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One of the ways to modify selected parameters of lime mortars is the use of biopolymers of animal origin, such as bone glue, skin glue, bovine blood, eggs, and casein. These are protein-based biopolymers. Casein is an example of an organic polymer produced from cow's milk. The aim of the work was to investigate the possibilities of improving selected properties of mortars based on hydrated lime and metakaolin. The mixture was modified with powdered technical casein in amounts of 0.5%, 1.5%, 1%, 1.5%, and 2% as a partial mass replacement for the binding mixture. Additionally, the influence of increasing the amount of water on the properties of the mortar with a casein admixture of 2% was checked. This study examined consistency, shrinkage, water absorption, capillary action, porosity, flexural, compressive strength, and Young's modulus. The admixture of casein influenced the properties of the mortar, but not in all cases, and it was possible to determine a clear trend related to the variable amount of casein. Strength properties deteriorated as the amount of casein increased. When air bubbles were introduced into the mortar after the casein was dissolved, the porosity increased as the amount of admixture increased. The moisture properties improved; namely, casein led to a reduction in water absorption and water absorption caused by capillary action. No relationship was observed between the amount of casein and the drying shrinkage. Increasing the amount of water in the mixture led to the expected effects, i.e., an increase in porosity, shrinkage, and water absorption, and a decrease in mechanical strength.

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The article concerns the issue of non-invasive moisture sensing in building materials. Two techniques that enable evaluating the value of the relative permittivity of the material, being the measure of porous material moisture, have been utilized for the research. The first is the microwave technique that utilizes the non-contact measurement of velocity of microwave radiation across the tested material and the second is the time domain reflectometry (TDR) technique based on the measurement of electromagnetic pulse propagation time along the waveguides, being the elements of sensor design. The tested building material involved samples of red ceramic brick that differed in moisture, ranging between 0% and 14% moisture by weight. The main goal of the research was to present the measuring potential of both techniques for moisture evaluation as well as emphasize the advantages and disadvantages of each method. Within the research, it was stated that both methods provide similar measuring potential, with a slight advantage in favor of a microwave non-contact sensor over surface TDR sensor designs.

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The article concerns the electric techniques of moisture detection that are based on the evaluation of the apparent permittivity of the tested medium. The main goal of the research was to evaluate the non-invasive Time Domain Reflectometry (TDR) sensors' sensitivity by measuring the span of elements and material moisture. To that aim, two non-invasive sensor designs were investigated for their sensitivity in the evaluation of the apparent permittivity value of aerated concrete. Sensors A and B were characterized by the spacing between the measuring elements equal to 30 mm and 70 mm, respectively. The tested samples differed in moisture, ranging between 0 and 0.3 cm3/cm3 volumetric water content. Within the research, it was stated that in the case of the narrower sensor (A), the range of the sensor equals about 30 mm, and in the case of the wider design (B), it equals about 50 mm. Additionally, it was stated that material moisture influences the range of sensor influence. In the case of the dry and low-saturated material, it was not possible to evaluate the range of sensor sensitivity using the adopted method, whereas the range of sensor signal influence was visible for the moist material.

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Organic admixtures based on polysaccharides are used in construction for modifying the properties of mortars and concretes. Gum arabic is an example of a polysaccharide-based biopolymer. The aim of the article was to investigate the possibilities of improving the strength parameters of a binder paste based on hydrated lime and metakaolin. The paste was modified with powdered gum arabic at 1%, 3% and 5% (by mass) as a partial replacement for the binder mix. The influence of the admixture on the pore size distribution as well as flexural and compressive strength was investigated. The admixture enhanced the total porosity of the paste, increasing the pore diameter compared with the reference formulation. The increase in porosity, in turn, did not reduce the mechanical strength. Conversely, the admixture in the amount of 3% and 5% caused a significant increase in the flexural (by about 300% in relation to reference paste) and compressive strengths (by 25% and 60%, respectively). The tested pastes were used as a binder in a composite based on hemp shives. The influence of binder modification on the water absorption and compressive strength of hemp concrete was tested. The strength of the composite soaked in water was also tested. The modification of the binder with gum arabic in the amount of 3% and 5% increased the compressive strength of hemp concrete (not soaked in water) by 53% and 92%, respectively and reduced the mass absorptivity by 6.6% and 10.4%, respectively.

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The aim of the research presented in the article was to check the differences in the hygro-thermal and mechanical properties of hemp-lime composites with different shives fractions, depending on the direction of mixture compaction. The research part of the paper presents the preparation method and investigation on the composites. Thermal conductivity, capillary uptake, as well as flexural and compressive strengths were examined. Additionally, an analysis of the temperature distribution in the external wall insulated with the tested composites was performed. The results confirm that the direction of compaction influences the individual properties of the composites in a similar way, depending on the size of the shives. The differences are more pronounced in the case of the composite containing longer fractions of shives. Both thermal conductivity of the material and the capillary uptake ability are lower in the parallel direction of the compaction process. Composites exhibit greater stiffness, but they fail faster with increasing loads when loaded in the direction perpendicular to compaction.

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Raw clay is used nowadays in construction as a component of mortars and plasters and as a binder in composites based on straw or shives. It is a material with good sorption properties and vapor permeability, but it is susceptible to shrinkage, is not resistant to water, and also is characterized by low mechanical strength, which makes it impossible to be used, for example, in external plasters. Various additives and admixtures are used to improve selected properties of clay mortars. The article presents the research results and assessment of the effect of glauconite clay mortar modification with an admixture of linseed oil varnish on selected properties. Admixtures in the amounts of 1%, 2%, and 3% in relation to clay weight were used. Flexural and compressive strength, water resistance, shrinkage, drying capacity, density, and porosity of mortar, were tested. The admixture of linseed oil varnish in the amounts used in the investigation had a positive effect on some of the tested properties; regardless of the quantity of the admixture, the modified mortars had better parameters concerning flexural strength, shrinkage reduction, and water resistance than the reference mortar, without admixture.

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Different fractions of hemp shives are used in the mixtures of the hemp-lime composite. The market offers shives of different granulation. It depends on the type of industrial hemp and on the capabilities of decortication machines. The aim of the research presented in the article is to check differences in the mechanical and hygro-thermal properties of composites with different shives fractions. The research part of the paper presents the preparation method and investigation on hemp-lime composites. Apparent density, total porosity, thermal conductivity, capillary uptake, vapor permeability, specific heat, mass absorptivity, flexural and compressive strength were examined. The results confirm that the shives fraction influences the individual properties of the composites. Hemp-lime composites with fine shives are characterized by higher water absorption, thermal conductivity, mechanical strength, vapor permeability as well as lower capillary-lifting capacity and specific heat than composites with thick shives.

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The paper presents the results of research concerning three fiber materials-mineral wool, hemp fiber and wood wool-as loose-fill thermal insulation materials. The analysis used the material parameters determined in previous works conducted by the authors, such as thermal conductivity and air permeability in relation to bulk density. These materials exhibit open porosity; thus, convection is an essential phenomenon in the heat transfer process. The paper aimed at conducting thermal simulations of various frame wall variants which were filled with the above-mentioned insulation materials. The simulations were performed with the Control Volume Method using the Delphin 5.8 software. The studies accounted for the effect of wind pressure and the time of its influence on a wall insulated by means of fiber material with a thickness of 150 as well as 250 mm. The simulation enabled us to obtain such data as maximal R-value reduction and time to return to equilibrium after filtration for the analyzed materials. The study proved that heat transfer in these insulations strongly depends on the bulk density, thickness of the insulation and wind pressure. The decrease in R is reduced as the density increases. This results from the decreased air permeability characterizing the material. Wind washing causes lower R reduction than air filtration in all models. The greater the thickness, the longer it takes for the models to return to the equilibrium state following air filtration (and wind washing). This period is comparable for air filtration and wind washing. Hemp fibers were characterized with the strongest susceptibility to air filtration; in the case of wood wool, it was also high, but lower than for hemp fibers, while mineral wool was characterized with the lowest.

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The use of waste plants in the production of building materials is consistent with the principles of sustainable development. One of the ideas involves using hemp shives as an aggregate for the production of a composite used as a filling of the timber frame construction of the walls. The most important disadvantage of using the building materials based on organic components is their susceptibility to the water influence. The wall material is exposed to rising groundwater. The research part of the paper presented the preparation method and the investigation of the hemp-perlite-lime composites. Flexural and compressive strength, apparent density, total porosity, thermal conductivity, and mass absorptivity were examined. The main research part pertained to the analysis of capillary uptake occurrence in the composites, being the important phenomenon present in the external walls. The study on this phenomenon was carried out using the technique of indirect moisture evaluation-Time Domain Reflectometry (TDR). The indirect readouts were additionally verified with the traditional evaluation using the gravimetric method based on the PN-EN 1925 standard. The study proved that the tested composites were characterized by low apparent density, thermal conductivity, strength parameters, high total porosity, and mass absorptivity. The partial replacement of hemp shives by expanded perlite had a beneficial effect on the tested properties of composites.

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This article analyses the connection of the two types of floors on the ground (floors on joists and self-supporting floors), with the external wall made of a hemp-lime composite for the occurrence of thermal bridges. Several factors that may affect the heat transfer in the junction were taken into account: the level of the floor on the ground, the wall thickness, the thermal conductivity of the composite, and the location of the timber frame construction. The technology of using hemp and lime is relatively new, and there is a lack of such analyses in the literature. The two-dimensional (2D) heat-transfer in the described construction joints was analyzed based on the finite-element method with the use of the THERM 7.4 software. The results were presented as averaged and linear thermal transmittance coefficients dependent on the above mentioned factors. The possibility of surface condensation was also checked. The differences in the values of the thermal transmittance of the junction between the two variants of ground floors reached around 0.13%-1.67% and the values of linear thermal transmittance factor reached approximately 2.43%-10.13%. The junctions with the highest floor level showed a decrease in the thermal transmittance value by about 3.00%-5.77% and in the linear thermal transmittance, by about 21.98%-53.83%, compared to the junctions with the lowest floor level. Calculations showed that almost all analyzed junctions are free from surface condensation causing mould growth, because the minimum temperature factors f0.25 were higher than 0.78 (except for junctions with the lowered floor levels). The junction with a floor on the timber joists showed better thermal parameters than the junction with a self-supporting floor in each of the analyzed variants. By increasing the level of floor insulation, it is possible to limit the thermal bridges and improve the thermal properties of the junction.

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This paper presents the results of research aimed at finding the possible ways of disposing of ceramic waste material, focusing mainly on the possibility of using it as aggregates in concretes exposed to an aggressive chemical environment (municipal sewage). The research part presents the preparation method and investigation of waste ceramic aggregates (red, glazed and sanitary ceramic aggregates). A suitable ratio of coarse to fine aggregates was selected, and their density, absorptivity and crushing strength were examined. All examined aggregates were also subjected to SEM analysis. Red ceramic aggregate is characterized by a greater degree of crushing compared to glazed and sanitary ceramic aggregate, by 205.7% and 439.4%, respectively. Another part of the research was to compare the properties of concrete with traditional aggregate (gravel, basalt) and with ceramic waste aggregate. The tested parameters included consistency, apparent density, absorptivity, flexural and compressive strengths of concretes. The study proved that the absorptivity of recycled composites is higher than that of traditional composites by 20.8⁻24.7%. The concrete based on sanitary ceramic waste has the highest strength parameters. Its compressive strength is higher by 10.5% and flexural strength by 5.9% compared with the basalt aggregate concrete. The compressive strength of sanitary ceramics concrete is higher by 42% and by 59% compared with concrete based on glazed ceramic and red ceramic aggregate, respectively. The last part of the research was to examine the resistance of concrete to aggressive environment. The scope of the work included the preparation of the research environment in the form of solutions with an increased concentration of aggressive agents (hydronium, sulfate, magnesium, ammonium ions). Among the concretes with ceramic aggregate, the highest decrease in the compressive strength was demonstrated by the concrete based on red ceramics (128.2%), while the smallest was demonstrated by the concrete based on sanitary ceramics (aggregate from sanitary ceramics (15.4%). The mass loss at different time intervals and compressive strength loss of samples stored in solutions were tested. The smallest weight loss caused by aggressive environment attack was recorded in the concrete based on ceramic sanitary and glazed aggregate (20.2% and 34.5%, respectively, after 120 days of aggressive environment).

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The article presents the results obtained in the course of a study on prospective application of flax/hemp wastes as a filling material of lime-based composites in the construction of low-energy buildings. The utilized filler comprised the hydrated lime with clay and Portland cement used as additives. The analysis involved evaluation of such properties as porosity, density, thermal conductivity, absorptivity, permeability, as well as compressive and flexural strength. Depending on the quantity of the filler, the properties of the composite changed. This, in turn, enabled to evaluate whether the utilized composite met the thermal requirements established for low-energy buildings. Afterwards, the obtained data were cross-referenced with the results gathered in the case of a room built of autoclaved aerated concrete. In order to prevent reaching the critical surface humidity, the internal surface temperature had to be calculated. Moreover, the chances of interstitial condensation occurring in the wall made of the analyzed lime-flax-hemp composite were determined as well. The study showed that the composite exhibits low strength, low density, low thermal conductivity, and high absorptivity. The external walls made of the lime-flax-hemp composite receive a limited exposure to condensation, but not significant enough to constitute any threat. The requirements established for low-energy buildings can be met by using the analyzed composite.