Durability Issues Research Articles

Performance of agro-wastes and chemical admixtures used in concrete: A review

Concrete is an artificial composite material made up of four main components: cement, fine aggregates, coarse aggregates, and water. Because of its adaptability, durability, and economic issues, it has rapidly gained popularity as a construction material around the globe. The manufacturing process of cement leads to the release of significant quantities of the greenhouse gas carbon dioxide. Finding alternatives to cement and natural aggregates is becoming more necessary and important.The ash that is produced when agricultural waste is burned as a fuel presents a few problems, such as the contamination of the soil, but it also has the potential to be used as a cement substitutebecause of its pozzolanic qualities. This research paper explores the utilization of agro-waste ashes, including Corn cob ash (CCA), Rice husk ash (RHA), Palm oil fuel ash (POFA), wood waste ash (WWA), bamboo leaf ash (BLA), Coconut husk ash (CHA), Groundnut shell ash (GSA), and sugarcane bagasse ash (SCBA), as substitutes for cement in concrete mixtures. Additionally, it delves into a comprehensive examination of various chemical admixtures such as water reducing, corrosion inhibiting, shrinkage reducing which are commonly employed to improve concrete performance. The use of agricultural waste in cement and concrete could lead to a range of benefits which include reduced CO2 emissions, improved strength and durability properties of concrete resulting lower the production costs of concrete. Chemical admixtures help to attain stronger and durable concrete.

Durability assessment of concrete with natural and Linz Donawitz slag as coarse aggregates

Rapid growth of infrastructure has resulted in incessant consumption of natural aggregates in cement concrete leading to its depletion. Efforts have been made to utilize industrial by-products such as steel slag aggregates in concrete as partial replacement for natural aggregates. However, the utilization of Linz Donawitz (LD) slag aggregates in concrete is very limited compared to other slag aggregates. The limited utilization could be attributed to the expansive nature of LD slag aggregates, which may result in durability issues. In this study, the compressive strength and durability characteristics of concrete with 100% LD slag coarse aggregate are investigated considering three different cement types, including Ordinary Portland Cement (OPC), Portland Pozzolana Cement (PPC) and Portland Slag Cement (PSC) for all the mixtures. LD slag and control concrete were examined for durability by conducting water permeability, electrical resistivity, drying shrinkage, rapid chloride penetration (RCPT) and water absorption tests. X-Ray Diffraction (XRD) analysis along with the microstructural investigations using SEM-EDS was carried out to supplement durability results. The compressive strength results indicated that LD slag concrete depicted higher strength than control concrete and there was a steady increase in strength with curing duration. Interestingly, PSC concrete depicted higher rate of strength gain compared to other cements. Further, LD slag concrete depicted low permeability and water absorption compared to control concrete, where it can be anticipated lower freeze–thaw damage. RCPT results indicated lower penetration of chloride ions representing delayed corrosion of steel in LD slag concrete. Overall, LD slag concrete depicted enhanced durability than control concrete.

The characteristics and emissions of low-pressure densified torrefied elephant dung fuel briquette

Elephant dung is the camp's undigested fiber waste. For more effective waste management, the conversion of dung to torrefied solid and the formation of solid torrefied into fuel briquettes, as well as their properties, were investigated. The dung was improved through torrefaction at 280ºC for 150 sec in a pilot-scale reactor with a feeding rate of 600 g/h. The torrefied elephant dung had 17 MJ/kg of HHV, a solid yield of 79%, and a fixed carbon content of 20%. A mixture of torrefied dung, binder, and water was compressed at 40 bars to a density of 860 kg/m3, or 12 GJ/m3. Their H/C and O/C atomic ratios were in the range of typical biomass. However, due to their moisture content of over 7%, the HHV of the fuel briquettes was below 17 MJ/kg. Moreover, their thermal efficiency was less than 7% due to durability issues, despite having a great fuel ratio and thermal stability. The combustion of these briquettes resulted in less than 850 ppm of CO. To improve the combustibility of this solid biofuel, it is recommended to develop a production process and a suitable stove specifically for these briquettes.

Hydrogen Fuel Cell Vehicles: Opportunities and Challenges

This paper provides an in-depth review of the current state and future potential of hydrogen fuel cell vehicles (HFCVs). The urgency for more eco-friendly and efficient alternatives to fossil-fuel-powered vehicles underlines the necessity of HFCVs, which utilize hydrogen gas to power an onboard electric motor, producing only water vapor and heat. Despite their impressive energy efficiency ratio (EER), higher power-to-weight ratio, and substantial emissions reduction potential, the widespread implementation of HFCVs is presently hindered by several technical and infrastructural challenges. These include high manufacturing costs, the relatively low energy density of hydrogen, safety concerns, fuel cell durability issues, insufficient hydrogen refueling infrastructure, and the complexities of hydrogen storage and transportation. Nevertheless, technological advancements and potential policy interventions offer promising prospects for HFCVs, suggesting they could become a vital component of sustainable transportation in the future.

Durability and microstructure analysis of concrete made with volcanic ash: A review (Part II)

Abstract Concrete is the most frequently employed man-made material in modern building construction. Nevertheless, the serviceability of concrete structures has been significantly reduced owing to a variety of durability issues, especially when serving in a non-ideal environment and exposed to internal/external attacks such as chloride penetration, carbonation, sulfate, and so on. Several scholars have performed numerous studies on the strength and microstructure features of volcanic ash (VA) concrete and have discovered encouraging findings. However, since the information is spread, readers find it difficult to evaluate the benefits of VA-based concrete, limiting its applicability. As a result, a detailed study is required that offers the reader an easy approach and highlights all essential facts. The goal of this article (Part Ц) is to conduct a compressive review of the physical and chemical aspects of VA and its impact on concrete durability and microstructure properties. The findings demonstrate that VA considerably improves concrete durability owing to pozzolanic reaction and micro-filling voids in concrete materials. Cost–benefit analysis shows that 10% utilization of VA as cement decreased the overall cost by 30%. The assessment also notes a research gap that must be filled before VA may be utilized in practice.

Effect of Transition Metal Dichalcogenide Based Confinement Layers on the Performance of Phase-Change Heterostructure Memory.

Phase-change random-access memory is a promising non-volatile memory technology. However repeated phase-change operations can cause durability issues owing to defects formed by long-distance atom diffusion. To mitigate these issues, phase-change heterostructure (PCH) devices with confinement material (CM) layers based on transition metal dichalcogenides (TMDs) such as TiTe2 have been proposed. This study implements PCH devices with additional TMDs, including NiTe2 and MoTe2 , alongside TiTe2 , and analyzes their characteristics by examining the differences in the CM layers. The results show that the NiTe2 -based PCH device demonstrates a RESET current of 1.4mA, 38% lower than that of the TiTe2 -based device, enabling low-power operation. Furthermore, the MoTe2 -based PCH device exhibits a cycling endurance exceeding 107 cycles, a five-fold improvement in durability compare with the TiTe2 -based device. The performance differences observe in each PCH device can be attributed to the variation in the material properties, such as the cohesive energy and electrical conductivity, of the TMDs used as the CM layer. These results provide critical clues to improve the performance and reliability of conventional PCH memory devices.

Integrated 3D Mapping and Diagnosis for the Structural Assessment of Architectural Heritage: Morano's Parabolic Arch.

The architectural heritage of the 20th century is affected by several conservation problems in terms of material preservation, structural analysis, and reuse. Among these, material degradation and durability issues are the ones that have the most effect on the health state and, consequently, the survival of the constructions of the period. In order to conduct a proper analysis for preservation purposes, an interdisciplinary approach is necessary. The parabolic arch in Morano sul Po (Italy) is a reinforced concrete landmark in the Casale Monferrato area and is related to the industrial vocation of the territory, which is indissolubly linked to the cement production chain. The present paper reports the results of a non-destructive test campaign by a Politecnico di Torino multidisciplinary group, which combined acquisitions using different methods. The paper highlights the importance of a structured procedure to integrate different information coming from different techniques. The aim was to assess the health state of the structure and define the best procedures for building an information system based on the as-built modeling strategy, which could serve as the basis to provide conservation guidelines.

Control of Mechanical Properties of FRP (Fiber-Reinforced Plastic) via Arrangement of High-Strength/High-Ductility Fiber in a Blended Fabric.

Carbon fiber-reinforced plastic (CFRP) has been widely investigated as a reinforcement material to address the corrosion and durability issues of reinforced concrete (RC). To improve the strain of FRP grids, we investigated the effect of single-fiber types, hybrid ratios, and stacking patterns on the strain of the composite materials. Blended fabrics in which different fibers are woven were used to further improve the strain of carbon fibers (CFs). In the blended fabrics, CFs with high tensile strength were mixed with high-strain glass fibers (GFs) or aramid fibers (AFs). Fibers with different mechanical properties were mixed to improve the strain without reducing the tensile strength of the composite materials. The fiber arrangement direction was controlled by CF/GF blended fabric. CFs are arranged in the direction parallel to the tensile load direction with no strength degradation, and GFs are arranged in the direction perpendicular to the increase in strain. Compared to the mechanical properties of the single CF composites, the fabrics obtained via an FRP mixing method proposed in this study showed an increase in the tensile strength by 7% from 568.17 to 608.34 MPa with no strength degradation and an increase in strain by 34% from 0.97% to 1.30%.

Multicriteria performance assessment of sustainable recycled concrete produced via hybrid usage of basalt, polypropylene and glass fiber

Fiber hybridization is a new and effective way of altering the inherent low mechanical properties and durability issues of recycled concrete by using a multi-fiber approach. Research conducted thus far is majorly focused on studying the effects of hybrid fibers on the basic mechanical properties of recycled concrete and no attention is given to the multicriteria-based performance assessment, which is highly important from the perspective of practical applications. The current study is an effort in this regard that intends to evaluate, compare, and rate the multicriteria-based performance of a total of eleven mix formulations prepared with a single and hybrid usage of basalt fiber (BF), polypropylene fiber (PPF) and glass fiber (GF). In addition, two mineral admixtures namely pulverized flyash (PFA) and ground granulated blast furnace slag (GGBFS) were used. From the results of mechanical properties, it is determined that mix formulations comprising hybrid 0.75 %BF-0.25 %PPF and 0.5 %BF-0.5 %GF had the highest strength improvement of 16–21% in compressive strength, 36–49% in splitting tensile strength, and 54–71% in flexural strength. The freeze–thaw assessment revealed that the use of hybrid fibers together with PFA and GGBFS resulted in superior durability performance of recycled concrete specifically in terms of lower length variation (0.055%), lower mass loss (0.39%) and higher UPV (4137 m/s) after 300 cycles. From the cost analysis, it is observed that MRC-1BF had the highest net cost increase of 121.7% of all mixes. Lastly, the multicriteria analysis revealed that the hybrid BF-GF and BF-PPF based MRC had the best performance score and ranking of all formulations, thus implying that their practical use would be highly beneficial in terms of mechanical performance as well as cost-effectiveness.

Review on the Degradation Mechanisms of Metal-N-C Catalysts for the Oxygen Reduction Reaction in Acid Electrolyte: Current Understanding and Mitigation Approaches.

One bottleneck hampering the widespread use of fuel cell vehicles, in particular of proton exchange membrane fuel cells (PEMFCs), is the high cost of the cathode where the oxygen reduction reaction (ORR) occurs, due to the current need of precious metals to catalyze this reaction. Electrochemists tackle this issue in the short/medium term by developing catalysts with improved utilization or efficiency of platinum, and in the longer term, by developing catalysts based on Earth-abundant elements. Considerable progress has been achieved in the initial performance of Metal-nitrogen-carbon (Metal-N-C) catalysts for the ORR, especially with Fe-N-C materials. However, until now, this high performance cannot be maintained for a sufficiently long time in an operating PEMFC. The identification and mitigation of the degradation mechanisms of Metal-N-C electrocatalysts in the acidic environment of PEMFCs has therefore become an important research topic. Here, we review recent advances in the understanding of the degradation mechanisms of Metal-N-C electrocatalysts, including the recently identified importance of combined oxygen and electrochemical potential. Results obtained in a liquid electrolyte and a PEMFC device are discussed, as well as insights gained from in situ and operando techniques. We also review the mitigation approaches that the scientific community has hitherto investigated to overcome the durability issues of Metal-N-C electrocatalysts.

Study on binary and ternary systems with cement, hydrated lime and fly ash: thermogravimetric analysis, mechanical analysis and durability behaviour

The use of high percentages of substitution of Portland cement by pozzolans can provoke the total consumption of portlandite. The present research proposes the study of ternary systems of Portland cement (PC), fly ash (FA), and hydrated lime (CH). After 180 days of curing, the mortar with 50% substitution of PC by FA obtained 65.9 MPa versus the mortars with an addition of 20% of CH and control mortar (100 PC) that obtained 69.9 MPa and 76.7 MPa respectively: this behavior is very positive value considering that tested FA containing mortars had a 50% of Portland cement. Regarding the effect of the amount of extra hydrated lime on durability issues, the evolution against carbonation of PC-FA and PC-CH-FA mortars was studied: the reduction of carbonation velocity was around a 37% for the mortar with CH respect the PC-FA mortar.

Effect of Curing Regime on the Mechanical Properties and Durability of Steam Cured-Concrete

The application of pre-cast components in building structures has become increasingly widespread, with projects often utilizing steam curing methods. The utilization of pre-fabricated concrete has demonstrated the capacity to enhance construction efficiency. However, strength and durability issues arising from steam curing of concrete have become prominent considering the quality of concrete construction. The use of fly ash and slag in steam-cured concrete to improve its performance has gained extensive popularity. While research into single-blended mineral admixtures has been conducted with notable achievements, the study of steam-cured concrete with binary blended mineral admixtures remains relatively limited. This paper focuses on the mechanical properties and durability of steam-cured concrete with mineral admixtures (fly ash and slag), exploring the influence of mineral admixture ratios and steam-curing regimes on the mechanical properties and durability of concrete. The properties of the steam-cured concrete were further analyzed through compressive strength tests, mercury intrusion porosimetry, and thermogravimetric analyses. It was found that when fly ash and slag were added in equal proportions, the compressive strength and microstructure of the concrete were optimized. In addition, the optimized static resting time and constant temperature time should be controlled as 3 h and 6 h, respectively, to improve the compressive strength and microstructure of the steam-cured concrete.

Serviceability performance of buildings founded on rubber–soil mixtures for geotechnical seismic isolation

ABSTRACT Base isolation is a low-damage seismic design strategy that can be used for constructing resilient structures. Geotechnical seismic isolation (GSI) is a new category of emerging base isolation techniques that has attracted global interest in the past decade. Research on GSI based on rubber-soil mixtures (RSM) has focused on structural performance under earthquake actions, whilst there are concerns over the serviceability limit states (SLS) requirements in relation to (i) human comfort under strong winds and (ii) ground settlement under gravity, which may induce cracking and durability issues in structures. This article presents the first study on the serviceability performance of buildings constructed with the GSI-RSM system. The finite element model of a coupled soil-foundation-structure system has been validated by data recorded from geotechnical centrifuge testing. The numerical estimates of ground settlement have also been compared with analytical predictions. It is concluded that the GSI-RSM system can satisfactorily fulfill the SLS requirements.

Mechanism of inhibitors in control of corrosion of steel in concrete

Reinforced concrete is the most abundantly used material in the infrastructure industry. Corrosion of reinforcing steel is the most critical and significant problem that the building industry faces. This durability issue is primarily caused due to chloride attack or carbonation of concrete. Among other techniques used in producing high-performance concrete, the use of corrosion inhibitors is the most attractive from the view of cost and ease of application. There is a diverse range of available corrosion inhibitors that are classified based on their origin, mechanism of protection, and composition. This paper covers a critical overview of the different mechanisms of corrosion protection offered by corrosion inhibitors. Furthermore, the stricter enforcement of environmental rules has prompted and inspired researchers to focus on developing non-toxic and ecologically acceptable corrosion inhibitors. This paper also gives a brief account of the ecological sustainability and toxicity issues concerning the commercially available inhibitors and the versatility and effectiveness of green corrosion inhibitors compared to synthetic corrosion inhibitors. This account of corrosion inhibitors attempts to contribute towards developing awareness and understanding of the primary mechanism of protection and the use of innovative and green materials to increase the service life of steel-reinforced concrete.

Cryosuction Experiments on Concrete Containing Ground Granulated Blast-Furnace Slag: Influence of Temperature, Air Entrainment And Salt

Abstract Frost deterioration of concrete is an important durability issue for structures exposed to high degree of saturation, low temperatures and de-icers. The material can then be severely damaged with internal cracking and/or scaling of the surface, which can lead to e.g. reduced protection of the reinforcement and loss of load bearing capacity. Experiments with liquid uptake in concrete using different temperature cycles was made to study cryosuction. The material used was concrete with different air content and different replacement levels of ground granulated blast-furnace slag (GGBS). The concrete samples were preconditioned by capillary suction. Three temperature conditions were used: constant temperatures of +20 °C and -20 °C, and temperature that cycled between -20 °C and +20 °C. As liquid medium, deionized water and a 3% NaCl salt solution were used. Air entrainment generally increased the liquid uptake. The amount of GGBS and the NaCl concentration in the liquid did not have any significant impact on the liquid uptake in these experiments.

Operando Reconstructed Molecule Fence to Stabilize NiFe‐Based Oxygen Evolution Catalysts

AbstractEconomical NiFe‐based oxygen evolution reaction catalysts have recently gained attention for their potential to accelerate green hydrogen production through water electrolysis. However, their practical application is limited by durability issues caused by the leaching of Fe sites during operation. Here an operando reconstructed molecule fence, that is, sulfate‐anchored aromatic ring molecule, is proposed to inhibit the leaching of Fe atoms and improve the durability of NiFe‐based catalysts. With this design, the sulfate not only immobilizes the aromatic ring as the protective layer to ensure long‐term service but also leaves space for beneficial site exposure and mass penetration. Molecule fence‐protected NiFe‐based catalysts exhibit excellent stability to withstand continuous high current densities of 100 mA cm−2 for over 2200 h and frequent current fluctuations and under start‐up/shut‐down events for over 200 h. Furthermore, the implementation of optimized catalysts in industrial water electrolysis equipment operates steadily for over 100 h with an energy consumption of ≈4.18 kWh m−3 H2.

Design of Strain-Hardening Natural TRM Composites: Current Challenges and Future Research Paths

This paper discusses the challenges in using natural fibers for the development of textile-reinforced mortar (TRM) composites with pseudo-strain-hardening and multiple cracking behavior. The particular characteristics of natural vegetal fibers are analyzed with reference to data from the literature. It is concluded that the efficient use of these fibers as composite reinforcement requires the development of treatment or impregnation protocols for overcoming durability issues, eliminating crimping effects in tensile response and imparting dimensional stability. Relevant experimental research on the synthesis and performance of natural TRMs is reviewed, showing that the fabrication of such systems is, at present, largely based on empirical rather than engineering design. In order to set a framework regarding the properties that the constituents of natural TRM must meet, a comparative analysis is performed against inorganic matrix composites comprising synthetic, mineral and metallic reinforcement. This highlights the need for selecting matrix materials compatible with natural fibers in terms of stiffness and strength. Furthermore, a rational methodology for the theoretical design of natural TRM composites is proposed. First-order analysis tools based on rule-of-mixtures and fracture mechanics concepts are considered. Based on the findings of this study, paths for future research are discussed.

Innovative Composite Materials for Improving Structural Integrity and Longevity in Civil Engineering Applications

The following research is on substantial developments of composite materials to improve the structural integrity and durability of construction in civil engineering. Traditional materials—like steel and concrete—have a host of problems associated with them, such as being vulnerable to corrosion, requiring frequent maintenance, and having limited lifespan. This paper reviews such issues in relation to the application of composite materials that are known to have improved properties, such as high strength-to-weight ratios, improved corrosion resistance, and better durability. The challenge posed to civil engineering, however, remains to be the limited durability and high maintenance cost of traditional construction materials. Due to environmental and mechanical stresses, these materials degrade and have resulted in frequent repairs and replacements, eventually increasing lifecycle costs of infrastructure projects. Key objectives of this research include the investigation of the very latest developments in composite materials, the assessment of their impact on the structural integrity and longevity of civil engineering constructions, and the economic benefits of reduced maintenance and longer service life for structures due to these improved materials. These are some of the contributions of the study: it showed that composite materials have much better performance than traditional materials in load-carrying capacity, resistance, and life; comparative analyses establishing dramatic money saving by large order in maintenance cost and lifecycle cost using composites, as compared to traditional materials; and showing the versatility of composite materials for general civil engineering applications like bridges, tunnels, pipelines, and building structures. The results show that composite materials increase the life span of constructions and structures related to civil engineering by a tremendous amount: for example, the load-bearing capacity is improved by 20%, the life span of pavement and bridges increased by 200–400%, the maintenance frequency by 50%, and the maintenance cost by 60%, which justifies their economic benefits very clearly. It has improved thermal insulation, reduced weight for the structural components, and more resistance to degradation by environmental elements, which makes composites a better solution compared with conventional materials. Generally speaking, this paper tries to bring out the prospect of composite materials in application for civil works, providing an alternative that will address issues of durability, cost, and flexibility in infrastructure.

Magnesium phosphate cement incorporating sheep wool fibre for thermal insulation applications

The increasing use of synthetic fibres in clothing and the high quality of sheep wool fibre (SWF) from the Australian and New Zealand market leads to a decline in the interest in SWFs produced in European countries, considering them as waste that could be valorised within the framework of a circular economy. The use of natural fibre in cement-based composites presents the main issue of durability due to the alkaline pH media of conventional cement. The use of a low-pH cement could improve the viability of combining natural fibres in this low-pH cement as matrix for developing composites. One of these low-pH cements is magnesium phosphate cement (MPC). As a ceramic material the MPC presents high thermal conductivity (∼1 W m−1 K−1) to be used as isolating material. The present work combines MPC formulated with an industrial by-product (low-grade magnesium oxide; LG-MgO) and Spanish SWF, to develop new sustainable cement-based materials (Sust-MPC-SWF) for thermal building insulation applications. The physical, thermal, and mechanical properties of Sust-MPC-SWF were evaluated to determine the optimal formulation through a design of experiments (DoE). Thirteen formulations designed by DoE were conducted with different sheep wool fibre/cement (SWF/C) and sheep wool fibre/extra water (SWF/EW) ratios. A statistical model was obtained and the optimal formulation (SWF/C = 0.36 and SWF/EW = 0.25) was validated. The increase in SWF content led to an enhancement of thermal and acoustic insulation properties of Sust-MPC-SWF, with similar results to other building materials commercialized with these features.

Recent Advanced Synthesis Strategies for the Nanomaterial-Modified Proton Exchange Membrane in Fuel Cells.

Hydrogen energy is converted to electricity through fuel cells, aided by nanostructured materials. Fuel cell technology is a promising method for utilizing energy sources, ensuring sustainability, and protecting the environment. However, it still faces drawbacks such as high cost, operability, and durability issues. Nanomaterials can address these drawbacks by enhancing catalysts, electrodes, and fuel cell membranes, which play a crucial role in separating hydrogen into protons and electrons. Proton exchange membrane fuel cells (PEMFCs) have gained significant attention in scientific research. The primary objectives are to reduce greenhouse gas emissions, particularly in the automotive industry, and develop cost-effective methods and materials to enhance PEMFC efficiency. We provide a typical yet inclusive review of various types of proton-conducting membranes. In this review article, special focus is given to the distinctive nature of nanomaterial-filled proton-conducting membranes and their essential characteristics, including their structural, dielectric, proton transport, and thermal properties. We provide an overview of the various reported nanomaterials, such as metal oxide, carbon, and polymeric nanomaterials. Additionally, the synthesis methods in situ polymerization, solution casting, electrospinning, and layer-by-layer assembly for proton-conducting membrane preparation were analyzed. In conclusion, the way to implement the desired energy conversion application, such as a fuel cell, using a nanostructured proton-conducting membrane has been demonstrated.