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In recent years, the aging of existing reinforced concrete deck slabs of road bridges in Japan has been attributed to the deterioration of the concrete on the upper surface, and partial replacements have been carried out as a measure to extend service life. This study comparatively verifies the effectiveness of the partial cross-section replacement method, using a wheel load running test and focusing on the combination of the removal method of the existing concrete and the repair material. An appropriate method of partial replacement of existing reinforced concrete deck slabs is also proposed.

In this work, novel microporous layers (MPLs) were developed based on fluorinated ethylene propylene (FEP), as a hydrophobic agent, and carboxymethylcellulose (CMC), as a wettability modulator and rheology controller for the inks, which were deposited onto pre-hydrophobized macroporous gas diffusion layers (GDLs). Higher CMC amounts led to higher dynamic viscosities of the inks, which induced the formation of a more compact and less cracked MPL surface. Different concentrations of CMC were tested and the experimental measurements showed a threshold limit pointing out an optimal composition that positively affected the electrochemical performances at medium-low relative humidity (RH), which is important to mitigate the need of saturating inlet gases. Durability of the best performing samples was assessed by means of an ad hoc developed accelerated stress test (AST) and compared to one of the conventional FEP-based GDMs. It was found that a lower decrement of both the output power density and the overall cell efficiency can be obtained upon the ASTs with the novel samples.

The research objective of this paper is to investigate the effect of different types of cement and different climatic conditions on the durability of reinforced concrete structures to understand and address issues of durability and erosion. The types of cement used were CEM I 42.5N, CEM II/A-M (P-LL) 42.5N and CEM II/B-M (W-P-LL) 32.5N. Mixtures of three different cement mortars and six different concretes were prepared with these three types of cement. Cement mortars were produced according to the European standard EN 196-1. Concrete mixtures were of the strength classes C25/30 and C30/37. Concrete mixtures produced according to the specifications of the European standard EN 206 may have a shorter service life due to carbonation-induced corrosion if the choice of the cement type is not made carefully. The results indicate that the carbonation rate of concrete mixtures is significantly influenced by the type and strength class of the cement used. Using meteorological data from six regions of Greece, an empirical carbonation prediction model for these regions was obtained.

International audience; Developing alternatives to platinum (Pt) and iridium (Ir) in proton exchange membrane water electrolyzers is crucial on the way to viable energy provision schemes. However, although it seems difficult to substitute Ir, alternatives exist for Pt at the PEMWE cathode. Here, we report on the synthesis and the characterization of efficient and durable hydrogen evolution reaction (HER) nanocatalysts based on MoS2 supported on high surface area carbon. Citric acid was used as a chelating agent to control the size of the crystallites (1.4 nm) and thus the density of active sites (slab edges). Inspired by successful approaches in catalysis for hydrodesulfurization reactions, conventional 2H MoS2 was sequentially doped with cobalt (Co) then 1 wt. % of Pt. Overpotentials of 188 mV, 140 and 118 mV at 10 mA cm-2 are reported for MoS2/C, Co-MoS2/C and Pt1%-CoMoS2/C, respectively. This result is attributed to the weakening of Hads binding energy of the promoted MoS2 edge active sites (because the promoting atoms are mostly located at the edges). Associated with small metal dissolution rates (monitored in situ, during HER), our findingsdemonstrate that metal promotion (doping) is a promising route to replace platinum by earth-abundant elements in acidic water electrolyzers.

This present research and explores the properties of concrete's structural and durability High-density polyethylene granules (HDPE) are partly replaced by the coarse aggregate. Five separate concrete mixtures of grade M30 have been built to partially replace the coarse aggregate from 1% to 5%. The properties of strength and durability such as compressive strength, split tensile test, flexural test and durability test such as rapid chloride permeability test, acid test, alkaline test, sulphate test assault. In the acids, the samples will equate with control concrete after 190 days for durability test cubes. The experiment is conducted to evaluate how much the acid attacks on the concrete. The loads are determined by an average of 3 for the compressive strength, split tensile, flexural test.

The life span of a structure depends on the strength and durability of concrete. The use of mineral admixtures in concrete plays a major role in achieving higher strength and durability characteristics. At present nanotechnology is being used in the concrete to decrease the permeability of concrete and also to extend the life service. Nanomaterials are extremely small in size which when used in concrete, improves the strength and reduces porosity. This study gives the characteristics of concrete when Nanosilica (NS) and Multi-Walled Carbon Nanotubes (CNT) were added to it. Manufactured sand was used as a fine aggregate in replacement of natural river sand. For conventional and nano-concrete, the durability characteristics were assessed by conducting water absorption, sorptivity, accelerated corrosion, and carbonation tests after 28 days and 90 days of curing. The formation of hydration products was studied through microstructural analysis by SEM and XRD. Closely packed concrete was achieved with the addition of NS and CNT. The permeability and porosity were reduced for nano-concrete because of the filler effect of nanomaterials.

Carbon Nano Tubes are strongest known materials known till now which can be ideally used in conventional concrete to tailor its functionalities. As water cement ratio governs the strength, serviceability and durability of concrete so its important to know the effect of Carbon Nano Tubes on basic properties of concrete. In order to analyze fresh and hardened properties of conventional concrete 0.5% Carbon Nano Tubes by weight of cement was incorporated in concrete mixes having water cement ratio 0.40, 0.45, 0.48.0.50 and 0.50. It was observed at 0.45 water cement ratio compressive, split tensile and Moment of resistance was greater by 8.89%, 28.9% and 5.33% respectively in comparison to Reference mixes while workability diminued by 38.40% and water absorption decreased by 0.03%. Also Coefficient of relationship R2 for water absorption and water-cement ratio of Carbon Nano Tube reinforced concrete was found as high as 0.97. Scanning electron microscopic analysis revealed dispersion of Carbon Nano Tubes and their bridging effect.

The concrete is expected to have features like high fluidity, self-compact ability, high strength, high durability, greater serviceability and long service life of concrete structures. rationalised and labour-saving benefits in manufacture and placement of concrete SCC is a highly designed concrete which addresses these needs. In this work the SCC samples with different percentage addition of ggbfs, fly ash and polypropylene fibres cured with Concentrated Sulphuric acid (H2SO4) and Sodium hydroxide (NaOH) at the period of 60, 80 and 120 days and it was tested under the temperature of 200 °C and 400 °C and it was tested for the compressive strength. Comparing the results with the samples without addition of polypropylene fibres (1% and 2%) there is a marked improvement in the compressive strength.

GFRP bars reinforced in submerged or moist seawater and ocean concrete is subjected to highly alkaline conditions. While investigating the durability of GFRP bars in alkaline environment, the effect of surrounding temperature and conditioning duration on tensile strength retention (TSR) of GFRP bars is well investigated with laboratory aging of GFRP bars. However, the role of variable bar size and volume fraction of fiber have been poorly investigated. Additionally, various structural codes recommend the use of an additional environmental reduction factor to accurately reflect the long-term performance of GFRP bars in harsh environments. This study presents the development of Random Forest (RF) regression model to predict the TSR of laboratory conditioned bars in alkaline environment based on a reliable database comprising 772 tested specimens. RF model was optimized, trained, and validated using variety of statistical checks available in the literature. The developed RF model was used for the sensitivity and parametric analysis. Moreover, the formulated RF model was used for studying the long-term performance of GFRP rebars in the alkaline concrete environment. The sensitivity analysis exhibited that temperature and pH are among the most influential attributes in TSR, followed by volume fraction of fibers, duration of conditioning, and diameter of the bars, respectively. The bars with larger diameter and high-volume fraction of fibers are less susceptible to degradation in contrast to the small diameter bars and relatively low fiber's volume fraction. Also, the long-term performance revealed that the existing recommendations by various codes regarding environmental reduction factors are conservative and therefore needs revision accordingly.

Resumo Este trabalho tem como objetivo avaliar a durabilidade do gesso com a adição de hidrorrepelente quando submetido ao envelhecimento acelerado. Para isso foram utilizados gesso e hidrorrepelente de massa. Foi fixada a relação água/gesso em 0,7 e utilizados os teores de 0,2% e 0,4% de hidrorrepelente em relação à massa de gesso. O gesso de referência (sem hidrorrepelente) e o gesso contendo hidrorrepelente de massa foram avaliados na idade “zero” e após 10 e 20 ciclos de secagem e molhagem. Foram realizados ensaios de dureza, resistência à compressão, absorção por imersão total, absorção por capilaridade e análise de MEV e EDS. Aos 20 ciclos de envelhecimento acelerado, houve redução das propriedades mecânicas; em contrapartida, manteve-se uma redução considerável, tanto da absorção por imersão, quanto da absorção por capilaridade nos corpos de prova contendo o hidrorrepelente em comparação aos corpos de prova de referência. Em relação à microestrutura, mesmo aos 20 ciclos, foi possível identificar a presença do hidrorrepelente formando um “filme” sobre os cristais de gesso, tendo sido identificado um percentual maior do hidrorrepelente na região mais superficial do corpo de prova. Tais resultados mostram a eficácia do hidrorrepelente como barreira de proteção diante do envelhecimento acelerado. Abstract This paper aims to evaluate the durability of plaster with the addition of water repellent, when subjected to accelerated aging. For this process, plaster and water repellent were used. The water/plaster ratio was set at 0.7 and contents of 0.2% and 0.4% of water repellent were used, in relation to the plaster mass. The prototype plaster (without water repellent) and the plaster containing mass water repellent were evaluated at “zero” age, after 10 and 20 drying and wetting cycles. Tests of hardness, compressive strength, total immersion absorption, capillary absorption and SEM, and EDX analysis were performed. At 20 accelerated aging cycles, there was a reduction in mechanical properties; at the same time, there was considerable reduction in both immersion absorption and capillary absorption in the specimens containing the water repellent, compared to the prototype specimens. Regarding the microstructure, even at 20 cycles, it was possible to identify the presence of water repellent forming a “film” above the plaster crystals, with a higher percentage of water repellent being identified in the most superficial region of the specimen. These results show the effectiveness of water repellent as a protective barrier against accelerated aging.

Large quantity of water is required during the conventional curing methods. This becomes challenging in the areas facing water scarcity and for concreting work in high rise structures. In this work, we present a solution for the need of concrete which does not require extra water for curing. In the proposed solution, calcium lignosulfonate in different percentage was introduced as a self-curing agent in fresh concrete. The hardened concrete with calcium lignosulfonate was cured at ambient condition whereas the hardened concrete without calcium lignosulfonate was submerged in water for curing. The properties of fresh and hardened concrete with and without calcium lignosulfonate are compared. The results show a continuous increase in slump with the increase in calcium lignosulfonate, however, 0.3% calcium lignosulfonate is identified as an optimum percentage for desired mechanical property. The durability under saline environment is studied in term of loss in strength. Further, the change in strength is correlated with the mineralogical changes studied using X-ray diffraction results.

The aim of this study is to produce durable self-compacting concrete (SCC) using different fractions of recycled steel slag aggregates (SSA) by replacing natural aggregate. For this purpose, a series of nine mixing proportions were designed with a constant water-to-cement ratio of 0.34 and a change of SSA ratio replacing natural coarse or fine aggregates by weight from 0 to 50% (increments of 12.5%). For freshly mixed SCC, the flowability, passing and filling abilities, segregation and viscosity were observed by slump flow, slump-flow time (T500), L-box and V-funnel empirical tests. Mechanical properties were tested for compressive and flexural strengths, while the durability characteristics were conducted for water absorption and permeability, sulfate attack and freeze–thaw action (F/T). Non-destructive measurement approaches (i.e. ultrasonic pulse velocity and resonance frequency) were involved in the F/T testing. The test results indicate that the incorporation of SSA in SCC is suitable and improves the mechanical strength and durability properties, and that enhancement is more pronounced at higher SSA increments, especially when replacing the coarse natural aggregate partially by coarse SSA.

Ground-granulated blast-furnace slag and dolomite are by-products from the steel manufacturing and rock crushing industries, respectively. The addition of dolomite to a slag-based geopolymer matrix can improve its engineering properties and reduce disposal problems. This paper discusses the effect of alkali solution concentration, curing temperature and different proportions of slag and dolomite on the strength of geopolymer mortars. For maximum strength, the optimum ratio of slag and dolomite was found to be 70:30. Microstructural studies such as scanning electron microscopy and X-ray diffraction showed the co-existence of both calcium silicate hydrate and aluminosilicate gel in the slag–dolomite geopolymer matrix. Improved durability properties such as high resistance to water absorption, sorptivity and chemical attack can lead to the application of slag–dolomite geopolymer matrices in all types of structural elements.

Experimental investigation has been performed to study the leakage and wear characteristics of carbon seal working at high circumferential speed. To expand the scope of application, two newly designed carbon seals were compared: #1 Carbon Seal (CS1) with the inner diameter of 136 mm and including 4 segments, #2 Carbon Seal (CS2) with the inner diameter of 212 mm and including 6 segments. Air leakage tests were firstly conducted in the Medium-speed Seal Test Rig. The pressure ratio changed from 1.04 to 2.02 with the rotating speed varying from 0 to 18300 r/min. Of paramount concern was the durability test, including 300 h running time accumulated by three different working conditions, which was separately implemented on each carbon seal. The morphology variation of the friction surface, wear and leakage were recorded. Results indicated that the leakage monotonously increases with the pressure ratio and decreases with the rotating speed. Comparing with CS1, more typical features exist on the friction surface of CS2, which are generated by more severe wear. Continually, leakage characteristics deteriorate. Furthermore, fitted formula has been educed for the life prediction of carbon seal, which could provide some supports for aero-engine design.

Reinforcement corrosion is the risk most frequently cited to justify concrete durability research, especially where it is induced by chlorides. Surface-applied corrosion inhibitors are widely used to mitigate the corrosion process both for carbonation and chlorides of steel reinforcement in concrete. They are applied onto the surface of hardened concrete and penetrate towards steel reinforcement. This paper discusses the corrosion inhibition performance of a new generation of a dual-phase surface-applied corrosion inhibitor (DP-SACI), and its efficiency in corrosion induced by chlorides over 3% referred to cement mass, and also in pre- and post-cracked structures. This corrosion mitigation activity was evaluated onsite for almost four years, in a sea wall exposed to XS1 ambiance. The electrochemical techniques used were based on the determination of the electrical resistivity of concrete, the half-cell corrosion potential and the steel corrosion rate (from linear polarization resistance measurements). All of these electrochemical parameters provide accurate information for on-site structures about the efficiency over the time of surface-applied corrosion inhibitors. The effectiveness of the dual-phase surface-applied corrosion inhibitor proved to be up to 99%, even with ongoing corrosion and 0.3 mm cracks near the rebar. The use of DP-SACI provides a non-destructive repair method that inhibits the corrosion process and increases the service life of the element.

In this study, the use of expanded polystyrene and expanded perlite as lightweight aggregates for the preparation of lightweight geopolymers is tested. The geopolymers’ performance was evaluated through physical, mechanical and thermal testing. Polypropylene fibers were used as reinforcement agents, while the long-term durability was assessed though repeated wet–dry and freeze–thaw cycles and sorptivity tests. The results showed that the introduction of lightweight aggregates in the geopolymer mixes decreased the compressive and flexural strength of the specimens by 77% and 35%, respectively. However, the density and thermal conductivity were substantially improved because of the addition of low-density aggregates. The fiber reinforcement of lightweight samples led to a drastic increase in flexural strength by 65%, leaving unaffected the compressive strength and density of the specimens. The freeze–thaw and sorptivity tests were also improved after the introduction of both aggregates and fibers. Lightweight geopolymer composites exhibiting density in the range of 1.0–1.6 g/cm3, compressive strength of 10–33 MPa, flexural strength of 1.8–6.3 MPa, thermal conductivity of 0.29–0.42 W/mK, and sorptivity of 0.031–0.056 mm/min0.5 were prepared.

In this study, through experimental research and an investigation on large datasets of the durability parameters in ocean engineering, the values, ranges, and types of distribution of the durability parameters employed for the durability design in ocean engineering in northern China were confirmed. Based on a modified theoretical model of chloride diffusion and the reliability theory, the service lives of concrete structures exposed to the splash, tidal, and underwater zones were calculated. Mixed concrete proportions meeting the requirement of a service life of 100 or 120 years were designed, and a cover thickness requirement was proposed. In addition, the effects of the different time-varying relationships of the boundary condition (Cs) and diffusion coefficient (Df) on the service life were compared; the results showed that the time-varying relationships used in this study (i.e., Cs continuously increased and then remained stable, and Df continuously decreased and then remained stable) were beneficial for the durability design of concrete structures in marine environment.

The valorization of local by-products in the manufacture of a new range of sand concrete and the improvement of their properties, will lead to seek an arrangement between performance and cost in order to achieve a resistant material. Waste recycling affects two very important affect namely the environmental impact and the economic impact. The main objective of our work is to contribute to optimize the formulation of sand concrete as part of the recovery of waste, which is harmful to the environment given its bulky and unattractive nature, it is waste plastic. Most PET bottles become waste after use, causing environmental problems. To solve this problem, a method for recycling PET bottles as fibers to strengthen concrete is proposed. Two types of plastic waste are added to sand concrete; the first concerns the recycling of post-consumer bottles in PET, in the form of polyester fiber supplied by the company RET-PLAST and the second type concerns the packaging belts made of polyethylene terephthalate (PET). The properties in the fresh state (workability and density) and in the hardened state (compressive strength, tensile strength and water absorption) of the various produced concretes are analyzed and compared against their respective controls. From the experimental results, it can be concluded that the reinforcement of the cement matrix with PET fibers with a rate of 1% improves the mechanical properties of sand concrete as well as a remarkable decrease in its water absorption capacity.

Specifications for durability that are based on performance tests on concrete during the early stages of construction are finding acceptance throughout the world. In South Africa the durability index (DI) approach has been accepted into local specifications. This raises a challenge in the design of a concrete mixture for a construction project that takes account of the variability in materials and test conditions to ensure that the concrete will achieve the specification requirements when subjected to DI testing on in-situ samples. This paper proposes a statistical approach to accounting for this variability in concrete mixture design with oxygen permeability index (OPI) testing, in a manner that acknowledges the variability of both laboratory-based and in-situ sample testing for compliance. The OPI test results obtained on nominally similar concretes on actual construction projects undertaken by the South African National Roads Agency Limited (SANRAL), which included the DI-based specifications, were used to illustrate the operation of the proposed approach. The results show that the target value of OPI to be achieved in the design of concrete mixtures is influenced by the level of quality control on construction sites but that this can be managed through an appropriate statistical approach.

The COVID-19 pandemic continues to have devastating consequences on health and economy, even after the approval of safe and effective vaccines. Waning immunity, the emergence of variants of concern, breakthrough infections, and lack of global vaccine access and acceptance perpetuate the epidemic. Here, we demonstrate that a single injection of an adenoassociated virus (AAV)-based COVID-19 vaccine elicits at least 17-month-long neutralizing antibody responses in non-human primates at levels that were previously shown to protect from viral challenge. To improve the scalability of this durable vaccine candidate, we further optimized the vector design for greater potency at a reduced dose in mice and non-human primates. Finally, we show that the platform can be rapidly adapted to other variants of concern to robustly maintain immunogenicity and protect from challenge. In summary, we demonstrate this class of AAV can provide durable immunogenicity, provide protection at dose that is low and scalable, and be adapted readily to novel emerging vaccine antigens thus may provide a potent tool in the ongoing fight against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). ispartof: MOLECULAR THERAPY vol:30 issue:9 pages:2952-2967 ispartof: location:United States status: published

The Durability of Concrete has been vital to all the manufacturer and researchers. The Concrete has been on top always in providing Strength and durability of structures. On other side, we have been facing many challenges like long term Poor Performance, less durable, poor performance against acid and sulphate attack etc. Many researchers are working to improve these drawbacks using nano particles. Nano technology is one of the emerging techniques to improve the mechanical properties of concrete as well as the performance of concrete. The modifications are required to sort out these problems in concrete mass. It has been seen that using nano particles material, the tensile strength, susceptibility to chemical attack, corrosion of reinforcement, low durability has been sorted out up to a good extent. In this study, I have tried to improve mechanical and chemical properties of concrete like Compressive strength, durability, resistive against corrosion, acid attack resistance, workability etc. using Nano Silica material. The target study is to get the best proportion of concrete ingredient added with nano silica and to get the best out come with that proportion in terms of better mechanical and Chemical Properties.

This poster received the outstanding poster award from the RILEM Week Kyoto 2022.

In this thesis, the carbonation of functionally graded concrete is investigated through a combination of experimental and analytical approaches. The properties of functionally graded concrete vary throughout the cross-section to satisfy performance requirements in a resource-efficient manner. In this research, functional grading of concrete elements is achieved by casting discrete layers of concretes possessing different properties. Layers are cast in the fresh state to prevent formation of a cold joint and associated interface weakness. Carbonation is the process of environmental CO2 diffusing into and reacting with concrete, thereby changing its chemical composition. It is a durability concern for concrete structures, since carbonated concrete does not provide adequate corrosion protection to embedded reinforcement. Increased resistance to carbonation has traditionally been achieved by increasing the cement content in concrete elements, which increases embodied carbon. Carbonation presents as a surface phenomenon. As such, the concrete mix adopted at the outside face is of most concern when designing carbonation-durable elements. Given the ability to relate properties to performance, functional grading presents a promising approach to providing carbonation durability with reduced cement content. In such an element, a high-cement carbonation durability layer could be placed in exposed areas, but retaining low-cement concrete as the material in the bulk remainder. This would have theoretically equivalent durability to a single-mix element cast from the high-cement mix, but significantly lower cement content. The presented research seeks to answer the question “Is layered functional grading a viable method of reducing cement contents in concrete elements without sacrificing carbonation durability?''. This is achieved by first understanding the carbonation behaviour of single-mix concrete specimens, thus establishing baseline processes for accelerated carbonation testing and the influence of material parameters on carbonation performance of different concrete mixes. Next, machine learning is applied to predict properties of concretes from mix composition, such as carbonation performance. Following this, the carbonation of layered functionally graded specimens is experimentally investigated, and the results are used to validate a derived model for the carbonation depth in layers. Finally, it is acknowledged that structural cracking could provide a route for CO2 penetration beyond the depth of a carbonation durability layer. Therefore, a further experimental series investigates the cracking behaviour of layered prisms under loading and their carbonation performance when subjected to simultaneous cracking and carbonation. Digital image processing methods are implemented in multiple areas to improve the detection and analysis of carbonation fronts from phenolphthalein indication tests. Overall, the results demonstrate that layered functionally graded concrete elements offer a viable route to cement reduction, without loss of carbonation durability. Therefore, it is recommended that practitioners consider this approach to design durable structures with reduced cement consumption.

This research aims to combine the effects of waste glass and Nano-silica powder on the properties of fiber-reinforced self- compacting mortar. A detailed study was undertaken to investigate the effect of different glass powder contents as cement replacement on the behavior of mortar. For this purpose, Portland cement was partially replaced by 10%, 15%, and 20% waste glass powder alone, and then in combination with 2% substitution levels for Nano-silica. The amount of water-binder ratio and cementitious materials content were considered constant. Fresh properties of specimens were determined using slump flow, and v-funnel flow time tests, mechanical properties were determined by compressive strength, and tensile strength tests, and durability characteristics evaluated by water absorption, and resistance to sulfuric acid attack. Microstructural morphology of specimens was also assessed by scanning electron microscopy. It was observed that the workability slightly decreased and improved mechanical and durability properties could be achieved. The SEM micrographs illustrated more densified pore structure of the mortars containing waste glass powder which leads to increase in strength and durability of specimens. &nbsp

Concrete durability is the ability of concrete to resist environmental impact or chemical attack in a long time without substantial deterioration. The aim of this study is to provide a durability plan for concrete structures to encompass the 100-year design life. The coastline concrete structure design requirements are formulated considering a case study of twin bridges in Ballina regions, Australia, which can be extended to other type of concrete structures. The proposed durability plan incorporates concrete strength, provided cover thickness and construction methods for each structural component. This paper elaborates the service life design of twin bridges and conducts durability design, employing the first principles for environmental loads affecting structural components. The realistic model for chloride induced corrosion, based on diffusion theory and carbon dioxide diffusion model, are also included in this study. In addition, the specifications of concrete and other preventive measures are described. The chloride modelling of the bridges has been conducted using a realistic model based on diffusion theory. It has been revealed that 100 years of design life can be achieved by using 65% slag in the concrete of bridge deck. The findings suggest that fibre boards and supplementary cementitious materials both are notably effective to maintain a durability of 100 years.&nbsp

Hydrated cement is one of the complex composite systems due to the presence of multi-scale phases with varying morphologies. Calcium silicate hydrate (C–S–H), which is the principal binder phase in the hydrated cement, is responsible for the stiffness, strength, and durability of Portland cement concrete. To understand the mechanical and durability behavior of concrete, it is important to investigate the interactions of hydrated cement phases with other materials at the nanoscale. In this regard, the molecular simulation of cement-based materials is an effective approach to study the properties and interactions of the cement system at the fundamental scale. Recently, many studies have been published regarding atomistic simulations to investigate the cement phases to define/explain the microscopic physical and chemical properties, thereby improving the macroscopic performance of hardened binders. The research in molecular simulation of cementitious systems involves researchers with multidisciplinary backgrounds, mainly in two areas: (1) cement chemistry, where the hydration reactions govern most of the chemical and physical properties at the atomic scale; and (2) computational materials science and engineering, where the bottom-up approach is required. The latter approach is still in its infancy, and as such, a study of the prevailing knowledge is useful, namely through an exhaustive literature review. This state-of-the-art report provides a comprehensive survey on studies that were conducted in this area and cites the important findings.

To lessen the residential sector environmental burdens from the energy consumption of household appliances, notable efforts have been directed to replace existing energy-consuming appliances by new energy-efficient equipment. However, less attention has focused to understand the optimum operating period of households so reduced greenhouse gas emissions can be achieved. Conventional household appliances should be preferably replaced with new designs featuring improved energy efficient models, along with reduced environmental burdens associated with the manufacturing of the new products. Such studies, to the best of our knowledge, have not been extensively investigated. To address this gap, the global warming potential during the life cycle of three representative household appliances, a microwave oven, a dishwasher and a washing machine is analyzed using a cradle-to-grave life cycle assessment. To provide guidelines towards impact reduction, the current situation and four new scenarios focused on material efficiency, recycled material, renewable electricity and responsible consumption are analyzed. Depending on the scenario, impacts of 84-261, 317-1330, and 533-1375 kg.CO2 eq/lifetime are obtained for a microwave, a dishwasher and a washing machine, respectively. Balancing energy efficiency and life- time when replacing a class A appliance, operating periods of 3.4-30, 2.7-26.2 and 4.6- 33.9 years for microwaves, dishwashers, and washing machines, render the lowest CO2 footprint. These results may assist manufacturers, policymakers and citizens to promote environmentally sustainable production and consumption patterns. (C)22 The Authors. Published by Elsevier Ltd on behalf of Institution of Chemical Engineers. The authors are grateful for the support provided through the Basque Government (IT-1365-19) and the University of the Basque Country (GIC-18/22) grants.

Distributed applications such as key-value stores and databases avoid frequent writes to secondary storage devices to minimize performance degradation. They provide fault tolerance by replicating variables in the memories of different nodes, and using data consistency protocols to ensure consistency across replicas. Unfortunately, the reduced data durability guarantees provided can cause data loss or slow data recovery. In this environment, non-volatile memory (NVM) offers the ability to attain both high performance and data durability in distributed applications. However, it is unclear how to tie NVM memory persistency models to the existing data consistency frameworks, and what are the durability guarantees that the combination will offer to distributed applications. In this paper, we propose the concept of Distributed Data Persistency (DDP) model, which is the binding of the memory persistency model with the data consistency model in a distributed system. We reason about the interaction between consistency and persistency by using the concepts of Visibility Point and Durability Point. We design low-latency distributed protocols for DDP models that combine five consistency models with five persistency models. For the resulting DDP models, we investigate the trade-offs between performance, durability, and intuition provided to the programmer.

[EN] Monitoringreinforced concrete structures (RCS) is essential to ensure their service life. Monitoring the parameters associated with deterioration processes can be key for proactive maintenance. A gap exists between engineering practices and sensor technology innovation in the construction field, which prevents more development and widespread applications of using voltammetric sensors and a multivariate analysis. This review demonstrates the effectiveness of voltammetric stainless steel (SS) sensors, plus a principal component analysis (PCA), to detect the aspects involved in corrosion processes; e.g. concrete carbonation or presence of chlorides. Sensors were embedded in different concrete mixtures and exposed to different conditions. Electrochemical techniques were applied. Then the results were analysed by a PCA, which defined the durability control model. This model is able accurately detect the concrete state, which is verified by the model¿s validation. This novel system helps to sustainably preserve the service life of RCS., This work was supported by the Universitat Politecnica de Valencia, Ayudas a Primeros Proyectos de Investigacion (PAID-06-18) through the Lengua Electronica Voltametrica para el Control de Durabilidad en Hormigones under Grant SP20180245. The work of Ana Martinez Ibernon was supported by the Spanish Ministry of Science and Innovation for the Predoctoral Scholarship under Grant FPU 16/00723. The associate editor coordinating the review of this article and approving it for publication was Prof. Rosario Morello.

En este trabajo nos proponemos hacer un aporte para esclarecer el sentido y la función de la experiencia en el marco de la teoría del conocimiento de Hume. Para ello examinaremos dos interpretaciones que pueden reconstruirse en la literatura secundaria: la que la entiende como impresiones simples de sensación y la que la concibe como patrones de percepciones conectadas. Consideramos que la primera perspectiva no es adecuada para comprender el rol epistémico de la experiencia, lo que nos inclina hacia la segunda interpretación. Sin embargo, esta última no ha sido lo suficientemente desarrollada por los autores que la sugieren. Nuestro propósito es llevar a cabo esa tarea pendiente, ofreciendo una serie de precisiones que la hacen más robusta a los fines de elucidar por qué para Hume la experiencia es la piedra de toque en el conocimiento sobre cuestiones de hecho. Así, mostraremos que el sentido que adquiere la experiencia en las inferencias causales es el de casos que recogemos mediante la observación y organizamos en colecciones o patrones, los que funcionan como evidencia para establecer o justificar enunciados epistémicos. Por último, para comprender la especificidad de su función en este tipo de inferencias, distinguiremos la experiencia de las impresiones y del hábito. This paper aims at clarifying the meaning and function of experience within the framework of Hume's theory of knowledge. In order to do so, I will examine two interpretations that can be reconstructed in secondary literature: the one which understands experience as simple impressions of sensation and the one that conceives it as patterns of connected perceptions. I argue that the first perspective is not suitable to understand the epistemic role of the experience, which inclines me towards the second interpretation. However, this interpretation has not been sufficiently developed by the authors who suggest it. My purpose is to carry out this task, offering a series of clarifications that make it more robust in order to elucidate why, for Hume, experience is the touchstone concerning knowledge about matters of fact. Thus, I will show that the meaning of experience within causal inferences is related to cases that we collect through observation and arrange into collections or patterns, which work as evidence to establish or justify epistemic statements. Finally, in order to accurately understand its function within this type of inferences, I will distinguish experience from impressions and habit. Fil: Calvente, Sofía Beatriz. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación. Instituto de Investigaciones en Humanidades y Ciencias Sociales (UNLP-CONICET); Argentina.

The use of concrete materials in Portugal, namely reinforced concrete, began in the 19th century. However, during the 20th century, the increase in the application of this composite material, alongside the use of hydraulic binders, led to a disruption of traditional construction techniques and enhanced generalized application in concrete structures, combining aesthetics with functionality. In this paper, the authors will present and discuss several physical and mechanical characteristics of reinforced concrete materials from 12 award-winning architectural buildings constructed between the 1930s and the end of the 20th century in Lisbon, Portugal. These results are vital to evaluate their durability, as those buildings have an undiscussable heritage value in the context of 20th-century buildings’ valorization. Furthermore, the results will contribute to the knowledge of the current state of conservation of these materials and will allow an understanding of the evolution in the application of national regulations during this period.

The aim of this research was to study the effect of incorporating waste rubber aggregates on the physical, mechanical, thermal and durability performance of Self-Compacting Sand Concrete SCSC mixtures. For this purpose, the separately developed Rubberized Self-Compacting Sand Concrete RSCSC were prepared with three fractions of rubber grains where the natural aggregates were replaced with powder rubber, sand rubber and gravel rubber and four addition ratios (5, 10, 15 and 20%) as volume rates. The performed fresh properties using slump-flow, spreading, t500, sieve stability and air-entrained content tests proved better results for the RSCSC in comparison with reference concretes. Hardened state characterization of the concretes exhibited decreases in the mechanical properties of the RSCSC but the thermal conductivity and the dynamic elastic modulus were improved. Assessment of the concrete’s durability was accomplished through determination of apparent porosity, capillary absorption. Therefore, RSCSC to be can used in structural elements of dense reinforcement and complex formwork. Furthermore, this allows promising solution to reduce the impact of waste tyres on the environment and fight pollution.

Multi-storey car park buildings with steel–concrete composite floor structures are widespread in construction due to the distinct benefits of the implemented structural system. Although there are various possibilities for accomplishing composite action between a steel beam and a concrete slab, some solutions, such as friction-grip bolts commonly applied in the 1970s, did not show good durability. An example is the multi-storey car park building “Obilićev venac” in Belgrade. This case study presents two methods for life extension of the car park building structure. Both approaches focus on applying welded headed studs with the primary intention of providing a durable shear connection. While the first method has been applied during the structure’s reconstruction, the second method is proposed as a novel solution for implementation in steel–concrete composite floors. The application of the proposed connection is discussed and the results of the experimental and numerical research conducted are presented.

Background This study aimed to investigate the impact of the intensity of prior accumulated work on the decline in power output in elite/international level road cyclists, comparing the effects of prior continuous moderate intensity versus intermittent high intensity cycling. Methods Nine elite/international level road cyclists (age 26.2 ± 4.0 years; body mass: 66.6 ± 5.5 kg; height: 176 ± 0.4 cm) conducted a 12-min field test (12 minfresh) during two consecutive training camps. Participants then performed both a 150-min moderate intensity continuous (MIC) work bout or a 150-min high intensity intermittent (HII) race simulation in randomized order, cross-over design. After each condition a 12-min field test (12 minfatigue) was completed. Results Absolute and relative 12 minfresh power output were not significantly different between training camps (p > 0.05). The 12 minfatigue power after HII was significantly lower than 12 minfatigue after MIC (∆ = 14 W; p = 0.014). Participants recorded more percentage time (%Time) in heart rate (HR) zone 3 (∆ = 9.2%; p = 0.003) and power output band between 5.0–7.9 W $$\cdot$$ ∙ kg−1 (∆ = 8.9%; p = 0.002) as well as higher total work (∆ = 237 kJ; p ≤ 0.001) during HII. Conclusion These findings reveal that the decline in power output is higher after HII compared to MIC cycling work bouts. This suggests that the quantification of total work and intensity should be used in conjunction to predict a distinctive decline in power output. Future research is required to better understand the mechanisms of endurance “durability” in elite/international level road cyclists.

The present research analyzes the influence of the use of silica fume and nanosilica particles as a partial substitute of cement on the physical-mechanical properties of concrete pavers. For this purpose, silica fume was replaced with rates of 5%, 10%, and 15%, and nanosilica in percentages of 1%, 1.5% and 3% by cement weight, and in a final stage a combination of both materials with percentages of the optimal results obtained for each one. The use of 15% of silica fume, 3% nanosilica and the combination of both materials, resulted in an increase in compressive strength by 28%, 12% and 23%, respectively in comparison with the control mix. In addition, it was understood that the simultaneous use of these materials positively influences the qualities of concrete as well as its single use. The concrete pavers with optimal percentages and their combination, subjected to the tests established in the NTE INEN 3040: 2016 standard, obtained very satisfactory results. Finally, it was concluded that the additions of silica fume and nanosilica particles in substitution of cement, allows to obtain concrete pavers with better performance both for mechanical resistance and durability and constitute a viable alternative for the manufacture of a new type of concrete pavers that contributes to reuse of alternative materials, by-products of industrial processes, generating an environmental benefit. En el presente estudio se utilizó micro y nano partículas de sílice en la fabricación de adoquines de hormigón como sustituto parcial del cemento, lo que contribuye directamente en la disminución del consumo energético, así como la reducción de la emisión de gases como el CO2 generados en la descarbonización de la piedra caliza durante el proceso de clinkerización, los cuales agravan el efecto invernadero. El objetivo principal de esta investigación es establecer la influencia de la mezcla de micro-nano partículas de sílice en las propiedades físico-mecánicas del adoquín de hormigón. Para este estudio, se reemplazó el microsílice por cemento, con tasas de reemplazo de 5%, 10%, y 15% (al peso) y de nanosílice en porcentajes de 1%, 1.5% y 3% (al peso). La prueba de resistencia a la compresión a los 28 días mostró que los adoquines con un reemplazo del 15% de microsílice y 3% de nanosílice aumentaron su resistencia en un 28% y 12%, respectivamente en comparación con mezcla de control. Por último, se realizaron dos mezclas mix (combinación de nano y microsílice) con los porcentajes óptimos encontrados anteriormente (15% microsílice + 3% nanosílice) y una con menores valores de remplazo (7.5% microsílice + 2% nanosílice), con el fin de obtener la mejor combinación, en cuanto a resistencia. La prueba de resistencia a la compresión a los 28 días mostró que la mezcla mix, con un reemplazo del 15% de microsílice y 3% de nanosílice aumentó dicha resistencia en alrededor del 23%, en comparación con mezcla de control. La última fase de la investigación consistió en someter a los especímenes óptimos a los ensayos especificados en la norma técnica ecuatoriana para adoquines prefabricados de hormigón NTE INEN 3040: 2016, de los cuales se obtuvieron resultados muy satisfactorios. Finalmente se concluyó que las adiciones de nano y micro partículas de sílice en sustitución de cemento, permiten obtener adoquines con mejores desempeños tanto por resistencias mecánicas como por durabilidad y constituyen una alternativa viable para la fabricación de un nuevo tipo de adoquín que contribuya a la reutilización de materiales alternativos, subproductos de procesos industriales, generando un beneficio ambiental.

This paper aims to assess the mechanical and long-term durability performance of reactive powder concrete (RPC) containing granite powder (GrP) as cement replacement and waste glass powder (GP) as quartz sand replacement. The workability and mechanical behaviour of RPC containing various proportions of GrP and GP are assessed for different water/binder (w/b) ratios (0.3, 0.35, 0.4, and 0.45). The water resistance and tightness of RPC are measured by monitoring the electrical resistivity, water absorption, sorptivity, and chloride migration over a one-year period. Results reveal that substitution of GrP and GP at optimum levels of 15% and 30% respectively enhances the performance of RPC with the achievement of satisfiable workability at a 0.35 w/b ratio. A significant increase in the resistance towards chloride penetration and electrical resistivity was also observed with increasing ages. Thus, glass powder and granite powder can be considered as alternative construction materials providing economical and ecological efficiency.

Increased temperature and carbon dioxide concentration caused by climate change will aggravate the creep shrinkage and structural durability of concrete bridges. Overloading also has a great impact on the time-dependent reliability of existing bridges. This research paper analyses the time-dependent reliability of bridges based on climate change and overload. By improving the concrete carbonation model and referring to the B4 model of concrete creep, the effects of ambient temperature and humidity on concrete under different emission-reduction scenarios were considered. At the same time, given the serious problems of vehicle overload in China, combining different overload scenarios with climate change led to the establishment of a time-dependent reliability model for precast-concrete bridges. The results showed that as the overload rate increased, the time-dependent reliability degradation rate of a case study bridge accelerated. Under the scenario considering both high greenhouse gas emissions and the maximum overload rate, the service life of the case study bridge decreased to 50% of its design life.

A series of experimental tests on reinforced concrete specimens with normal uncoated and epoxy-coated reinforcing bars (ECRBs) was carried out. A comprehensive report of the specimens, from material level to overall performance, is presented in this paper. At the material level, evaluation of the epoxy coating thickness showed that the production quality was not good. Some mechanical properties of bars with a thinner coating were better than those of their uncoated counterparts, while an increase in coating thickness offset the better mechanical properties and decreased the bond strength. Regarding durability, a comparison of the corrosion behaviour of the reinforcing bars and chloride penetration of the concrete cover in unloaded, statically-loaded and fatigue-loaded test specimens showed that higher fatigue loads and longer fatigue loading cycles decreased the corrosion resistance of the bars and increased the chloride penetration. The ultimate loads of the specimens were reduced and comparatively lower values were obtained for beams with bars with thicker coatings. The results of this work highlight the interrelationships among materials performance, durability and ultimate performance to achieve sustainable design for concrete elements with ECRBs in chloride-containing environments.

Combined-accelerated stress testing (C-AST) is developed to establish the durability of photovoltaic (PV) products, including for degradation modes that are not a priori known or examined in standardized tests. C-AST aims to comprehensively represent the sample, stress factors, and their combinations using levels at the statistical tails of the natural environment. Acceleration factors for relevant climate sequences within the C-AST cycle with respect to the Florida USA climate are estimated for selected degradation mechanisms. It is found that for degradation of the outer backsheet polymer layer, the acceleration factor of the tropical climate sequence (the longest of the climate sequences) is f (T, G) = 17.3 with ultraviolet photodegradation; for polyethylene terephthalate hydrolysis (backsheets), f (T, RH) = 426; for electrochemical corrosion (PV cell), f (I) = 14.1; and for PbSn solder fatigue f (ΔT, r (T)) = 17.3. Here, T is the module temperature, G is the broadband spectrum irradiance on the plane of array of the module, RH is the relative humidity on the module surface, I is the leakage current through the module packaging, and r(T), the number of temperature reversals. The methods discussed herein are generally applicable for evaluating acceleration factors in other accelerated test methods.

Currently, the introducing of basalt and natural fibers into different geopolymer swift growth of geopolymers. Despite of geopolymers have good properties such as fire resistance, flame resistance, higher compressive strength and higher durability, they suffer from low tensile strength and flexural strength. Different types of fibers were used to increase flexural strength, tensile strength, fracture toughness and ductility of geopolymers. The current article goals to brief the available earlier studies focused on the effect of basalt fibers and different natural fibers on the properties of geopolymers.

[ES] En la presente tesis doctoral se exponen los resultados obtenidos en el desarrollo inicial de un sistema multisensor, tipo lengua electrónica voltamétrica, para el control de la durabilidad de las estructuras de hormigón armado (EHA). Aunque los sistemas multisensores son ampliamente utilizados en diferentes ámbitos, como el del medio ambiente o de la industria alimentaria, su uso en las EHA es novedoso. Igualmente, resulta novedosa la utilización de sensores voltamétricos que, como se demuestra en esta tesis, son de gran eficacia en el análisis de parámetros relacionados con el deterioro del hormigón armado, mejorándose los modelos de durabilidad obtenidos a través de sensores potenciométricos. Todo ello, sin ser aumentada de manera inabordable la complejidad electrónica y computacional del sistema. El prototipo de lengua electrónica diseñado es un sistema de sensores híbridos que consta de cuatro electrodos de trabajo (Au, Ag, Ni e INOX). Se dice que es híbrido porque se usan técnicas tanto voltamétricas (voltametría cíclica) como impedimétricas (espectroscopia de impedancia). Se han utilizado metales nobles (Au y Ag), metales no nobles (Ni) y aleaciones de alta durabilidad (acero inoxidable) con el fin de obtener un comportamiento electroquímico más variado. En la fase previa al desarrollo del sistema se seleccionaron los metales a utilizar en los sensores que formarían parte del sistema multisensor. Para ello se realizó un número ingente de ensayos con distintos metales (Ir, Rh, Pt, Au, Ag, W, Ni y INOX), tanto en disolución (simulando las condiciones de disolución de poro del hormigón), como en hormigón, con el fin de ser seleccionados aquellos metales de cuya respuesta se pudiera extraer una mayor información. Una vez finalizada la fase previa se estudió la respuesta aislada de cada uno de los metales seleccionados (Au, Ag, Ni e INOX), dividiéndose el estudio en 3 fases: ¿ Fase 1. Estudio en disolución: se analizaron los procesos que tienen lugar sobre la superficie del electrodo en disoluciones que simulaban distintas circunstancias que se pueden dar en el hormigón (variación de la disponibilidad de O2, variación del pH y presencia del anión cloro). Los resultados obtenidos se compararon con los encontrados en literatura. ¿ Fase 2. Estudios hechos con el sensor embebido en hormigones convencionales sin adiciones. Se embebieron sensores voltamétricos en hormigones convencionales de distinta relación agua/cemento. Seguidamente, se analizaron las probetas bajo distintas circunstancias que tuvieran influencia en el desencadenamiento y cinética de los procesos de corrosión como son: o Variaciones en la disponibilidad de O2 y H2O. o Carbonatación del hormigón. o Presencia de Cl-. ¿ Fase 3. Se desarrollaron modelos que permitieran identificar variaciones en parámetros relacionados con el deterioro del hormigón armado o estimar y predecir el parámetro de interés. Terminado el estudio de la respuesta aislada de los cuatro sensores, se procedió a evaluar la respuesta cruzada de los sensores siguiendo los protocolos propios de las lenguas electrónicas. Tras analizar y comparar las respuestas aisladas y cruzadas de los sensores, se propuso una rutina de trabajo que en un futuro ayude a optimizar los recursos, tanto operacionales como de fabricación, utilizados en el sistema. Para finalizar, se hizo un estudio inicial para tratar de mejorar la autonomía del sistema, evaluando el efecto producido al simplificar la configuración de celda, reduciendo el número de electrodos de tres a dos., [CA] En la present tesi doctoral s'exposen els resultats obtinguts en el desenvolupament inicial d'un sistema multisensor, tipus llengua electrònica voltamètrica, pel control de la durabilitat de les estructures de formigó armat (EFA). Encara que l'ús d'aquest tipus de sistema està molt expandit en l'àmbit del medi ambient i de la indústria alimentària, el seu ús en les EFAs és molt nou. Igualment, resulta nova la utilització de sensors voltamètrics, que com és demostra en aquesta tesi, són de gran eficàcia en la determinació de les condicions del formigó armat, millorant-se considerablement els models de durabilitat obtinguts mitjançant sensors potenciomètrics. Tot això, sense augmentar la complexitat electrònica i computacional del sistema d'una forma inabordable. El prototip dissenyat de llengua electrònica és un sistema de sensors híbrids compost per quatre elèctrodes de treball (Au, Ag, Ni i acer inoxidable). Es diu que és híbrid perquè en el sistema de sensors s'utilitzen tècniques voltamètriques i impedimètriques. S'han utilitzat metalls nobles (Au i Ag), metalls no nobles (Ni) i aliatges d'alta durabilitat (acer inoxidable). Amb la finalitat d'obtindre un comportament electroquímic més variat. En la fase prèvia al desenvolupament del sistema, es van seleccionar els metalls a utilitzar en els sensors que formarien part del sistema multisensor. Per a això es va realitzar una quantitat ingent d'assajos amb diferents metalls (Ir, Rh, Pt, Au, Ag, W, Ni i acer inoxidable), tant en dissolució com en formigó, amb l'objectiu de seleccionar aquells metalls dels quals es poguera aconseguir més informació amb la seua resposta. Una vegada finalitzada aquesta fase prèvia, es va estudiar la resposta aïllada de cadascun dels metalls seleccionats (Au, Ag, Ni i acer inoxidable). L'estudi es va dividir en tres fases: ¿ Fase 1. Estudis en dissolució: es van analitzar els processos duts a terme sobre la superfície de l'elèctrode en dissolucions que simulaven diferents circumstàncies que es poden donar en el formigó (variació de la disponibilitat d' O2, variació de pH i presència de l'anió clor). Els resultats obtinguts es van comparar amb els trobats en la literatura. ¿ Fase 2. Estudis fets amb els sensors embeguts en formigó: es van embeure els sensors voltamètrics en formigons convencionals de diferent relació aigua/ciment i sense adicions. A continuació, es van analitzar les provetes sota diferents circumstàncies que tingueren influència en el desencadenament i cinètica dels processos com són: o Variacions en la disponibilitat d' O2 i H2O. o Carbonatació del formigó. o Presencia de Cl-. ¿ Fase 3. Desenvolupament de models que possibiliten identificar variacions en paràmetres relacionats amb el deteriorament del formigó armat o estimar i predir el paràmetre d'interès. Finalitzat l'estudi de la resposta aïllada dels quatre sensors, es va avaluar la resposta creuada mitjançant protocols propis de les llengües electròniques (PCA i PLS). Després d'analitzar i comparar les respostes aïllades i creuades dels sensors, es va proposar una rutina de treball que un futur ajude a optimitzar els recursos, tant operacionals com de fabricació, utilitzats al sistema. Per acabar, es va fer un estudi inicial per a tractar de millorar l'autonomia del sistema, avaluant l'efecte produït al simplificar la configuració de cel·la, reduint el nombre d'elèctrodes de tres a dos., [EN] In this thesis the results obtained in the development of a multisensor system, known as electronic voltametric tongue, for the reinforcement concrete structures' (RCS) durability control are exposed. Although the use of this multisensor system is widespread in different fields such as: the food industry and environmental control, its use in RCS monitoring is very novel. It is equally novel the use of voltametric sensors, this kind of sensors are very efficient in determining concrete conditions, improving the durability models obtained through potentiometric sensors, all without overly increasing the system's electronic and computational complexity The electronic tongue prototype designed is a hybrid sensor system made up of four working electrodes (Au, Ag, Ni and stainless steel). It has been referred to as hybrid because in the system voltametric and impedimetric electrochemical techniques are used. Noble metals (Au and Ag), non-noble metals (Ni) and high-durability alloys (stainless steel) have also been used with the purpose of achieving a more varied electrochemical behaviour. In the previous development phase of the system, the metals involved in the development of the electronic tongue were selected. In order to do this, a variety of tests with different metals were performed (Ir, Rh, Pt, Au, Ag, W, Ni and SS), in both dissolution (different concrete pore solution conditions were simulated) and hardened concrete. This allowed us to choose the metals which responses contained the most information. The next steps focused on the study of the selected sensors isolated response: ¿ Phase 1: simulation of concrete pore solution in dissolution systems. The results were compared with those already existing in the bibliography. ¿ Phase 2: studies with the sensors embedded in different standard concretes without additions. The samples were tested in different conditions involved in the rebars corrosion kinetics (variations in O2 and humidity availability, concrete carbonation and chlorides presence). ¿ Phase 3: Development of estimation models for the parameters of interest. After finishing the study of the isolated sensors' response, a cross-evaluation of their response was performed using typical protocols used in the electronic tongues (i.e. PCA and PLS). After analysing and comparing the isolated and crossed sensor's response, an optimized multisensory routine work was proposed which could, in the future, help optimize the resources used in the system. Finally, a study was carried out to improve the system's autonomy, in which the repercussion of the cell configuration simplification by means of the removal of the reference electrode was evaluated., La autora quiere expresar su agradecimiento al Ministerio de Educación, Cultura y Deporte por la beca predoctoral FPU 16/00723

Perovskite-type oxides are considered as promising alternatives to the scarce and expensive precious metal-based electrocatalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Here, we report a Bi0.15Sr0.85Co0.8Fe0.2O3-δ (BiSCF) perovskite prepared by the conventional solid-state reaction method as a novel bifunctional oxygen electrocatalyst in alkaline media. BiSCF shows excellent electrocatalytic activities towards both OER and ORR with a low OER overpotential ( η OER @ 10 mA c m − 2 = 354 mV), good chemical reaction kinetics (Tafel slope = 94.21 mV dec−1 and 72.8 mV dec−1 for OER and ORR, respectively), and excellent durability (i.e., η OER @ 10 mA c m − 2 increases from 354 mV to 404 mV within 24 h; better durability than the commercial 30 wt.% Pt/C at 0.4 V vs RHE regarding ORR). It also presents the best bifunctional property among the reported perovskites. The excellent electrocatalytic properties of BiSCF can be attributed to its abundant oxygen vacancies and rich oxidation states of Co and Fe. With high activities, excellent stability and easy fabrication, BiSCF is expected to be a promising bifunctional oxygen electrocatalyst for renewable energy conversion and storage devices.

The combination of glass powder (GP) with pozzolanic additions to replace clinker can develop new types of binders (ternary cement) with improved physical and mechanical properties, thereby enabling a reduction in consumption of clinker and natural resources, and the minimisation of the carbon dioxide emissions. In this context, the present work is an attempt to study the influence of GP with two different specific surface areas (Blaine) GP30 = 300 m2/kg and GP45 = 450 m2/kg, combined with slag, on the mechanical behaviour and durability of mortars. The mechanical properties were investigated using compressive and flexural strength tests. Aspects related to durability were examined as well by water-accessible porosity, capillary absorption and sorptivity tests. The replacement rate of cement by GP varied from 10 to 20% and the proportion of slag was fixed at 10%. The results showed that a binary mortar made with 20% GP45 replacement showed increases in 90 day compressive strength, while ternary mortar with 20% GP45 + 10% slag replacement gave the best result. The same trend is also valid for durability properties examined in this study. The combined use of GP and slag at 30% replacement levels seemed to perform better compared with using GP alone.

Few studies have reported the effect of cement content and surcharge pressure on the drying−wetting durability of cement-stabilised clayey soil. The aim of this research was thus to understand the effect of these two factors on the drying−wetting durability of cement-stabilised clayey soil. Clayey soil, dredged from Taihu Lake in Wuxi, China, was stabilised with three different cement contents. Drying−wetting tests were performed on the cement-stabilised clayey soil under five different surcharge pressures and direct shear tests were conducted using a modified conventional direct shear device. The cement content was found to have a significant effect on the drying−wetting durability of the cement-stabilised clayey soil. Drying−wetting appears to decrease the shear strength of clayey soil with a low cement content, whereas drying−wetting appears to increase the shear strength of clayey soil with a high cement content. The variation in shear strength of the cement-stabilised clayey soil is attributed to drying-induced bond damage and drying-temperature-induced hydration and pozzolanic reactions. The surcharge pressure had a significant impact on the drying−wetting durability in a certain range. The findings are interesting from a practical perspective for earthworks involving cement-stabilised clayey soils.

Endowing strain sensors with superhydrophobicity is of great importance to guarantee their long-term service under harsh environments (such as wet, acid, alkali and salt atmospheres), whereas, the development of superhydrophobic strain sensors remains a great challenge. Herein, we realized a superhydrophobic and highly sensitive sensor for subtle human motion detection by designing a superhydrophobic and electrically conductive coating on cotton textile, via a facile drop-coating method. The resultant strain sensor showed a large water contact angle of 161.3 ° and a low sliding angle of 3.8 ° The superhydrophobic characteristics can keep almost unchanged even after undergoing 1000 peeling cycles, 1000 stretching-release cycles, and 1000 bending-releasing cycles, revealing its excellent mechanical robustness. High sensitivity with the maximum gage factor of 169 was achieved for the strain sensor under a small strain of 0–10%, and the sensing performance also showed well durability. Moreover, our sensor can effectively detect various subtle human physiological signals and body motions even under harsh conditions. These admirable features make the sensor promising applications in wearable electronics, personalized health monitoring, sound recognition, and so on.

The strength and durability of structures are strongly influenced by damage from steel corrosion caused by chloride ions. This chloride-induced corrosion mechanism is investigated yearly. However, the strength and durability of steel fibre recycled concrete (SFRC) in chloride environments have rarely been studied. By changing the water–cement ratio of SFRC blocks, the sodium chloride (NaCl) concentration of the soaking solution, soaking time and the number of chloride-ion-permeating surfaces, a series of compressive strength experiments were performed, where the chloride ion content of tested blocks was measured. The results showed that the water–cement ratio of blocks greatly influences the strength and durability of SFRC and that the sodium chloride concentration of the soak solution, and the number of chloride-ion-permeating surfaces, also affects the blocks to a certain degree. A water–cement ratio of 0·45 should be chosen due to its low chloride ion content and high compressive strength. The water–cement ratio and the number of chloride-ion-permeating surfaces can be controlled more easily in practical engineering, it is therefore necessary to optimise the best water–cement design ratio and add a water-repellent coating on the SFRC surfaces to ensure the durability of the structure.

Prefabricated pavement is increasingly applied worldwide due to the rapid construction on-site. This paper presents a state-of-the-art review of the precast systems and assembly connection of concrete slabs, as well as the precast pavement features. The previous research indicates that (1) Both Super-Slab and Michigan systems are recommended with the satisfied road performance close to the cast-in-place. (2) Flexible base material is suggested for the fabricated pavement for the satisfied leveling and stress distribution. (3) To prevent the voiding phenomenon of the fabricated pavement, the sand cushion course, dry mixed mortar or self-leveling mortar, and other flowable materials could be used for the secondary leveling of the base after the pavement splicing. (4) Two-direction dowel bars are recommended for slab connections of the fabricated pavement, which helps to improve the load transfer capacity of the joints and enhance the durability of the fabricated pavement structure. (5) The sealing treatment of precast slab joints needs strengthening to reduce the impact of surface runoff on the base course. (6) The further research focuses are designing with functional, composite, mechanized, intelligent, lightweight, and flexible pavement slabs. Besides, pavement mechanical properties induced by temperature overlapping traffic loads need to be revealed.

In the saline soil environment of western China, salts can corrode ordinary cement concrete seriously, and the durability of concrete structure deteriorates gradually until it fails. This impedes the application of ordinary Portland cement concrete in this area. Aiming at the problem of the short service life of concrete in the harsh environment of western China, this study examines the performance of nano-CaCO3 modified concrete in a sulfate environment. The durability of the concrete was evaluated by the apparent phenomena on the relative quality evaluation parameter, the relative dynamic elastic modulus evaluation parameter, and the comprehensive damage evaluation parameter. The microstructure of corroded products was investigated using scanning electron microscopy to reveal the deterioration mechanism. The results show that the addition of 1% nano-CaCO3 can enhance the resistance of concrete to sulfate corrosion, and the service life of concrete structures will increase significantly.

Overhead electric supply lines are subject to water and ice accumulation, causing noise and weight increase, and leading to faults or failures. In this research, micro-textures were laser-ablated on aluminium substrates representative of overhead line conductors to achieve superhydrophobic properties. Samples were then subjected to a range of tests to measure the resilience and durability of such surfaces to conditions experienced by overhead line conductors. Tests to examine thermal ageing, thermal cycling, UV exposure, long term ambient outdoor environment exposure, and corona exposure testing were conducted and the evolution of surface superhydrophobicity was quantified. A high degree of resilience was observed for most of the testing. The feasibility of manufacturing upscale is discussed in addition to optimising test methods.

Nonvolatile ionogels have recently emerged as promising soft electrolyte materials due to their high ionic conductivity and good durability. However, the compatibility between polymer networks and ...