Search Results (286)

Stretchable semiconductors capable of maintaining electrical performance under large mechanical deformation are essential for reliable wearable electronic devices. However, polymer semiconductors often suffer from electrical degradation when subjected to tensile strain. In this study, electrical stability under strain was achieved by using a rubber-blended poly(2,5-bis(2-octyldodecyl)-3,6-di(thiophen-2-yl)diketopyrrolo[3,4-c]pyrrole-1,4-dione-alt-thieno[3,2-b]thiophene) (DPPT-TT) polymer semiconductor based on a conjugated polymer/elastomer phase separation-induced elasticity (CONPHINE) structure. Unlike most previous studies on fully stretchable thin-film transistors (TFTs), which primarily report overall performance changes under mechanical strain, this work systematically identifies the dominant origin of electrical performance degradation through a stepwise electrical analysis encompassing the gate insulating layer, the semiconductor layer, and complete devices. Bottom-gate top-contact (BGTC) and bottom-gate bottom-contact (BGBC) devices were fabricated on rigid Si/SiO₂ substrates to examine the intrinsic properties of the DPPT-TT/styrene-ethylene-butylene-styrene (SEBS) CONPHINE film. As a result, the device exhibits 90% mobility retention even at 100% tensile strain applied parallel to the charge transport direction. Quantitative resistance analysis using the Y-function method reveals that variations in channel resistance play a dominant role in strain-induced performance degradation, whereas changes in contact resistance contribute only marginally. These findings demonstrate that stabilizing channel resistance, rather than contact resistance, is important for achieving high mobility retention under large mechanical deformation, thereby providing concrete and quantitative design guidelines for reliable stretchable TFTs. Full article

This study presents a life cycle assessment of a low-cost pilot-scale wastewater treatment system that combines solar photocatalytic oxidation with Nature-based Solutions (NBSs) for a specially constructed wetland (CW). The prototype was designed and assessed for its efficiency in treating urban wastewater and its environmental impact on agricultural irrigation reuse. Evaluations were performed with the SimaPro software, applying the Impact ReCiPe Medpoint methodology, which includes characterization and selection of the relevant environmental issues steps. The results demonstrate the potential of this hybrid system for providing high-quality treated wastewater suitable for agricultural reuse in water-scarce regions. The analysis reveals that the operational phase, mainly driven by energy consumption for pumping, aeration, and photocatalytic processes, accounts for over 85–98% of the total global warming potential (GWP), primarily due to reliance on fossil-based electricity. Conversely, the construction phase significantly impacts land use and toxicity categories, with concrete and substrate production contributing around 95% to land occupation and 97% to human toxicity. The photocatalytic subsystem also contributes notably to embodied carbon at 42.4%, owing to energy-intensive manufacturing. The results underscore the importance of optimizing operational energy efficiency and selecting sustainable materials to mitigate environmental burdens. The integrated system demonstrates promising potential for producing high-quality treated effluent suitable for agricultural reuse in water-scarce regions, supporting sustainable water management. These findings provide important insights for reducing ecological impacts and advancing environmentally sustainable wastewater treatment solutions. Full article

This research presents a comprehensive evaluation of semi-elastic polyurethane adhesives used for bonding wooden flooring, with a particular focus on both domestic (oak) and exotic hardwood species (teak, iroko, wenge, merbau). Given the increasing interest in sustainable construction practices and the growing use of diverse wood species in flooring systems, this study aimed to assess the mechanical, morphological, and surface properties of adhesive joints under both standard laboratory and thermally aged conditions. Mechanical testing was conducted according to PN-EN ISO 17178 standards and included shear and tensile strength measurements on wood–wood and wood–concrete assemblies. Specimens were evaluated in multiple aging conditions, simulating real-world application environments. Shear strength increased post-aging, with the most notable improvement observed in wenge (21.2%). Tensile strength between wooden lamellas and concrete substrates remained stable or slightly decreased (up to 18.8% in wenge), yet all values stayed above the 1 MPa minimum requirement, confirming structural reliability. Surface properties of the wood species were characterized through contact angle measurements and 3D optical roughness analysis. Teak exhibited the highest contact angle (74.9°) and the greatest surface roughness, contributing to mechanical interlocking despite its low surface energy. Oak and iroko showed high wettability and balanced roughness, supporting strong adhesion. Scanning electron microscopy (SEM) revealed stable adhesive penetration across all species and aging conditions, with no signs of delamination or interfacial failure. The study confirms the suitability of polyurethane adhesives for durable, long-lasting bonding in engineered and solid wood flooring systems, even when using extractive-rich or dimensionally sensitive tropical species. The results emphasize the critical role of surface morphology, wood anatomy, and adhesive compatibility in achieving optimal bond performance. These findings contribute to improved material selection and application strategies in flooring technology. Future research should focus on bio-based adhesive alternatives, chemical surface modification techniques, and in-service performance under cyclic loading and humidity variations to support the development of eco-efficient and resilient flooring systems. Full article

The growing demand for low-carbon, resource-efficient, and multifunctional construction materials has intensified interest in solutions that can support both circular economy strategies and sustainable urban development. Expanded perlite—a lightweight volcanic material with low embodied energy and multiple functional properties—is increasingly considered a potential component of circular and nature-based material systems. This paper critically examines whether expanded perlite can serve as a sustainable alternative in civil engineering applications, contributing to reduced material consumption, improved thermal performance, and lower environmental impact across the life cycle. The review provides an overview of current applications of expanded perlite in lightweight concretes, insulation systems, green roofs, water-retention substrates, and other technologies relevant to resilient and net-zero cities. It also identifies key research gaps related to long-term durability, large-scale implementation, and life-cycle assessment, while emphasizing the need for proper handling procedures due to health concerns associated with dust exposure. By situating expanded perlite within the context of circular design and low-carbon construction, the paper highlights its potential role in decarbonizing the built environment and advancing the transition toward climate-resilient and regenerative urban systems. Full article

Fibre reinforced cementitious matrix (FRCM) systems are composite materials that are increasingly used for retrofitting masonry and reinforced concrete structures. Their behaviour does not depend only on the mechanical properties of the fibres and the matrix. Therefore, it is essential to perform tensile tests on FRCM coupons, as well as additional tests to investigate whether the interaction between the FRCM system and the substrate can be considered a perfect bond. The aim of this paper is to numerically simulate the behaviour of concrete beams retrofitted with two FRCM composite systems assuming perfect bond. The results of the numerical simulations were compared with experimental data, and it was observed that the adopted models successfully capture the cracking behaviour of both the concrete and the FRCM, as well as overall structural response of the specimens. The main finding was that the behaviour of concrete beams retrofitted with FRCM can be effectively estimated using a macro-modelling approach in numerical simulations. The ultimate load obtained experimentally is between 2% and 20% higher than the numerical value. This is safe and accurate enough for engineering purposes. Full article

In urban plantings, mined sand and scoria are commonly used as low-nutrient substrates to improve plant establishment and growth. However, reliance on mined materials conflicts with sustainability policies promoting resource circularity and waste reuse. Construction wastes are readily available, and while their high alkalinity and density may limit plant growth, incorporating organic matter, like pine bark, can ameliorate these issues. We investigated whether construction waste amended with pine bark can support plant growth. We evaluated physical and chemical properties of 12 substrates combining four mineral components—scoria (mined), sand (recycled), crushed concrete (recycled), and crushed rock (recycled)—with pine bark (10%, 20%, and 50% v/v). We then tested eight of these substrates in a container experiment, evaluating the growth of two woody shrubs: Alyogyne huegelii and Goodenia ovata. All mineral components were alkaline (pH 9.2–12.3), with crushed concrete remaining hyper-alkaline despite pine bark addition. Greater pine bark volumes improved air-filled porosity but reduced water retention. Substrates with 50% v/v pine bark had lower plant biomass compared to those with 10% v/v. However, plant biomass was similar across all mineral components. This demonstrates that construction waste–pine bark substrates can support plant growth in urban plantings, supporting broader sustainability goals in cities. Full article

Reinforced concrete (RC) beams strengthened with carbon-fabric-reinforced cementitious matrix (CFRCM) systems have shown potential for restoring flexural performance, yet their effectiveness under different corrosion levels remains insufficiently understood. This study presents a numerical investigation of the flexural behaviour of simply supported RC beams externally strengthened with CFRCM plates. Refined finite element models (FEMs) were developed by explicitly incorporating the steel–concrete bond-slip behaviour, the carbon fabric (CF) mesh–cementitious matrix (CM) interface, and the CFRCM–concrete substrate interaction and were validated against experimental results in terms of failure modes, load–deflection responses, and flexural capacities. A parametric study was then conducted to examine the effects of CFRCM layer number, steel corrosion level, and longitudinal reinforcement ratio. The results indicate that the baseline flexural capacity can be fully restored only when the corrosion level remains below approximately 15%; beyond this threshold, none of the CFRCM configurations achieved full recovery. The influence of the reinforcement ratio was found to depend on corrosion severity, while increasing CFRCM layers enhanced flexural performance but exhibited saturation effects for thicker configurations. In addition, corrosion level and CFRCM thickness jointly influenced the failure mode. Comparisons with design predictions show that bilinear CFRCM constitutive models are conservative, whereas existing FRP-based design codes provide closer agreement with numerical and experimental results. Full article

Cool roof and green roof have been acknowledged as effective heat mitigation strategies for fighting against the urban heat island (UHI). However, empirical data in hot–humid climate are still insufficient. Experimental conventional, cool and green roofs (three types) were established to comprehensively investigate the thermal performances in Hong Kong under typical summer conditions, as retrofitting strategies for an office building. The holistic vertical thermal behavior was investigated. The comparative cooling potentials were assessed. The results reveal a “vertical thermal sequence” in peak temperatures of each substrate layer for the conventional, cool and green roofs on a sunny day. However, local reversion in the thermal sequence may occur on a rainy day. Green roof-plot C (GR_C) demonstrates the highest thermal damping effect, followed by plot B (GR_B), A (GR_A) and the cool roof (CR) in summer. On a sunny day, the thermal dampening effectiveness of the substrates in the three green roofs is consistent: drainage > soil > water reservoir > root barrier. The holistic vertical thermal profiling was constructed in a high-rise office context in Hong Kong. The diurnal temperature profiles indicate all roof systems could effectively attenuate the temperature fluctuations. The daily maximum surface temperature reduction (SDMR) was introduced for cooling potential characterization of the cool roof and green roofs with multiple vegetation types. On a sunny day, the cool roof and green roofs all showed significant cooling potential. SDMR on the concrete tile of the best performing system was GR_C (26 °C), followed by GR_B (22.4 °C), GR_A (20.7 °C) and CR (13.3 °C), respectively. The SDMR on the ceiling ranked as GR_C, GR_B, GR_A and CR, with 2.9 °C, 2.4 °C, 2.1 °C and 2.1 °C, separately. On a rainy day, the cooling effect was still present but greatly diminished. A critical insight of a “warming effect at the ceiling” of the green roof was revealed. This research offers critical insights for unlocking rooftop cooling potential, endorsing cool roof and green roof as pivotal solutions for sustainable urban environments. Full article

Modern Earth observation combines high spatial resolution, wide swath, and dense temporal sampling, producing image grids and sequences far beyond the regime of standard vision benchmarks. Convolutional networks remain strong baselines but struggle to aggregate kilometre-scale context and long temporal dependencies without heavy tiling and downsampling, while Transformers incur quadratic costs in token count and often rely on aggressive patching or windowing. Recently proposed visual state-space models, typified by Mamba, offer linear-time sequence processing with selective recurrence and have therefore attracted rapid interest in remote sensing. This survey analyses how far that promise is realised in practice. We first review the theoretical substrates of state-space models and the role of scanning and serialization when mapping two- and three-dimensional EO data onto one-dimensional sequences. A taxonomy of scan paths and architectural hybrids is then developed, covering centre-focused and geometry-aware trajectories, CNN– and Transformer–Mamba backbones, and multimodal designs for hyperspectral, multisource fusion, segmentation, detection, restoration, and domain-specific scientific applications. Building on this evidence, we delineate the task regimes in which Mamba is empirically warranted—very long sequences, large tiles, or complex degradations—and those in which simpler operators or conventional attention remain competitive. Finally, we discuss green computing, numerical stability, and reproducibility, and outline directions for physics-informed state-space models and remote-sensing-specific foundation architectures. Overall, the survey argues that Mamba should be used as a targeted, scan-aware component in EO pipelines rather than a drop-in replacement for existing backbones, and aims to provide concrete design principles for future remote sensing research and operational practice. Full article

The deterioration of concrete hydraulic structures caused by chemical factors, seepage, and environmental stress necessitates advanced protective coatings that enhance durability, flexibility, and environmental sustainability. Conventional protective systems often exhibit limited durability under combined hydraulic, thermal, and chemical stress. In this study, a novel polyfluorosilicone-based coating system is presented, which integrates a deep-penetrating nano-primer for substrate reinforcement, a crack-bridging polymer intermediate layer for impermeability, and a polyfluorosilicone topcoat providing UV and weather resistance. The multilayer architecture addresses the inherent trade-offs between adhesion, flexibility, and durability observed in conventional waterproofing systems. Informed by a mechanistic study of interfacial adhesion and failure modes, the coating exhibits outstanding high mechanical and performance characteristics, including a mean pull-off bond strength of 4.56 ± 0.14 MPa for the fully cured triple-layer coating system, with cohesive failure occurring within the concrete substrate, signifying a bond stronger than the material it protects. The system withstood 2.2 MPa water pressure and 200 freeze–thaw cycles with 87.2% modulus retention, demonstrating stable mechanical and environmental durability. The coating demonstrated excellent resilience, showing no evidence of degradation after 1000 h of UV aging, 200 freeze–thaw cycles, and exposure to alkaline solutions. This water-based formulation meets green-material standards, with low volatile organic compound (VOC) levels and minimal harmful chemicals. The results validate that a multi-scale, layered design strategy effectively decouples and addresses the distinct failure mechanisms in hydraulic environments, providing a robust and sustainable solution. Full article

This work addresses the influence of Ni on the natural passivation process of stainless steels (SSs) in alkaline media simulating concrete pore solution by a combination of electrochemical and X-ray photoelectron spectroscopy (XPS) surface analysis. It was found that the involvement of Ni in the passive film on the SS promoted Fe depletion at the passive film/substrate interface and increased the content of Cr oxide during natural passivation, thereby enhancing the corrosion resistance of the passive film. The passive film with Ni has a higher breakdown potential and can be more easily re-passivated compared with a passive film without Ni. Full article

Nitrogen oxides (NO_x) emitted mainly from vehicle exhaust significantly contribute to urban air pollution, leading to photochemical smog and secondary particulate matter. Photocatalytic technology has emerged as a promising solution for continuous NO_x decomposition under ultraviolet (UV) irradiation. This study developed an eco-friendly permeable concrete incorporating activated loess and zeolite to improve roadside air quality. The high porosity and adsorption capability of the concrete provided a suitable substrate for a TiO₂-based photocatalytic coating. A single-component coating system was optimized by introducing colloidal silica to enhance TiO₂ particle dispersibility and adding a binder to secure durable adhesion on the concrete surface. The produced permeable concrete met sidewalk quality standards specified in SPS-F-KSPIC-001-2006. Photocatalytic NO_x removal performance evaluated by ISO 22197-1 showed a maximum removal efficiency of 77.5%. Even after 300 h of accelerated weathering, the activity loss remained within 13.8%, retaining approximately 80% of the initial performance. Additionally, outdoor mock-up testing under natural light confirmed NO_x concentration removal and formation of nitrate by-products, demonstrating practical applicability in real environments. Overall, the integration of permeable concrete and a durable, single-component TiO₂ photocatalytic coating provides a promising approach to simultaneously enhance pavement sustainability and reduce urban NO_x pollution. Full article

Construction and demolition waste, when used as the substrates of constructed wetlands, provide notable environmental benefits: purification performances and substantial economic advantages compared with conventional substrates such as gravels. However, the high effluent pH induced by waste concrete severely restricts its practical application in such systems. The body of research focused on overcoming this limitation is rather limited. To address this limitation, this study proposed a strategy based on the configurations of acid alkaline substrates. A pilot-scale vertical flow constructed wetland experiment was carried out to evaluate the feasibility of this approach through three treatments: (1) waste concrete alone (Concrete), (2) waste concrete as the upper layer combined with perlite (an acidic substrate (Concrete + Perlite)), and (3) a uniform mixture of waste concrete and perlite (Mixed). The results demonstrate that the Concrete treatment exhibited a persistent high pH problem, where the effluent pH values remained above 9, even after five months of operation. In contrast, the Concrete + Perlite and Mixed treatments effectively mitigated the excessive effluent pH (<8.2). Relative to the Concrete treatment, both the Concrete + Perlite and Mixed treatments significantly enhanced the removal efficiencies of chemical oxygen demand (COD) (from 43.7% to above 68.5%), total nitrogen (TN) (from 31.8% to above 86.5%), and ammonium nitrogen (NH₄⁺-N) (from 96.7% to 96.9%), whereas the removal efficiency of total phosphorous (TP) showed only a slight decrease. No significant differences in pollutant removal performance were observed between the Concrete + Perlite and Mixed treatments. Moreover, the Concrete + Perlite and Mixed treatments substantially increased the bacterial diversity within the substrate biofilm compared with the Concrete treatment, although differences in the bacterial community composition between the Concrete + Perlite and Mixed were relatively minor. Overall, configuring pH-balanced substrates through the combination of acidic and alkaline matrices provided effective and sustainable integrity for promoting the resource of construction and demolition waste in constructed wetlands. Full article

This study investigates the effects of surface roughness and interfacial agents on the bond performance of geopolymer–concrete composites (GCCs). Firstly, cement concrete substrates with four surface roughness conditions, including cast surface, drawn surface, chiseled surface and split surface, were prepared and their surface roughness was quantitatively characterized by the Joint Roughness Coefficient (JRC) based on the 3D surface morphology reconstruction technique. The GCC specimens were prepared by casting geopolymer concrete on cement concrete substrates and using three interfacial agents in the bonding interface. Then, the splitting tensile tests were conducted on GCC specimens and the effect of surface roughness and interfacial agents on the bonding strength and failure behavior of GCC was discussed. Finally, the empirical model of the bonding strength of the GCC was proposed by considering surface roughness, interfacial agent, and geopolymer tensile strength simultaneously. The results show that with increasing JRC, the bonding strength of GCC shows a trend of slow increase followed by significant increase, and the failure modes transitioned from interfacial debonding to concrete matrix failure. Among the bonding agents, geopolymer slurry achieved the highest bonding strength, followed sequentially by untreated interfaces, SBR-modified cement paste, and expansive agent-modified cement paste. The results also show that the empirical model can accurately predict the interface splitting tensile strength of GCC under different surface roughness and interfacial agents, with a prediction accuracy of 0.92. Full article

This study systematically investigates the influence of concrete substrate surface texture characteristics on the adhesion strength of waterborne epoxy coatings. By employing surface treatment techniques such as brush scouring and grinding, the surface roughness, pore structure, and three-dimensional morphology of concrete substrates were quantitatively analyzed using laser scanning and parameter modeling. The correlation between texture parameters (e.g., three-dimensional arithmetic mean roughness S_a and proportion of the hole area) and coating adhesion strength under varying curing temperatures (−18 °C, 20 °C, 40 °C, and 60 °C) was evaluated through pull-off tests and Pearson Correlation Analysis. Results indicate that the absolute proportion of hole area (A_a) (r ≈ −0.93) and S_a (r ≈ −0.81) are key factors affecting adhesion. Surface treatments, including 5 h scouring and 40 min grinding, enhanced pull-off strength by 40–60% by optimizing mechanical interlocking. A nonlinear regression model was established to predict adhesion strength, suggesting an operational S_a range of approximately 0.35–0.40 mm for the current coating system at 20 °C. Temperature significantly modulated the adhesion mechanism; low-temperature curing exacerbated pore defects, while high-temperature conditions intensified thermal stress. Practical guidelines to improve permeability include optimizing the surface roughness through grinding, strictly controlling the absolute proportion of holes, and using preheated or low-viscosity resin in a low-temperature environment. Full article