Buffer Value Research Articles

Novel Approach to Making Environmentally Friendly Plaster: A Moisture Buffer Value of Plaster Made of Wastepaper and Different Glues

Novel Approach to Making Environmentally Friendly Plaster: A Moisture Buffer Value of Plaster Made of Wastepaper and Different Glues

Recycling waste tiles and waste catalysts for high-strength eco-porous ceramics in building applications

This study explores an innovative approach to recycling waste tiles and spent catalytic materials from the petrochemical industry, aiming to create ecological porous ceramics (eco-PC) as sustainable building materials. The production process involved high-pressure sintering at 5 MPa and temperatures of 900–1050 °C. Extensive testing revealed that eco-PC meets CNS 9737 standards for flexural strength, with heavy metal concentrations (measured using microwave-assisted acid digestion) within regulatory limits, confirming the materials’ recyclability. The eco-PC samples exhibited water absorption between 7.90% and 35.33%, with higher sintering temperatures reducing absorption due to vitrification, while increased waste catalyst content raised absorption due to retained porosity. Porosity ranged from 16.35% to 47.42%, influenced by sintering temperature and waste catalyst content. Loss on ignition (0.14–1.63%) was affected by the decomposition of waste catalyst and sintering temperature. Flexural strength varied from 3.36 to 179.09 N/mm2, and modulus of rupture from 458 to 16,718 N, all exceeding CNS 9737 requirements. Conversely, higher catalyst content decreased strength due to limited densification of aluminum oxide. X-ray diffraction identified quartz as the primary phase, FTIR analysis showed surface functional groups (Si–O–Si and Si–O–Al), and SEM revealed a dense structure at 1050 °C due to liquid-phase sintering. Optimal eco-PC samples with 30–40% catalyst substitution and sintering temperatures of 900–1000 °C achieved a moisture buffering value (MBV) of 3.69 g/m2·%RH@8h, ideal for humidity regulation due to high surface area and pore volume. This research demonstrates the potential to transform waste into green building resources through an efficient, cost-effective, and eco-friendly process.

Influence of bio-aggregates on the physical and hygrothermal properties of bio-concretes

The escalating demand for sustainable and energy-efficient buildings has driven research into innovative construction materials such as bio-concrete. This study assesses the influence of bio-aggregates such as bamboo particles, wood shavings, and rice husk in volume ranging from 40 % to 50 % on bio-concrete's physical and hygrothermal properties. Three bio-concrete types were fabricated: Bamboo Bio-Concrete (BBC), Wood Bio-Concrete (WBC) and Rice Husk Bio-Concrete (RHBC), while maintaining a constant cementitious matrix and varying the bio-aggregate volume. In order to characterize the bio-concretes various analyses and tests were carried out such as scanning electron microscopic (SEM) analyses and Moisture Buffer Value (MBV) tests for bio-aggregates in addition to tests for apparent density, thermal conductivity, capillary water absorption, drying index test, MBV and water vapor permeability (WVP) for the studied bio-concretes. Results reveal that despite diverse microstructural characteristics, all bio-aggregates exhibited MBV values above 3.0 [g/ (m2% RH)], highlighting their role in determining hygrothermal properties. An increase in bio-aggregate volume led to improved hygrothermal properties for bio-concretes (thermal conductivity between 0.19 and 0.25 W/m.K and MBV and WVP in the range of 2.31–3.79 [g/ (m2.% RH)] and 1.11–1.97 × 10−11 [kg/(m.s. Pa)] respectively). Bamboo bio-concrete consistently exhibited higher density values, while rice husk bio-concrete demonstrated superior moisture dynamics and water vapor permeability. Wood bio-concretes exhibit intermediate behavior between bamboo and rice husk bio-concrete. A statistical analysis confirmed these trends. The study underscores bio-concrete's potential for passive hygrothermal regulation in internal building applications, contributing to enhanced energy efficiency and sustainable construction practices.

Application and environmental sustainability assessment of microbial induced calcite precipitation in asphalt concrete crack repair

ABSTRACT Cracks are a major factor affecting the durability of asphalt concrete. Microbial-induced calcite precipitation (MICP) represents an eco-friendly method for repairing these cracks compared to conventional methods. This study investigates the repair of artificial prefabricated asphalt concrete cracks using MICP, assessing uniaxial compressive strength, permanent deformation, moisture buffering, and water sensitivity for different crack depth conditions. Microscopic analysis using SEM/EDS and X-ray micro-computed tomography was conducted. The results show that MICP reduces void fraction by 75% and increases uniaxial compressive strength and ultrasonic velocity by approximately 20%, while improving creep stiffness modulus, moisture buffering value, and resilient modulus ratio by 5%-10%. The effectiveness decreases with increasing crack depth. Calcite particles cluster within 20 mm from the crack top, enhancing mechanical properties. MICP is feasible for repairing shallow cracks. An analysis of the energy consumption and carbon emissions of the MICP technology using a life cycle assessment demonstrates that the industrial preparation processes of calcium sources and urea produce substantial carbon emissions and energy consumption, accounting for 68.31% and 94.64% of the total process, respectively, revealing that it is crucial to explore alternative materials in the future to reduce the environmental impact.

Hygrothermal characterization of cement mortar composites incorporating micronized miscanthus fibers

This work investigates both the moisture dependence of thermal properties and the hygric behavior of cement mortars incorporating different proportions of micronized miscanthus fibers up to ∼7 wt%. The experimental program encompasses thermal characterization at dry (10 % RH), moderate (50 % RH), and saturated (100 % RH) states of samples, along with hygric characterization of the various mortar specimens through sorption-desorption tests, water vapor permeability assessment, Moisture Buffer value (MBV) determination, and capillary absorption tests. Thermal measurements showed a significant decrease in thermal conductivity with the addition of fibers. For a given biobased mortar composition, conductivity values were almost identical at dry/moderate RH level but exhibited an increase at saturation. This shift was attributed to the fibers' absorptive properties, which lead to a higher water content within the samples in saturated humidity environments. Collectively, the moisture sorption, moisture buffering capacities, water vapor permeability, and capillary absorption properties demonstrated consistent enhancement with rising fiber content, confirming the significant impact of plant fibers on the material's hygrothermal properties. In addition, the GAB model (Guggenheim- Anderson- de Boer) was used to fit the sorption and desorption isotherms, yielding a good correspondence with experimental data. Finally, mortars with the higher fiber contents (M7.5 F and M10F with 5.70 wt% and 6.94 wt% of fibers, respectively) combined high hygroscopicity and low thermal conductivity values (even under moisture-saturated conditions), making them promising candidates for applications requiring both good hygric performance and effective insulation properties.

Seasonal stability of the rumen microbiome contributes to the adaptation patterns to extreme environmental conditions in grazing yak and cattle

BackgroundThe rumen microbiome plays an essential role in maintaining ruminants’ growth and performance even under extreme environmental conditions, however, which factors influence rumen microbiome stability when ruminants are reared in such habitats throughout the year is unclear. Hence, the rumen microbiome of yak (less domesticated) and cattle (domesticated) reared on the Qinghai-Tibetan Plateau through the year were assessed to evaluate temporal changes in their composition, function, and stability.ResultsRumen fermentation characteristics and pH significantly shifted across seasons in both cattle and yak, but the patterns differed between the two ruminant species. Ruminal enzyme activity varied with season, and production of xylanase and cellulase was greater in yak compared to cattle in both fall and winter. The rumen bacterial community varied with season in both yak and cattle, with higher alpha diversity and similarity (beta diversity) in yak than cattle. The diversity indices of eukaryotic community did not change with season in both ruminant species, but higher similarity was observed in yak. In addition, the similarity of rumen microbiome functional community was higher in yak than cattle across seasons. Moreover, yak rumen microbiome encoded more genes (GH2 and GH3) related to cellulose and hemicellulose degradation compared to cattle, and a new enzyme family (GH160) gene involved in oligosaccharides was uniquely detected in yak rumen. The season affected microbiome attenuation and buffering values (stability), with higher buffering value in yak rumen microbiome than cattle. Positive correlations between antimicrobial resistance gene (dfrF) and CAZyme family (GH113) and microbiome stability were identified in yak, but such relationship was negatively correlated in cattle.ConclusionsThe findings of the potential of cellulose degradation, the relationship between rumen microbial stability and the abundance of functional genes varied differently across seasons and between yak and cattle provide insight into the mechanisms that may underpin their divergent adaptation patterns to the harsh climate of the Qinghai-Tibetan Plateau. These results lay a solid foundation for developing strategies to maintain and improve rumen microbiome stability and dig out the potential candidates for manufacturing lignocellulolytic enzymes in the yak rumen to enhance ruminants’ performance under extreme environmental conditions.

Hygrothermal and mechanical characterization of novel hemp-lime composites with enhanced consistency

Hemp-lime composites have captured attention in the construction industry due to their sustainability and excellent hygrothermal performance. However, variability and inconsistent performance have hindered their widespread adoption. This research introduces a novel approach to improve the uniformity and hygrothermal characteristics, aiming for reproducibility and consistency comparable to traditional insulation materials. This method included (1) reducing hemp particle size to coarse (1.33 mm), medium (0.92 mm), and fine (0.72 mm) particles; (2) maximizing the hemp proportion to 70 % by weight; and (3) standardizing dry density using vibration techniques. The findings indicate dry density variability reduction in all samples, with a coefficient of variation ranging from 0.16 % to 2.36 %. The hygrothermal analysis demonstrates enhanced insulation and moisture-buffering properties, along with reduced directional disparity in thermal conductivity (1.2–6.8 %) compared to the control sample, particularly in samples with fine particle sizes. Thermal conductivity was within the range of 0.0535–0.0667 W/m K, considerably lower than previously reported values. Also, a positive correlation is observed between moisture-buffering and hemp ratio, indicating that higher hemp ratios in the composite lead to increased moisture capacity, with moisture buffer values of 2.47, 2.28, and 2.12 g/m² RH corresponding to the binder-to-hemp ratio of 30:70, 40:60, and 50:50 by weight, respectively.

Assessing the impact of moisture buffering properties of materials on indoor environmental quality: A study on a recycled material plaster

This study examines Moisture Buffer Value (MBV) of interior finishing layers, which impacts buildings internal relative humidity, thus indoor environmental quality. The MBV depends on material's moisture capacity and vapour diffusion resistance factor, both of which depends on relative humidity. The paper aims to (i) characterize a new recycled material plaster that includes construction and food industry waste through laboratory measurements, (ii) use dynamical building simulations to quantify the impact of the MBV of existing and the new interior plaster on relative humidity in real design scenarios, and (iii) evaluate how changing the definition of the MBV to consider its dependence on indoor air relative humidity can improve its accuracy. Results show that the plaster's moisture buffering properties significantly reduce the variations of the relative humidity of interior climates compared to a vapour-tight finishing layer. The performances of the new plaster made with recycled materials are comparable to those of the other plasters. The new MBV definitions (“Dynamical MBV″ and “Summer/Winter MBV”) show a significantly improved correlation with the relative humidity variations of indoor climates of buildings, observed in dynamic simulations, with respect to the typically used practical MBV. The new definitions are therefore promising for practical applications.

Characterization and optimization of desulfurized construction gypsum modified with functionalized nanocellulose

This study focuses on the development and characterization of a novel composite material based on flue gas desulfurization (FGD) gypsum modified with functionalized nanocellulose. The incorporation of 0.1 wt% nanocellulose into the FGD gypsum matrix resulted in significant improvements in mechanical strength, water resistance, and thermal insulation properties. The flexural and compressive strength of the optimized composite increased by 32 % and 27 %, respectively, compared to the control sample. The water absorption decreased by 22 %, and the softening coefficient increased from 0.72 to 0.85, indicating enhanced water resistance. The thermal conductivity of the composite was reduced by 31 %, showcasing its potential as an energy-efficient building material. SEM analysis revealed a refined microstructure with improved interfacial bonding between the nanocellulose and gypsum matrix, while FTIR spectroscopy confirmed the presence of chemical interactions between the components. The moisture buffering capacity of the composite was also superior, with a 38 % higher moisture buffering value than the control sample. These findings highlight the potential of functionalized nanocellulose as a reinforcing agent in FGD gypsum-based composites, offering a promising solution for the development of high-performance, eco-friendly building materials.

Эколого-агрохимическая оценка устойчивости серой лесной почвы к воздействию загрязнения и урожайность картофеля при применении удобрений

The article presents studies in potato agrocenoses and an assessment of the gray forest soil of the Ryazan region using various levels of mineral and organomineral nutrition. It was found that to achieve an average level of stability, the buffering value of agro-gray soil should not be lower, according to the adsorption isotherm at a concentration point of 10 mM/l, 2 l/kg for zinc, copper, cadmium and lead. Exceeding the PBSgm value of 2-4 l/kg means a transition to a high level of stability. In the experiment on potato yield, the maximum yield was obtained on the variant with the action of an organomineral fertilizer system – 283.7 c/ha, which is 114.5 c/ha more than on the control variant (without fertilizers). We note the high yield obtained according to the variant with the action of the organomineral fertilizer system (248.2 c/ha, + 79.0 c/ha), which indicates the high efficiency of nutrition in the potato agrocenosis. Keywords: SOIL, POTATOES, NON-CHERNOZEM ZONE, POTATOES, YIELD, FERTILIZER

Moisture buffer value for hygroscopic materials with different thicknesses

Moisture buffer value (MBV) is a critical parameter for assessing hygroscopic material's ability to moderate indoor humidity variation. The original MBV theory is strictly valid only for a semi-infinite (or “very thick”) material. When the material is thinner than semi-infinite, the material's thickness will affect its moisture buffering ability. The existing MBV theory is inapplicable. This study proposed a new numerical method to calculate a material's MBV at different thicknesses. The proposed model is simple and efficient. The relation between a material's MBV and thickness and the optimal thickness can be obtained without extensive experimental measurement. What's more, the material's adsorption and desorption isotherms, as well as the material's hysteresis loop and scanning isotherms, are incorporated in the proposed model, making it applicable to advanced desiccant materials like Metal-Organic Frameworks (MOFs). MIL-100(Fe), one of the most promising MOF candidates for indoor humidity control, was used to validate the newly developed model. MBVs of MIL-100(Fe) samples with different thicknesses were measured, and the experimental data closely matched the simulated results. Finally, a building energy consumption simulation model was developed based on the proposed numerical model. A MOF panel with its optimal thickness was placed in the BESTEST typical office room located in Copenhagen. The results show that MOF can reduce about 30 % of the energy consumption of air conditioning in a purely passive way.

Mechanical and hygrothermal properties of hemp-silica bio-composites

This research investigated the development of a fast-drying silica-based binder for hemp concrete products with enhanced mechanical and thermal properties. Hemp-silica bio-composites were prepared by mixing hemp shivs with a two-component binder system composed of liquid sodium silicate and tributyl citrate (TBC). Compressive strength, thermal conductivity, moisture buffering value, cyclic moisture resistance and microstructure of hemp-silica composites were analysed, and the results were compared with those of hemp-lime concrete. Hemp-silica blocks with shiv-liquid sodium silicate mass ratio of 1:3.75 and TBC content of 37.5 wt% of sodium silicate dry matter produced a compressive strength of 0.56 MPa only after 3 days of drying and 1.92 MPa after 28 days. These were higher than hemp-lime blocks at the same density range. Hemp-silica panels showed a thermal conductivity of 0.101 W/mK and an excellent moisture buffering value of 3.49. Hemp silica formed an open porosity with large air gaps between the particles and a water-resistance silica-based layer on the shiv surface producing a higher moisture resistance compared to hemp-lime systems. This paper focuses on the development of a novel fast-drying binder system with a potential for use in conjunction with other lingnocellular plant aggregates to form low-carbon and efficient multifunctional building materials.

Super-stable modified wood for enhanced autonomous indoor humidity regulation

The crucial development of materials that automatically adjust indoor humidity, a significant factor in human health and daily life, has gained importance due to the emphasis on energy conservation. Wood, with its natural hygroscopic properties, is effective in this regard but faces challenges of deformation and cracking due to moisture content changes. Herein, we introduced an innovative in-situ wood modification strategy, which integrated deep eutectic solvent (DES) impregnation with heat treatment, producing dimensionally super-stable modified wood for enhanced autonomous indoor humidity regulation. This modification process focused on creating more robust cross-linking structures within the amorphous regions of the wood cell wall. As a result, water-induced deformation of natural wood was significantly reduced, as evidenced by an anti-swelling efficiency exceeding 80%, ensuring the long-term reliability of DES-modified wood in varying humidity environments. Additionally, the introduction of additional pores and hygroscopic sites in the cell wall enhanced the natural wood’s moisture buffering value by 2.5 times, showcasing the superior ability of DES-modified wood to control indoor humidity effectively. Moreover, the DES-modified wood also exhibited commendable flame retardancy and antibacterial properties. Consequently, this novel modified wood emerges as a reliable material for indoor humidity regulation, promoting healthier indoor conditions and offering a sustainable alternative for energy-efficient construction practices.

Hygroscopicity and Morphology of Bio-Based Boards—The Influence of the Formulation

The internal structures and the hygroscopicity of bio-based boards consisting of giant reed (Arundo donax L.) and hazelnut shells as bio-aggregates, and a sodium silicate solution as the adhesive, were investigated. The aim was to evaluate the influence of each material (the bio-aggregates and adhesive) and their distributions in the boards on the final performance. By carrying out X-ray computed tomography, the internal structures and the porosities of the boards were determined, allowing important considerations of their hygroscopicity. The voids’ percentages were between 26% and 36% of the total volume of the composites. Both the materials and the composites demonstrated high hygroscopicity. In particular, the mixtures of the bio-aggregates and the sodium silicate allowed reaching a moisture buffering value of 7.44 g/(m2%RH) for the A. donax-based composite, 3.86 g/(m2%RH) for the hazelnut-shell-based composite, and 4.65 g/(m2%RH) for the mixture-based composite. Besides the identification of the contributions of the materials, a detailed discussion of the assessed properties was carried out to use these bio-based boards in vernacular historic construction. The results show how the aggregate type and the adhesive content affected the final behavior, demonstrating the importance of a conscious material choice. Furthermore, helpful information for the future development of these types of bio-based boards and their possible optimization was provided.

Effect of Posidonia oceanica on the hygrothermal characterization of compacted earth blocks

A hygrothermal characterization of new construction materials, namely unstabilized and Posidonia oceanica fiber stabilized compressed earth blocks, were studied in this work. In the first part, the sorption-desorption isotherms of unstabilized blocks were compared with others stabilized with raw and treated fibers to detect the effect of adding fibers. The results revealed an improvement in hygric properties after the addition of raw fibers. Moreover, the Guggenheim-Anderson-de Boer (GAB), the Oswin, and Brunauer, Emmet, and Teller (BET) models successfully fitted experimental sorption-desorption isotherms curves. In the second step, the moisture buffer value and water vapor permeability were evaluated under dynamic conditions. According to the classification of the NORDTEST project, the innovative and new compacted earth blocks studied in this paper seem to be excellent moisture regulators because they have an MBV greater than 2 g/ (m2. %RH). In fact, BAFBB samples (block with crushed Posidonia oceanica) achieved the best results. These formulations recorded an ideal water buffer coefficient equal to 2.66 g/ (m2.%RH)

A feasible re-use of an agro-industrial by-product: Hazelnut shells as high-mass bio-aggregate in boards for indoor applications

The present work investigates the feasibility of producing boards, with unconventional materials, namely hazelnut shells as a high-mass bio-aggregate and a sodium silicate solution as a no-toxic adhesive, and discusses possible applications based on an extensive characterization. The aim is to define a feasible reuse of a largely produced agro-industrial by-product to reduce the high environmental impact caused by both the construction and the agriculture sectors, by proposing a building composite that improves indoor comfort. The presented combination of aggregate-adhesive generated a product with characteristics interesting to explore. The thermal conductivity is moderated, and the composite achieved values of σmax = 0.39 N/mm² for flexural strength and σmax = 2.1 N/mm² for compressive strength, but it showed high sorption capacity with a moisture buffering value of about 3.45 g/(m² %RH), and a peak of sound absorption between 700 and 900 Hz. Therefore, the boards' most promising performance parameters seem to be their high hygroscopicity and acoustic absorption behaviour, namely in the frequency range of the human voice. Hence, the proposed composite could improve indoor comfort if applied as an internal coating board.

Development of a fast moisture prediction model based on the moisture buffer value theory

Moisture transfer in buildings significantly affects indoor thermal comfort, energy consumption, and durability of construction materials. It is crucial to predict the moisture storage and transfer in building simulations accurately. However, moisture transfer was neglected in many simulation tools for building performance analysis. In those calculation tools, including a moisture model, moisture transfer has been either estimated by simple approximations or calculated by complex combined heat, air, and moisture transfer (HAMT) models that require orders of magnitude more computing time than simple calculations. In this study, a new moisture prediction model with fast solution time and reasonable accuracy was developed based on the moisture buffer value (MBV) theory. The moisture buffer value was initially designed to quantify the moisture buffering ability of porous building materials. Very little research has been conducted to use MBV for calculating building energy performance directly. This paper first studied the MBVs under different boundary conditions (i.e., square wave and harmonic wave variation of vapour content), and then a time-average MBV was proposed. Experiments were carried out to get the parameters for the new FMBM model. Finally, simulation tests were conducted to compare the FMBM model with other moisture prediction models (e.g. EC, EMPD and HAMT models). The results indicate that the FMBM can provide a fast and reasonably accurate solution for indoor moisture prediction.

Super adsorbent bio-polymer additive to improve hygroscopic and acoustic properties of a conventional lime plaster

The paper introduces a new lime plaster composition, with a Super Bio-Polymeric Adsorbent (SABP), for interior applications to improve hygrothermal and acoustic comfort. Alginate SABP is added to a conventional lime plaster to improve hygroscopic and acoustic performance. The hygrothermal and acoustic properties of the modified plaster are compared with the ones of the original plaster with a preliminary moisture uptake test, the evaluation of the sorption isotherm, the moisture buffering value (MBV), and the acoustic absorption. The results show a significant increase in the equilibrium moisture contents and the MBV (from 0.7 to 6.2 g/(m2⋅%RH)). At the same time, the sound absorption coefficient is slightly improved, increasing 0.1-0.2 at frequencies higher than 500 Hz compared to the reference conventional lime plaster. The paper describes the material characterization: the sorption isotherm and the MBV are obtained using a dynamic vapor sorption (DVS) analyzer. The acoustic absorption is measured using the impedance tube method.

Moisture buffer value for hygroscopic materials with different thickness

Moisture buffering is the capacity of hygroscopic building materials or adsorbents to mitigate the humidity fluctuations in the indoor environment through the adsorption/desorption phenomenon. NORDTEST proposed the moisture buffer value to quantitively characterize the moisture buffering capacity of porous materials. Materials with high moisture buffer values have a higher ability to passively control indoor humidity conditions and thus reduce building energy consumption and improve indoor thermal comfort. However, the ideal moisture buffer value theory is based on the assumption that the thickness of the studied materials should exceed the penetration depth of that material. This assumption significantly limits the application of moisture buffer value theory to thin-layer materials, such as textiles, desiccant coating, wallpaper, wood wall panels, etc, which represent a large proportion of moisture buffering in the built environment. In this study, we developed a new numerical model to calculate moisture buffer values for hygroscopic materials with different thicknesses. Experimental measurements were also carried out to validate the solutions. The moisture buffer value of a new kind of desiccant (metal-organic frameworks) under different thicknesses were measured by climatic chamber tests. Simulated results showed agreement with both the measurements and theory. The results indicate that the new moisture buffer value model can be used to find the optimal thickness of desiccant coating or hygroscopic materials for autonomous indoor humidity control.

Characterization of an Arundo donax-based composite: A solution to improve indoor comfort

Arundo donax (giant reed or giant cane) is a widely available, perennial, invasive, non-food crop, present worldwide and employed for several uses, including building practices. Considering the increasing demand for sustainable building materials, A. donax can be an efficient solution. This study investigated its properties as a bio-aggregate mixed with a sodium silicate solution as an adhesive. A horizontal analysis that provided a general characterization of the composite was carried out. The results showed that the A. donax-based composite had an apparent density of 517 kg/m³, thermal conductivity of 0.128 W/(m.K), and high hygroscopicity, with a moisture buffering value of 4.33 g/(m² %RH), property that could be both an advantage for indoor comfort and a drawback. The uncommon sound absorption behaviour can be comparable to granular materials, with the highest sound absorption coefficient values, α, between 600 Hz and 700 Hz. Due to the range and the shape of the acoustic absorption property, this material may be helpful in acoustic treatments for speech noise. The mechanical tests defined flexural and compressive strength, respectively, 0.35 N/mm² and 0.9 N/mm², ensuring applicability. Above all, these tests opened new possible solutions for A. donax-based composite production either alone or in combination with other agro-industrial wastes and justified further tests, such as fire resistance and bio-susceptibility.