Effects Of Aggressive Environments Research Articles

Determination of operational properties of paint coating materials

Problem. Varnishes are used in all branches of industry and economy. With their help, you can protect metals from the effects of aggressive environment, prevent from the negative effects of corrosion, preserve consumer properties, and give the treated surface an aesthetic look. One of the methods of protecting metal from corrosion is the application of coatings, including paints and varnishes, which form a protective film on the surface of the metal and prevent corrosion processes on the surface. Methodology. The research was conducted on the operational characteristics of enamel-type paint coatings: paint powder UD-1028-07040-T and soil FL-03K. Determination of moisture absorption of the free coating film was carried out using the desiccator method. In order to determine the penetration time of aggressive solutions through the paint coating film, an electrochemical method was used, whose purpose is to determine the change in the electrochemical potential of the object under study during the penetration of aggressive solutions through the paint coating film to the metal. The study of the hardness of paint coatings was carried out by the method of static indentation, respectively, using a microhardness meter. Originality. The research results showed the advantage of the UD-1028-07040-T powder paint coating over the FL-03K soil, which can be explained by such factors as the structure of the paint coating, the porosity of the surface, and the phenomenon of adhesion between the paint and the surface on which it is applied. Practical value. Powder paint UD-1028-07040-T absorbs water much less (up to 2.12%) compared to FL-03K soil (up to 5.14%), this indicates a relatively higher porosity of FL-03K soil; it is confirmed by the results of porosity determination, which was 1 point. When determining the penetration time of aggressive solutions through the paint film, it was found that FL-03K soil quickly passes aggressive solutions through its surface (in 144 hours) compared to powder paint (192 hours). This indicates that the use of powder paint in conditions involving contact with aggressive substances will be more appropriate.

The role of ABC-transporters in homeostasis, cancer pathogenesis and therapy

ABC transporters (ATP Binding Cassette (ABC) transporters) are proteins, which play a dual role in the substances transport across the membrane. On the one hand, they transport nutrients and other molecules inside the cell to supply the necessary nutrients, on the other hand, these proteins excrete some endogenous and exogenous substrates from the cell to maintain their homeostasis in the body and prevent from effects of aggressive environment. ABC transporters play a role in the pathogenesis of various metabolic disorders. In addition, a large amount of evidence has been accumulated about the participation of these proteins in oncogenesis because of their involvement into initiation, progression, invasion and metastasis of tumors, as well as development of multidrug resistance phenotype. Currently, these proteins are attractive therapeutic targets, influence on which can significantly increase the effectiveness of anticancer therapy and improve the prognosis of patients with oncological diseases, including recurrent, metastatic and inoperable forms.The review provides information on drugs that affect the functional activity of ABC transporters and the mechanisms of their action, and also presents the results of clinical trials of these inhibitors.

Phase-field modeling of pitting and mechanically-assisted corrosion of Mg alloys for biomedical applications.

A phase-field model is developed to simulate the corrosion of Mg alloys in body fluids. The model incorporates both Mg dissolution and the transport of Mg ions in solution, naturally predicting the transition from activation-controlled to diffusion-controlled bio-corrosion. In addition to uniform corrosion, the presented framework captures pitting corrosion and accounts for the synergistic effect of aggressive environments and mechanical loading in accelerating corrosion kinetics. The model applies to arbitrary 2D and 3D geometries with no special treatment for the evolution of the corrosion front, which is described using a diffuse interface approach. Experiments are conducted to validate the model and a good agreement is attained against in vitro measurements on Mg wires. The potential of the model to capture mechano-chemical effects during corrosion is demonstrated in case studies considering Mg wires in tension and bioabsorbable coronary Mg stents subjected to mechanical loading. The proposed methodology can be used to assess the in vitro and in vivo service life of Mg-based biomedical devices and optimize the design taking into account the effect of mechanical deformation on the corrosion rate. The model has the potential to advocate further development of Mg alloys as a biodegradable implant material for biomedical applications. STATEMENT OF SIGNIFICANCE: A physically-based model is developed to simulate the corrosion of bioabsorbable metals in environments that resemble biological fluids. The model captures pitting corrosion and incorporates the role of mechanical fields in enhancing the corrosion of bioabsorbable metals. Model predictions are validated against dedicated in vitro corrosion experiments on Mg wires. The potential of the model to capture mechano-chemical effects is demonstrated in representative examples. The simulations show that the presence of mechanical fields leads to the formation of cracks accelerating the failure of Mg wires, whereas pitting severely compromises the structural integrity of coronary Mg stents. This work extends phase-field modeling to bioengineering and provides a mechanistic tool for assessing the service life of bioabsorbable metallic biomedical devices.

Sulfuric acid resistance of concrete containing coal waste as a partial substitute for fine and coarse aggregates

The vulnerability of concrete to sulfuric acid attack requires much attention in both design and maintenance. Taking the waste management approach into account, this study utilized coal waste (CW) as a partial replacement for fine and coarse aggregates. The use of CW as aggregate replacement materials in concrete is a novel topic. Regarding the literature, concrete mixtures with CW aggregates showed relatively similar strength properties to conventional concrete. However, the effects of aggressive environments on the concrete containing CW aggregate have not been addressed. Here, the effects of sulfuric acid attack on the key properties, such as split tensile strength (STS), compressive strength (CS), weight loss, and ultrasonic wave velocity (UWV), were thoroughly assessed. Moreover, scanning electron microscope (SEM) images have been captured to discern the morphology changes. Various CW dosages (0%, 5%, 10%, 15%, and 20% by weight of dry aggregates) were used. The results revealed that higher CW contents led to more water absorption and stiffer mixtures with lower workability. The weight loss of the samples showed an increasing trend with increasing CW contents. The split tensile strength and compressive strength of samples without sulfuric acid attack were enhanced by using 5% and 10% CW. After exposure to the sulfuric acid solution, the strength of CW-concrete samples was continuously decreased by increasing CW contents. The UWV values were decreased by increasing CW contents, which induce more porosity and lower integrity in concrete elements. SEM images show that the use of CW led to the formation of Ca (OH)2 crystals that were not wet, needles of ettringite, and gypsum, which severely hurt the properties of permeability, durability, and strength.

UV Sensor Based on Surface Acoustic Waves in ZnO/Fused Silica.

Zinc oxide (ZnO) thin films have been grown by radio frequency sputtering technique on fused silica substrates. Optical and morphological characteristics of as-grown ZnO samples were measured by various techniques; an X-ray diffraction spectrum showed that the films exhibited hexagonal wurtzite structure and were c-axis-oriented normal to the substrate surface. Scanning electron microscopy images showed the dense columnar structure of the ZnO layers, and light absorption measurements allowed us to estimate the penetration depth of the optical radiation in the 200 to 480 nm wavelength range and the ZnO band-gap. ZnO layers were used as a basic material for surface acoustic wave (SAW) delay lines consisting of two Al interdigitated transducers (IDTs) photolithographically implemented on the surface of the piezoelectric layer. The Rayleigh wave propagation characteristics were tested in darkness and under incident UV light illumination from the top surface of the ZnO layer and from the fused silica/ZnO interface. The sensor response, i.e., the wave velocity shift due to the acoustoelectric interaction between the photogenerated charge carriers and the electric potential associated with the acoustic wave, was measured for different UV power densities. The reversibility and repeatability of the sensor responses were assessed. The time response of the UV sensor showed a rise time and a recovery time of about 10 and 13 s, respectively, and a sensitivity of about 318 and 341 ppm/(mW/cm2) for top and bottom illumination, respectively. The ZnO/fused silica-based SAW UV sensors can be interrogated across the fused silica substrate thanks to its optical transparency in the UV range. The backlighting interrogation can find applications in harsh environments, as it prevents the sensing photoconductive layer from aggressive environmental effects or from any damage caused by cleaning the surface from dust which could deteriorate the sensor's performance. Moreover, since the SAW sensors, by their operating principle, are suitable for wireless reading via radio signals, the ZnO/fused-silica-based sensors have the potential to be the first choice for UV sensing in harsh environments.

Влияние агрессивных условий на каталитические материалы в системах очистки отработавших газов судовых дизелей

Object and purpose of research. This paper discusses porous permeable catalysts used in converters of marine engines. The purpose of this study was to investigate the effect of aggressive environments upon catalytic properties and parameters of the materials used for catalytic conversion. Subject matter and methods. The paper suggests a procedure for experimental studies intended to investigate the effects of aggressive environments in marine diesels contributing to gas-thermal corrosion. It also presents a test rig for investigation of hot gas flow effects upon corrosion properties of porous permeable catalytic materials. Main results. The study yielded the data on gas-thermal corrosion effects upon properties and parameters of porous permeable catalysts used in exhaust gas converters of marine power plants. Conclusion. The results of the study make it possible to estimate the extent of aggressive environment effects of exhaust gas conversion system upon the properties of its catalysts, as well as to adjust the chemistry of catalytic material in accordance with the requirements to conversion quality of exhaust gases.

New approach for the mix design of high-strength concretes valorization of local aggregates

Purpose The purpose of this paper is to make a contribution to understanding the influence of factors such as the water/cement (W/C) ratio and the granular class on the mechanical and physical properties of high-strength concretes (HSCs). In the formulations of HSC, aggregates by their high mass and volume proportion play an important role. When selecting aggregates, it is necessary to know their intrinsic properties. These properties influence the performance of concrete, in particular the quality of the granulate cimentary adhesion. Design/methodology/approach This experimental study focused on the effect of W/C ratio (0.25, 0.30, 0.35), the effect of replacing a part of cement by silica fume (SF) (8%), the effect of fraction of aggregate on properties of fresh and hardened concrete, the effect of different environment conversation like drinking water and sea water on compressive strength and the study of absorption of water and softening using the mix design method of the University of Sherbrooke combined with the Dreux-Gorisse method which gives good results. Findings At the end of our work, the examination of the results obtained made it possible to establish the correlations between the formulations studied and the physicomechanical characteristics of the concrete compositions (HSC25, HSC16, HSC8). The results of this study show that the use of three granular classifications (DMAX8, DMAX16 and DMAX25) and three report W/C (0.25, 0.30 and 0.35) in two different conservation environment (drinking water and sea water) give HSCs, HSC25 with an W/C = 0.25 ratio has reached the largest mechanical strength of 90 MPa for different environments of conservation. For selecting aggregates, it is necessary to know their intrinsic properties, these properties influence the strength of concrete. In general, there is a slight decrease in the compressive resistance of the specimens stored in seawater, it can be said that the conservation life has not had effect on the resistance (28 days). The effect of aggressive environment can appear in the long term. Research limitations/implications Mixed design and concrete fabrication with a 28-day compressive strength of up to 68 MPa or more of 90 MPa can now be possible used in Jiel (Algeria), and it should no longer be considered to be used only in an experimental domain. Addition of SF in concrete showed good development of strength between 7 and 28 days, depending on the design of the mix. Practical implications Concrete containing 8% SF with W/B of 0.25 has higher compressive strength than the other concretes, and concretes with SF are more resistant than concretes without SF, so it is possible to have concrete with a compressive strength of 82 MPa for W/C 0.25 without SF. Like as a result, we can avoid the use of SF to affect the strength of concrete at compressive strength of 68 MPa, and a slump of 21 cm, because the SF is the most expensive ingredient used in the composition of concrete and is therefore very important economically. One of the main factors of production of HSC above 90 MPa is use of aggregate DMAX25, which is stronger with W/B of 0.25 and 0.30. Social implications This mixtures leads to a very dense microstructure and low porosity and produces increased permeability of HSC and is able to resist the penetration of aggressive agents. This combination has a positive effect on the economy of concrete. Originality/value The combination of the Dreux-Gorisse method with the Sherbrook method is very beneficial for determining the percentage of aggregates used, and the use of coarse aggregates of Jijel to obtain HSC with 90 MPa and 16 cm of workability.

Erratum: Visualization and evaluation of concrete damage in-service headworks by X-ray CT and non-destructive inspection methods

Morozova N, Shibano K, Shimamoto Y, Tayfur S, Alver N and Suzuki T (2022) Visualization and evaluation of concrete damage in-service headworks by X-ray CT and non-destructive inspection methods. Front. Built Environ. 8:947759. doi: 10.3389/fbuil.2022.947759Due to a production error, there was a mistake in Table 3 as published. The table columns were left aligned instead of right aligned. The corrected Table 3 appears below. Due to a production error, the text of the last paragraph of the Introduction on page 3 was duplicated.The corrected paragraph is as follows:"In this study, damage evaluation of concrete core samples is investigated by applying NDT parameters. The samples were taken from an in-service reinforced concrete structure, which has been subjected to the influence of aggressive environmental effects. Then, X-ray CT procedure was conducted on the specimens to detect and visualize the crack distributions After scanning, concrete damage was evaluated by the dynamic modulus of elasticity measured by UPV and resonant frequency tests. Results indicate that the decrease in mechanical properties of the concrete could be evaluated by comparing the geometrical properties of cracks with the dynamic modulus of elasticity, because both these parameters are affected by the internal actual cracks, thus, the damage of concrete could be quantitatively evaluated."The publisher apologizes for these mistakes. The original version of this article has been updated.

Durability and Microstructure Characteristics of Concrete with Supplementary Cementitious Materials

Considering the environmental impact of cement manufacturing industries, this paper concerns the potential of using supplementary cementitious materials (SCMs), like fly ash and ground granulated blast furnace slag, as being essential to replacing the existing Ordinary Portland Cement (OPC). The objective of this paper is to study the microstructural characteristics of concrete with SCMs and improve the durability of the product to increase the lifespan of concrete structures. Replacement SCMs in OPC are 0, 40, 50, and 60 by percentage of cement weight, and we have taken a water-binder ratio of 0.40 for M40 grade and 0.28 for M60 grade concrete. The physical properties and chemical composition of OPC, Ground Granulated Blast-furnace Slag (GGBS), and fly ash were identified, and three different experiments were conducted to determine the resistance to penetration of chloride ions and corrosion processes. The rapid chloride permeability test, accelerated corrosion, and sorptivity tests were employed to measure concrete's resistance to the effects of aggressive environments and examine the durability properties. The most performed grade samples were analyzed as individual microspheres with Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDXS), and X-ray diffraction. Significant improvements in various concrete properties were achieved through the partial replacement of fly ash and GGBS with cement. Doi: 10.28991/CEJ-2022-08-04-05 Full Text: PDF

Influence of the Integration of Geopolymer Wastes on the Characteristics of Binding Matrices Subjected to the Action of Temperature and Acid Environments.

Recycling geopolymer waste, by reusing it as a raw material for manufacturing new geopolymer binding matrices, is an interesting asset that can add to the many technical, technological and environmental advantages of this family of materials in the construction field. This can promote them as promising alternatives to traditional materials, such as Portland cements, which are not so environmentally friendly. Recent studies have shown that the partial replacement of reactive aluminosilicates (metakaolin and fly ash) up to a mass rate of 50% by geopolymer waste does not significantly affect the compressive strength of the new product. In line with these findings, this paper investigates the effects of aggressive environments, i.e., high temperatures (up to 1000 °C) and acid attacks (pH = 2), on the characteristics of these new matrices. Different techniques were used to understand these evolutions: mineralogical analysis by X-ray diffraction (XRD), thermogravimetry-differential thermal analysis (TGA-DTA), mechanical characterization and scanning electron Microscopy (SEM) observations. The results are very satisfactory: in the exposure temperature range explored, the new matrices containing geopolymer waste suffered losses in compressive strength similar to those of the matrices without waste (considered as materials reference). On the other hand, the new matrices exhibited good chemical stability in acid media. These results confirm that the reuse of geopolymer waste is a promising recycling solution in the construction sector.

Small-Scale Test of Transparent Adhesives in Glass Structures under Shear Stress and Their Ageing Resistance

Glass load-bearing structures, which have been popular in recent years, require careful attention to detail, because with improper design there is a concentration of stress leading to failure and subsequent collapse of the structure. Mechanical connections are mainly used but there are disadvantages such as stress peaks, weakening of the cross-section, or aesthetic reasons. Adhesive connections eliminate these disadvantages. The lack of information and standards about adhesives (except for silicones) obstruct their wide-ranging use. Especially problematic is an ageing of adhesive and its influence on the mechanical properties. This study is focused on experimental testing of two transparent epoxy adhesives that were used for small-scale specimens with float glass. Two sets of specimens were prepared for each adhesive. The first set was an unaged reference set, the second set was exposed to an artificial ageing method based on EN ISO 9142. The specimens were subjected to shear stress in a displacement controlled test. One adhesive showed good mechanical properties in the reference set, but resistance to artificial ageing was poor. The second adhesive does not achieve good mechanical properties in the reference set in comparison to the first adhesive. The artificial ageing method was devastating for the second adhesive. Poor mechanical properties of the second adhesive could be caused by the age of the uncured adhesive. The first adhesive can only be recommended for the interior where the adhesive is not exposed to aggressive environmental effects.

Effect of Crystallization Additives on Durability of Cement Composites in Aggressive Environments

This article analyses the effect of crystallization additives on the long-term durability of self-compacting concretes (SCCs) in relation to specific types of chemically aggressive environments. The effect of both an inorganic acid solution and the aggressive solutions produced during plant ensilage were tested, while the effect of diesel on these modified concretes was also investigated. Attention was given to the effect of crystallization additives on the characteristically capillary porous structures of self-compacting concrete, specifically in terms of the long-term durability of SCCs in relation to the above-stated chemically aggressive solutions. The effect of aggressive environments was evaluated through a set of physical-mechanical trials and physical-chemical analyses.

Anchorage System in Old Post-Tensioned Precast Bridges

Abstract The first precast post-tensioned bridges in Slovakia are approaching 60 years of their service life. Facing an aging infrastructure, it is necessary to assess their present structural condition and residual life expectancy. Different types and methods of anchorage system were developed and available for first post-tensioned bridges around the world. The reliability and functionality of anchorages contribute to the proper behaviour of post-tensioning system. The considerable effect of aggressive environment (frost, chloride salts, humidity) and environmental load (CO2) leads to corrosion of anchorages and prestressing steel with the risk of a sudden unexpected damage to bridge. The research work deals into finding more details of this structural part. During the demolition of damaged post-tensioned bridges built in 1960s several anchorages were removed and analysed. The material properties, size parameters and performed tensile tests of a wedge anchorage system are summarised in this paper. The findings from this study can be used as input parameters for numerical simulation and durability assessment of similar aged existing post-tensioned bridges.

STATISTICS OF FAILURES AND MONITORING OF THE STATE OF POOLS AND PROTECTIVE HERMETIC FENCES OF NUCLEAR POWER PLANTS

Assessment of the technical condition of the main systems and structures is one of the main stage tasks of technical diagnostics of NPP elements. One of the important elements of the hermetic volume of the protective shells of nuclear power plants is a storage pool (SP) of spent nuclear fuel (SNF). For provision of SNF storage the appropriate systems and structures are used: SNF handling system, SP cooling system and SP by itself. Pools are made of monolithic reinforced concrete with stainless steel lining intended to retain cooling water (boric acid solution) and protect the concrete from direct effect of aggressive environments. Emergency leaks may occur through the SP lining during operation of a nuclear power plant. Materials used for pool structures must be radiation resistant and resistant to a boric acid solution. The structure of the storage pool must be earthquake-proof, must allow monitoring of emergency leaks and maintain a controlled water level in case of leaks for the time period until the fuel will be discharged. Features of failures during operation, results of research and recommendations for extending the service life of storage pools at domestic nuclear power plants with VVER are considered. Assessment of the technical condition of the main structures of the SP provides for specialized research. Thus, the SP survey generally involves visual and instrumental examination of the bottom lining, internal lining, as well as concrete walls and bottom.

Modern cement-based waterproofings for hydraulic structures protection

Hydrotechnical structures of water management and land reclamation complex from the moment of commissioning are subject to aggressive environmental effects: hydrostatic water pressure, alternating freezing and thawing, moistening and drying, corrosive action of salts dissolved in water, dynamic action of ice. The trouble-free operation of structures with long-term aggressive environmental factors is possible only in the case of providing their protection (reinforcement) with effective insulating, anticorrosive, high-strength, wear-resistant and cavitation-resistant composite materials.
 Waterproofing coatings, which arrange on the surface of reinforced concrete structures, plays an important role in ensuring operational reliability and durability of hydraulic structures. Having rather low cost of waterproofing coatings as compared to the cost of structures the fate of their responsibility in terms of ensuring the durability and operational reliability of the structures is high enough. Waterproofing coatings serve as a barrier to an aggressive environment and thus protect structures from destruction.
 Notwithstanding the importance of waterproofing protection, this issue is not given due attention today. Therefore, filtration of water through the structures of water-reclamation facilities is a common phenomenon. Water filtration through damaged concrete of hydraulic structures causes dissolution and leaching of water with calcium hydroxide (leaching), which further causes the decomposition of other components of the cement stone and leads to the dilution of the concrete structure and to the strengthening of drip filtration. Drip filtration increases over time, then jet filtration develops, which can lead to complete destruction of the structure. Therefore, providing waterproofing protection of structures is an important engineering task in their construction and operation.
 One of the determining factors for the effectiveness of waterproofing is the right selection of material. Traditional waterproofing materials on a bituminous basis have insufficient physical-mechanical properties and durability. However, modern technologies of waterproofing protection of concrete and reinforced concrete structures are based on the use of effective composite materials with high physical, mechanical and protective properties. Depending on the type of binder, waterproofing materials can be based on bitumen, bituminous-mineral, bitumen-polymer, coal, polymer compositions, as well as on the basis of cements and polymer cements.
 The selection of a waterproofing material should be made taking into account the specifics of the operating environment and the conditions of use. The most common in the construction of gluing roll materials on a bituminous basis can only partially satisfy the need for hydraulic engineering, as for the waterproofing of hydraulic structures. There are high requirements with regard to the aggressiveness of the environment and their low repairsability.
 The most promising for use in the technology of arrangement of waterproofing coatings on concrete and reinforced concrete structures of hydraulic engineering facilities of water management and reclamation complex are polymer cement mixtures, binders in which are Portland cement modified with polymer latex dispersion powder (for two-component).
 Creation of effective polymer cement waterproofing compositions is based on optimization of the ratio of interpenetrating meshes of polymers and crystal matrix hydrates. Modification of cement systems by polymers allows to increase adhesion and deformation characteristics, fracture resistance and corrosion resistance of polymer cement composites. Depending on the components included in the mixture, waterproofing coatings may be rigid or elastic. Rigid formulations are a water-mixed, dry mixture that includes a vinyl acetate copolymer and designed for waterproofing concrete and reinforced concrete structures with low water filtration. Elastic waterproofing materials are usually two-component. These materials are used for waterproofing structures that are susceptible to deformation, as well as surfaces with a high degree of water filtration and where cracks up to 1 mm are formed. Elastic two-component formulations are dry mixtures with the addition of redispersible polymer powders. They consist of two components: a dry mixture of modified fine cement and aqueous latex polymer, usually acrylic.
 The content of polymer latex in the mixture has a significant effect on the rheological properties of polymer-cement mixtures and on the physical and mechanical properties of waterproofing coatings made of them. Thus, the introduction of a redispersible polymer powder Axilat L 8262 in a waterproofing mixture in the amount of up to 10% by weight of cement increases the mobility of the mixture from 3,2 to 8,0 cm, increases the adhesive strength of the coating to concrete from 0,45 to 1,95 MPa, increases its bending strength from 6,9 to 7,9 MPa, reduces its water absorption in 24 hours from 7,02% to 0,35% .

Effect of aggressive environment on durability of concrete containing fibrous rubber shreds and silica fume

AbstractThe present study deals with the investigation of durability properties of reinforced concrete fabricated by incorporating fiber type rubber shreds as fine aggregate in concrete and silica fume as a supplementary cementitious material. Concrete designs were produced to replace natural fine aggregate and cement by rubber shreds, and silica fume, respectively. The concrete mixes were studied for compressive strength up to 365 days, abrasion resistance, and water absorption up to 28 days. The carbonation and acid resistance (H2SO4 and HCl) properties were studied up to 90 and 180 days, respectively. Corrosion samples were tested up to 18 months for both macrocell current and half‐cell potential. The incorporation of rubber shreds lowered the compressive strength of concrete and resistance to water absorption, carbonation, and corrosion. However, the resistance to abrasion and acid attack was enhanced on the utilization of rubber shreds in concrete. The presence of silica fume considerably enhanced the mechanical and durability properties of rubber shreds concrete and lowered the probability of corrosion.

The effects of aggressive environments on the mechanical properties of basalt plastics

A review and analysis of changes in mechanical properties of basalt fibers (BF) and basalt composite materials under effects of aggressive environments in reference to foreign and Russian scientific literature has been carried out. The changes in the physical and mechanical properties of the fiberglass (FG) and basalt plastic (BP) have been compared. The analysis shows that BF is a good alternative to fiberglass for elaboration of composite materials for various purposes. In the most aggressive alkaline environments, BP resistance is higher as compared with that of FG. If required, BF resistance to chemically active media could be increased by midifying its composition and applying protective layers and heat treatment of fibers. For extended use of BP as an effective structural material under various climatic conditions, including in the Arctic, long-term tests of 10 or more years are advisable and relevant, with control of changes in their mechanical parameters and an analysis of processes of climatic aging developing in BP.

Effects of Aggressive Environment on the Durability of Concrete Produced with Binary and Ternary Blend Cement

Effects of Aggressive Environment on the Durability of Concrete Produced with Binary and Ternary Blend Cement - written by Gana Matthew Sunday , Erasmus P. D. , Shehu I. A published on 2020/02/29 download full article with reference data and citations

Modeling of corrosion-mechanical behavior of multi-element metal structures of transport works in real-world conditions

The article is part of the author’s dissertation research. Multi-element metal structures are widely used in the construction of transport structures (metal spans, trusses of railway bridges, overpasses, etc.). During operation, such structures are subjected to the joint effect of loads, temperatures, and corrosive media. In accordance with this, the task of predicting the behavior of such structures seems to be relevant. It consists in the development of effective models oriented to the calculation of the bearing capacity of structural elements subjected to corrosive wear. The article discusses the most common corrosion damage to metal multi-element structures of transport facilities, the classification of corrosion processes according to the nature of the surface destruction, the main types of metal elements and bridge structures. The main parameters characterizing the corrosive wear of metal structures were determined. Ways to account for the effect of aggressive environment on metal structures, i.e. well-known mathematical models and work, in which attention is paid to the problem of corrosion, wear modeling. The process of identifying corrosion wear models (determining unknown model coefficients) is described. The system of equations for determining the coefficients of a mathematical model of corrosive wear is given. The values of the coefficients of the models used to predict the behavior of structures, with a different choice of an intermediate point are given. A statically indefinable flat five-element truss of arbitrary cross section, part of the rods of which works in tension and part in compression is considered. For this design solves the problem of assessing durability. To solve this problem, use the corrected Euler method. The obtained numerical values of the durability of trusses of five rods, depending on the lengths of the rods.

Cavitation erosion of glass fibre reinforced polymer composites with unidirectional layup

Glass fibre reinforced polymer (GFRP) composites are increasingly used in marine applications and can be subjected to aggressive environmental effects, one of which is cavitation. This study investigates the behaviour of unidirectional GFRP composites exposed to cavitation erosion generated using an ultrasonic transducer. Cavitation erosion tests were performed in accordance with the ASTM G32 standard. All specimens were preconditioned to eliminate the influence of water absorption on the mass loss caused by cavitation. The erosion process was monitored with a microscope and the mass loss was measured at regular periods. The tested specimens were scanned with X-ray computed microtomography. The research findings indicated that the erosion process was affected by several parameters including specimen thickness, distance between fibre bundles, bundle shape and distribution. The initiation and development of erosion damage were highly influenced by the surface condition. Cavitation erosion traced parts of fibre bundles located closer to the surface creating trenches and valleys on the surface. The regions with thick epoxy layers above and between fibre bundles were much less susceptible to erosion damage. Several erosion mechanisms were identified and discussed. The research findings also highlighted the difficulties in characterising ultrasonic cavitation erosion of GFRP composites using acoustic impedance and mean erosion depth.