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Povzetek: The production of textile-reinforced concrete (TRC) requires less materials and energy in comparison with conventional concrete reinforced with steel rebars, which draws some solutions towards the production of net zero concrete that the Cement and Concrete Industry sector should reach by 2050. To go one step further, this study investigates the development of flax based meshes as basic components for a reinforcement grid in cementitious materials. Flax strands and hybrid strands (combination of flax strands and glass or basalt rovings) were impregnated with an epoxy resin to form meshes. The physical and mechanical properties of the flax based meshes were assessed and the alkaline resistance of these reinforcing materials was evaluated to determine their durability in a cementitious matrix. At isoweight of reinforcement, the flax-based meshes demonstrated the best performance in terms of specific modulus and specific strength compared to the hybrid meshes. The hybrid meshes from the control batch displayed specific properties in the same range, whether they were constituted of AR-glass or basalt. However, the use of alkali-resistant glass rovings strongly mitigated the degradation of the mechanical properties of the hybrids meshes by making them less affected by the alkaline environment, among all the reinforcement meshes. In contrast, hybrid meshes with basalt experienced an extensive reduction in tensile strength and strain after exposure to alkaline environment, due to the corrosion of the basalt fibres. Pull-out tests revealed maximum bond strengths for the flax based meshes embedded in a high-performance concrete matrix.
Ključne besede: alkali, cement, flax, reinforcement
Objavljeno v DiRROS: 27.08.2025; Ogledov: 744; Prenosov: 415
Celotno besedilo (4,01 MB)
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Povzetek: Formaldehyde is a common indoor air pollutant with hazardous effects on human health. This study investigated the efficiency of biocarbon (BC) functionalized with variable contents of MnO2 for formaldehyde removal in ambient conditions via integrated adsorption-photocatalytic degradation technology. The sample with the highest formaldehyde removal potential was used to prepare a functional coating made of acrylic binder mixed with 20 wt% of the particles and applied on beech (Fagus sylvatica L) substrate. SEM images showed that MnO2 was deposited around and inside the pores of the BC. EDX spectra indicated the presence of Mn peaks and increased content of oxygen in the doped BC compared to pure BC, which indicated the successful formation of MnO2. Raman spectra revealed that the disorder in the BC's structure increased with increasing MnO2 loadings. FTIR spectra of BC–MnO2 samples displayed additional peaks compared to the BC spectrum, which were attributed to MnO vibrations. Moreover, the deposition of increased MnO2 loadings decreased the porosity of the BC due to pores blockage. The BC sample containing 8 % Mn exhibited the highest formaldehyde removal efficiency in 8 h, which was 91 %. A synergetic effect between BC and MnO2 was observed. The formaldehyde removal efficiency and capacity of the coating reached 43 % and 6.1 mg/m2, respectively, suggesting that the developed coating can be potentially used to improve air quality in the built environment.
Ključne besede: biocarbon, manganese dioxide, catalytic degradation, functional coating, built environment
Objavljeno v DiRROS: 30.01.2025; Ogledov: 1010; Prenosov: 743
Celotno besedilo (6,69 MB)
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Povzetek: With wood regaining substantial interest as a construction material due to sustainability concerns and aesthetics trends, efficient and safe protection methods are needed to prevent the discouloration and the loss of mechanical properties of this renewable and UV-sensitive material. In this study, sustainable coatings comprising 0 to 20 wt % biocarbon (BC) dispersed in tung oil were developed for wood protection. BC particles were added as ultraviolet (UV) absorbers and were produced by various carbonization routes. The BC powders were characterized in terms of particle size and surface functional groups by Fourier-Transform infrared, and the UV and visible absorbance of dispersed BC powders in water solutions were related to these characteristics. Two wooden substrates (beech and oak) were coated with the developed coatings and the samples underwent six months of onsite weathering. While the total colour change of uncoated samples and tung oil-coated substrates without BC kept increasing over time and resulted in a clear alteration of the wood surface aesthetics, an increased BC content in the coatings led to enhanced colour stability, with alteration of the colour close to 2 for both wood species after six months of weathering for 10 and 20 wt% BC. Coating with tung oil made the wooden substrates, initially hydrophilic, become hydrophobic, and the further introduction of biocarbon increased hydrophobicity. However, the increase in BC content was not correlated with an increase in water repellence, the highest water contact angle being observed for 5 % BC, and no further improvement in hydrophobicity was observed with higher BC content. The weathering negatively affected the water repellence of all the samples (i.e., reference samples and coated samples with various BC content). However, the introduction of 20 % BC best protected the decrease in water repellence induced by the onsite weathering.
Ključne besede: biocarbon, biochar, coating, wood protection, hydrophobic coating, wettability
Objavljeno v DiRROS: 30.05.2023; Ogledov: 1956; Prenosov: 1505
Celotno besedilo (6,19 MB)
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