Search Results (50)

Contemporary muralism has gained increasing cultural and social relevance in recent years, becoming a prominent form of urban artistic expression. However, its outdoor exposure makes it highly vulnerable to environmental degradation, raising significant challenges for long-term preservation. While solar radiation is widely recognized as a main agent of deterioration, the impact of rainfall has received comparatively little attention. This study addresses this gap by evaluating the durability of commercial protective coatings applied to modern paints (alkyd, acrylic, and styrene-acrylic) under simulated rain exposure. The ageing protocol replicates approximately 10 years of cumulative rainfall in Central-Southern Europe. A key innovation of this research is the use of a custom-built rain chamber, uniquely designed to expose a large number of samples simultaneously under highly uniform and controlled rain conditions. The system ensures reproducible exposure through a precision-controlled moving platform and programmable rain delivery. A comprehensive set of analytical techniques was employed to assess morphological, chemical, and functional changes in the coatings and paints before and after ageing. Results highlight the limited performance of current protective materials and the need for more effective solutions for the conservation of contemporary outdoor artworks. Full article

This research addresses urban inequality by focusing on the rehabilitation of communal rooftops in Ciutat Vella, Barcelona, the city’s historic district, where residential vulnerability is concentrated in a particularly dense heritage urban environment with a shortage of outdoor spaces. Using participatory methodologies, this research develops low-cost, removable, and recyclable prototypes aimed at improving social interaction, technical performance, and environmental conditions. The focus is on vulnerable populations, particularly the elderly. The approach integrates a bottom–up process and scalable solutions presented as a Toolkit of micro-projects. These micro-projects are designed to improve issues related to health, safety, durability, accessibility, energy savings, and acoustics. In addition, several possible material solutions for micro-projects are examined in terms of sustainability and cost. These plug-in interventions are designed for adaptability and replication throughout similar urban contexts and can significantly improve the quality of life for people, especially the elderly, in dense historic environments. Full article

The widespread phase-out of long-chain per- and poly-fluoroalkyl substances (PFASs) has created an urgent need for durable, fluorine-free water-repellent finishes that match the performance of legacy chemistries while minimising environmental impact. Here, the performance of an eco-friendly hybrid organic–inorganic treatment obtained by the in situ hydrolysis–condensation of triethoxy(octyl)silane (OS) in an amino-terminated polydimethylsiloxane (APT-PDMS) aqueous dispersion was investigated. The sol was applied to plain-weave cotton and polyester by a pad-dry-cure process and benchmarked against a commercial fluorinated finish. Morphology and chemistry were characterised by SEM–EDS, ATR-FTIR, and Raman spectroscopy; wettability was assessed by static contact angle, ISO 4920 spray ratings, and AATCC 193 water/alcohol repellence; and durability, handle, and breathability were evaluated through repeated laundering, bending stiffness, and water-vapour transmission rate measurements. The silica/PDMS coating formed a uniform, strongly adherent nanostructured layer conferring static contact angles of 130° on cotton and 145° on polyester. After five ISO 105-C10 wash cycles, the treated fabrics still displayed a spray rating of 5/5 and AATCC 193 grade 7, outperforming or equalling the fluorinated control, while causing ≤5% loss of water-vapour permeability and only a marginal increase in bending stiffness. These results demonstrate that the proposed one-step, water-borne sol–gel process affords a sustainable, industrially scalable route to high-performance, durable, water-repellent finishes for both natural and synthetic textiles, offering a viable alternative to PFAS-based chemistry for outdoor apparel and technical applications. Full article

Poly(butylene adipate-co-terephthalate) (PBAT) is a promising biodegradable polymer with balanced mechanical properties and excellent degradability, making it an ideal material to reduce plastic pollution. However, its susceptibility to ultraviolet (UV) degradation, due to photosensitive aromatic rings and carbonyl groups in its structure, limits its use in outdoor settings like mulch films. Conventional methods of incorporating small-molecule UV stabilizers face challenges such as poor compatibility, uneven dispersion, and migration under environmental conditions, reducing their effectiveness over time. This study developed a novel strategy to enhance PBAT’s UV resistance by chemically bonding UV-stabilizing moieties directly into its molecular chains to address these limitations. A novel UV absorber containing a polymerizable group was synthesized and copolymerized with PBAT’s main chain, creating an intrinsically UV-stable PBAT. The UV-stable PBAT was evaluated for UV resistance, mechanical performance, and durability through accelerated aging and solvent extraction tests. The results demonstrated that UV-stable PBAT exhibited exceptional light stabilization effects, with no detectable UV absorber leaching in ethanol even after 114 h, whereas PBAT blends lost nearly 90% of UV-0 within 24 h. Furthermore, UV-stable PBAT maintained 67.1% tensile strength and 48.8% elongation at break after aging, which exhibited the best mechanical retention performance. Even when subjected to solvent extraction, the 42.6% tensile strength retention outperformed the PBAT blends. This innovative chemical modification overcomes the limitations of additive-based stabilization, offering improved durability, compatibility, and performance in outdoor applications. Our research provides key insights into the fundamental properties of PBAT films for UV resistance, demonstrating their potential for use in demanding fields such as agricultural films. Full article

Biodegradable mulch films were developed over the last decades to replace polyethylene, but their short durability and higher costs still limit their diffusion. This work aimed to test an innovative composite mulching film constituted by a mixture of carboxylmethyl cellulose, chitosan and sodium alginate, enriched or not with an inorganic N- and P-source to help the microbial breakdown in soil. The trial was carried out using outdoor mesocosms cultivated with lettuce plants with high-density planting. Commercial Mater-Bi^® and a polyethylene film were taken as control treatments. Air temperature and humidity monitored daily during the 51 d cropping cycle remained within the ideal range for lettuce growth with no mildew or fungi infection. Visible mechanical degradation of the experimental biopolymers occurred after 3 weeks; however, Mater-Bi^® and polyethylene remained unaltered until harvest. Chemical soil variables (TOC, TN, CEC, EC) remained unchanged in all theses, whereas the pH varied. The yield, pigments, total phenols, flavonoids and ROS scavenging activity of lettuce were similar among treatments. Despite their shorter life service (~3 weeks), polysaccharide-based mulching films showed their potential to protect lettuce plants at an early stage and provide yield and nutraceutical values similar to conventionally mulched plants, while allowing a reduced environmental impact and disposal operations. Full article

Traditional structural damage detection relies on multi-sensor arrays (e.g., total stations, accelerometers, and GNSS). However, these sensors have some inherent limitations such as high cost, limited accuracy, and environmental sensitivity. Advances in computer vision technology have driven the research on vision-based structural vibration analysis and damage identification. In this study, an optimized Lucas–Kanade optical flow algorithm is proposed, and it integrates feature point trajectory analysis with an adaptive thresholding mechanism, and improves the accuracy of the measurements through an innovative error vector filtering strategy. Comprehensive experimental validation demonstrates the performance of the algorithm in a variety of test scenarios. The method tracked MTS vibrations with 97% accuracy in a laboratory environment, and the robustness of the environment was confirmed by successful noise reduction using a dedicated noise-suppression algorithm under camera-induced interference conditions. UAV field tests show that it effectively compensates for UAV-induced motion artifacts and maintains over 90% measurement accuracy in both indoor and outdoor environments. Comparative analyses show that the proposed UAV-based method has significantly improved accuracy compared to the traditional optical flow method, providing a highly robust visual monitoring solution for structural durability assessment in complex environments. Full article

Silicone structural glazing (SSG) sealants are crucial sealing materials in modern building curtain walls, whose performance degradation may lead to functional and safety issues, posing significant challenges to building safety maintenance. This study comprehensively investigated the effects of temperature, humidity, stress, and ultraviolet (UV) irradiance on the durability of SSG sealants through multi-gradient matrix aging tests, revealing the influence patterns of these four aging factors on tensile bond strength (TBS). Based on aging test data and degradation patterns, a novel degradation model for TBS aging was established by incorporating all four aging factors as variables, enabling the model to reflect their combined effects on TBS degradation. The unknown parameters in the model were calculated using the Markov chain Monte Carlo (MCMC) algorithm and validated against experimental data. A recursive algorithm was developed to predict TBS degradation under actual service conditions based on the degradation model and environmental records, with verification through outdoor aging tests. This study established a service life prediction methodology that combines the degradation model with environmental data through recursive computation and standard-specified strength limits. The results demonstrate that increasing temperature, humidity, stress, and UV irradiation accelerates TBS changes, with influence intensity ranking as UV irradiation > temperature > humidity > stress. Synergistic effects exist among all four factors, where UV irradiation shows the most significant coupling effect by amplifying other factors’ combined impacts, while UV’s primary influence manifests through such synergies rather than independent action. Among temperature, humidity, and stress combined effects, temperature contributes approximately 50%, temperature–humidity interaction about 35%, with temperature-related terms collectively accounting for 90%. The degradation model calculation results show excellent agreement with experimental data (R² > 0.9, MAE = 0.019 MPa, RMSE = 0.0245 MPa). The characteristic TBS minimum value considering material discreteness and strength assurance rate serves as a reliable criterion for service life evaluation. The proposed prediction method provides essential theoretical and methodological foundations for ensuring long-term safety and maintenance strategies for glass curtain walls. Full article

Ensuring the durability of concrete pavements against chloride ingress is critical, yet the relationship between electrical resistivity and chloride penetration remains underexplored. This study evaluates the effectiveness of entrained air and fly ash in mitigating chloride ingress using an electrical resistivity model and surface resistivity tests. Concrete samples with varying entrained air contents (0% to 10%) and Class C or Class F fly ash underwent three-year ponding tests in temperature-controlled indoor water baths and outdoor CaCl₂-NaCl brine solutions. The results indicate that lower entrained air contents led to a more rapid increase in resistivity, with concrete mixes incorporating Class C fly ash exhibiting 1.5 times greater resistivity gains than those with Class F fly ash. Surface resistivity tests revealed that reaction factors were 67% higher in specimens with 3.5% entrained air compared to 10.0%, while decreasing by 57% and 41% in concrete mixes containing Class F and Class C fly ash, respectively, across all chloride concentrations. Using back-calculated environmental factors, corrosion initiation potential in concrete pavements was projected for exposure periods of up to 50 years. These findings provide insights for optimizing entrained air and fly ash formulations to enhance pavement performance and durability. Full article

Radiative cooling is a passive cooling strategy that dissipates heat externally through the atmospheric window (8–13 μm). This study presents a radiative cooling film with a simple and cost-effective fabrication process. The film was fabricated by mixing SiO₂ hollow microspheres with a UV-curable resin, employing a photopolymerization-induced phase separation method. The resulting gradient refractive index structure enhanced thermal radiation emissivity. At an optimal silica-to-resin mass ratio of 1:1.5 and a film thickness of 1.1 mm, the film achieved a solar reflectivity of 85% and an emissivity of 91% within the atmospheric window. Outdoor experiments conducted in both summer and winter demonstrated stable cooling performance. Under a solar irradiance of 796.9 W/m² (summer), the film reduced surface temperature by 10 °C compared to ambient air and 20 °C compared to an uncoated glass substrate, achieving a radiative cooling power of 76.7 W/m². In winter (solar irradiance of 588.8 W/m²), the film maintained a significant cooling effect, though with reduced efficiency due to lower solar exposure. Furthermore, long-term stability tests over six months showed that the film retained high solar reflectivity and infrared emissivity, indicating good durability. Overall, the developed radiative cooling films demonstrate excellent optical properties, structural stability, and cooling efficiency, making it a promising candidate for real-world radiative cooling applications. Further studies on environmental resilience and optimization under diverse climatic conditions are necessary for broader deployment. Full article

Wood, a vital material for both modern and heritage objects, is particularly susceptible to degradation caused by water due to its hydrophilic nature and porous structure. Therefore, developing sustainable strategies to protect wood is of significant importance. This study aims to produce a highly hydrophobic coating for the protection of wood following a straightforward procedure and using materials that are compatible with wood. First, nano/sub-microlignin (NL) is isolated and produced from beech wood through a one-step tailored organosolv process. Next, NL is incorporated into Sivo 121, a water-borne and solvent-free silane system recommended by the manufacturer for protecting wood surfaces. Composite coatings containing various concentrations of NL and Sivo 121 are applied to chestnut (Castanea spp.) and oak (Quercus spp.). The impact of NL concentration on the contact angles of water drops (CAs) and colour changes (ΔE) of the treated wood specimens is investigated. The coating with 4% w/w NL demonstrates enhanced hydrophobicity (CA = 145°) and has a negligible effect on the colour of pristine oak (ΔE < 3). The wetting properties of coated oak are not affected after 100 tape peeling cycles. However, the coating exhibits poorer performance on chestnut, i.e., CA = 135°, which declines after 80 peeling cycles, and ΔE > 5. The drop pH does not have any noticeable effect on CA. The latter remains stable even after prolonged exposure of coated oak and chestnut samples to artificial UV radiation and outdoor environmental conditions. Finally, the composite coating offers good and comparable protection for both wood species in the biological durability soil burial test Full article

In some occasions, outdoor steel structures like wind towers, bridges, winter sports facilities, and so on are subjected to extreme environmental conditions with the presence of ice and/or with below-zero temperatures. Sometimes in these situations, surface protection of the steel structure is usually designed using hot-dip galvanizing to improve its durability. In these special circumstances, the structure’s connections are also exposed to adverse climatic agents. International standards and codes such as Eurocode 3 or EN1090-2 do not provide indications for these cases. In this experimental research, 24 specimens of non-slip joints with hot-dip galvanized faying surfaces and HV M16 and M20 bolts have been studied. Twelve specimens were subjected to fourteen twelve-hour freeze-thaw cycles, with temperature oscillation and periodic immersion in water. Next, six of the connections were subjected to a slip test under monotonic load at a temperature of −20 ± 0.5 °C and the other six at room temperature. The results were compared with joints kept at room temperature and not subjected to freeze-thaw cycles for the same period of time. The main conclusion of this piece of research is that the short-term slip resistance behavior of joints with hot-dip galvanized surfaces is not reduced for the cases studied. Full article

Wood, a natural and renewable material, is extensively utilized in furniture, construction, and outdoor landscapes due to its sustainability and esthetic appeal. However, exposure to environmental elements, particularly sunlight, leads to photodegradation, affecting wood’s chemical and physical structure. This degradation results in color fading, increased surface roughness, and reduced mechanical properties, shortening the lifespan of wooden products. Artificial accelerated photodegradation tests have become a crucial method for studying wood’s aging process under controlled laboratory conditions, mimicking prolonged exposure to sunlight. This review explores the mechanisms behind wood photodegradation, focusing on the effects of UV radiation on wood’s major components—cellulose, hemicellulose, lignin, and extractives. Additionally, it summarizes the latest advancements in experimental design for artificial aging tests, including factors like radiation source selection, temperature, and humidity control. The paper also highlights performance characterization methods for evaluating the impact of photodegradation on wood’s physical, chemical, and mechanical properties. Understanding these processes is essential for enhancing the durability of wood products and developing effective treatments for wood preservation in outdoor environments. Full article

Wood plastic composites (WPCs) have recently gained attention as alternatives to traditional wood materials for outdoor use, thanks to their enhanced moisture resistance and durability, which extends their service life. Discolouration as well as surface erosion has been observed during weathering for both WPCs with untreated and heat-treated wood. However, aspects such as changes in surface hydrophobicity, chemistry, and erosion in terms of microplastic formation have received less attention; this research aimed to evaluate these factors during natural weathering. Four types of WPC samples, consisting of 50% wood particles (untreated and heat-treated) and 50% polypropylene, were naturally weathered in Latvia for two years. The samples measured 240 mm × 240 mm × 5 mm. Results showed rapid colour changes, microcracks, and exposed wood particles, suggesting microplastic formation. ATR-FTIR analysis showed increased absorption at 1715 cm⁻¹ (carbonyl groups) and at 3410 cm⁻¹ and 3460 cm⁻¹, typical of wood, indicating chemical changes on the surface. These changes influenced surface hydrophobicity, roughness, and water penetration. In a relatively short exposure time, WPCs without proper additives undergo significant changes in their aesthetic and physical properties, leading to surface erosion and potential microplastic formation. This could challenge the perception of WPCs as environmentally friendly materials. Full article

The search for solutions that reduce the environmental impact of construction has driven the development of new materials. Bio-concrete represents a significant advance, presenting itself as an alternative to traditional concrete. Recent studies point to durability in outdoor conditions as one of the main challenges in its application. This paper presents natural durability studies performed on bamboo bio-concrete, produced with a bamboo particle volume of 50%. A surface treatment of applying resin externally was tested to reduce water ingress during weathering. The bio-concretes were exposed to natural and outdoor weather conditions for twelve months, and meteorological records were collected during the study period. The effect and influence of the external resin was investigated using visual surface analysis, uniaxial compression, modulus of elasticity and scanning electron microscopy. In terms of visual aspects, the resin was not effective in preventing loss of gloss, while in terms of microstructure, these samples showed better adhesion between the bamboo particles in the matrix. The compressive strength showed significant reductions of 60% (stress) and 73% (Young’s modulus) after twelve months of weathering. External resin could improve microstructures from surfaces to internal portions and more effectively preserve the mechanical strength of bio-concrete. Full article

Water scarcity is a serious threat to the survival and development of mankind. Interfacial solar steam generation (ISSG) can alleviate the global freshwater shortage by converting sustainable solar power into thermal energy for desalination. ISSG possesses many advantages such as high photothermal efficiency, robust durability, and environmental friendliness. However, conventional evaporators suffered from huge heat losses in the evaporation process due to the lack of efficient thermal management. Herein, hydrophilic Tencel yarn is applied to fabricate a three-dimensional double-layer fabric evaporator (DLE) with efficient multi-stage thermal management. DLE enables multiple solar absorptions, promotes cold evaporation, and optimizes thermal management. The airflow was utilized after structure engineering for enhanced energy evaporation efficiency. The evaporation rate can reach 2.86 kg·m⁻²·h⁻¹ under 1 sun (1 kW·m⁻²), and 6.26 kg·m⁻²·h⁻¹ at a wind speed of 3 m·s⁻¹. After a long duration of outdoor operation, the average daily evaporation rate remains stable at over 8.9 kg·m⁻², and the removal rate of metal ions in seawater reaches 99%. Overall, DLE with efficient and durable three-dimensional multi-stage thermal management exhibits excellent practicality for solar desalination. Full article