; consequently, it does not play a significant role in regulating indoor comfort conditions. Overall, there is confirmation of the temperature and moisture buffering capabilities of rammed earth walls during both warm and cold periods of the year, which is consistent with other reports in the literature. The findings of this research provide a better insight into clay as a material for rammed earth walls for more efficient design and construction, offering potential improvements regarding indoor comfort, energy efficiency, and sustainability. The data also provides useful information in the fields of architecture and civil engineering regarding the use of clay as an eco-friendly building material. The results emphasise the importance of thoroughly understanding the thermophysical properties of clay to ensure the efficiency of rammed earth construction. Full article

This study investigates the coupling effect of mechanically activated nepheline-syenite (NS) and mineral wool melt waste (MWMW) on the physical–mechanical properties of a ceramic body. The results indicate that an optimal amount (10–20%) of NS additive promotes the formation of the smallest pore size from 0.001 to 0.01 µm, as well as improves physical, mechanical, and durability properties of the ceramic samples with MWMW, when fired at temperatures between 1000 and 1080 °C. As the NS content increases, the composition becomes more alkaline, leading to enhanced vitrification and the formation of a glass phase during firing. This reduces open porosity, modifies pore size distribution, and enhances compressive strength and frost resistance. An NS content of 15% produces the best results, increasing the smallest pore fraction and yielding favourable properties, such as reduced open porosity, water absorption and density, increased compressive strength, and does not affect the linear shrinkage. The frost resistance test demonstrates that the coupling effect of NS additive and MWMW improves the samples’ resistance to freeze–thaw cycles, with the best performance observed at 15% NS content. The study also highlights the usefulness of structural parameters and ultrasound testing for assessing and predicting the frost resistance of ceramic samples. Full article

The presence of arsenic in water for human consumption is of concern, especially in developing countries, and the design of simple and economic treatments for arsenic removal is imperative. In this paper, three low-cost technologies were evaluated for As(V) or As(III) (5 mg L⁻¹) removal: (1) zerovalent iron (Fe(0)), as powdered (μFe(0)) and iron wool (wFe(0)); (2) coagulation-flocculation with Al₂(SO₄)₃ or FeCl₃; and (3) adsorption on a natural clay. μFe(0) was more efficient than wFe(0), requiring a minimal dose of 0.25 g L⁻¹ to achieve [As(V)] < 0.01 mg L⁻¹ after 288 h; the reaction time was reduced to 168 h under stirring. When starting from As(III), partial oxidation to As(V) was observed, and removal was not complete even after 648 h with 1 g L⁻¹ μFe(0). As(V) removal using FeCl₃ and Al₂(SO₄)₃ was very fast and completed in 15 min with 0.25 g L⁻¹ of both reagents. However, Al₂(SO₄)₃ was not efficient to remove As(III). With the clay, doses higher than 50 g L⁻¹ and times longer than 648 h were needed to remove both As species. Arsenic leached from μFe(0) used to treat As(III) was almost negligible. Thus, Fe(0) may be the best alternative for low-cost, small-scale applications. Full article

Mulching techniques can comprise a solution that better utilizes precipitation and irrigation water in such a manner that mitigates soil degradation and drought damage; however, there are still gaps in the literature with regard to the effect of the use of mulch materials on the development of plant–soil–microbe interactions. Waste fibers, as alternative biodegradable mulch materials, are becoming increasingly prominent. The effect of wool mulch (WM) on water use efficiency, with regard to pepper seedlings, was investigated in different soil types (sand, clay loam, peat) in a pot experiment. Two semi-field experiments were also set up to investigate the effect of WM–plant interactions on sweet pepper yields, as compared with agro textiles and straw mulches. Soil parameters (moisture, temperature, DHA, β-glucosidase enzymes, permanganate-oxidizable carbon) were measured during the growing season. The effect of WM on yield and biomass was more significant with the less frequent irrigation and the greater water-holding capacity of soils. Microbiological activity was significantly higher in the presence of plants, and because of the water retention of WM, the metabolic products of roots and the more balanced soil temperature were caused by plants. In the sandy soil, the straw mulch had a significantly better effect on microbiological parameters and yields than the agro textiles and WM. In soils with a higher water capacity, WM is a sustainable practice for improving the biological parameters and water use efficiency of soil. The effect of WM on yields cannot solely be explained by the water retention of the mulch; indeed, the development of biological activity and plant–soil–microbe interactions in the soil are also contributing factors. Full article

Agro-biogenic stabilization of expansive subgrade soils is trending to achieve cost-effective and sustainable geotechnical design to resist distress and settlement during the application of heavy traffic loads. This research presents optimized remediation of expansive clay by addition of proportionate quantities of waste renewable wool-banana (WB) fiber composites for the enhancement of elastoplastic strain (Ԑ_EP), peak strength (S_p), resilient modulus (M_R) and California bearing ratio (CBR) of expansive clays. Remolded samples of stabilized and nontreated clay prepared at maximum dry density (γ_dmax) and optimum moisture content (OMC) were subjected to a series of swell potential, unconfined compressive strength (UCS), resilient modulus (M_R) and CBR tests to evaluate swell potential, Ԑ_EP, M_R, and CBR parameters. The outcome of this study clearly demonstrates that the optimal WB fiber dosage (i.e., 0.6% wool and 1.2% banana fibers of dry weight of clay) lowers the free swell up to 58% and presents an enhancement of 3.5, 2.7, 3.0 and 4.5-times of Ԑ_EPT, S_p, M_R and CBR, respectively. Enhancement in Ԑ_EP is vital for the mitigation of excessive cracking in expansive clays for sustainable subgrades. The ratio of strain relating to the peak strength (Ԑ_PS) to the strain relating to the residual strength (Ԑ_RS), i.e., Ԑ_PS/Ԑ_RS = 2.99 which is highest among all fiber-clay blend depicting the highly ductile clay-fiber mixture. Cost-strength analysis reveals the optimized enhancement of Ԑ_EPT, S_p, M_R and CBR in comparison with cost using clay plus 0.6% wool plus 1.2% banana fibers blend which depicts the potential application of this research to economize the stabilization of subgrade clay to achieve green and biogeotechnical engineering goals. Full article

Climate change and resource and energy depletion are already impacting ecosystems and societies around the world. As a result, environmental sustainability has become one of humanity’s priority challenges. This study aims to use ecological multilayer material in order to reduce the impact of carbon and energy needs of heating in severe climates in which people die each year from cold. The combination of the investigated multilayer material gives a low thermal transmittance (U = 0.361 W·m⁻²·K⁻¹). A simulation using the software TRNSYS was established to estimate the yearly heating and cooling needs in the building with the developed multilayer material in a semi-arid climate. The yearly energy demands for heating and cooling were compared to a normal wall with conventional bricks; 47% of energy was saved by the use of the multilayer material wall. The use of the multilayer material permits a low ratio of energy needs of 24 KWh/m²/year for cooling needs and 43 KWh/m²/year for heating. Full article

Chinese solar greenhouses (CSGs) are characterized by unique walls to reduce the transmission of heat and promote the energy conservation in winter production, which promotes cultivation in the northeast region of China in winter. Effective selection of insulation material is important for the CSG based on the energy consumption and economic analysis. However, choosing the thickness of the insulation material in walls often discussed with the structure of CSG. There is a lack of research combing the optimal insulation thickness for improving the energy conservation. The aim of this study was to find the optimum insulation thickness during the energy conservation based on the structure of walls, the energy consumption in local climatic conditions, the cost of insulation material, and economic payback period over a lifetime. By the economic analysis of insulation thickness, thermal resistance, lifetime energy saving, and payback period, three kinds of typical walls (clay brick (CB), hollow concrete block (HCB) and fly ash block (FAB)) combed with four insulation materials including the expanded polystyrene, the foamed PVC, the perlite, and the rock wool were calculated. The optimum insulation thickness can be found when energy savings reached the maximum. In the northeast region, the association of FAB with rock wool as the insulation layer was the most economic composite wall structure. The optimum insulation thickness was 0.05 m, with the cost only 5 USD/m². The thermal resistance of composite wall had a significant effect on the payback period. When thermal resistance increased from 0.2 to 1.2 m²K/W, the payback period varied from 0.4 to 4.3 years. What is more, the energy consumption in local climatic conditions had a more significant effect on payback period. It can be assumed that insulation materials are more favored in cold climatic regions where heating degree-days over 1600 °C days for payback periods is less than 2 years. These results have strong practical and economical significance in saving energy and improving the environment of CSG. Full article

This study aims to check the compatibility of a selection of waste and recycled biopolymers for rammed earth applications in order to replace the more common cement-based stabilization. Five formulations of stabilized rammed earth were prepared with different biopolymers: lignin sulfonate, tannin, sheep wool fibers, citrus pomace and grape-seed flour. The microstructure of the different formulations was characterized by investigating the interactions between earth and stabilizers through mercury intrusion porosimetry (MIP), nitrogen soprtion isotherm, powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The unconfined compressive strength (UCS) was also evaluated for all stabilized specimens. Three out of five biopolymers were considered suitable as rammed earth stabilizers. The use of wool increased the UCS by 6%, probably thanks to the combined effect of the length of the fibers and the roughness of their surfaces, which gives a contribution in binding clay particles higher than citrus and grape-seed flour. Lignin sulfonate and tannin increased the UCS by 38% and 13%, respectively, suggesting the additives’ ability to fill pores, coat soil grains and form aggregates; this capability is confirmed by the reduction in the specific surface area and the pore volume in the nano- and micropore zones. Full article

The development and implementation of “green” technologies in the construction sector, which ensure natural resource conservation, reduce harmful emissions and provide utilization of industrial waste, are key issues in material engineering of the XXI century. Extensive research has been devoted to solving these issues, including research in the field of concrete science. Still, the issue of developing concrete compositions with increased corrosion resistance remains much less studied. At the same time, reactive aggregates from industrial waste can have positive effect on durability of concrete, and the best result can be achieved by means of modification of a concrete mixture with highly effective additives. The article presents the research data in two lines—the study of applicability of reactive aggregates from waste products of nonmetallic and ceramic industries, mineral wool production and concrete scrap for production of corrosion-resistant concretes, as well as the assessment of possibility of Portland cement quantity reduction in a concrete mixture on local raw materials due to the introduction of additives based on polycarboxylates. The article presents the research evidence of the effect of dust and clay particles content on the quality of concrete with a polycarboxylate additive. The article describes the studies of corrosion resistance of concrete samples based on production wastes in sulfate environments and under the influence of carbon dioxide. The developed concrete compositions with waste use can be recommended for widespread application, rational use of resources, and production of durable high-quality concretes. The application of additives based on polycarboxylates makes it possible to produce concretes with the reduction of cement consumption in the mixture by 10–20% and decrease in the mode of thermo-wet treatment by two times. Full article

The aim of this study was to investigate the flammability of ecologically friendly, 100% natural larch and poplar bark-based panels bonded with clay. The clay acted as a fire retardant, and it improved the fire resistance of the boards by 12–15% for the surface and 27–39% for the edge of the testing specimens. The thermal conductivity was also analyzed. Although the panels had a density ranging from 600 to 900 kg/m³, thermal conductivity for the panel with a density of 600 kg/m³ was excellent, and it was comparable to lightweight insulation panels with much lower densities. Besides that, the advantage of the bark clay boards, as an insulation material, is mostly in an accumulative capacity similar to wood cement boards, and it can significantly improve the climatic stability of indoor spaces that have low ventilation rates. Bark boards with clay, similar to wood cement composites (wood wool cement composites and wood particle cement composites), have low mechanical properties and elasticity. Therefore, there their use is limited to non-structural paneling applications. These ecologically friendly, 100% natural and recyclable composites can be mostly used with respect to their thermal insulation, acoustics and fire resistance properties. Full article

Animal health measures mainly rely on vaccination or chemical control for major pests and pathogens, causing issues of residue, toxicity and development of resistance. For example, control of Sheep flystrike and lice-infestation affecting the Australia’s sheep/wool industry (>3.5 B) have developed resistance to nearly all control chemicals used in the past. Topicals RNAi provides an innovative clean-green, non-toxic, environmentally sustainable biological control solution. Biodegradable clay particles as carriers can be used to deliver double stranded RNA (dsRNA), the key trigger molecule of RNA interference pathway. As an early proof of concept, we investigated the stability dsRNA loaded on two types of Clay particles: Clay 1 (releases dsRNA under acidic conditions) and Clay 2 (releases dsRNA under alkaline conditions) on cattle hide. Cattle skin was treated with Cy3 labelled dsRNA alone and Cy3 labelled dsRNA loaded on Clay1 or Clay2. The skin samples treated with the Cy3 formulations were imaged using confocal microscopy. Once imaged, the skin samples were washed and stored at room temperature for 5 days, later the samples were re-imaged to detect the fluorescent signal (Figure 1). The dsRNA loaded on clay particles was stable unlike naked Cy3-dsRNA which degraded and was not visible after washing. This increased inherent stability of the dsRNA molecules, combined with the environmental stability afforded by the Clay particles, offers promise to provide a sustainable solution for animal health. Topical RNAi can reduce reliance on trade withholding periods of meat/wool without chemical residues, enhance animal welfare and increase production of premium quality meat/wool, improve export potential, competitiveness and long-term profitability of livestock industry. Full article