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This article focuses on a thorough review of the utilisation of the wavelet transform in the analysis of durability and structural health monitoring in automotive components. The evolving trend in research in automotive engineering structural integrity analysis has shifted from traditional laboratory experiments to a focus on signal processing and simulation-based methodologies over the past 30 years. This shift has motivated researchers to explore the application of the wavelet transform for signal processing in the analysis of structural integrity. The study is divided into five sections: the first section provides an introduction to durability analysis in automotive applications and highlights the advancement of research trends. The following section discusses the time and frequency domain signal processing approaches and their limitations. Next, the third section provides the theoretical background of the wavelet transform, including the continuous and discrete wavelet transforms. The fourth section emphasises the applications of wavelet transform as a signal processing tool in the durability and structural health monitoring of automotive components. Lastly, the summary highlights the importance of wavelet transform as a signal processing tool in automotive applications.

Conventional cement production is a major source of CO2 emissions. As a result, there is an increasing emphasis on finding sustainable alternatives for cement and their appropriate proportion in concrete. This investigation explores the optimization of supplementary cementitious materials (SCM) like ultrafine fly ash (UFFA) and silica fume (SF) content in high-performance concrete (HPC). The study includes the production of binary and ternary concrete mixes by replacing Portland cement with UFFA and SF at 0, 5, 10, and 15 %. A total of 16 mixes were prepared and evaluated in three stages. The first stage involved assessing the mechanical properties using compressive strength test and non-destructive test (NDT) results at various intervals. The second stage included durability tests, such as water absorption, volume of voids, and water permeability tests. In the third stage, characterization studies like XRD, TGA, and FTIR were conducted on the finalized mixes at 28 and 90 day intervals to find the optimum mix. The NDT findings revealed that all HPC mixes had superior quality, with a velocity of more than 5 km/s. From the test results, the ternary mix U10S15 exhibited superior compressive strengths of 104.28 MPa at 90 days of curing. The durability test results also demonstrated that the blend U10S15 showed a lower water absorption of 1.26 %, indicating a 44.9 % reduction in water absorption with extended curing. The FTIR and TGA analysis of HPC mixes demonstrated that blending the optimal amounts of UFFA and SF results in a dense microstructure. The mixture U10S15 exhibits a considerable peak shift from 950 to 980 cm⁻1. XRD peaks confirmed the presence of extra hydration peaks in blended specimens at 28° of 2θ. The optimized HPC mix containing 10 % UFFA and 15 % SF (U10S15) is appropriate for water-retaining structures due to its high strength, lower permeability, and higher particle packing effect.

This study examined the effects of thermal modification (TM) using spent engine oil as the heat transfer medium on the physico-mechanical properties and decay resistance of Bambusa spinosa Roxb. and Dendrocalamus asper (Schult. & Schult.f.) Backer. The TM process was conducted at three temperatures (140, 160 and 180 °C) and three durations (30, 60 and 90 minutes), coded as T1 to T9. The tests followed ASTM D 143–94 and ASTM D 2017–05 standards. The results revealed that thermally modified bamboo samples exhibited noticeable aesthetic colour changes, with a gradual darkening towards brown, and significantly improved dimensional stability, demonstrated by reductions in water absorption (27–75 %), thickness swelling (25–89 %), and equilibrium moisture content (31–64 %) compared with control samples. However, a decrease in flexural strength was observed at the highest temperature and longest duration (T9: 180 °C for 90 min), with reductions of 54–56 %. Despite this decrease in mechanical strength, the decay resistance of the T9-treated samples was comparable to chemically preserved bamboo, classifying them as highly resistant to decay fungi. Overall, the study demonstrated that spent engine oil is an effective medium for the thermal modification of bamboo when conducted in a controlled temperature setting.

This study investigates of using recycled concrete aggregates along with the reinforcement of polyolefin fibers to augment both the compressive strength and durability of concrete, in alignment with the principles of sustainable development. This study experimentally investigated the compressive strengths and durability of composite polyolefin fiber-reinforced recycled aggregate concrete (PFRRAC) exposed to chloride and acidic environments. For this purpose, 150 cubic concrete samples of 100 × 100 × 100 mm with various combinations of recycled aggregates and polyolefin fibers were made and subjected to axial compressive loading. The results show that the addition of fibers significantly enhances the compressive strength of concrete, with an increase of up to 34.36 % at 5 % fiber content. However, increasing the proportion of recycled aggregates reduces the compressive strength, with reductions ranging from 21.12 % to 43.85 % as the recycled aggregate content rises to 70 %. Moreover, the combination of fibers and recycled aggregates demonstrates potential for improving the sustainability and durability of concrete under challenging environmental conditions, particularly in chloride and acidic environments. In acidic environments, the inclusion of fibers significantly enhances the resistance to strength reduction. Furthermore, the study uncovers that a higher concentration of recycled aggregates exacerbates the reduction in strength in chloride-rich settings, emphasizing the imperative nature of meticulous mix design and material selection. The findings for the integration of even minor quantities of polyolefin fibers to amplify the performance and sustainability of concrete mixtures, especially when utilizing recycled aggregates, thus promoting eco-friendly construction practices.

Nanomaterials are incorporated to improve the characteristics of conventional concrete materials. Among them, Titanium dioxide (TiO2) nanoparticles exhibit sustainable concrete features such as optimization of materials, improvement of structures, recycling, and innovative waste management in materials and processes. This paper thoroughly elaborates on the effect of TiO2 nanoparticles on the composites of cement which in turn modifies the physical, mechanical, and ability to resist any chemical action, climate change, and abrasion; Furthermore, this study emphasizes the small fragment size, increased surface area and photocatalytic properties of cementitious composites. The key parameters for choosing TiO2 nanoparticles encompass their strength, antimicrobial characteristics, and stability against external environmental factors, covering a wide range of compatibility issues and exploring the fundamental characteristics of the material imbibing in cement. The present review includes the basic features of TiO2 nanoparticles, their utilization in cement, the fabrication processes, and influential factors on the workability of concrete. The review also comprises the workability of fresh concrete, mechanical qualities related to compressive, flexural, and tensile strength, and durability variables such as electrical resistivity, permeability, carbonation resistance, freeze-thaw cycles, and sulfate attack resistance. The report further investigates the ideal dosage of TiO2 nanoparticles and compares it to other nanomaterials utilized in cementitious compositions. More importantly, it emphasizes nano-titanium dioxide's ability to deal with pollutants in urban areas, notably nitrogen oxides (NOx), via its photocatalytic characteristics. The study explains how nano-TiO2 affects the microstructure of cement-based materials, resulting in improved durability, performance, and mechanical characteristics. Finally, this study outlines present problems and recommends future research using nano-TiO2 in cement-based materials.

Concrete, essential to global infrastructure, confronts urgent environmental challenges due to its high carbon footprint and resource-intensive production. In response, researchers are exploring nanoparticles, such as nano-silica (nS) and nano-titanium dioxide (nT), to enhance sustainability and performance. This review examines recent advances in their application. Nano-silica, prized for rapid hydration and enhanced strength, emerges as a promising additive. Studies indicate nS accelerates cement hydration, densifies the matrix, and improves durability and impermeability. Silica-based nano-coatings on glass textile-reinforced composites bolster bond strength and resilience. Similarly, nT offers diverse benefits to concrete. Beyond its traditional applications in photocatalysis, nS has been proven to refine pore structure, increase compressive strength, and enhance resistance to elevated temperatures. Additionally, nT adds to the self-cleaning properties of concrete surfaces, making it a promising additive for sustainable construction practices. Despite these advancements, challenges persist in the effective dispersion of nanoparticles within concrete matrices and ensuring their economic feasibility and regulatory compliance. Addressing these challenges will require interdisciplinary collaboration and innovative approaches to optimize dispersion methods, mitigate health risks, and develop robust regulatory frameworks. Future research directions should focus on developing multifunctional nanomaterials capable of imparting multiple desirable properties to concrete simultaneously, such as self-sensing, self-cleaning, and energy harvesting capabilities. Furthermore, efforts to optimize manufacturing processes and scale up production will be essential to realizing the full potential of nano-modified concrete in addressing the sustainability challenges facing the construction industry.

The present study explores the potential of producing an alternative ASTM Type IL portland-limestone cement (PLC) using up to 20 % eggshell powder (ESP) by mass as crushed ESP is similar in chemical composition to limestone. To this aim, the hydration, durability, and mechanical properties of the ESP blended cementitious system (using ASTM Type I/II portland cement) are compared to a commercially available ASTM Type IL cement system containing approximately 10 % limestone. ESP was prepared by milling for 3 h upon drying. Characterization of the ESP was done by x-ray diffraction for phase analysis, scanning electron microscopy for microstructural observation, and laser diffraction analysis for particle size distribution. A range of experimental tests were undertaken on both the ASTM Type I/II cement replaced with ESP and the ASTM Type IL systems. Results revealed that the utilization of up to 20 % ESP enhanced the heat of hydration secondary peak (C3A) by increasing the aluminate phase kinetics in the blended system at a favorable pH pore solution. Also, an accelerating effect on the setting time (increased by 20–100 mins) was observed for ESP samples. Chemical shrinkage, compressive strength, and degree of hydration were similar between the ESP and PLC samples. Results also revealed that ESP particles were relatively more effective in minimizing drying shrinkage by 20–35 %, which is attributed to possible internal curing effects. Overall, 10 % ESP blended with ASTM Type I/II cementitious system was similar to the 10 % limestone containing PLC system and could be used as waste material in producing an alternative ASTM Type IL cement.

In recent years, a discernible surge in greenhouse gas emissions has precipitated severe global warming, with the construction industry identified as a notable contributor, particularly through carbon dioxide emissions from cement production. As concrete stands as the second most extensively utilized material globally, its pervasive use amplifies the release of potent greenhouse gases. This paper introduces a novel approach to carbon capture in concrete materials by employing CO2 adsorbents that synergistically enhance the carbonization reaction, thereby augmenting capture efficiency. Biochar emerges as a promising candidate for carbon capture due to its robust CO2 adsorption capacity and its eco-friendly, cost-effective, and low-carbon production process. For instance, typically 1 ton of biochar has potential to sequester 3 ton of carbon dioxide from the environment. Various studies have explored the integration of biochar into concrete materials, aiming to improve mechanical, durability, and thermal properties, as well as the overall functionality of formed concrete composites. Beyond its role in enhancing concrete properties, biochar presents itself as an effective carbon sequestering agent with or without modification which is also reviewed in this paper. Concurrently, research efforts are underway to investigate the reinforcement properties and selective CO2 sorption capabilities of cellulose-based materials in concrete composites. Noteworthy attributes such as abundance, biodegradability, renewability, and cost-effectiveness position cellulose-based materials as promising alternatives to traditional reinforcing agents. This paper provides a comprehensive review of the latest advancements in the utilization of biochar and cellulose materials in concrete composite applications. Emphasis is placed on evaluating the durability, mechanical properties, and carbon capture potential of concrete composites augmented with biochar and cellulose. The synthesis of research progress in this domain serves to elucidate the current state of knowledge and offers insights into the future prospects of biochar and cellulose-enhanced concrete composites in the context of sustainable construction practices.

The alkali-activated materials have properties like commonly used cementitious materials, however, it does not have burning steps at high temperatures that emit large amounts of CO2 into the atmosphere. The main precursor used in the production of activated alkali materials is metakaolin, which in general has a heterogeneous chemical and mineralogical composition and high shrinkage. Therefore, the objective of this research is to evaluate the production potential of an alternative precursor based on calcined clay, aiming to standardize the material's shrinkage parameters. The properties of mechanical strength to bending and linear shrinkage, in the face of exposure to degradation cycles such as wetting/drying in saline environment and ice and thaw cycles, were analyzed to simulate and predict real application situations. The results indicate that the calcined clay has a lower mechanical strength than the composition containing metakaolin, due to its lower reactivity. However, in degradation simulations, it is observed that the calcined clay has greater durability than the composition with metakaolin, since it has less shrinkage. The compositions with calcined clay reached a maximum content of 1.2%, while compositions with metakaolin reached shrinkage of around 6%. In function, it is concluded that it is possible to use the alternative precursor based on calcined clay in alkali activated materials.

Phosphogypsum has often been used as an effective and environmentally friendly binder for partial replacement of cement, improving the engineering properties of slurries with high water content. However, the influence of phosphogypsum on the physicomechnical properties of stabilized soil subjected to wetting–drying cycles is not well understood to date. In this study, the effect of phosphogypsum on the durability of stabilized soil was studied by conducting a series of laboratory experiments, illustrating the changes in mass loss, pH value and unconfined compressive strength (qu) with wetting-drying cycles. The test results showed that the presence of phosphogypsum significantly restrained the mass loss in the early stage (lower than the 4th cycle), which in turn led to a higher qu of stabilized soil than that without phosphogypsum. After the 4th cycle, a sudden increase in mass loss was observed for stabilized soil with phosphogypsum, resulting in a significant drop in qu to a value lower than those without phosphogypsum at the 6th cycle. In addition, the qu of stabilized soils correlated well with the measured soil pH irrespective of phosphogypsum content for all wetting–drying tests. According to the microstructure observation via scanning electron microscope (SEM) and X-ray diffraction (XRD) tests, the mechanisms relating the sudden loss of qu for the stabilized soils with phosphogypsum after the 4th wetting-drying cycle are summarized as follows: (i) the disappearance of ettringite weakening the cementation bonding effect, (ii) the generation of a larger extent of microcrack, and (iii) a lower pH value, in comparison with the stabilized soil without phosphogypsum.

The icing of wind turbine blades leads to a decrease in output power, seriously jeopardizing the economic benefits and operational reliability of wind farms. Conventional deicing techniques require expensive equipment and consume a large amount of energy. Low-interfacial toughness coatings without energy dissipation are believed to be a highly potential passive deicing technology. However, the durability in service is facing challenges. Herein, low-interfacial toughness PDMS coatings were prepared by physical blending. Through the optimization of added plasticizers and SiO2, PDMS coatings with excellent large-scale deicing performance were obtained. The constant deicing force and ice adhesion strength were reduced to 14.69 N/cm and 12.63 kPa, respectively. Moreover, a systematic durability assessment of the PDMS coating was carried out to address the actual operating conditions of wind turbines. Fortunately, the results showed that the PDMS coating could withstand 200 icing/deicing cycles while maintaining constant deicing force and ice adhesion strength of less than 50 N/cm and 30 kPa, respectively. After long-term thermal aging (21 days), UV irradiation (42 days) and salt spray corrosion (20 days), the PDMS coating still retained superior icephobicity and outstanding large-scale deicing performance. This work contributes to the research and development of low-interfacial toughness materials for large-scale deicing applications on wind turbine blades.

Geopolymer composites (GC) have drawn much attention regarding sustainable cementitious materials in recent years. Polyvinyl alcohol (PVA) fiber is often added into GC to improve properties of the composite. In order to better understand the effect of PVA fiber on properties of GC and its mechanism, this paper sums up the advance in properties of PVA fiber-reinforced geopolymer composites (PVA-FRGC). Viscosity of GC increases with the increase of PVA fiber, so a reduced setting time and poor flowability of GC occurs. This paper expounds that PVA fiber with moderately high content and short length has significant effects on mechanical properties of GC. Most mechanical performances of GC can be tremendously improved thanks to fiber-bridge effect. Besides, it's worth noting that 0.2%–0.3% content of PVA fiber has optimal enhancement in compressive strength of GC. The details also contain the enhancement of PVA fiber incorporation on durability of GC, and related models used in predicting performance of PVA-FRGC are expounded. In addition, the strengthening mechanism from scanning electron microscope (SEM) images showed that PVA fibers had strong chemical bond strength and friction bond strength with geopolymer matrix, and future work need to be done is recommended. In general, PVA-FRGC has an excellent performance on mechanical properties and durability compared with plain GC. The paper is designed to make contributions for development of green building materials. This paper aims to provide guidance for the application of PVA fiber in GC and serve as support for practical application of PVA-FRGC in construction engineering.

As the demand for sustainable construction materials rises, hemp-infused concrete has emerged as a promising solution to reduce carbon emissions and promote eco-friendly building practices. This review critically assesses hemp concrete's mechanical, thermal, and durability properties, highlighting its potential for widespread adoption in various industries. Hemp's porous structure contributes to improved thermal insulation, soundproofing, and biological resistance, making it suitable for in-fill materials, plastering, and insulation applications. However, its low compressive and flexural strength remains challenging, limiting mainstream use. Hemp content and composition variations have resulted in differing properties, necessitating further research to optimize the material. The study identifies the growing collaboration among countries to promote bio-based materials but acknowledges the lack of standardized norms for hemp concrete in general construction. It stresses the importance of developing uniform standards to ensure consistent quality, performance, and regulatory compliance. This study explores the properties of hemp-infused concrete. It assesses its potential as a sustainable building material while identifying gaps in research and standardization needed for its widespread adoption in the construction industry.

A novel type of cementitious composite was proposed and studied, where recycled polyvinyl chloride (PVC) aggregate was employed as fine aggregate to partially replace the fine aggregates of sand in varying proportions. The fine aggregates of sand were replaced at five volume ratios (5 %, 10 %, 20 %, 30 %, and 50 %). A series of experiments were carried out to evaluate the workablity, mechanical properties and durability of the proposed cementitous coposites with PVC. The scanning electron microscopy (SEM) was applied to study the relationships between the mechanical properties and microstructures. The results showed that the fluidity increased by 12.5 % with a 50 % PVC replacement. However, the dry density decreased by 5 %, and water absorption increased with a higher PVC content. The compressive strength declined by 3.7 %, 6.1 %, 6.3 %, 11.5 %, and 28.8 % as the replacement ratio increased from 5 % to 50 %; while, the flexural strength decreased by 3.7 %, 6.8 %, 9.8 %, 17.0 %, and 23.5 %, respectively. The relative dynamic elastic modulus showed a 12.2 % reduction at 50 % PVC replacement. These decreases are attributed to the weaker bonding between PVC particles and the cement matrix, increased porosity, and micro-cracks at the interface transition zone, as confirmed by the SEM examination. The microstructural analysis revealed more porous and cracked interface zones with a higher PVC content, which impacted the mechanical properties of the composites. Despite the reduction in the mechanical strength, the durability of the composite improved significantly, with an enhanced resistance to chloride ion penetration and freeze-thaw cycles.

The use of crushed sand instead as a substitute for river sand has gained importance in construction practices due to the limited availability of river sand. This study examines the physical and microstructural impacts of crushed sand on mortar carbonation. Using X-ray Diffraction (XRD), Thermo-Gravimetric Analysis (TGA), and Scanning Electron Microscopy (SEM). We highlight the influence of substituting river sand with crushed sand after exposure to 3 % CO2 in an accelerated carbonation chamber for 28 days. The mass fractions of Ca(OH)2 and CaCO3 were determined by thermogravimetric analysis, and a decrease in porosity was observed with an increasing proportion of crushed sand in the mixture. Partial or total substitution of river sand with crushed sand, for environmental purposes, shows improved resistance against CO2 attack. Our study reveals the beneficial effects of crushed sand in reducing porosity and carbonation compared to river sand.

Ammonia protonic ceramic fuel cells (NH3-PCFCs) are highly appealing energy conversion technologies due to their high efficiency, environmental responsibility, and benign safety features. Nonetheless, progress in NH3-PCFCs is notably impeded by the restricted performance and insufficient lifespan of standard Ni-cermet anodes for ammonia cracking, especially at 550 °C or below. Herein, we report an efficient ammonia cracking layer with a formula of xCo3O4/100-xBaZr0.8Y0.2O3-δ (Co/BZY) (x=10, 20, 30), which is deposited onto the Ni-BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (BZCYYb) anode to significantly enhance the NH3 decomposition catalytic activity, thereby improving the performance and durability of NH3-PCFCs at low temperatures. The cells with the addition of a 20Co/80BZY anode catalytic layer (ACL) exhibit low area-specific resistance (ASR) and promising operational longevity under NH3 conditions. At 550°C, the NH3-PCFCs with a 20Co/80BZY ACL exhibit a high peak power density of 0.626 W cm−2 and promising operation durability. This study provides important guidance for constructing high-performance and durable NH3-PCFCs.

Urbanized oil-rich regions, such as Ahvaz, Iran, face significant geotechnical challenges due to widespread oil contamination in soils. This contamination poses a major problem for construction projects, particularly with the increasing installation of oil pipelines within city limits, which exacerbates soil pollution risks. Addressing this challenge, the present study explores an innovative solution using pumice powder (PP), a natural silica-based stabilizer, to improve the long-term geotechnical properties of oil-contaminated fine-grained soils. This research fills a critical knowledge gap by evaluating the effectiveness of PP in stabilizing soils contaminated with varying oil concentrations (4 %, 7 %, and 10 %) and treated with different percentages of PP (5 %, 10 %, and 15 %). The comprehensive investigations in this study included assessments of mechanical properties, durability, microstructural changes through field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and chemical properties using Fourier transform infrared analysis (FTIR). The findings revealed that 10 % PP significantly increased the soil's long-term unconfined compressive strength by up to 370 %, enhanced durability, and reduced susceptibility to cracking, marking a sustainable alternative to environmentally costly traditional stabilizers. This novel use of PP not only fills a crucial knowledge gap concerning the long-term structural integrity and resilience of such soils but also advances the field towards more sustainable and ecologically responsible soil stabilization practices, contributing broadly to environmentally friendly construction methodologies in the oil-rich regions.

Superabsorbent polymers (SAP) are considered as a promising assortment of chemical admixtures which present novel prospects for influencing the properties of cementitious materials in the fresh, setting, and hardened states. However, the diversity of commercial SAP, especially in terms of monomers, crosslinking agents, and synthesis methods, still poses many obstacles in their large-scale application. Therefore, this review aims to shed light on intrinsic absorption and release mechanism of various SAP and its impact on rheological properties, mechanical properties, shrinkage properties, and durability for cementitious materials. Our research findings indicate significant differences in the water absorption and release mechanisms between ionic and non-ionic SAP. The swelling of non-ionic SAP is dependent on the osmotic pressure formed between the polymer network and the solution. In contrast, ionic SAP not only exhibits osmotic properties but also generates charged hydrophilic groups in solution, which is a crucial factor contributing to polymer swelling. The water absorption characteristics of SAP facilitate the regulation of early cement matrix hydration and ensure the long-term stability of the concrete structure. These attributes are crucial for maintaining stable development in cement hydration and ensuring the overall structural integrity over time. The knowledge gleaned from this review offers a robust framework for the further research work on SAP and serves as support for practical application of internally cured concrete in construction engineering that need to withstand challenging environmental conditions.

This study investigates the potential of using recycled concrete aggregate (RCA) derived from construction and demolition waste as a replacement for natural aggregate in cement-stabilized macadam (CSM). Various substitution rates of RCA, ranging from 0 % to 100 %, were examined with a focus on mechanical properties and durability, including unconfined compressive strength (UCS), indirect tensile strength (ITS), compressive elastic modulus, drying shrinkage, frost resistance, scour resistance, and water damage resistance. Nanoindentation was used to analyze the interfacial transition zones (ITZs) within the CSM. The results show that with a fixed cement content, the UCS, ITS, and compressive elastic modulus decrease as the RCA content increases. Higher RCA content also leads to reduced drying shrinkage, frost resistance, scour resistance, and water damage resistance. Nanoindentation revealed that ITZ1 and ITZ2 have similar thicknesses (∼50 μm), while ITZ3 is about 80 μm thick, highlighting the intricate physical composition of ITZs, including pores, low-density C-S-H, high-density C-S-H, and Ca(OH)2. These findings provide critical insights for optimizing sustainable CSM design using RCA, thereby promoting environmental sustainability in road construction.

The Australian construction sector faces a dual challenge of high demand for concrete bricks and the need for sustainable materials. This research investigates eco-friendly structural concrete brick formulations, incorporating pond ash and unwashed recycled glass sand. It aims to provide scientific evidence on their engineering performance as per AS/NZS 4455.1:2008 standard, thermal insulation, and fire resistance properties. Additionally, microstructural, chemical, and pore-structure analyses are carried out to gain insights into the reaction mechanisms and the evolution of their properties. Findings indicate that bricks with 15 % pond ash and 20 % unwashed glass sand meet structural requirements with compression strength of 29.63 MPa at 28 days. Enhanced thermal insulation is observed due to the lower densities of pond ash and glass sand. After a 2-hour exposure to elevated temperatures, the unexposed surface of these bricks remains below 180°C, satisfying fire resistance criteria for wall elements. However, microstructure and chemistry analyses suggest lower compression and tensile strength comparable conventional bricks because of low reactivity of the pond ash and the smooth surface of the glass sand.

The effect of different coal bottom ash (CBA) gradings on ground granulated blast furnace slag (GGBS) binary blended cement mortar is not well-documented in current literature. Therefore, previous studies have reported inconsistent and contradictory effects of using various CBA gradings as a fine aggregate replacement in mortar and concrete. Hence, the present work aimed to establish the influence of different coal bottom ash (CBA) gradings, which is crucial for reducing coal power plant waste by utilising larger fractions of CBA in mortar and concrete without compromising its hardened properties. Specifically, this study investigated the optimal grading of coal bottom ash (CBA) for natural sand replacement in ground granulated blast furnace slag (GGBS) binary blended cement mortar. The research examines three CBA gradings: passing 10 mm sieve (R-CBA), passing 4.75 mm sieve (S-CBA), and grading according to BS EN12620 (Gr-CBA) at 20 %, 40 %, and 60 % sand replacement levels for comparison. Resultant mortar specimens were tested at 7, 28, and 91 days for mechanical strength, fluid transport, and drying shrinkage. Results show that all CBA gradings performed better than the control mix (with river sand only). The Gr-CBA mix outperformed the S-CBA mix by up to 29 % in strength due to highly consistent grading. R-CBA mix exhibited optimal performance compared to the other two CBA mix up to 30 % in strength. The coarser grading of the R-CBA mix enhances the interfacial transition zone and aggregate-binder bond and, hence, exhibited a better performance. This study highlights the potential use of R-CBA grading to increase the CBA reuse rate in mortar or concrete while maintaining desirable performance.

Unlike traditional steel bars, the long-term performance of GFRP (glass fiber reinforced plastic) bars in natural erosion environments remains unclear. This study simulated the water environment at the entrance of the Chai River, a tributary to Dianchi Lake in China, and investigated the mechanical properties of GFRP bars under varying corrosion concentrations. Microstructural analysis using SEM (scanning electronic microscopy) was also conducted to uncover the degradation mechanism. The results showed that after 180 days of immersion in natural water and exposure to environmental concentrations of 5 times, 10 times, and 20 times, the tensile strength of GFRP bars exhibited reductions of 2.8 %, 4.2 %, 7.2 %, and 9.5 %, respectively. However, the compressive strength decreased by 38.0 %, 48.6 %, 50.2 %, and 53.2 % under the same condition. As the number of corrosion cycles increased, the rate of strength decline decreased gradually. The combined action of hydroxyl ions generated through bicarbonate hydrolysis and water molecules in the solution led to the breakdown and swelling of the resin matrix, ultimately causing detachment at the fiber-resin interface. An analysis was conducted on the time-shifted regression equation of the accelerated conversion factor (ASF) under different concentrations, based on the correlation between natural erosion and acceleration testing. It was observed that a strong correlation exists between the strength retention rate and the natural erosion environment at 5 times the concentration. Finally, an improved time-shift method based on the Arrhenius theory was proposed to predict the tensile strength of GFRP bars in a natural erosion environment.

Polymer mortars have attracted immense interest as effective and rapid repair materials in the modern construction industry owing to their advantages over conventional Portland cement mortar. Various types of polymer binders, such as unsaturated polyester resin (UPR), have been used in polymer mortar owing to their low cost, excellent strength, high workability, and rapid curing. However, the brittleness of Unsaturated polyester resin mortar (UPRM) limits its applications in construction. Herein, we investigated the feasibility of reutilizing locally available industrial crumb rubber (CR) (CR,

The use of seawater and sea sand in concrete is becoming more prominent, particularly for marine structures, as a solution to the shortage of freshwater and natural aggregates. This research evaluates the durability of concrete made with seawater, fly ash, and recycled sea aggregates. Various techniques, including SEM-EDS, FTIR, M-Ct, and TG/DTA, were employed to analyze the microstructure of this concrete. Mechanical properties were assessed by measuring the compressive strength after 28 days. The findings indicated that higher proportions of sea-based materials increased porosity, while FTIR showed the absence of portlandite due to the use of sulfate-resisting cement. SEM-EDS confirmed XRD results quantitatively. Compressive strength improved with up to 50 % replacement of the original composition. The study demonstrates that incorporating seawater enhances the pozzolanic properties of cement, increasing the formation of Calcium-Silicate-Hydrate (C-S-H) gel, which contributes to a dense microstructure and good mechanical strength comparable to conventional freshwater concrete. These results support the use of seawater, sea sand, and recycled aggregates as sustainable alternatives, balancing structural performance and environmental sustainability in construction materials.

The utilization of coal gangue (CG) as a substitute for cement in building materials offers an effective solution to mitigate resource wastage and environmental pollution caused by CG accumulation while also reducing carbon dioxide (CO2) emissions. This paper employs orthogonal experiments to examine the effects of CG content, water/binder ratio (w/b), and foam content on the mechanical, thermal insulation, and durability properties of coal gangue foam concrete (CGFC). Additionally, we explored the properties of CGFC incorporating organic agricultural waste. Microscopic analyses focused on phase composition, morphology, and pore structure, providing crucial insights into how these experimental factors affect FC properties. The results indicate that foam content significantly impacts the mechanical properties of the concrete, while the w/b ratio is critical for its thermal insulation and water absorption capabilities. Introducing agricultural waste fibers notably enhances thermal insulation and freeze-thaw durability. Specifically, adding 1 % of 15 mm processed straw fibers (PST) optimally improved CGFC performance by creating a stronger bond with the hydration products. Preparing FC using inorganic coal gangue and organic solid waste is essential for effective waste management and the development of energy-efficient insulation applications in the construction sector.

This study used recycled aggregate (RA) and mineral additions to design large-pore sandy recycled concrete (LPSRC) using a design porosity (DP) of 25 %, 20 %, and 15 %. Thus, the related effects of recycled coarse aggregate (RCA), recycled fine aggregate (RFA) and fly ash (FA) on the compressive strength, frost resistance (using slow and fast freezing methods), and sulfate attack properties of LPSRC were systematically studied. Moreover, to reduce the error between the design and theoretical porosity values, the bulk density ratio adjustment method was employed to design the theoretical porosity. The results of binarization analysis demonstrated that the deviation of the actual porosity caused by the sidewall effect was ∼2 %, which should be considered during DP design and performance evaluation. The compressive strength of the LPSRC after 56 curing days increased by 35.9 % on average as the DP was reduced from 25 % to 15 %. In a freeze–thaw cycle test, the slow freezing method was more accurate for evaluating the frost resistance of the LPSRC. Under the same conditions, the mass loss rate of the LPSRC calculated using the slow and fast freezing methods was 3.2 % and 7.62 %, respectively. This distinction is pivotal for establishing reliable frost resistance criteria for LPSRC in cold-weather applications, complementing previous research in the field. In terms of sulfate deterioration resistance, compressive strength corrosion factors decreased with increasing DP. Additionally, damage was mainly concentrated at the contact interface between RCA and the cement matrix, while the aggregate itself showed relatively little damage, suggesting RCA application has a positive effect on improving preparation of the LPSRC. Specifically, as DP increased from 15 % to 25 %, the average reduction in the compressive strength corrosion factors for LPSRC after 30 and 60 times of dry–wet cycle were 9.64 % and 8.37 %, respectively, illustrating a clear correlation between higher DP and reduced sulfate resistance. This study contributed to the LPSRC design and production using RCA, RCF and FA, that positively impacts to the sustainable development of the construction industry and helps to evaluate the effectiveness of RA in macroporous concrete. Moreover, the strategic implementation of design porosity has been shown to optimize the structural integrity and performance of the concrete, achieving a balance between strength and workability, which is crucial for the concrete's durability and its ability to adapt to various environmental conditions.

Stone masonry structure has been widely utilized in dam construction due to its low cost and easy operation. However, its long-term durability has also been raised wide concern. Based on the demolition of the Kada dam, this study investigated whether the durability of block stones and mortar in the stone masonry dams can be guaranteed under the influence of combined factors, such as freeze-thaw cycles, water seepage, and high-velocity erosion. Through a combination of on-site sampling and laboratory testing, the physical properties, mechanical performance, composition, and pore characteristics of the block stones and mortar, predominantly composed of limestone, were thoroughly examined and evaluated. The results indicate that both the crest and center block stones exhibit a dense structure, with a saturated compressive strength exceeding 50 MPa, meeting the strength requirements for the reconstruction of new buried concrete gravity dams, which could supply sound foundation for the reuse and recycling during reconstruction of the dam.

Fewer studies related to the durability of multi-source solid waste geopolymer cementitious materials and the massive accumulation of industrial solid waste are urgent problems to be solved in practice in Inner Mongolia, China. In this paper, blast furnace slag (BFS), fly ash (FA), and calcium carbide slag (CCS) are used as the main raw materials to prepare geopolymer cementitious materials (BFCG) with Calcium Carbide Slag as the Ca-source alkali activator and NaOH as the Na-source alkali activator, considering their durability properties. By assessing the indicators of mechanical performance, engineering performance, and the synergistic mechanism of Ca2+ and Na+ in multi-source solid waste geopolymer, four sets of BFCG ratio optimization schemes are selected. XRD, FT-TR, SEM-EDS, and other testing methods are used to analyze its freeze–thaw resistance and acid–alkali-salt corrosion resistance. The following conclusions are drawn: the BFCG prepared under the synergistic excitation of Ca2+ and Na+ has better resistance to freezing and thawing, as well as acid-alkali-salt corrosion, both of which are in accordance with the standard specifications for road construction in China. After the freeze–thaw cycles, BFCG still has more three-dimensional network-like silica-aluminate structures, a compact micromorphology, and small pores. Its strength loss rate is 0.56 %–15.56 %, the mass loss rate is 0.19 %–1.26 %, and the relative dynamic modulus is 79.56 %–100.25 %. In a NaOH environment, the crystal type of BFCG did not change significantly, and the resistivity coefficients are 115.78 %–143.54 %. In a Na2SO4 environment, the decalcification or dealumination of C-A-S-H gel leads to the formation of a gel rich in silicon, magnesium, and aluminum phases, with a corrosion resistance coefficient of 101.8 %–119.96 %. In a HCl environment, HCl erosion inhibits the growth of hydration product crystals, with corrosion resistance coefficients ranging from 73.83 % to 97.24 %. BFCG-D has the best resistance to freezing and thawing as well as acid and alkali corrosion. BFCG-D has the best resistance to freezing and thawing as well as acid and alkali corrosion. These studies show that BFCG offers a promising solution for improving the durability of road base materials and reducing industrial solid waste.

Bamboo scraps/magnesium oxychloride composites (BS/MOC) is a new low-carbon and eco-friendly building material, which is composed of magnesium oxychloride cement (MOC) as the matrix and bamboo scraps as the reinforcing materials. However, the poor strength and durability of BS/MOC under special environmental conditions seriously restrict its application range. To solve the above problems, citric acid (CA), D-gluconic acid sodium salt (GS), and styrene-acrylate emulsion (SAE) were used as modifiers to improve BS/MOC properties. The effect of modifier addition on the mechanical strength and durability of BS/MOC was investigated under dry-wet cycling environments. The phase composition, microstructure, pore structure, and Clˉ concentration of BS/MOC were characterized by XRD, TGA, SEM, MIP, and ICS-600. The results showed that CA and GS improved the interface adhesion between bamboo scraps and MOC matrix, and both inhibited the hydration reaction of the residual MgO and the hydrolysis of phase 5 crystals, resulting in good mechanical properties and microstructural stability of BS/MOC under dry-wet cycles. GS outperformed CA in refining pore structure, improving mechanical properties and durability of BS/MOC under identical dry-wet cycles. Conversely, the addition of SAE increased initial defects and interfacial transition zones in the BS/MOC matrix, and increased the total porosity and the harmful pores content, which negatively affected the mechanical properties and durability of BS/MOC.

The escalating demand for methods to diminish cement usage without compromising the strength and durability of concrete mixtures has led to an intensified exploration of alternative mixture ingredients. Nano silica has emerged as a prominent supplementary cementitious material, recognized for its capability to partially substitute cement. Despite this potential, there was a gap in the literature on the effects of nano silica on the concrete’s fresh and hardened properties, particularly when used in conjunction with silica fume. This gap motivated the current investigation, aiming to capture and compare the effects of incrementally substituting silica fume with nano silica in self-consolidating concrete (SCC). For this purpose, four nano silica dosages—1%, 2%, 3%, and 5%— were considered as replacements for silica fume. A range of experiments, including slump flow, T50 time, and L-box tests, were conducted to assess the workability of the developed SCC mixtures. Subsequent analyses focused on key mechanical attributes, including the static modulus of elasticity, compressive strength, and tensile strength. The research further encompassed water absorption, penetration depth, and electrical resistivity evaluations to understand the durability characteristics of the developed mixtures. The scanning electron microscopy (SEM) analyses complemented these tests, offering a microstructural perspective to further explain the outcomes. This investigation’s findings offer novel insights into leveraging nano silica’s distinctive properties to achieve the desired SCC properties while reducing the environmental impact of this class of mixtures.

Heritage sites built with natural stone are at risk from fires, which can alter stone properties and compromise its structural integrity. Over 60 studies in the past three decades have examined fire impact on natural stone, providing insights for their prevention and restoration. The primary objectives are to develop effective strategies to mitigate fire risks, protect heritage structures, and ensure the preservation of our cultural legacy. Two noteworthy Portuguese limestones used as heritage building materials: Lioz (LL) and grey Ançã stone (GAS), were studied regarding the effect of high-temperature exposure for simulating fire at 200 °C, 400 °C and 600 °C, followed by cooling in water to reproduce fire extinguish in natural stone buildings. The findings provided insights into how the different temperatures impact the stone morphological, physical and mechanical properties. Color measurements (CIE L*a*b*) showed a color difference from 3 to 32 %; SEM-EDS confirmed microstructure modifications after fire exposure with cracks formation and intragranular porosity development. Among the diverse physical and mechanical properties of the stones, uniaxial compressive strength decreased from 1 to 33 %, Leeb D hardness decreased up to 12.2 %, lowering in open porosity was detected in the range 70–289 % and ultrasound speed propagation were significantly affected after thermal cycle at 600 °C with a negative variation reaching 49 %. Results from TGA show a loss of mass due to retained water (∼40 °C) and loss of hydration water at ∼ 120 °C in both limestones. The total mass loss (∼42–∼44 %) is associated with the loss of H2O, CO2. In conclusion, stones with higher toughness and compression strength exhibited reduced damage at high temperatures due to their enhanced resistance to fracturing under stress. As limestone's mechanical strength decreases under high temperatures, it's advisable to increase its thickness to ensure sufficient support for loads and intended conditions of use. The deficiency of analysis on limestone's mechanical decay from fire reveals a significant knowledge gap regarding the complete extent of damage and deterioration in stone heritage structures.

Background: The rapid spread of pyrethroid resistance has led to a change in strategy, going from pyrethroid-based nets to PBO + pyrethroid-treated nets. Although these new nets may significantly improve the control of pyrethroid-resistant mosquitoes, their durability in the field remain not yet well documented. This study investigates the durability and washing resistance of Olyset-Plus nets in the city centre and rural areas of Bertoua, Cameroon. In each site, a semi-structured questionnaire was administered to at least 190 households with an Olyset-Plus net. Factors such as net use, physical integrity and bioefficacy were recorded. Bioassays were conducted on the collected nets to assess their bioefficacy and resistance to washing. They were tested against wild Anopheles gambiae sensus lato (s.l.). Unused nets and the Kisumu strain were used as controls. Washing and cone testing of the nets was carried out according to standard WHO protocols. Results: A high rate of net use by children was recorded in the urban area (89.1% (106/119)) compared to the rural area (39.7% (118/297)). The majority of Olyset-Plus nets inspected 82.2% (162/197) in the rural area and 88% (206/234) in the urban centre were in good condition (Hole Index

This study focuses on creating a superhydrophobic, durable, and exceptionally transparent coating with dual-scale roughness by naturally formed raspberry-like particles. This approach facilitates the management of surface roughness at both single and dual scales through variations in surface functionalization temperature. We illustrated that adjusting the temperature of organosilanes functionalization on the surface allows for various reactions, such as the direct grafting of metallic precursors or their polymerization on the surface, resulting in the formation of large raspberry-like particles.We investigated the impact of nanoparticle concentration, functionalization duration, and reaction temperature on surface properties. Our results reveal that a concentration of 1.5 % SiO2 nanoparticles, combined with surface functionalization using TCMS for 4 h at 3 °C, provides the optimal conditions for creating a surface that combines superhydrophobicity, transparency, and acceptable durability. The resulting surface exhibits an impressive contact angle of 158.9°, a sliding angle of 2°, and a transmittance rate of 82 %.Furthermore, the coating demonstrates remarkable resistance to abrasion for up to 35 cycles and can withstand temperatures up to 280 °C. It also offers enhanced protection against UV radiation for 50 h and improved resistance to sand abrasion for up to 30 s, enduring bombardment pressures of up to 6 bars. Moreover, the coating presents several advantages in terms of surface cleaning.

Summary: Background: Longitudinal changes in vaccination-induced immune response remain inadequately characterized in adolescents. We present long-term safety, immunogenicity, and COVID-19 incidence following a 2-dose mRNA-1273 100-μg primary series, and immunogenicity following a single dose of mRNA-1273 50 μg in vaccine-naïve adolescents. Methods: TeenCOVE (NCT04649151) Part 1 randomized adolescents (12–17 years) to 2-dose mRNA-1273 100 μg (n = 2490) or placebo (n = 1243) 28 days apart. Subsequently, placebo recipients (n = 91) could receive open-label mRNA-1273. Primary objectives included prespecified adverse events through 12 months; secondary objectives were COVID-19 incidence and neutralizing and spike-binding antibodies (nAbs/bAbs) against SARS-CoV-2 (ancestral/variants) through 12 months (study period: December 2020–January 2022). In Part 2, vaccine-naïve adolescents (n = 52) received up to 2 doses of mRNA-1273 50 μg; interim analysis included Day 28 (D28) nAbs post-injection 1 in SARS-CoV-2-baseline-positive participants (serologic/virologic evidence of prior infection). Findings: In SARS-CoV-2-baseline-negative adolescents (N = 369), mRNA-1273 induced robust nAb responses versus baseline (geometric mean concentration [GMC] = 11; 95% CI, 11–12) at D28 (1868 [1759–1985]), 6 months (625 [583–670]) and 12 months (550 [490–618]) post-injection 2. Similar bAb responses were observed to alpha/beta/delta/gamma variants; nAb/bAb responses were similar in SARS-CoV-2-baseline-positive adolescents. The 2-dose mRNA-1273 100-μg primary series was generally well-tolerated; one case of nonserious, moderate, probable acute myocarditis resolved by 8 days from symptom onset. A single dose of mRNA-1273 50 μg in SARS-CoV-2-baseline-positive adolescents induced higher D28 nAb GMCs against ancestral SARS-CoV-2 than 2-dose mRNA-1273 100 μg in young adults (geometric mean ratio = 4.322 [3.274-5.707]). Interpretation: The overall risk–benefit profile of mRNA-1273 remains favorable in adolescents, with durable 12-month immune responses against SARS-CoV-2 (ancestral/variants). A single mRNA-1273 50-μg injection in vaccine-naïve adolescents elicited robust immune responses against SARS-CoV-2. Funding: This project has been funded in whole or in part with federal funds by the Department of Health and Human Services, United States; Administration for Strategic Preparedness and Response, United States; Biomedical Advanced Research and Development Authority, United States, under Contract No. 75A50120C00034. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Department of Health and Human Services or its components.

Torrefied biomass is a vital green energy source with applications in circular economies, addressing agricultural residue and rising energy demands. In this study, ML models were used to predict durability (%) and mass loss (%). Firstly, data was collected and preprocessed, and its distribution and correlation were analyzed. Gaussian Process Regression (GPR) and Ensemble Learning Trees (ELT) were then trained and tested on 80 % and 20 % of the data, respectively. Both machine learning models underwent optimization through Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) for feature selection and hyperparameter tuning. GPR-PSO demonstrates excellent accuracy in predicting durability (%), achieving a training R2 score of 0.9469 and an RMSE value of 0.0785. GPR-GA exhibits exceptional performance in predicting mass loss (%), achieving a training R2 value of 1 and an RMSE value of 9.7373e-05. The temperature and duration during torrefaction are crucial variables that are in line with the conclusions drawn from previous studies. GPR and ELT models effectively predict and optimize torrefied biomass quality, leading to enhanced energy density, mechanical properties, grindability, and storage stability. Additionally, they contribute to sustainable agriculture by reducing carbon emissions, improving cost-effectiveness, and aiding in the design and development of pelletizers. This optimization not only increases energy density and grindability but also enhances nutrient delivery efficiency, water retention, and reduces the carbon footprint. Consequently, these outcomes support biodiversity and promote sustainable agricultural, ecosystem, and environmental practices.

The long-term bond degradation and strength retention of flexural bond prisms strengthened with carbon fiber-reinforced polymer (CFRP) composite and galvanized steel mesh (GSM) systems, bonded to concrete using epoxy adhesives and cement-based mortar under aggressive conditioning regimes are compared in this paper. Notched prisms strengthened using low-cord density steel mesh (LSM) with epoxy (SME-strengthened) and cement mortar (SMM-strengthened), and CFRP-epoxy systems were weathered under saline water and direct sunlight for a period of 28 and 540 days. The results of the study were analyzed based on experimentally obtained ultimate load (Pu) values and empirically calculated average bond shear stress (τavg) and prism strength retention (Rp) values. The bond strength degraded by 39 and 34 % in CFRP strengthened, 2.9 and 33 % in SME strengthened, and 2.8 and 10.8 % in SMM-strengthened specimens following the 540-day exposure to saline water and direct sunlight, respectively. The average prism retention ratio was calculated to be 0.61 and 0.66 for CFRP-strengthened, 0.97 and 0.67 for SME-strengthened, and 0.97 and 0.89 for SMM-strengthened specimens after 540 days of saline water and direct sunlight exposure. Flexural prism environment strength reduction factors (CE) were proposed as 0.60, 0.95, and 0.95 for CFRP, SME, and SMM-strengthened specimens under saline water exposures and 0.65, 0.65, and 0.85 for CFRP, SME, and SMM strengthened specimens under direct sunlight exposures. Saline water exposure was observed to be most critical to all strengthening systems. Although CFRP-strengthened specimens showed minimum degradation in load-carrying capacity under both conditioning regimes, they showed maximum bond strength reduction in contrast to SMM-strengthened specimens. It was observed that the choice of bonding agent significantly influenced the extent of bond strength degradation under extreme exposure regimes, like those that prevail in the UAE and the Persian Gulf.

In the process of research and development of self-healing concrete, it is observed that there are three main factors controlling the self-healing effect of concrete: first, the bacteria with repair ability and strong vitality; Second, the carrying capacity of the carrier and the matching degree with concrete; The third is the concentration of bacteria. This paper focuses on the mechanical properties of Bacillus subtilis self-healing concrete with sisal fiber, PVA, and expanded perlite as the carrier. To better study the mechanical properties of self-healing concrete caused by the carrier, the experiment adopts the design parameters of C30 concrete and conducts experiments on compressive resistance, flexural resistance, freeze-thaw cycle, and sulfate corrosion resistance to analyze the influence of different carriers on the mechanical properties of self-healing concrete, and obtains the best carrier. The concentration gradients of three groups of bacterial solution were set as 2od, 2.5od, and 3od, respectively, for comparison to avoid the influence of bacterial concentration. It compared the impact of bacterial solution concentrations on the specimen's mechanical properties, and the effect of carriers was also analyzed. The experimental results show that the mechanical properties of the specimen using 2.5od bacterial liquid concentration with PVA as the carrier have peaked. With the increase in bacterial solution concentration, the specimens' comprehensive mechanical properties increased first and then decreased. The compression resistance of the specimen with PVA is higher than that of the specimen with sisal fiber and expanded perlite. At the same time, the frost resistance and corrosion resistance of the PVA carrier specimen is also higher than that of the specimen with sisal fiber and expanded perlite carrier.

To fully realize the potential of solid oxide electrolysis (SOE) systems, improvements in long-term durability and scalability are required. Investigating and comparing different degradation mechanisms under different conditions is crucial. A multi-scale cell to system level time-dependent simulation framework for SOE systems including various degradation phenomena is presented. Galvanostatic, Potentiostatic, and Potentio-Galvanostatic operation, a combination of the two previous modes, are investigated. The time and space evolution of various performance and degradation parameters are compared. Potentio-Galvanostatic operation consistently maintains stable efficiency throughout its lifetime. Near thermoneutral condition is maintained in Potentiostatic and Potentio-Galvanostatic operations, while degradation eventually leads to exothermic operation in Galvanostatic mode. Cathode overpotential is higher in Galvanostatic operation, while in Potentio-Galvanostatic operation, it drops over time as the temperature increases. After 25,000 h of operation under specified conditions, the area-specific resistance (ASR) experiences a 51% and 62% increase in Galvanostatic and Potentiostatic operations, respectively, while Potentio-Galvanostatic operation results in only a 4% increase compared to the beginning of life. Interconnect oxidation is most pronounced in Potentio-Galvanostatic mode, highlighting the need for high-quality steels and coatings in this operation strategy. Over time, in Galvanostatic operation, the current density shifts from being highest at the inlet towards the outlet.

Background & Aims: Hepatic recompensation may be achieved in patients with decompensated cirrhosis due to chronic hepatitis B (CHB) upon effective suppression of viral replication by nucleos(t)ide analogues (NAs). However, the optimal timing and predictors of recompensation and the subsequent clinical course of patients with CHB with vs. without recompensation are not well-defined. Methods: This study was a retrospective extension of a multi-centre prospective cohort, focusing on patients with CHB and decompensated cirrhosis treated with entecavir. We followed patients beyond treatment week 120 until a second decompensation event or June 2023. We identified the optimal timing and predictors of recompensation by week 120, evaluated durability of recompensation in patients fulfilling recompensation criteria by week 120 and examined late recompensation in those who did not fulfil it by week 120. Results: At treatment week 24, serum albumin ≥34 g/L predicted recompensation by week 120. The Brec-PAS model offered good predictive ability for recompensation by week 120. Of the 283 patients who finished 120 weeks of therapy, 175 were followed beyond week 120 (median follow-up: 240 weeks). Among the 106 patients achieving recompensation by week 120, 92 (86.8%) maintained recompensation for another 120 (72-168) weeks. Among the 69 patients without recompensation by week 120, 40.6% attained late recompensation during the subsequent 120 (72-168) weeks. Additionally, hepatocellular carcinoma incidence was lower in the recompensated group (5.0% vs. 16.13%, p = 0.002). Conclusions: A serum albumin ≥34 g/L at treatment week 24 predicted recompensation by week 120. Recompensation achieved by week 120 of NA treatment is maintained in >80% of patients in the long term. Some patients may achieve recompensation only after >120 weeks of NA treatment. The incidence of hepatocellular carcinoma was reduced but not completely abolished after recompensation. Impact and implications: Our research provides a meaningful contribution to understanding the long-term prognosis of recompensation in patients with chronic hepatitis B and decompensated cirrhosis, as well as to evaluating the predictive value of serum albumin levels, offering a comprehensive view of clinical outcomes after recompensation. The significance of early biomarkers in guiding therapeutic decisions is highlighted, shedding light on the continued benefits and possible risks after recompensation. This enhances the capability for more precise prognostic evaluations and informed therapeutic strategies. For healthcare providers, these insights afford a detailed perspective on patient monitoring and intervention planning, underscoring the need for ongoing assessment past the initial recompensation phase.

The prevailing practices of geopolymer concrete (GC) preparation use a high concentration of alkali activators, which is uneconomical. It is imperative to develop GC of low-concentration activators with enhanced durability for field implementation. Mechanochemical activation of geopolymer increases the reactivity of its raw materials by converting the crystalline phase to an amorphous phase. It has been illustrated in the present study that mechanochemical activation aids in achieving GC of desired properties at low concentrations of alkali activators. The mechanochemical activation of ground granulated blast furnace slag (GGBS) with sodium metasilicate was carried out to prepare GC of low (2 M) and high (12 M) alkali concentrations. The Portland slag cement-based concrete (PC) was cast to compare the durability performance of GC. The durability of the three concrete mixes was examined in terms of water absorption, the volume of permeable voids (VPV), water and chloride permeability, homogeneity, and acid resistance. The microstructural characterization of concrete samples exposed to acid were carried out by X-ray diffraction, field emission scanning electron microscope, and energy dispersive X-ray spectrometer. The results indicated that GC with a low concentration of activator exhibited lesser water absorption, VPV, and permeability, whereas it offered higher resistance to acids and chloride ion penetrability. Low-concentration GC had a dense and compact structure due to the coexistence of geopolymeric and hydration products, leading to better performance than high-concentration GC and PC. The evaluation of cost and carbon emission of PC, and GC mixes suggests GC as a sustainable alternative to traditional concrete. Although PC is economically viable, the study suggest use of GC with low alkali concentration due to its environmental benefits with a minor increase in cost.

Desert Sand Autoclaved Brick(DSAB) represents a novel type of building wall material. To investigate the performance of this wall material in the high-intensity cold regions of Xinjiang, this study, based on the(GB/T 11945–2019) ''Autoclaved sand-lime solid brick and solid block'' standard, explores the impact of varying lime content, forming pressure, autoclaving time, and autoclaving temperature on compressive strength. The aim was to determine an appropriate preparation process for DSAB that meets meets MU15-grade requirements. Additionally, experimental research was conducted on the micro-pore structure, freeze-thaw durability, and carbonation performance of the manufactured MU15-grade DSAB. Furthermore, microscopic analysis methods were employed to analyze the mechanisms behind the changes in the strength of the DSAB throughout the various experiments. The research findings are as follows: The optimal preparation parameters for producing MU15-grade DSAB are a forming pressure of 20 MPa, an autoclaving time of 8 h, and an autoclaving temperature of 180 ℃. Mercury intrusion porosimetry(MIP) revealed that DSAB has a total porosity of 38.19%, an average pore diameter of 55.86 nm, total pore volume of 0.175 mL/g, and total pore area of 12.56 m2/g. The majority of pore spaces consist of harmful and more harmful pores. DSAB exhibits favorable freeze-thaw durability. After 30 freeze-thaw cycles, the strength loss rate is only 7.0%, and the mass loss remains within 1%. After carbonation, the newly formed CaCO3 and SiO2 fill the brick's pores, transforming pre-existing harmful large pores into harmless tiny pores. After complete carbonation, the carbonation coefficient reaches 1.17.

This study investigates the potential benefits of using the 150 nm level Hydrogen Nanobubble Water (HNBW) in cement concrete. Given the significant greenhouse gas emissions associated with the cement and concrete industry, enhancing building materials performance and environmental friendliness becomes crucial. In this work, experiments were conducted to evaluate the various properties of this particular concrete formulation such as hydration heat, compressive strength, slump, air content, water absorption, electrical resistivity, rapid chloride permeability, and SEM. The results of the analysis showed that the HNBW improved the workability of the concrete by 50%. The HNBW improved the mechanical properties and durability of the concrete, resulting in an increase in compressive strength of 18.03% at 3 days and over 6% at 7 and 28 days. It reduces water absorption while improving electrical resistivity and chloride permeability resistance. Additionally, SEM imaging confirms that HNBW contributes to a more compact structure with pore and micro-crack size, thereby improving the overall performance of the concrete. Therefore, hydrogen nanobubbles, as a nanomaterial, exhibit favorable effects in meeting the demands of concrete.

Ultra-high-performance concrete (UHPC) possesses remarkable structural and durability characteristics, yet its widespread acceptance is hindered by cost inefficiency and environmental concerns. To address these challenges, this study investigates the impact of waste glass and limestone powder as partial substitutes for silica fume and cement in UHPC. For this, three distinct formulations are studied (Control, Optimized-1, and Optimized-2), representing different dosages of waste glass and limestone powder. The research focuses on six critical properties (compressive strength, modulus of elasticity, ultrasonic pulse velocity, initial surface absorption, density absorption, voids, and chloride ion penetration) evaluated at different ages (1, 7, 28, and 90 days for compressive strength, and 7, 28, and 90 days for the remaining properties). So, a total of 171 test specimens were examined, with 3 samples for each age and formulation. Statistical analysis, using ANOVA, assessed and confirmed the significance of the factors in the experimental results. The findings provide comprehensive insights into the UHPC formulations, highlighting the influence of waste glass and limestone powder on specified properties over varying ages. The research reveals that, despite the optimized blends exhibiting lower compressive strength values, all mixes surpass the 150 MPa threshold for cylindrical samples at the 90-day mark. Moreover, the Control mix consistently outperforms the optimized blends in modulus of elasticity at all ages, meeting ACI 239 criteria. The void content analysis shows encouraging trends, with all formulations displaying voids of less than 5% on the seventh day, improving during the curing process. Notably, Optimized-2 demonstrates superior performance over the Control mix after 90 days. Chloride ion penetration is minimal for all blends after 90 days, confirming the effectiveness of mineral admixtures. ANOVA analysis confirms significant impacts of formulation and age on various UHPC characteristics, emphasizing the consistent reduction in performance with alternative mineral additions. The interaction between formulation and age implies variations in property evolution, suggesting potential convergence with alternative formulations.

This research investigated the effect of wet and dry cycles on the performance of polypropylene fiber-reinforced cellular lightweight fly ash geopolymer (PPF-CLFAG). The fly ash (FA) was used as the primary material. The polypropylene fiber (PPF) contents of 0, 1, and 2% by fly ash weight and the air foaming agent (AF) contents of 0, 1, and 2% by total weight were used. The research analyzed the durability and microstructural properties of the PPF-CLFAG samples under number of wetting-drying cycles (N). The compressive strength, flexural strength, dry density, weight change, physical appearance, and FESEM-EDX of the PPF-CLFAG samples were conducted under various solution types, including H2O, Na2SO4, MgSO4, and HCl. The results showed that AF, PPF, and N affected the durability and microstructural properties of the PPF-CLFAG samples. Compressive strength, flexural strength, dry density, and weight change in Na2SO4-exposed PPF-CLFAG samples increased with N, in contrast to samples exposed to H2O, MgSO4, and HCl solutions, which demonstrated the reduction of compressive strength, flexural strength, dry density, and weight change. Notably, samples with 0%AF and immersed in Na2SO4 solution exhibited maximum compressive strength and flexural strength, particularly at PPF concentrations of 1% and 2%, reaching 38.30 MPa and 8 MPa, respectively. Moreover, the highest dry density of the sample with 0%PPF and 0%AF was at 1887 kg/m3, while the lowest dry density of 914 kg/m3 was observed in samples with 2%PPF and 2%AF. Additionally, samples soaked in MgSO4 exhibited surface discoloration and slight corrosion, while those in HCl displayed a yellow color due to the formation of a yellow FeCl3 solution. Examination through FESEM images revealed voids within the samples caused by AF and induced a transition zone between the PPF and paste, leading to increased porosity. The elements Si, Al, Na, and Ca in all samples subjected to the w-d cycle in various solution types indicated the coexistence of C-S-H and C-A-S-H gels with N-A-S-H gel.

Self-healing concrete presents an innovative and eco-friendly solution with the potential to reduce maintenance costs through self-activated crack repair. This study examined the effect of varying bacterial content across different environmental conditions. Additionally, the coupling effect between bacteria and steel fiber to enhance the mechanical and physical properties at different ages has been investigated. Bacillus Sphaericus (B. Sphaericus) was incorporated into the concrete at concentrations of 2 × 109 (CFU/ml), and different bacterial percentages selected utilizing calcium lactate as a nutrient source. Bacterial content of 0.0 %, 0.25 %, 1.0 %, and 2.5 %, cured in both fresh water and magnesium sulfate water solution, were tested to examine concrete behavior in harsh environments. Additionally, steel fibers at volume fraction percentages (Vf%) of 1.0 % and 1.5 %, along with 1.0 % bacterial content, were tested to highlight their combined effect. Tests were conducted at different ages to measure compressive, tensile, and flexural strengths. In addition, SEM and EDS analyses for cracked and uncracked specimens were performed. The results showed a significant increase in the long-term compressive, tensile, and flexural strengths at 180 days by 47 %, 80 %, and 50 %, respectively, with a bacterial content of 2.5 %. Moreover, the incorporation of steel fibers, 1.0 % and 1.5 % content, in the bacterial concrete resulted in a long-term compressive strength increase at 180 days by 45 % and 55 %, respectively with 1.0 % bacterial content, compared to 15 % and 27 % for 0 % bacteria. Curing in sulfate-rich water, concrete specimens exhibited increasing compressive strength at 180 days from 47 MPa for 0 % bacteria to 77 MPa with 2.5 % bacteria content. Despite lower initial strength of 29 MPa at 7 days, bacterial incorporation led to significant strength improvements, highlighting effective self-healing even in aggressive curing environments.

The presence of clay in aggregate is frequently associated with the deterioration of concrete properties. The objective of this study was to investigate the effects of varying clay contents on the mechanical properties, freeze-thaw resistance, permeability and water absorption behavior of concrete. Additionally, the differences in the permeability, and water absorption behavior of the surface layer and interior of concrete were comparatively analyzed using self-designed tests. The results indicate that the presence of a minimal quantity of clay did not diminish the compressive strength and static compressive modulus of elasticity of concrete. However, it did result in a reduction in the tensile properties and durability of concrete. Furthermore, the mechanical properties, freeze-thaw resistance, and anti-permeability of concrete were significantly diminished when the clay content reached 1.6%. Furthermore, this study proposed an innovative evaluation method for dividing the water absorption behavior of concrete into three stages, which more accurately reflected the trend of water absorption behavior in concrete. It was found that the sorptivity and permeable porosity of concrete in the three stages exhibited a strong correlation. The presence of clay increased the sorptivity and permeable porosity of concrete, with the most pronounced effect observed in the initial water absorption stage. Moreover, the permeable porosity of the interior of concrete was found to be reduced in comparison to that of the surface layer of concrete at all ages with varying clay contents, with the reduction ranging from 10.7% to 14.7%. In practical engineering construction, it is recommended that the clay content be kept within reasonable limits, and the effect of the clay content on the properties of the surface layer of concrete be given greater attention.

Glass fiber reinforce polymer (GFRP) bars have better durability than traditional steel bars, but there are few studies on their long-term performance in actual service environments especially the marine environment. To investigate the durability of GFRP bars used in cross-sea bridges, this research delves into the performance of 132 such bars, spanning diameters of 10, 12, 16, and 25 mm, in an environment that closely mimics real-world condition. The GFRP bars, encapsulated in concrete, were submerged in seawater solution, maintained at either room temperature or 60°C, for periods spanning from 0 to 183 days. Then the tensile strength and elastic modulus degradation of GFRP bars were investigated by tensile tests. Scanning electron microscope (SEM) was also used to analyze the micro-degradation mechanism of GFRP bars. In addition, this paper compares the four existing models for predicting long-term mechanical properties of GFRP bars with the experimental data, so as to determine the formulas and methods to be used in the design. The result shows that the elastic modulus of GFRP bars after 183 days of immersion in concrete pore solution was almost unchanged while the tensile strength decreased significantly. Among them, the tensile strength of 10 mm diameter GFRP bars decreased by 41.52 %, after 183 days of immersion at high temperature (60°C). The SEM method revealed that the main cause of such phenomena was the weakening of the bond between the fibers and matrix, which led to a decrease in the interface property. Finally, by fitting and comparing the relationship between the test data and the existing prediction models for the long-term mechanical properties of GFRP bars, the residual tensile strength of GFRP bars used in the actual project of Yanzhou Bridge for 100 years was predicted according to the optimal prediction model, i.e. the Serb model, and the results showed that the residual strength of GFRP bars is able to meet the current standard requirement.

An assessment of the freeze–thaw durability of pervious concrete was conducted using a rapid freezing method to investigate the durability of modified pervious concrete within a freeze–thaw environment. The optimal proportion of the modified material was determined by evaluating the mass-loss rate and the relative dynamic elastic modulus as indicators of freeze–thaw performance. Scanning electron microscopy (SEM) was employed to observe microcrack propagation and reaction products. A freeze–thaw damage model, based on the Weibull probability distribution, was formulated. Freeze–thaw damage analysis and life prediction assessment were carried out using curves such as freeze–thaw damage velocity curves, freeze–thaw damage acceleration curves, failure rate curves, and reliability life curves. The outcomes revealed that the inclusion of polyacrylonitrile (PAN) and silica ash had a favourable impact on improving the frost resistance of pervious concrete at later stages. The optimal proportions for PAN fibre and silica ash were determined as 0.6 % and 8 %, respectively. As the number of freeze–thaw cycles approached approximately 52.03 times, the freeze–thaw cycle velocity peaked. Subsequently, the freeze–thaw damage velocity was categorised into three stages based on the freeze–thaw damage acceleration curve. The degradation of pervious concrete due to freeze–thaw cycles followed a typical loss-type failure pattern. Notably, a 50 % increase in PAN fibre content resulted in a 62.92 % reduction in failure rate. Furthermore, a predictive analysis was conducted to estimate the lifespan of pervious concrete in a representative freeze–thaw region in China was performed.

One of the critical environmental issues in the Chegeni area (Lorestan Province, western Iran) is the production of a large volume of limestone wastes during the quarrying operations. Releasing limestone wastes in the areas neighboring the quarries has caused visual damage to the environment, and adverse effects on the quality of the soil, running water, and groundwater used for agricultural and drinking water purposes. One solution to this issue can be recycling limestone wastes to produce building materials. In the present study, a comprehensive laboratory program is planned for the durability evaluation of the limestone wastes under harsh environments for their suitability as aggregate in concrete. For this purpose, five aging tests, including freeze-thawing (F-T), salt crystallization (SC), acid attack (AA), wetting-drying (WD), and heating-cooling (HC), were conducted on the limestone sample up to 60 cycles. After every 10 cycles, the physico-mechanical characteristics of the sample, including porosity (n), Brazilian tensile strength (BTS), point load index (PLI), and P-wave velocity (Vp) were determined. Moreover, the pores structure modification of the sample subjected to aging tests was examined through scanning electron microscopy (SEM). Data analyses revealed that the sample is highly vulnerable to the AA and SC processes but is durable against FT, WD, and HC actions. These results were in good agreement with the SEM data such that the sample exposed to AA and SC underwent more changes in their pore structure compared to FT, WD, and HC. Among the physico-mechanical characteristics, the Vp and PLI had the highest and the lowest accuracy, respectively, in the durability evaluation of the sample exposed to aging tests. Based on the data analysis, limestone wastes can be used as aggregate in concrete in environments with the possibility of FT, WD, and HC. However, this type of concrete is not suitable for conditions with occurrences of the AA and SC. Finally, in addition to reducing the environmentally harmful impacts of the study area, using limestone wastes as aggregate in the construction of concrete can also be a practical solution for sustainable development from an economic viewpoint. The results of the present study can be used for assessing limestone wastes produced in other areas of Iran and the world.

Clay is a globally abundant material and can potentially be used as a cement substitute after calcination. Though kaolinitic clay exhibits notable reactivity, the potential of low-grade clay with relatively low kaolinite content remains underexplored. This study comprehensively analyzed the chemical and mineralogical composition of marine clays at various locations and depths in Singapore, assessing their feasibility for preparing limestone calcined clay cement (LC3). The hydration kinetics and microstructure development of LC3 pastes, incorporating calcined marine clay, were investigated by XRD, isothermal calorimetry, SEM, and MIP. Additionally, a mini-migration test was employed to investigate chloride ion diffusion in LC3 pastes. The results revealed that Singapore marine clays contain relatively low kaolinite content (16–20% by QXRD). Despite a 25% reduction of 28 days compressive strength compared to reference OPC, LC3 samples exhibited outstanding resistance against chloride penetration regardless of kaolinite content (