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This study presents data on the use of shungite ore (the Bakyrchik deposit, Kazakhstan) and its concentrate as fillers in elastomer composites based on nitrile butadiene rubber. In addition to carbon, these shungite materials contain oxides of Si, Fe, K, Ca, Ti, Mn, and Al. The shungite concentrate was obtained through a flotation process involving five stages. The chemical composition analysis of these natural fillers revealed that during flotation, the carbon content increased 3.5 times (from 11.0 wt% to 39.0 wt%), while the silicon oxide content decreased threefold (from 49.4 wt% to 13.6 wt%). The contents of oxides of K, Ca, Ti, Mn, and Al decreased by less than 1%, and iron oxide content increased by 40% (from 6.7 wt% to 9.4 wt%). The study explored the impact of partial or full replacement of carbon black (CB) of P 324 grade with the shungite ore (ShO) and the shungite concentrate (ShC) on the vulcanization process and the physical–mechanical properties of the rubber. It was found that replacing CB with ShO and ShC reduces Mooney viscosity ML (1 + 4) 100 °C of the rubber compounds by up to 29% compared to the standard CB-filled sample. The use of the shungite fillers also increased scorch time (ts) by up to 36% and cure time (t90) by up to 35%. The carbon content in the shungite fillers had little influence on these parameters. Furthermore, it was demonstrated that replacing 5–10 wt% of CB with ShO or ShC improves the tensile strength of the rubber. The results of the flotation enrichment process enable the assessment of how these shungite fillers affect the properties of the composites for producing rubbers with specific characteristics. It was also found that substituting CB with ShO or ShC does not significantly affect the rubber's resistance to standard oil-based media. The findings indicate that Kazakhstan's shungite materials can be used as fillers in rubber to partially replace CB. [ABSTRACT FROM AUTHOR]

In recent years, construction has increased at previously uninhabited high altitudes with the development of winter tourism and population growth. Therefore, it is necessary to examine the soil behaviour at low temperatures and high altitudes. This study investigated the physical properties and mechanical behaviours of soil samples collected from four mountainous regions, including settlement areas. In addition, new frostheaving pressure and strength prediction charts have been developed. Based on sieve analysis, the soil samples from the Kaçkar, Palandöken, Erciyes, and Ilgaz Mountain areas were classified as silty gravel or sand. With increasing elevation, the percentage of coarse particles in soil samples increased, whereas the proportion of fine particles decreased. A new device was developed to investigate the mechanical behaviour of soil samples at low temperatures (0°C and below). The highest frost strength (7274.5 kPa) and heaving pressure (43.97 kPa) were measured in soils with high fine-grain content. A statistical evaluation of the test results was performed, and it was determined that the most influential variables for estimating frost heaving and strength were the fine-grain ratio, soil temperature, and water content. ANN analyses were performed using these variables, and ternary strength and frost-heaving pressure estimation diagrams were developed. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the mechanical and physical properties of wood-fibre insulation panels (WFIP) from fibres of various hardwood and softwood species, which were produced in a refiner by thermo-mechanical pulping. WFIP with a raw density of 100 kg m–3 for rigid panels and 50 kg m–3 for flexible mats were manufactured using a dry process with hot-steam (rigid panels) and hot-air (flexible mats). The rigid panels were bonded by polymeric diphenylmethane diisocyanate (pMDI, 5 wt% related to the weight of the dry fibre material), and the flexible mats were bonded with 7 wt% bi-component (Bico) fibres. The study showed that hardwood fibres can in principle be used to produce WFIP for both rigid panels and flexible mats. Investigation of the fibre structure and porosity of the WFIP by computed tomography (CT) on smaller samples revealed neither correlations between porosity and bulk density of the fibres, nor between porosity and thermal conductivity, nor between porosity and mechanical properties. The physical-mechanical properties, thermal conductivity and flammability were different for the various wood species studied. Overall, WFIP made from beech showed the best properties of the hardwoods and were comparable to those made of softwoods. [ABSTRACT FROM AUTHOR]

To investigate the possibility of fast-growing timber to manufacture structural LVL, in this paper, two commonly used flame retardants APP and BX were selected to carry out flame retardant treatment on fast-growing poplar veneer. The structure of LVL was designed and proper manufacturing parameters were proposed. After that, the physical-mechanical properties and flame retardancy of LVL were tested. The results showed that, in terms of physical and mechanical properties, the impregnation peeling rate of the flame retardant LVL increased compared with that of the control group, but it was within the range of the standard, and the decrease in the mechanical properties of the LVL treated with the two kinds of flame retardant was not obvious, and both of them could reach the strength requirements of veneer laminates for structural use. The flame retardancy of two kinds of LVL increased significantly, but the effect of APP was better, and the specimen treated with APP had an oxygen index of more than 32%, which reached the standard of B1 grade. The results of the study will promote the application of fast-growing materials in the structural field, which has good economic and social benefits. [ABSTRACT FROM AUTHOR]

In order to study the mechanism of destruction of rocks of various genesis and the formation of fractured reservoirs at great depths, laboratory studies of rock samples in the loading conditions of comprehensive pressure with registration of acoustic emission (AE) and parameters of the process of changing the strength and deformation properties of samples were carried out. The spatial distributions of the hypocenters of AE events for each sample were investigated. By the nature of the distributions, the fracture geometry is described, then visually compared with the position of the formed macrofractures in the samples as a result of the tests. The time trends of the amplitude distribution b, set by the Guttenberg – Richter law, were calculated, which were compared with the loading curves and trends of the calculated AE activity. Based on the analysis of the AE process for three types of rocks – igneous (urtites), metamorphic (apatite-nepheline ores), and sedimentary (limestones) – parameterization of acoustic emission was carried out to determine the features of the deformation process and related dilatancy. As a result, three types of destruction of samples were identified, their geometry and changes in strength and seismic criteria were established.

Abstract The replacement of natural aggregate in concrete with artificial and/or recycled one has recently gained attention as meaningful strategy to reduce the environmental impact of structural concrete and promote circular economy principles. This study investigated the possibility to use Reclaimed Asphalt Pavement (RAP), in the “as received conditions”, as a partial or complete substitution of natural aggregate for structural concrete. RAP aggregate was firstly characterized in terms of grain size distribution, density, assessment of fines, chloride content, moisture content and water absorption. Subsequently, a total of twenty-four concrete mixes were designed, considering two cement types, two w/c ratios and several aggregate substitution percentages. For each mix, properties at the fresh and hardened state were investigated, such as workability, density and total open porosity, compressive strength, dynamic modulus of elasticity, and electrical resistivity. Results showed that RAP has a good potential to be used in reinforced concrete, provided that different water absorption and moisture content are considered in the mix design. RAP concrete was characterized by a lower density and increased total open porosity; however, an accurate tailoring of the concrete recipe could compensate the strength loss for several applications. Other properties, such as electrical resistivity and the relationship between dynamic modulus of elasticity and compressive strength did not result significantly altered by the presence of RAP.

Abstract The safety of rock landscapes in Mount Wuyi is significantly impacted by acid rain and wet-dry cycles. In this paper, the decay characteristics of the physical–mechanical properties of red glutenite were investigated under acidic wet-dry cycles. A systematic approach, including cold field emission scanning electron microscopy (CFE-SEM), image processing techniques, and X-ray diffraction (XRD), was proposed to investigate the damage mechanism of red glutenite under acidic wet-dry cycles. The results indicate that with increasing solution acidity and wet-dry cycles, dry density (DD), longitudinal wave velocity (LWV), uniaxial compressive strength (UCS), and elastic modulus (EM) of red glutenite significantly decrease. Under different acidic conditions, DD, LWV, and UCS exhibit exponential decay with wet-dry cycles, while EM exhibits linear decay. A regression fitting was employed to establish a prediction model for UCS, which exhibited a better capability in predicting the correlation between UCS, pH, and the number of wet-dry cycles. Microscopic comprehensive analysis reveals that the interaction between rock dissolution and desiccation is the primary factor leading to changes in the microstructure and mineral composition of red glutenite, culminating in the decay of its physical–mechanical properties. This study holds significant guidance implications for the preservation of cultural and natural heritage in Mount Wuyi.

The scarcity of hardwoods from tropical forests makes the search for alternative species necessary for commercialization. This study aimed to establish groups of timber species from the Amazon Forest with potential for logging purposes through the assessment of their physical-mechanical properties, aiming to identify alternative species that can meet the market demands. We utilized data from the Forest Products Laboratory (LPF) (containing information on basic density and other wood mechanical properties) and the Timberflow platform, as well. We applied a multivariate cluster analysis technique with the aim of grouping species based on the technological characteristics of their wood and evaluating similarity among them to obtain homogeneous groups in terms of economic potential and utilization. The results indicated four homogeneous groups: Cluster 1 (40.72% of species, basic density-db: 690 kg m−3), Cluster 2 (13.92%, db: 260 and 520 kg m−3), Cluster 3 (27.32%, db: 550 and 830 kg m−3), and Cluster 4 (18.04%, db: 830 kg m−3). Most of the 20 listed species are classified as more commercially viable (70%), with high wood density. Species identified as alternatives include Dialium guianense and Zollernia paraensis for Dipteryx odorata, Terminalia argentea for Dinizia excelsa, Terminalia amazonia and Buchenavia grandis for Goupia glabra, and Protium altissimum and Maclura tinctoria for Hymenaea courbaril. The analysis highlighted the overexploitation of a restricted group of species and the need to find alternatives to ensure the sustainability of forest management. This study contributed to identifying species that can serve as alternatives to commercial ones, promoting a more balanced and sustainable forest management. [ABSTRACT FROM AUTHOR]

The paper presents our studies regarding the superior valorization of recycled low-density polyethylene (rLDPE) by compounding with thermoplastic starch (TPS) and ethylene propylene terpolymer elastomer (EPDM). Low-density polyethylene post-consumer waste from foil packaging was used for the experiments. The waste was mechanically recycled and the rLDPE granules obtained were characterized both from a physical-mechanical and structural point of view. In order to obtain new sustainable materials, rLDPE granules were mixed with TPS, EPDM, compatibilizers and crosslinking agents. The mixtures were obtained in a PlastiCorder Brabender mixer at 140°C, 30-80 rpm, working time 7 minutes. The obtained samples show very good resistance to abrasion, have very good values of Charpy impact strength and tensile strength, show very good behaviour to accelerated aging and to the action of some liquids, they have high hardness (51-53) °ShD and a Vicat softening point of 93-96°C. The new materials can be processed by methods specific to plastic materials (extrusion, injection, compression) in order to obtain finished products, and their fields of application can include: the footwear industry, the automotive industry, construction, packaging, agriculture, etc. The thermal analyses showed that up to a temperature of 130°C, the samples have good thermal stability, the mass loss being 0.33-0.79%. The LCA analysis of the composites shows a low environmental impact. The values of the carbon footprint range between 0.58 Kg CO2 eq/kg and 0.75 Kg CO2 eq /kg due to the use of recycled low-density polyethylene and optimised efficient production process. [ABSTRACT FROM AUTHOR]

This research aims to explore how functionally active structures affect the physical, mechanical, thermal, and fire-resistant properties of elastomeric compositions using ethylene–propylene–diene rubber as a base. The inclusion of aluminosilicate microspheres, microfibers, and a phosphorus–boron–nitrogen–organic modifier in these structures creates a synergistic effect, enhancing the material's heat-insulating properties by strengthening coke and carbonization processes. This results in a 12–19% increase in heating time for unheated sample surfaces and a 6–17% increase in residual coke compared to existing analogs. Microspheres help counteract the negative impact of microfibers on composition density and thermal conductivity, while the phosphorus–boron–containing modifier allows for controlling the formation of the coke layer. [ABSTRACT FROM AUTHOR]

This study investigated the effect of pouring temperature, Al-RHA composition and pattern thickness on fluidity length, surface roughness at Al-RHA composition (85:15, 80:20, 75:25) %, pouring temperature (650, 700, 750) °C, and pattern thickness (1, 2, 3, 4, 5, 6, 10) mm. The challenge in this study is to optimize the fluidity length and hardness but minimize the surface roughness and porosity of the composite. The results showed that raising the pouring temperature increased the fluidity length, surface roughness, hardness, and porosity. Higher pouring temperature caused an increase in fluidity length by 13.51–54.17 % when the temperature raised from 650 °C to 750 °C. This was accompanied by an increase in hardness by 1.96–10.69 %. However, higher temperature also resulted in increased surface roughness by 3.9–7.92 % and increased porosity by 1.3–3 %. The composition ratio of Al-RHA plays an important role in determining the physical and mechanical properties of the composites. Increasing RHA content tends to increase the fluidity length but increases the surface roughness, hardness, and porosity. The higher RHA content increases the fluidity length by 2.44–11.9 % and the hardness also increases by 1.26–12.87 %. However, the higher RHA composition also increases the surface roughness by 1.2–30.95 % and the porosity increases by 2–2.7 %. The larger pattern thickness increases the fluidity length by 10.53–60.42 %. Controlling the RHA content and pouring temperature is very important to improve the physical-mechanical properties of Al-RHA composites. The results have potential applications in industries that require special composite materials such as automotive, aerospace, machinery and agricultural equipment [ABSTRACT FROM AUTHOR]

The safety of rock landscapes in Mount Wuyi is significantly impacted by acid rain and wet-dry cycles. In this paper, the decay characteristics of the physical–mechanical properties of red glutenite were investigated under acidic wet-dry cycles. A systematic approach, including cold field emission scanning electron microscopy (CFE-SEM), image processing techniques, and X-ray diffraction (XRD), was proposed to investigate the damage mechanism of red glutenite under acidic wet-dry cycles. The results indicate that with increasing solution acidity and wet-dry cycles, dry density (DD), longitudinal wave velocity (LWV), uniaxial compressive strength (UCS), and elastic modulus (EM) of red glutenite significantly decrease. Under different acidic conditions, DD, LWV, and UCS exhibit exponential decay with wet-dry cycles, while EM exhibits linear decay. A regression fitting was employed to establish a prediction model for UCS, which exhibited a better capability in predicting the correlation between UCS, pH, and the number of wet-dry cycles. Microscopic comprehensive analysis reveals that the interaction between rock dissolution and desiccation is the primary factor leading to changes in the microstructure and mineral composition of red glutenite, culminating in the decay of its physical–mechanical properties. This study holds significant guidance implications for the preservation of cultural and natural heritage in Mount Wuyi. Highlights: The evolution characteristics of the physical–mechanical properties of the red glutenite under acidic wet-dry cycles are analyzed using exponential decay models and linear decay models. A UCS prediction model is established, which can better predict the UCS of the red glutenite under acidic wet-dry cycles. The damage mechanism of the red glutenite under acidic wet-dry cycles is comprehensively analyzed using CFE-SEM, image processing techniques, and XRD. [ABSTRACT FROM AUTHOR]

The effects of SO2, high temperature (600°C) and cooling type (slow and rapid) were investigated in this study as decay factors of a building stone (Encostinha Marble). Changes in colour, gloss, apparent density, open porosity, capillary water absorption and ultrasonic pulse velocity were assessed, complemented with SEM observations and XRD analysis. SO2 did not significantly react with the marble; no neoformed products were identified and only superficial changes were registered. Specimens became darker and duller. The increase in size of pre-existing microcracks and the development of new ones caused by high temperature, with a consequent increase in open porosity, was the main cause of the marked degradation of physical and mechanical properties. The cooling type was also shown to influence the physical and mechanical characteristics of the marble. A more pronounced increase in open porosity and capillary water absorption in specimens cooled by total immersion in tap water was observed. This increase was not in line with the corresponding decrease in ultrasonic parameter values. [ABSTRACT FROM AUTHOR]

This study evaluates the influence of varying proportions of nano-silica (NS) and microsilica (MS) as partial substitutes for cement in the formulation of high-performance concrete (HPC). Mechanical assessments, including compression, tension, flexural strength, dynamic modulus, Poisson's ratio, and elasticity measurements, were performed at intervals of 3, 7, 28, 56, and 91 days to understand the impact on HPC's structural characteristics. Additionally, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-Ray spectroscopy (EDS) were carried out to examine changes in microstructure. Results indicate that incorporating 15% microsilica in the concrete mix yields a more pronounced improvement in mechanical properties compared to adding only 3% nano-silica, surpassing even the combination of 15% microsilica and 3% nano-silica. This substitution approach enhances sustainability by reducing cement usage.

Due to their high tensile strength and toughness, natural fibers have been proposed as reinforcing material in mortars to reduce cracking. Coir fiber has excellent potential for reuse in cementitious matrices among the various fiber types. However, this material is hydrophilic and has a high extractive content, including wax, oils, and other components in the structure. Different chemical treatments are used to remove contaminants from the fiber surface of the coir to minimize the presence of these elements. This study evaluated chemically treated coir fibers in mortars based on cement and lime. The effects of two levels of coir addition (1% and 2% relative to cement mass) treated with oxalic acid at a concentration of 5% w/w for 2 h and sodium bicarbonate at 10% w/w for 120 h were evaluated. The effect of these variables on compressive and tensile strength, capillary water absorption, accelerated carbonation, and microstructure analysis using X-ray microtomography and scanning electron microscopy were investigated. The results showed that with the addition of 2% coir treated with oxalic acid, mortars increased compressive strength by 8% and 22% in the tensile strength. Moreover, it was found that the treatment minimizes the carbonation rate in mortars with coir fibers, whose pore size distribution is also affected by the presence of the fibers and the treatment type. It can be concluded that the fiber's chemical treatment improves its properties for use in mortars, considering a synergistic analysis, and can be used as an alternative for composite material production.

This paper presents the results of research on polyurethane viscoelastic foams (PUVFs) modified with biomaterials. This investigation looked at the effect of the biomaterials on the foaming processes, as well as the acoustical and selected physical-mechanical properties of the foams. Various types of rapeseed oil biopolyols and microcellulose were used to modify the materials. The analysis of properties covered a reference biopolyol-free sample and materials containing 10 wt.%, 20 wt.%, and 30 wt.% of different types of biopolyols in the mixture of polyol components. The biopolyols differed in terms of functionality and hydroxyl value (OHv). Next, a selected formulation was modified with various microcellulose biofillers in the amount of 0.5–2 wt.%. The PUVFs, with apparent densities of more than 210 kg/m3 and open-cell structures (more than 85% of open cells), showed a slow recovery to their original shape after deformation when the pressure force was removed. They were also characterized by a tensile strength in the range of 156–264 kPa, elongation at break of 310–510%, hardness of 8.1–23.1 kPa, and a high comfort factor of 3.1–7.1. The introduction of biopolyols into the polyurethane system resulted in changes in sound intensity levels of up to 31.45%, while the addition of fillers resulted in changes in sound intensity levels of up to 13.81%. [ABSTRACT FROM AUTHOR]

The concept of self-healing materials and the development of encapsulated curing agents represent a cutting-edge approach to enhancing the longevity and reducing the maintenance costs of cementitious structures. This systematic literature review aims to shed light on the parameters involved in the autonomous self-healing of cementitious materials, utilizing various encapsulated healing agents such as pellets, granules, and capsules. This review also identifies and selects studies that offer additional insights into the efficacy of the self-healing process in cementitious materials and the influence of these specific encapsulated healing agents on the physical mechanical properties of mortars. This comprehensive approach provides a deep understanding of the interplay between self-healing and the physical–mechanical properties of mortars containing these encapsulated healing agents. The main findings indicate that the cement-to-sand ratio, characteristics of fine aggregates, and encapsulation methods significantly impact crack control, self-healing efficiency, and properties of mortar in both fresh and hardened states. The content of encapsulated healing agents within the cementitious matrix affects both the initial workability or flow and subsequent mechanical properties. While pellets coated with PVA film typically reduce workability in the fresh state and compressive strength, capsules coated with Portland cement and sodium silicate mitigate these effects and improve crack sealing in fresh and hardened states without compromising the self-healing capacity of cracks. The three-point flexural test has emerged as the preferred method for a pre-crack assessment over 28 days, with variations depending on the type of healing agent used. As noted in the literature, water has been identified as the optimal environment for autonomous healing. These findings underscore the potential of encapsulation techniques to enhance self-healing capabilities through the controlled release of agents within the cementitious matrix, thereby advancing the research on and development of intelligent construction materials and increasing the durability of cement-based structures. [ABSTRACT FROM AUTHOR]

In this paper, we study the influence of densified microsilica and colloidal nanosilica admixtures on the mechanical strength and the microstructural characteristics of special mortars used for immobilizing radioactive concrete waste. The experimental program focused on the replacement of cement with micro- and/or nanosilica, in different proportions, in the basic composition of a mortar made with recycled aggregates. The technical criteria imposed for such cementitious systems, used for the encapsulation of low-level radioactive waste, imply high fluidity, increased mechanical strength and lack of segregation and of bleeding. We aimed to increase the structural compactness of the mortars by adding micro- and nanosilica, all the while maintaining the technical criteria imposed, to obtain a cement matrix with high durability and increased capacity for immobilizing radionuclides. The samples from all the compositions obtained were analyzed from the point of view of mechanical strength. Also, micro- and nanosilica as well as samples of the optimal mortar compositions were analyzed physically and microstructurally. Experimental data showed that the mortar samples present maximum compressive strength for a content between 6 and 7.5% wt. of microsilica, respectively, for a content of 2.25% wt. nanosilica. The obtained results suggest a synergistic effect of micro- and nanosilica when they are used simultaneously in cementitious compositions. Thus, among the analyzed compositional variants, the mortar composition with 3% wt. microsilica and 2.25% wt. nanosilica showed the best performance, with an increase in compressive strength of 23.5% compared to the control sample (without micro- and nanosilica). Brunauer–Emmett–Teller (BET) analysis and scanning electron microscopy (SEM) images highlighted the decrease in pore diameter and the increase in structural compactness, especially for mortar samples with nanosilica content or a mixture of micro- and nanosilica. This study is useful in the field of recycling radioactive concrete resulting from the decommissioning of nuclear research or nuclear power reactors. [ABSTRACT FROM AUTHOR]

Continuous efforts are being made to improve fertilizer efficiency by improving fertilizer technology, quality, and application rates. Granular organic fertilizers are more difficult to achieve uniform application because their physical–mechanical properties differ significantly from mineral fertilizers. The properties of granular organic fertilizers can best be determined experimentally. However, these studies are often quite complex. Modern engineering modeling software makes it possible to model the properties of granular fertilizers and their dispersion. This study deals with the theoretical and experimental verification of the physical–mechanical properties of organic bone meal granular fertilizer. For the verification of selected properties of bone meal granules, the following studies were carried out on the granules: determination of poured bulk density, static and dynamic angles of repose, static and dynamic friction coefficients of granule surface, etc. The results showed that for modeling fertilizer properties, it is sufficient to carry out a static compression test to determine the modulus of elasticity and a friction test between granules and the contacting surface to determine the static and dynamic friction coefficients. The remaining properties of the granules can be modeled and calibrated with the DEM software Altair EDEM 2023. [ABSTRACT FROM AUTHOR]

The wood-based panel industry is experiencing an excessive accumulation of solid residues from the production of medium-density fiberboard (MDF) panels and moldings. It is possible to create new MDF products with acceptable physical and mechanical properties by revaluing MDF residues. Additionally, those products' thermal properties can be improved by incorporating phase change materials (PCMs). This study aims to develop a wood-based fiberboard made of MDF residues, capable of storing thermal energy. Two types of PCMs (liquid and microencapsulated), two PCM ratios (2% and 6%), and two types of adhesives (urea-formaldehyde and phenol-formaldehyde) were used to produce eight different types of panels. The vertical density profile, thickness swelling, water absorption, internal bond (IB), and static bending properties—modulus of elasticity (MOE) and modulus of rupture (MOR)—were determined for each panel type. The specific heat of the panels was also determined. The results show the panels' densities were greater than 700 kg/m3. Thickness swelling in water improved by 23% compared to the reference value of the control panel PCMs after PCM incorporation. The highest IB value was 1.30 MPa, which is almost three times the minimum required by regulation standards. The incorporation of PCMs reduced the panels' bending properties compared to the properties of the control panels. Even though the values obtained are sufficient to comply with the minimum values set out in ANSI standard A208.2 with an MOE value of 2072.4 MPa and the values obtained are sufficient to comply with the minimum standards with an MOE value of 2072.4 MPa and an MOR value of 16.4 MPa, when microencapsulated PCM is used, the specific heat of the panels is increased by more than 100% over that of the control panels. This study developed fiberboards with adequate physical and mechanical properties and capable of storing thermal energy. [ABSTRACT FROM AUTHOR]

Despite numerous recent technological developments, conventional powder metallurgy (CPM) remains the most commonly applied technique for fabricating stainless-steel products. However, the compressibility of stainless-steel powders is still a critical issue. Martensitic stainless-steel powders (i.e., 17-4 PH) are significantly harder than austenitic stainless-steel powders (i.e., 316L and 1.4551). Herein, three different stainless-steel (DSS) powders (i.e., 17-4 PH, 316L, and 1.4551) were investigated using a high cold pressing pressure (i.e., 1.6 GPa) and a relatively low sintering temperature of 1200 °C during CPM. Dimensional and Archimedes density measurements, volume and radial shrinkage calculations, optical and scanning electron microscopy analyses, and compressive strength measurements were conducted to investigate the physical and mechanical properties. Using 1.6 GPa resulted in a 10 % and 6 % increase in the relative green density of the 17-4 PH and 316L samples, compared with the reported literature. For the first time, relative sintering densities of approximately 97 % and 99 % were obtained for 316L and 1.4551 at a sintering temperature of 1200 °C, respectively. Despite the insufficient sintering process, the relative density of the 17-4 PH sample increased by 2 % compared with the literature values reported for higher sintering temperatures. The shrinkage ratios were much lower than those reported in the literature. Furthermore, the present 316L samples achieved 90 % of the compressive yield strength observed in cast 316L, a 25 % increase compared with that previously reported in the literature. This study extends the CPM procedure for enhancing green densities, employing low sintering temperatures, and reducing the shrinkage values of stainless-steel powders with differing hardness.

Statistical regularities of porosity formation during climatic tests of plane-parallel composite materials are revealed. To predict changes in the physical and mechanical properties of composite materials, it is proposed to use the Balshin–Huttig relationship of dimensionless properties and porosity. Taking into account experimental data on the porosity of plane-parallel basalt-plastic and fiberglass composite materials, calculations are made to reduce their physical and mechanical properties. [ABSTRACT FROM AUTHOR]

The physical–mechanical properties (microhardness, Young's modulus, plasticity characteristic, shape recovery ratio) of the synthesized layers of Ti–Ni–Nb-based surface alloys of ~2 μm thickness, formed on the surface of TiNi alloy by the additive thin-film electron beam metho d were investigated by the instrumented indentation. It was found that the change in physical–mechanical properties in the synthesized surface alloys based on Ti–Ni–Nb is due to their layered structure. In particular, it is due to the thickness of the sublayers, their phase composition, and the structural states of the phases (nanocrystalline and amorphous). It was established that high strength and elastic-plastic parameters of the outer layer and a monotonic change in the physical–mechanical properties from the surface to TiNi substrate are provided in the surface Ti–Ni–Nb alloy with a lower volume fraction of the amorphous phase in the synthesized layers. It was found that the multilayer structure of the surface Ti–Ni–Nb alloy and the monotonically change in the physical–mechanical properties to the substrate ensure high mechanical compatibility of the synthesized layers of surface alloys with the TiNi substrate. [ABSTRACT FROM AUTHOR]

It is shown that the problem of improvement of the quality of solid rolled wheels was comprehensively solved by upgrading the currently available steel melting and pouring technologies and scientific search for more suitable modes of press rolling of the billets, antiflocking treatment and optimization of heat treatment parameters (heating for quenching, accelerated cooling and low-temperature tempering). It is quite obvious, however, that the quality of end products in this complex technological scheme of wheel production is largely initially determined by the steel properties, the influence of a range of metallurgical factors at the stage of metal melting in the furnace, out-of-furnace processing and pouring. [ABSTRACT FROM AUTHOR]

Biodegradable polymer-based bags were developed as an alternative to plastic. However, their degradation in environmental conditions has not been fully investigated and is often incomplete. Here, the decomposition of three types of biodegradable bags and one type of plastic bag in different types of environments was analyzed. Polymer bags were exposed for six weeks in water, soil, air and compost, while the control groups were stored in room conditions. All types of polymer bags were sampled twice (after 3 and 6 weeks), and different parameters of changes in physical–mechanical properties were measured. The research established significant differences in changes in mechanical properties between different types of biodegradable polymer bags, with 'white' and 'brown' bags showing the best decomposition potential. As expected, the largest change in the structure and physical–mechanical properties of all types of polymer bags was recorded in compost, and the smallest in air and water. [ABSTRACT FROM AUTHOR]

Geopolymers are an innovative material and a viable alternative to traditional Portland cement for use in the construction industry due to their ease of construction process, low energy consumption, and the wide range of raw materials from which they can be synthesized. The use of geopolymers in civil engineering is one of the most promising options for reducing the environmental impact and huge energy consumption in the production of Portland cement. The raw material for geopolymer is industrial wastes, which have the advantages of lower carbon emissions and lower energy consumption compared to traditional cement products. However, geopolymer has disadvantages such as low strength, easy cracking, and low production efficiency, which limit its engineering applications. The development of nanoscience has a significant impact on building materials. Incorporation of nanoparticles into a geopolymer matrix significantly improves its properties due to the reactivity of the nanoparticles, which can act as a filler agent, producing a dense matrix and reducing micropore growth, thereby significantly improving the properties of the geopolymer. Alumina nanoparticles (Al2O3) are among the most important metal oxides with promising applications. The role of nano-Al2O3 in improving the physical and mechanical properties of geopolymer materials has been noted by many researchers. This paper presents a state-of-the-art review of the latest research regarding the use of nanoaluminum oxide in geopolymers which leads to improved physical-mechanical properties, durability, and sustainability of these materials. [ABSTRACT FROM AUTHOR]

Roller-compacted concrete (RCC) for pavements has experienced problems with its physical-mechanical performance over extended periods due to ambient and in situ curing conditions. Accordingly, this study aimed to present multiple regression equations for calculating the physical-mechanical properties of RCC for pavements under different service and mix conditions. For this purpose, the research included two cement and two water contents, one reduced with admixture, and four combinations of temperature and relative humidity. For model calibration and definition of the equations, cubic and beam samples were fabricated to carry out physical-mechanical tests, such as moisture content, shrinkage, and modulus of rupture. Laboratory-obtained data were studied with the Response Surface Methodology (RSM) to determine the best regression equations. The main findings determined that the behavior of a mixture of RCC at a prolonged ambient exposure time is possible because the surface models and the RSM were consistent with the different service and mix conditions. The models showed an accuracy of 98.99% in detecting shrinkage changes from 12 to 16% cement with 5.65% water in dry to wet ambient conditions. Similarly, moisture content and modulus of rupture had a 98.27 to 98.88% fit. Finally, the drying shrinkage, with mixes of 12% cement and water content variations with water-reducing admixture and superplasticizer effects, had an adjustment of 94.87%. [ABSTRACT FROM AUTHOR]

This research focuses on the behavior of roller-compacted concrete (RCC) used in pavements, which are prone to deterioration affecting their performance. These deteriorations result from various causes, including traffic load, errors during construction, mix design, and ambient conditions. Among these, ambient conditions could lead to a marked variable impact on material behavior and durability depending on the conditions associated with each region. Accordingly, this study aims to deepen the understanding of the effect, which a broader range of ambient conditions and different mix designs have on the physical and mechanical properties of RCC. Measurements such as the amount of water vapor per kilogram of air were used to apply the findings comprehensively. The RCC analysis encompassed experimentation with different compositions, altering the cement water ratio amount, and adding a superplasticizer. The impact of curing on the materials was evaluated before subjecting them to various humidity and temperature conditions. Laboratory tests were conducted to measure performance, including moisture, shrinkage, compressive strength, and the progression of flexural fracture resistance over curing periods of up to 90 days. The results revealed a logarithmic correlation between shrinkage and ambient humidity, which is the most determining factor in performance. Mix optimization through increased cement and reduced water enhanced the tensile strength of the material. Furthermore, the curing process was confirmed to increase resistance to shrinkage, especially in the long term, establishing it as a crucial element for the structural stability of RCC, which is relatively insensitive to variations in ambient conditions. [ABSTRACT FROM AUTHOR]

This study aimed to develop laminate flooring composite using a combination of wood and waste tire rubber (WTR). Plywood panels were produced by using beech (Fagus orientalis), alder (Alnus glutinosa), and poplar (Populus) veneers in a 7-ply configuration. To enhance the physical-mechanical properties of the panels, three loadings of nano-SiO2 (0, 2, and 4 wt%) along with 2 wt% of hexamethyldisilazane (HMDS) were added. Commercial urea-formaldehyde (UF) resin and methylene diphenyl diisocyanate (MDI) were used to bind the wood layers and rubber layers together. The mechanical properties, including modulus of rupture (MOR), modulus of elasticity (MOE), impact strength (IS), hardness strength (HS), and physical properties, such as density (D), water uptake (WU), and thickness swelling (TS), were evaluated. The results showed that increasing the WTR content led to improvements in the physical properties (D, WU, and TS), while negatively affecting the mechanical properties (MOR, MOE, IS, and HS) of the resulting panels. However, the addition of nano-SiO2 improved both the physical and mechanical properties (MOR, MOE, and HS) of the panels. Furthermore, it was observed that the mechanical properties were enhanced with increasing the number of beech layers, although the WU of panels decreased compared to panels made with alder and poplar. Overall, the improvement in the physical properties of the panels followed the order of the arrangement of rubber layers > nano-SiO2 content > veneer layers.

The physical-mechanical properties of the Ti–Ni–Nb–Si-based surface alloy formed on the TiNi substrate using the electron-beam synthesis have been studied. The surface alloy has ~2 times higher values of the microhardness and elastic modulus than the TiNi-substrate. On the contrary, the values of the elastic-plastic parameters are close to those of the substrate. It was found that at a depth of ≤250 nm, the deformation behavior and physical-mechanical properties of the surface alloy differ due to the heterogeneity of the surface alloy structure. [ABSTRACT FROM AUTHOR]

High-temperate vacuum sintering has been used to obtain porous composite tungsten carbide alloy TNIC (W–Ni–Fe–Co) + 69 wt.% WC. The results of investigations into the microstructure and physical-mechanical properties of the alloy are presented. An experimental investigation has been conducted into the high-velocity interaction of cylindrical strikers made of this material with steel plates in the velocity range of 1200–1400 m/s. [ABSTRACT FROM AUTHOR]

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Abstract The objective of the study is to evaluate the properties of the plywood made from rubberwood veneers thermally treated at various temperatures. Rotary-peeled rubberwood veneers were thermally treated at 160, 170, 180, and 190 °C under 1 bar pressure. 5-ply plywood panels were produced using melamine urea formaldehyde (MUF) resin as binder. Dimensional stability, i.e., water absorption (WA) and thickness swelling (TS) as well as mechanical properties of the plywood were assessed. The results demonstrated that the dimensional stability of the plywood made from thermally treated rubberwood veneers improved as indicated by lower WA and TS values. The reduction in WA and TS values increased along with treatment temperatures. Darkening in the plywood as a result of heat treatment was observed. Meanwhile, heat treatment at 170 °C and 180 °C resulted in plywood with the highest modulus of rupture (MOR), modulus of elasticity (MOE) and shear strength. However, beyond that temperature, the mechanical strength of the plywood started to decline. Based on the findings in this work it appears that heat treatment of rubberwood veneers at temperatures ranging from 160 to 180 °C could have a potential to improve overall properties of plywood panels.

The concept of self-healing materials and the development of encapsulated curing agents represent a cutting-edge approach to enhancing the longevity and reducing the maintenance costs of cementitious structures. This systematic literature review aims to shed light on the parameters involved in the autonomous self-healing of cementitious materials, utilizing various encapsulated healing agents such as pellets, granules, and capsules. This review also identifies and selects studies that offer additional insights into the efficacy of the self-healing process in cementitious materials and the influence of these specific encapsulated healing agents on the physical mechanical properties of mortars. This comprehensive approach provides a deep understanding of the interplay between self-healing and the physical–mechanical properties of mortars containing these encapsulated healing agents. The main findings indicate that the cement-to-sand ratio, characteristics of fine aggregates, and encapsulation methods significantly impact crack control, self-healing efficiency, and properties of mortar in both fresh and hardened states. The content of encapsulated healing agents within the cementitious matrix affects both the initial workability or flow and subsequent mechanical properties. While pellets coated with PVA film typically reduce workability in the fresh state and compressive strength, capsules coated with Portland cement and sodium silicate mitigate these effects and improve crack sealing in fresh and hardened states without compromising the self-healing capacity of cracks. The three-point flexural test has emerged as the preferred method for a pre-crack assessment over 28 days, with variations depending on the type of healing agent used. As noted in the literature, water has been identified as the optimal environment for autonomous healing. These findings underscore the potential of encapsulation techniques to enhance self-healing capabilities through the controlled release of agents within the cementitious matrix, thereby advancing the research on and development of intelligent construction materials and increasing the durability of cement-based structures.

The objective was to evaluate the effect of layered composition on the properties of panels manufactured using Pinus taeda wood flakes particles, phenol-formaldehyde resin, a nominal density of 0.65 g/cm? and seven types of the panel layers compositions. The tests were carried out according to the series of European standards for woodbased panels. The results showed that the P6 panel type (20/60S/20 composition), with a randomly distributed central layer, exhibited greater dimensional stability. The panel P4 (30/40/30) showed better results for static bending properties in the parallel direction, whereas the P2 panel (10/80/10) did so in the perpendicular direction. The P3 Panel (20/60/20), showed a better balance of bending properties in both directions. The OSL displayed physical properties similar to OSB and better results for MOR and MOE results in the parallel direction, regardless of the layer composition. The quadratic regression based on the proportion of the parallel external layer enabled the estimation of parallel and perpendicular MOR and MOE losses and gains. [ABSTRACT FROM AUTHOR]

To solve the problem of poor texture decorative effects and inferior functional properties of a fast-growing wood, a combined dyeing and superhydrophobic modification method was proposed and applied. The pretreated wood (P-wood) was dyed based on the permeability variation of the earlywood and latewood. After the dyeing of the wood, the variation in color between the earlywood and latewood was significantly enhanced, and the value of texture contrast of the wood increased from 19.15 to 61.43, indicating that the texture decorative effect of the wood was effectively improved. Furthermore, dyed-superhydrophobic wood (DS-wood) was fabricated by depositing a superhydrophobic coating on the surface of dyed wood (D-wood) to improve its functional properties. The contact angle (WCA) and sliding angle (SA) of the wood were 153.1° and 7°, respectively. Because of the protection of superhydrophobic coating, the wood exhibited excellent color fastness to washing and light aging. In addition, DS-wood exhibited superior thermal stability and physical–mechanical properties. Additionally, DS-wood exhibited excellent abrasion resistance and chemical stability. This modification method of functional wood is simple, inexpensive, and environmentally friendly and has great potential for architectural and furniture applications. [ABSTRACT FROM AUTHOR]

This study aims to analyze the physical-mechanical properties and dynamic models of tissue-simulating hydrogels, specifically the photoacoustic (PA) response signals, by varying the concentrations of polyvinyl alcohol (PVA) and molecular weight (MW). A state-space model (SSM) is proposed to study the PVA hydrogels to retrieve the PA-related signal's damping ratio and natural frequency. Nine box-shaped PVA hydrogels containing saline solution were used, with five concentrations of PVA (7, 9, 12, 15, 20%) for MW1 and four for MW2. The results indicated that the concentration of PVA and MW played an important role in the PA wave's amplitude, arrival time, and speed of sound over the hydrogels. The SSM parameters showed that increasing PVA and MW concentrations improved the hydrogels' ability to absorb and transfer energy under the PA effect. These parameters were also found to be correlated with density and modulus of elasticity. Additionally, the concentrations of PVA and MW affected the absorption and optical scattering coefficients. The physical-mechanical properties, including porosity, density, and modulus of elasticity, improved as the concentration of PVA and MW increased. The ultimate goal of this study is to develop hydrogels as phantoms that can be used for tissue simulation and imaging. [ABSTRACT FROM AUTHOR]

Damage to the rocks of historic built heritage needs to be addressed to facilitate their conservation and restoration; the most serious damage is caused by environmental conditions and human activities. Buildings constructed with ignimbrite blocks bonded with lime mortar in Morelia, México, a UNESCO World Heritage site, were studied. The damage mainly occurs in the facades, on the surfaces of the rocks and in the mortar of the union exposed to climatic factors such as sun, rain, wind, and temperature changes, due to the actions of humans and vehicles emitting polluting gases; and due to pigeon excrement. This has caused the formation of patinas and flora, reduced the mechanical strength and exfoliation, decreased the density and cohesion in the mortar with rocks, and led to friction damage caused by people. In the facades of five buildings, the mechanical resistance and microstructural characteristics were indirectly determined by XRD, XRF, and SEM. The results were related to the climate, humans, and vehicular pollutant emissions. The damage was due to the environment, the influencing geographic orientation, and prevailing winds, rising capillary water on the facades, pigeon droppings, vehicular pollutant gases, and humans. Potential banks of healthy quarries were analyzed for use in the conservation and restoration of damaged monuments.

The purpose of this work was to investigate the effect of the burning environment on the properties and phase composition of clinker-based ceramic specimens made from loam with diatomite and bentonite clay in order to develop technological parameters for the manufacture of clinker products. The main raw material used for the experiments was local fusible loam from the Almaty deposit, which is the basis for the production of 75 and 100 grade ceramic bricks. Diatomite from Utesai deposit (Aktobe region) and highly plastic bentonite clay from Darbazin deposit (Turkestan region) were used as additives. Loam and bentonite clay were applied after grinding and sieving through a 1 mm sieve. Diatomite was applied after grinding and milling until it had completely passed through a 0.315 mm sieve. The raw materials are mixed after dosing, and then water is added in the amount required until a pliable mass is obtained. To investigate the properties of the products, standard cylinder samples were prepared with a diameter of 50 mm and a height of 50 mm. The cylinder samples were pressed on a hydraulic press at a pressure of 2–4 kN. The samples were dried in a desiccator at 95–100 °C for 2 h. After drying, the products were burning in a muffle kiln. The analysis of the properties of the burned products showed that the optimum ratio in the ceramic mixture of loam and diatomite to loam and bentonite clay is 85%:15%. After burning in a slightly oxidising environment at 1170 °C, the ceramic specimens correspond to Class 2 for the medium-density and compressive strength grades M 400 and M 500 (GOST 530-2012 (Government standard). X-ray diffractometric analysis showed that the products contain augite, quartz and anorthite as crystalline phases, with the former predominating. After burning in a reducing atmosphere, at 1170 °C, the properties of the samples have higher values compared to the samples burning in a weakly oxidising atmosphere. The resulting properties, according to the regulations, are characteristic of clinker bricks (DIN V 105-1 (technical requirements for clinker façade bricks). After burning in a reducing environment, the phase composition of the products changes qualitatively; in addition to augite and quartz, albite, diopside, orthoclase and haematite are present in the samples.