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The rapid increase in the number of electronic products worldwide, in terms of both variety and advanced technology, together with the decrease in costs, has led to the generation of a large amount of electronic waste (e-waste), which has significantly increased environmental pollution. This study was conducted to investigate the hypothesis that the adhesion of polymer binders and plastic origin e-waste will be more effective and stronger, and therefore have a positive effect on the permeability properties of polymer concrete and its behavior against aggressive solutions. For this purpose, quartz aggregates and gravel used as an aggregate in polymer concrete were replaced with 0%, 3%, 6%, 9%, 12% and 15% e-waste. In the study where unsaturated polyester resin was used as a binder, the changes in the permeability properties (capillary water absorption, rapid chloride permeability) of the e-waste polymer concrete and its behavior against aggressive solutions (acid and sulfate attacks) were evaluated after 7, 28 and 90 days. In addition, mechanical experiments were conducted and comparisons were made. After the control concrete, the highest compressive strengths were obtained from the polymer concrete specimens using 3% e-waste, measured as 59.05 MPa, 64.5 MPa and 73.05 MPa after 7, 28 and 90 days, respectively. The research showed that polymer concretes with capillary water absorption coefficient values close to zero after 90 days can be produced with using up to 9% e-waste. The use of e-waste as an aggregate in polymer concrete at 3%, 6% and 9% e-waste, in particular, produced concrete with a high resistance to acid and sulfate attacks. The hypothesis of the study was confirmed after extensive experiments. [ABSTRACT FROM AUTHOR]

Ferrochrome slag (FS) having favourable mechanical properties) may be gainfully utilised as concrete aggregate. The concrete specimens with FS, natural stones (NS) and NS concrete mixed with 2% chromium nitrate salt (CR) as coarse aggregate were prepared. The samples were cured in aggressive curing solution like sulphuric acid solution at pH 2 and 10% magnesium sulphate in order to examine its degradation aspects in terms of possible loss of strength, reduction of mass and the surface damage. The deterioration effects are assessed after 28, 56, and 90 days of curing. The results indicate that FS concrete has the minimum reduction of strength, least reduction of mass and less surface deterioration in comparison to concrete with NS and CR. FS has appreciable amount of environmentally deleterious residual chromium but almost all of these chromium contents are inherently immobilized in the slag matrix as evidenced in microstructure study. The concrete specimens using FS as coarse aggregate with its immobile chromium acting as passivation agent may provide better corrosion resistance and along with the usage of slag-based cement as binder furnish some protection measures against the corrosion effect under aggressive acid and sulphate action. This is the principal research significance of this work and it will provide a suitable platform for global research to explore the further work on the corrosion resistance of concrete bound FS exposed to different aggressive curing environment. [ABSTRACT FROM AUTHOR]

This article discusses the impact of the aggressive environment on the pattern of pore distribution, strength, and mass absorption of investigated samples. For this purpose, a physical and numerical research model has been developed based on Fick's second law and Zhurcov's theory. Consequently, computer tomography research revealed that pore redistribution was revealed in test samples due to exposure. The degradation model is proposed assuming that in the first stage of interaction between concrete constructions and aggressive medium, the product of interaction is accumulated in the surface of structures and pores. Interaction products in the form of needle-shaped crystals grow in time and create additional stress in the body of the structure, resulting in partial distribution of the surface of the structure due to the growth. In this state, the excretion of dissolved substances (in the form of citrate and calcium acetate), leaching of Ca(OH)2, and decalcination of CSH lead to a decrease in the strength of cement stone. Based on the developed numerical models, the dependences of aggressive environment impact on the on the parameters of the structure of cement composites at different exposure times were obtained. For the samples obtained during the activation of Portland cement in the electromagnetic mill, energy parameters of the destruction process are 1.85–2.2 times heavier than the control compositions. The samples obtained by activating Portland cement in the electromagnetic mill have a higher susceptibility to an aggressive environment (they absorb 1.8 times more energy per unit of time for structure transformation). However, the higher U-energy barrier (1.85 times greater than the control composition) provides both a longer term of exploitation and a lower kinetics of the change in the strength of the material. [ABSTRACT FROM AUTHOR]

Thermal barrier coatings (TBCs) are widely used to improve the oxidation resistance and high-temperature performance of nickel-based superalloys operating in aggressive environments. Among the TBCs, aluminide coatings (ACs) are commonly utilized to protect the structural parts of jet engines against high-temperature oxidation and corrosion. They can be deposited by different techniques, including pack cementation (PC), slurry aluminizing or chemical vapor deposition (CVD). Although the mentioned deposition techniques have been known for years, the constant developments in materials sciences and processing stimulates progress in terms of ACs. Therefore, this review paper aims to summarize recent advances in the AC field that have been reported between 2019 and 2023. The review focuses on recent advances involving improved corrosion resistance in salty environments as well as against high temperatures ranging between 1000 °C and 1200 °C under both continuous isothermal high-temperature exposure for up to 1000 h and cyclic oxidation resulting from AC application. Additionally, the beneficial effects of enhanced mechanical properties, including hardness, fatigue performance and wear, are discussed. [ABSTRACT FROM AUTHOR]

In this study, the impact of aggressive environments on the color characteristics of natural stone was thoroughly investigated. The research focused on samples of facing stones, namely: Kamyanobridsky labradorite, Bukynske gabbro, Pokostivsky granodiorite, and Kapustinsky granite. Experiments to determine the color changes of natural stone were conducted at a temperature of 20 °C in aggressive environments such as sodium hydroxide (NaOH) with a concentration of 40 g/L, sulfuric acid (H2SO4) – 40 g/L, and ammonium chloride (NaCl) – 40 g/L. The overall exposure duration was 50 days. Before placing the natural stone samples in an aggressive environment, their polished surface was scanned using a digital scanner. The average gloss value of the polished surface was also measured using a gloss meter BF-3. The natural stone samples were exposed to aggressive solutions, and measurements of gloss and color were taken every 240 hours. Prior to each new measurement of color characteristics and gloss of natural stone, they were thoroughly rinsed with distilled water and dried. In case of the appearance of white spots on the stone surface after drying, they were carefully wiped with a damp cloth. Scanned digital images were processed in specialized graphic programs to obtain color coordinates of the natural stone surface. The average value of color difference in the CIELab system was evaluated. As a result of the conducted research, it was determined that key changes in the color of stone facing surfaces occur within the first 30 days (720 hours) for rocks of the primary composition. This indicates the necessity of considering this period in project planning. Under the influence of aggressive solutions on rocks of the primary composition, during 720 hours, the most significant reduction in gloss indicators was observed when interacting with an acidic solution, specifically by 26 units, while the least impact was from the saline solution, reducing gloss by only 3.7 units. In rocks of acidic composition, the saline solution increased gloss by 3.3 units.

This article discusses the impact of the aggressive environment on the pattern of pore distribution, strength, and mass absorption of investigated samples. For this purpose, a physical and numerical research model has been developed based on Fick’s second law and Zhurcov’s theory. Consequently, computer tomography research revealed that pore redistribution was revealed in test samples due to exposure. The degradation model is proposed assuming that in the first stage of interaction between concrete constructions and aggressive medium, the product of interaction is accumulated in the surface of structures and pores. Interaction products in the form of needle-shaped crystals grow in time and create additional stress in the body of the structure, resulting in partial distribution of the surface of the structure due to the growth. In this state, the excretion of dissolved substances (in the form of citrate and calcium acetate), leaching of Ca(OH)2, and decalcination of CSH lead to a decrease in the strength of cement stone. Based on the developed numerical models, the dependences of aggressive environment impact on the on the parameters of the structure of cement composites at different exposure times were obtained. For the samples obtained during the activation of Portland cement in the electromagnetic mill, energy parameters of the destruction process are 1.85–2.2 times heavier than the control compositions. The samples obtained by activating Portland cement in the electromagnetic mill have a higher susceptibility to an aggressive environment (they absorb 1.8 times more energy per unit of time for structure transformation). However, the higher U-energy barrier (1.85 times greater than the control composition) provides both a longer term of exploitation and a lower kinetics of the change in the strength of the material.

Reinforcement corrosion is a phenomenon that affects not only the durability and serviceability of the structure itself but the economy of the countries, as well. In many cases, structures and bridges must be repaired or reconstructed as a result of corrosion of the reinforcement. In extreme cases, when maintenance is neglected, it is necessary to completely replace the structures with new ones, even if their planned service lifetime has not been reached ‐ it is not enough to strengthen them or it is economically inefficient. Corrosion of the reinforcement primarily causes a reduction in the cross‐sectional resistance of the load‐bearing elements by reducing the cross‐sectional area of the reinforcement, which means a reduction in the force in the reinforcement that it transmits. For this reason, it is necessary to know the rate of corrosion over time depending on the environment in which the element is located. The paper is focused on the experimental measurements of corrosion losses due to atmospheric corrosion on reinforcement samples using the field test. As a part of experimental measurements, corrosion rates on reinforcements of four diameters (diameters 6, 10, 14, and 25 mm) of steel for reinforcement, grade B 500B, are monitored at measuring stations and bridges in various aggressive environments. [ABSTRACT FROM AUTHOR]

The scientific article is devoted to the study of modern technologies for restoring the internal surfaces of critical parts of the structural elements of oil and gas pumps. By the method of critical analysis of defects, it was found that paraffin deposits and mechanical impurities are in the list of the main complicating factors leading to abrasive wear of the working surface of the parts being contacted. Asphalt-resin-paraffin deposits together with mechanical impurities are distributed unevenly, for example, along the diameter of the cylinder of the injection column, narrowing the passage section of the rod in different stroke length intervals. This phenomenon causes the rod to deviate from the design axis of the trajectory of movement and forms sections of the cylinder working under shock loads with maximum wear. Therefore, it is necessary to restore the degraded surface in places where maximum dynamic loads are applied. The patent search method and the evaluation of the claims allowed us to establish that the generally accepted methods of restoring internal surfaces are reduced to nitriding and chrome plating. Due to known technological shortcomings, these methods are limited in application, and it is impossible to restore the phase structure by these methods. To solve the technological problem of restoring the structure and modifying the inner surface of a small cylinder diameter, it is proposed to apply a coating with a ceramic protective layer based on nickel alloys of the carbide class, which has high hardness and inert properties. To restore the surface of worn parts in conditions of a limited coordinate space of long-dimensional elements of the RDP structure (pump and compressor pipes, a pair of cylinder-plunger and others), the authors propose a promising laser spraying.

Self-healing is recognized as a promising technique for increasing the durability of concrete structures by healing cracks, thereby reducing the need for maintenance activities over the service life and decreasing the environmental impact. Various self-healing technologies have been applied to a wide range of cementitious materials, and the performance has generally been assessed under 'ideal' laboratory conditions. Performance tests under ideal conditions, tailored to the self-healing mechanism, can demonstrate the self-healing potential. However, there is an urgent need to prove the robustness and reliability of self-healing under realistic simulated conditions and in real applications before entering the market. This review focuses on the influence of cracks on degradation phenomena in reinforced concrete structures, the efficiency of different healing agents in various realistic (aggressive) scenarios, test methods for evaluating self-healing efficiency, and provides a pathway for integrating self-healing performance into a life-cycle encompassing durability-based design. [ABSTRACT FROM AUTHOR]

The paper provides a short review of the history of the development of native and foreign regulatory requirements of testing for sulfide stress corrosion cracking. Systematic ambiguity (duplicated in the reviewed regulatory requirements) in the choice of test environment parameters and its influence on the interpretation of the results was revealed. A series of laboratory tests, the purpose of which was to specify the choice of the most favorable combinations of parameters (pH2S/pH combinations) of the test medium was conducted.

Film protection has become a crucial means to improve the corrosion and wear performance of key components in aggressive environment. In this study, the feasibility of using MoS2-based modified films in artificial seawater (3.5% NaCl solution) was evaluated by co-deposition of Ti to produce Ti–MoS2 composite and Ti/MoS2 multilayer films. The microstructure, wettability, mechanical, tribological and corrosion behavior of the Ti-modified MoS2-based films was contrasted to pure MoS2 film. The results show that the incorporation of Ti not only improves densification, but also promotes a transformation from a columnar to an amorphous film structure, leading to the improvement of mechanical properties of Ti–MoS2 composite film and Ti/MoS2 multilayer film. The friction coefficient curves of all of the three MoS2-based film in 3.5 wt% NaCl solution show stable values during the sliding process. The advantage of the preferential (002) growth orientation, improved mechanical properties and reduced hydrophobicity for both of the Ti-modified MoS2 films caused the decreased friction coefficient and wear rate in NaCl solution. The electrochemical results before and after friction show that the ranking of corrosion resistance is Ti/MoS2 multilayer > Ti–MoS2 composite film > pure MoS2 film, which is attributed to the compact microstructure and the presence of surface passive films.

With the rising demands of industry to increase the working temperature of gas turbine blades and internal combustion engines, thermal barrier coatings (TBC) were found to be an effective way to further enhance the lifetime of aero components through the improvement of mechanical properties and oxidation-resistance. Thus, this paper aims to review coating technologies with special emphasis on plasma-sprayed thermal barrier coatings (PS), and those produced by physical vapor deposition (PVD) and chemical vapor deposition (CVD) methods. Each technology was assessed in terms of its effectiveness to enhance the mechanical response and oxidation resistance of nickel-based parts working at high temperature. The effect of coating technology on mechanical strength, hardness, fatigue and creep of nickel alloys was discussed to reveal the potential candidates for future applications in aggressive environments. [ABSTRACT FROM AUTHOR]

One of the most dangerous types of cyclic effects, especially inherent in several regions in the world, is the alternating impact of wetting and drying on concrete and reinforced concrete structures. In the current scientific literature and practice, there is not enough fundamental and applied information about the resistance to wetting and drying of variotropic concretes obtained by centrifugal compaction methods. The purpose of the study was to investigate the effect of various technological, compositional, and other factors on the final resistance of variotropic concrete to alternating cycles of moistening and drying. For this, special methods for testing concrete samples were used in the work. It has been established that after strength gain as a result of hydration, there is a tendency for strength loss due to concrete wear. An acidic medium has the most negative effect on the strength characteristics of concretes made using various technologies, compared with neutral and alkaline media. The loss of strength of concrete when moistened in an acidic medium was greater than in alkaline and especially neutral media. The vibrocentrifuged concrete turned out to be the most resistant to the impact of an aggressive environment and the cycles of moistening and drying, compared to the centrifuged and vibrated concrete. The drop in strength was up to 7% less compared to centrifuged concrete and up to 17% less than vibrated concrete. [ABSTRACT FROM AUTHOR]

A mechanistic-chemometrics model for life prediction of P110S steel in deep-well environments with H₂S/CO₂ coexistence was proposed. The model was developed by considering the interaction mechanism between uniform and pitting corrosion, then modified using a multi-factor chemometric drive incorporating temperature/pressure, flow velocity, stress. Finally, the pit-to-crack transition was modeled using finite element design and direct current potential drop measurements, completing the life prediction process. The model predicts a lifespan of 2.28–5.25 years at different well depths, and this result was validated with on-site data, indicating the model's accuracy. The knowledge paradigm provided herein will assist in corrosion prediction. • A new chemometric-driven prediction model for P110S steel in deep-well environments has been established. • The model was reconstructed considering the interaction between uniform and pitting corrosion and pit-to-crack transition. • The Box-Behnken Design, Finite element analysis and DC potential drop measurement were applied to establish the model. • Comparison with the model and on-site data indicates that the mechanistic-chemometrics model is accurate and reliable. [ABSTRACT FROM AUTHOR]

The problem of assessing the strength and resource of critical engineering objects is considered. The operating conditions of objects are characterized by high-temperature non-stationary thermomechanical effects, which lead to degradation of the initial strength properties of structural materials by the mechanism of long-term strength. From the standpoint of the mechanics of a damaged medium, a mathematical model has been developed that describes the kinetics of the stress-strain state and the accumulation of damage during material degradation by the mechanism of long-term strength under conditions of a complex multiaxial stress state. An experimental-theoretical method for finding the material parameters and scalar functions of the constitutive relations of the mechanics of a damaged medium based on the results of specially set experiments on laboratory samples is proposed. The results of experimental studies and numerical modeling of the short-term high-temperature creep of VT6 titanium alloy under uniaxial and multiaxial stress states are presented. The numerical results are compared with the data of field experiments. Particular attention is paid to the issues of modeling the process of unsteady creep for complex deformation modes, accompanied by the rotation of the main areas of stress tensors, deformations and creep deformations, taking into account the effect of an aggressive environment, which is simulated by preliminary hydrogenation of laboratory samples to various hydrogen concentrations by mass. It is shown that the developed version of the constitutive relations of the mechanics of a damaged medium allows, with sufficient accuracy for engineering calculations, to describe unsteady creep and long-term strength of structural alloys under multiaxial stress states, taking into account the effect of an aggressive medium (hydrogen corrosion).

It was established that with increased concentrations of chlorides, sulfate-reducing bacteria, heterotrophic bacteria, thionic and iron bacteria the corrosion rate of the studied specimens of reinforcing steels sharply increases. The 40KhN and 09G2S steels had the highest resistance to corrosion, and the St.20 steel had the lowest resistance. The obtained data correlate with the results of numerical experiments reported in the publications of domestic and foreign researchers. For the first time, the data obtained from a series of experimental tests of reinforcing steels for cyclic strength showed that the steels characterized by low corrosion resistance also have a low resistance to cyclic strength, which can be explained by their degradation. The authors believe that, in the process of long-term operation of reinforced concrete structures in an aggressive environment, carbonization and chloritization of concrete, that is, its destruction occur. Further hydrogen charging of reinforced concrete causes embrittlement and reduction of the visco-plastic properties of the reinforcement, which in turn leads to the destruction of metal. The obtained results make it possible to develop metallurgical and technological measures to increase the durability of reinforced concrete structures: the use of chromium, nickel, and manganese alloyed steels for the manufacture of reinforcement with subsequent proper heat treatment; the use of modern high-strength concrete, which will ensure strong adhesion of concrete mortar to the surface of reinforcing bars. [ABSTRACT FROM AUTHOR]

The use of reinforced concrete in construction is in great demand in the modern world. Despite the high pace of technological development, reinforced concrete still needs more extensive research in its various areas. One of the most urgent problems of reinforced concrete structures is to improve the quality and duration of service life, taking into account the influence of an aggressive environment. Given the close interrelation of internal and external factors in these processes, it can be argued that the corrosion of reinforced concrete occupies a significant place in the design, calculation, construction and operation of reinforced concrete buildings and structures for various purposes. The article presents an overview analysis of the relationship between corrosion and the durability of reinforced concrete structures, including the influence of some internal factors in concrete on the safety of steel reinforcement in reinforced concrete. [ABSTRACT FROM AUTHOR]

To overcome massive pollution and energy consumption resulting from cement production in addition to concrete’s durability problems, geopolymer concretes (GPC) and mortars (GPM) are recently gaining increasing interest. GPCs are manufactured based on different ingredients such as Fly Ash, GGBS, and other Alumina-Silicate rich materials and polymerized by using alkali activator. However, based on the major polymeric constituent material and curing condition, the properties of GPC are determined. In Egypt, metakaolin (MK) is available in several locations, which after calcination exhibits satisfactory pozzolanic activity. MK is a good replacement of cements in concrete and GPC as it consumes less fuel and produces much lower pollutants. In this research, the durability of MK mixes, that can be utilized in normal construction locations are investigated. Metakaolin based geopolymer mortars (MK-GPM) with up to 60% OPC are made to investigate the effect of OPC inclusion on durability related characteristics. The influence of curing conditions at ambient temperature (23 ± 2 °C) as well as at 60 °C heat curing is also investigated. Water transport properties are evaluated. Durability related characteristics in terms of change in weight and compressive strength with time after exposure for 10 weeks to chemical solution (10% MgSO4, H2SO4 (pH=3) and 10% NaCl). Furthermore, microstructure properties are investigated through X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM) with energy dispersive X-ray spectroscopy (EDS) to identify the phase and chemical composition. The results reveal that, heat curing of MK-GPM reduces its sorptivity by 9 ± 2% and water absorption by 13 ± 3%. On the other hand, the inclusion of OPC in MK-GPM (by more than 5%) increases water absorption and sorptivity and consequently reduces durability. Although, MK-GPM shows better durability when exposed to aggressive environmental attacks, incorporating cement up to 20% demonstrates better durability performance than OPC mortar. The study of the microstructure of tested mixes explains and confirms the experimental results.

Two categories of GFRP specimens, in nominal diameters of 11.2 mm and 15.6 mm respectively, made of E-glass fibers and a vinylester resin were immersed in alkaline solution, saline solution and tap water solution at room temperature. The mechanical and durability properties of tested GFRP bar specimens were determined through direct tensile test and short-beam shear test after exposure to aggressive solutions for different days. The obtained results indicated that for all tested GFRP bar specimens the failure modes of fiber rupture in the tensile test and horizontal cracking in the short-beam shear test would not obviously change with the increasing of exposure period. However, the impact of immersion solutions on the durability degradation of mechanical properties of GFRP bars appeared in the ultimate strength and displacement at failure, and at room temperature the alkaline solution had a greater impact than another two solutions. Under the same exposure conditions, the resistance to the strength degradation of the GFRP bars with a larger diameter was better than that of the smaller GFRP bars. The comparison results indicated that the strength degradation trend of conditioned GFRP bars presented in our study was basically in agreement with the data given in previous studies.

One of the most dangerous types of cyclic effects, especially inherent in several regions in the world, is the alternating impact of wetting and drying on concrete and reinforced concrete structures. In the current scientific literature and practice, there is not enough fundamental and applied information about the resistance to wetting and drying of variotropic concretes obtained by centrifugal compaction methods. The purpose of the study was to investigate the effect of various technological, compositional, and other factors on the final resistance of variotropic concrete to alternating cycles of moistening and drying. For this, special methods for testing concrete samples were used in the work. It has been established that after strength gain as a result of hydration, there is a tendency for strength loss due to concrete wear. An acidic medium has the most negative effect on the strength characteristics of concretes made using various technologies, compared with neutral and alkaline media. The loss of strength of concrete when moistened in an acidic medium was greater than in alkaline and especially neutral media. The vibrocentrifuged concrete turned out to be the most resistant to the impact of an aggressive environment and the cycles of moistening and drying, compared to the centrifuged and vibrated concrete. The drop in strength was up to 7% less compared to centrifuged concrete and up to 17% less than vibrated concrete.

The paper reveals the relevance of the use of adhesive polymer materials for the restoration of cars and machinery. Prerequisites for creation of universal polyurethane adhesive compositions of new generation for restoration of cars with the improved adhesive, physical-technical and operational properties which possess high resistance to aggressive environments and made of materials of domestic production are created. The advantage of bonding is that this method of restoring the elements of the car is applicable to materials of different nature. Expediency of work is caused by presence in the market of expensive analogs of foreign production for restoration of details of cars in this connection there is a task in development of import substituting structures. Purpose: to study the degree of mass absorption of the adhesive composition in aggressive media. Methods: experimental studies to determine the effect of aggressive media on the adhesive composition are carried out in accordance with GOST No. 12020. Results: as a result of experimental studies, it was found that of the considered media, the most aggressive is water. It is the most polar of all considered aggressive media, has a number of features, for example, the small size of molecules. Scientific novelty: it was revealed that in most cases of exposure to aggressive media on samples of adhesive materials, there was a sharp increase in the degree of mass absorption for 20 days, and in the future the process is balanced. The Penza state University of architecture and construction has developed a fast-curing adhesive composition based on cold-curing polyurethanes in order to reduce the cost of restoring parts of various transport and technological machines. It can find application for restoration and repair of plastic elements of the car, and also in mechanical engineering. Practical significance: the main provisions and conclusions of the article can be used in the development of technologies for repair of automotive equipment with the use of polyurethane adhesive compositions. Experimental testing showed that the developed polyurethane modified adhesive compositions of a new generation with improved adhesive properties, reduced curing time, have high chemical resistance in almost all aggressive environments.

An experimental study was conducted to evaluate durability (compressive strength and mass loss%) in the modified sulfur concrete within aggressive environments. The modified sulfur concrete was prepared by adding recycled polymeric and filler materials that showed a noticeable enhancement for modified sulfur concrete characteristics. A durability comparison between modified sulfur concrete and traditional concrete was investigated at normal and aggressive environments (10% HCl and 3% NaCl). A cuboid shape with size (50 × 50 × 50mm) was used in this research to investigate the durability of both modified sulfur and traditional concrete. The modified sulfur concrete characteristics revealed high stable structure than traditional due to preventing a process of crystallization of sulfur that modified with polymer and fillers. The compressive strength was 10.87 – 22.5% increased for modified sulfur concrete compared to the traditional concrete at the normal environment. In the aggressive environments, the modified sulfur concrete illustrated high resistance strength compared to the traditional concrete. The comparison revealed a significant impact for 10% HCl and 3% NaCl on the traditional concrete. The compressive strength decreased between (88.78 – 96.17) % for traditional concrete compared to modified sulfur concrete in 10% HCl solution and (84.25 – 95.06) % in 3% NaCl solution. Furthermore, mass loss % of the modified sulfur concrete indicated high resistance compared to the traditional concrete in both 10% HCl and 3% NaCl solutions.

Strength prediction of concrete under the aggressive environment requires serious attention for all kind of significant concrete structures. However, concrete built with Ordinary Portland Cement (OPC), when subjected to the aggressive environment tends to deteriorate more rapidly than their projected life. Therefore, supplementary cementitious material (SCM) need to be introduced to enhance the strength performance of concrete. However, prediction of concrete compressive strength is also an important for the safety and quality control of concrete structures. Therefore, this study aims to develop empirical equation for the prediction of compressive strength of coal bottom ash (CBA) concrete exposed to aggressive environment that represents the marine environment. In this study, practically obtained results of compressive strength were compared with the theoretical obtained compressive strength values. The developed modified equation was validated through experimental data compared with ACI 209 and SRPS U.M1.048 standards. Hence, this study proposed a modified empirical equation that could be utilized for the expectation of compressive quality of concrete containing CBA. [ABSTRACT FROM AUTHOR]

This paper discusses heavy density (HDC) concrete performance by partially replacing the fine and coarse aggregate in concrete with magnetite in its fine and coarser form. Three series of mixes, namely HDC-I, HDC-II and HDC-III, were developed for the research. HDC-I series contained 10% magnetite powder (MP) and 10% quartz powder (QP) as fine aggregates, whereas the HDC-II series had 15% magnetite power MP and 5% QP. The replacement level of magnetite aggregate as coarse aggregate was maintained constant by 30%, 40% and 50% for both the series. HDC-III series mix was made by replacing coarse aggregate with a significant content of 50%, 60% and 70% of magnetite aggregate by weight. Only 20% of magnetite powder was used for replacing the fine aggregate in HDC-III. Silica fume and nano-silica were also used in a constant replacement proportion in cement by 10% and 1%. Various tests related to the mechanical and durability characteristics of the concrete were performed. Compared with conventional concrete mix, the results revealed that increasing the proportion of magnetite aggregate leads to a considerable increase in unit weight and other mechanical properties. Also, it was observed that quartz powder and magnetite did not fetch any significant benefit in the mechanical properties. [ABSTRACT FROM AUTHOR]

Concrete floors are most commonly used in animal housing. However, the specific environment of livestock buildings (moisture, urine, disinfectants) has a negative effect on concrete and leads to its corrosion. The influence of chemical and physical factors on concrete is reinforced by the development of microorganisms, which quickly adapt and use concrete as a living environment. To reduce the influence of an aggressive environment on the concrete floor, an experimental mixture of dry disinfectants was proposed. The components of the disinfection mixture have been selected taking into account the safety for animals and humans. The TPD-MS method was used to determine the change in the chemical composition of concrete. To study the microstructure of concrete, the method of scanning electron microscopy was used. Microbiological studies revealed bacteria A. Thiooxidans, S. aureus, E. coli, S. enteritidis, S. Сholeraesuis, C. Perfringen and micromycetes of the genus Cladosporium, Fusariums, Aspergillus, which contribute to the development of biological corrosion of concrete in livestock buildings. The fact of the negative impact of concentrated disinfectants on the structure of concrete was also established. As a result of the studies carried out, it was proved that a mixture of dry components for disinfection exhibits antimicrobial properties to varying degrees to the strains of field isolates of bacteria and fungi isolated in a pig-breeding farm. It was found that when using the proposed mixture of dry disinfectants in the research room of the pigsty, the relative humidity decreases by 38.5 %; ammonia content – by 46.2 %; hydrogen sulfide – by 57.8 %; microbial bodies – by 74.7 %, compared with the control room. It has been experimentally proven that the proposed mixture of dry disinfecting components has hygroscopic and antimicrobial properties and is promising for use in livestock farms. [ABSTRACT FROM AUTHOR]

Evaluation of the effect of corrosion inhibitor organic polyamines on the characteristics of cement pastes, concrete and steel reinforcement corrosion behavior. To achieve this objective, the mixtures were prepared by the addition corrosion inhibitor organic polyamines by 0%, 0.5%, 0.75%, 1%, 1.25%, 1.5%, 1.75%, 2% and 3% of Portland cement (CEMI). The rheological performance, setting times, physicomechanical characteristics, were investigated. The Various hydration products were evaluated using X-ray diffraction [XRD] and thermo-gravimetric analysis [TGA/DTG]. The localized corrosion of steel reinforcements was studied using electrochemical measurements and characterization methods (XPS) to determine the layer development and assess the efficiency of the inhibition. The results confirmed that the additions of corrosion inhibitor organic polyamines (SEDREEN-SS) up to 2% improvement the physico-mechanical characteristic of hardened cement pastes and concrete. It has been found that the addition of SEDREEN-SS inhibitor with concentration 1.25% was the optimum ratio of inhibition efficacy. The XPS results demonstrate that SS-inhibitor had migrated in through the concrete pores, and formed a protective film on the steel rebar surface. These results are promising for the SS-inhibitor in its ability to protect steel rebar in concrete in aggressive environments. • 2% of Corrosion inhibitor SS improvements the mechanical characteristic of cement pastes and concrete. • 1.25% of inhibitor SS the optimum ratio of inhibition for steel reinforcement corrosion in aggressive environment. • The XPS demonstrate that SS inhibitor had migrated at concrete pores and formed a protective film on the steel surface. [ABSTRACT FROM AUTHOR]

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It has been demonstrated in recent studies that, unlike generaluse cement (GU), glass powder (GP) performs better in concrete mixtures with high water-binder ratios (w/b) in terms of both mechanical properties and chloride ion permeability. This paper aims to deepen investigations on the behavior of concrete incorporating GP in aggressive outdoor environments such as chloride ion diffusion, carbonation, and sulfates as a function of w/b. For comparison purposes, concretes containing conventional supplementary cementitious materials (SCMs) such as Class F fly ash (FFA) and ground-granulated blast-furnace slag (GGBFS) along with control concrete were also studied. In general, GP-based concretes behaved as those containing SCM. Indeed, despite their high w/b, concrete incorporating GP better withstands sulfate attack than the reference. This was mainly attributed to the low chloride permeability of such concretes. Also, as commonly observed with SCM concretes, carbonation was higher with GP-based concrete and increased with w/b. [ABSTRACT FROM AUTHOR]

This paper describes the influence of crystalline admixtures on the chemical resistance of cement composites exposed to aggressive environments. The effect of the crystalline admixtures was determined by a series of physical-mechanical and innovative physicalchemical methods. Specifically, this concerned the measurement of flexural strength, compressive strength, determination of the dynamic modulus of elasticity by the ultrasonic pulse velocity test, and an analysis of the internal structure by mercury intrusion porosimetry and x-ray computed tomography. Physical-chemical analyses were also performed; namely an x-ray diffraction analysis to determine the mineralogical composition and electron microscopy to examine the microstructure. The use of non-destructive testing methods (ultrasonic pulse velocity test and computed tomography) made it possible to compare the properties of the same specimens for 16 months. The specimens were stored in reference laboratory conditions, a sodium sulphate solution and an ammonium chloride solution. The physical-mechanical tests and physical-chemical analyses clearly showed the benefit that crystalline admixtures have for the resistance of cementitious composites attacked by chemically aggressive solutions without affecting the fresh-mixture rheology or decreasing the strength of the composites. [ABSTRACT FROM AUTHOR]

Two categories of GFRP specimens, in nominal diameters of 11.2 mm and 15.6 mm respectively, made of E-glass fibers and a vinylester resin were immersed in alkaline solution, saline solution and tap water solution at room temperature. The mechanical and durability properties of tested GFRP bar specimens were determined through direct tensile test and short-beam shear test after exposure to aggressive solutions for different days. The obtained results indicated that for all tested GFRP bar specimens the failure modes of fiber rupture in the tensile test and horizontal cracking in the short-beam shear test would not obviously change with the increasing of exposure period. However, the impact of immersion solutions on the durability degradation of mechanical properties of GFRP bars appeared in the ultimate strength and displacement at failure, and at room temperature the alkaline solution had a greater impact than another two solutions. Under the same exposure conditions, the resistance to the strength degradation of the GFRP bars with a larger diameter was better than that of the smaller GFRP bars. The comparison results indicated that the strength degradation trend of conditioned GFRP bars presented in our study was basically in agreement with the data given in previous studies. [ABSTRACT FROM AUTHOR]

Copyright of News of Kazakhstan Science / Novosti nauki Kazahstana is the property of NCSTE (JSC National Center for State Scientific and Technical Evaluations) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The long-term strength of rods under tension in an aggressive environment is investigated. We consider rods of various shapes of a single-cell cross-section (circle, square, and rectangles with different aspect ratios), provided that the areas of these cross-sections are equal. To determine the level of inclusions from aggressive environment into the rod at different time moments, approximate diffusion equations based on the motion of diffusion fronts from the rod surface are used. The high accuracy of the obtained approximation is shown. To assess the influence of an aggressive environment on long-term strength, the Yu. N. Rabotnov kinetic theory with two structural parameters (material damage and concentration of environment elements in the rod material) is used. The dependence of the time to rupture for the rods with various cross-section shapes under the same level of tensile stress is obtained. It is shown that the time to rupture for a rod with square cross-section under the indicated conditions exceeds the time to rupture for a rod with circular cross-section. In the case of rods with the same cross-section shape, the relation of the cross-section perimeter to time to rupture for the rod is considered. The minimum time to rupture for the considered rods is observed for rods of rectangular cross-section with the smallest thickness [ABSTRACT FROM AUTHOR]

The present investigation focused on establishing a characterization of public used reinforced concrete constructions such as school units in the coastal zone of Chichiriviche and Tucacas in Venezuela’s Falcon State, exposed to highly corrosive environments and built with inadequate construction techniques. The ultimate aim was to make recommendations to regional bodies so that they could make structural interventions more precisely and assertively. The study was carried out in seven educational units, in which planimetric surveys were carried out, the collection of fault symptoms, tests in some structural members and finally a general evaluation of damages that allowed identifying their durability and particular recommendations for each school building. As a result, these units of different construction ages were in a better state of conservation, when compared directly to the sample evaluated in 2006 in private multifamily buildings, which were even younger than this sample. It was recommended for all cases that they apply a programmed and technical continuous maintenance system, which goes beyond the systems of paints whose substrate is not properly prepared, resulting in a process of superficial repair and aesthetic ineffective.

The corrosion of prestressed rock bolts (PRBs) has become a serious problem threatening the durability of prestressed anchorage structures during their service. This paper aims to investigate the corrosion damage mechanisms of the free lengths of PRBs subjected to an aggressive environment. During the experiment period, the corrosion behavior of the rock bolts was analyzed considering the influence of prestress under different pH (4, 5, 6, 7, and 8) amounts and several oxygen flow rates (OFR, 0 cm3/min, 40 cm3/min, 80 cm3/min, 120 cm3/min, and 160 cm3/min). Based on the electrochemical analysis, a corrosion rate (CR) development model of the PRBs related to the OFR was developed. The results indicated that the prestress had a great influence on the corrosion of the rock bolts. In the process of corrosion, the PRBs were in an activated state, and no passivation region was formed all the time. The corrosion degree of PRBs increased remarkably with an OFR ranging from 0 cm3/min to 80 cm3/min, and then it reached a threshold value. Additionally, the CR increment was insensitive to the OFR when the pH value was constant. It was observed that the loss rate of the ultimate elongation was larger than the other mechanical properties such as the ultimate tensile load loss rate and the elastic modulus. The effective stress loss of the PRBs under different conditions indicated that more attention is needed to be given to the specimens immersed in solutions with an OFR greater 40 cm3/min and pH lower than 6. [ABSTRACT FROM AUTHOR]

Abstract The Pourbaix diagram for HP-13Cr stainless steel (SS) in the aggressive oilfield environment has been revised. Extrapolation of thermodynamics data to elevated temperatures has been performed with the revised model of Helgeson. The area of the corrosion of HP-13Cr SS and the pH value of environment have been calibrated on the Pourbaix diagram using electrochemical measurements and surface analysis. The results indicated that the quinary Pourbaix diagram (Fe-Cr-H 2 O-Cl--CO 2) can be obtained by the overlap of three ternary Pourbaix diagrams, i.e., Fe-Cr-H 2 O, Fe-Cr-Cl- and Fe-Cr-CO 2 and the operational area located in the passivity region composed of Cr 2 O 3 and Cr(OH) 3 (s). Highlights • The Pourbaix diagram for HP-13Cr SS in the aggressive environment has been developed. • The corrosion area was calibrated on the Pourbaix diagram by using electrochemical measurements and surface analysis. • The corrosion of HP-13Cr SS located in the passivity region. Cr 2 O 3 and Cr(OH) 3 (s) were the composition of the passive film. • Pourbaix diagram for 10-6 mol/L dissolved species was suitable to describe the corrosion of HP-13Cr SS in such environment. [ABSTRACT FROM AUTHOR]

Highlights • Waste crumb rubber up to 5.5% replacement was evaluated as a potential substitute of fine aggregate for production of acid resistant concrete. • The formed minerals and molecular groups after acidic exposure were analysed through XRD and FTIR analyses. • FESEM and TGA/DTA analyses were employed to verify the changed microstructure after acidic exposure. • At 4% substitution level acid resistance improves. Abstract Disposal of waste rubber is afflicting ecological balance across the globe. In recent years, the rate of dumping of this material has amplified. One possible approach to solve this issue is to utilize this rejected material as a replacement of fine aggregate in concrete. Hence, this study examines the behaviour of concrete with crumb rubber at various substitution levels (4%, 4.5%, 5% and 5.5%) under an acidic (sulphuric acid) aggressive environment. Performance was judged by evaluating change in weight, compressive strength and microstructure. Results show that with inclusion of crumb rubber, material separation of concrete reduces which prevents its rupture and disintegration. This was verified by X-ray diffraction, fourier transform infrared spectroscopy, thermogravimetric analysis and field emission scanning electron microscopy tests. Hence, using crumb rubber as a replacement of fine aggregate up to 4% prevents significant fall in performance under such an aggressive condition. This will also reduce the dependency on natural fine aggregate for the manufacture of concrete for non-structural elements. [ABSTRACT FROM AUTHOR]