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Purpose Macro synthetic steel fibers were incorporated into the concrete material as a toughening agent to improve the corrosion and cracking resistances of concrete in a sulfate-containing service environment.Design/methodology/approach To study the basic mechanical properties of this system, an accelerated concrete degradation test was designed to evaluate the influence of the sulfate ions on the concrete. A three-point bending test was carried out in the laboratory to evaluate the fracture toughness. The thickness of the damaged concrete layer and changes of microstructure of the degraded concrete were monitored by using ultrasound, scanning electron microscopy and X-ray diffraction detection methods.Findings The results showed that compared to the performance of ordinary concrete, in an exposure environment containing sulfate ions, the structure compactness of macro synthetic steel fiber concrete was improved, degradation resistance to the sulfate solution was enhanced and the fracture resistance performance was improved significantly.Originality/value The thickness of the degradation layer on the macro synthetic steel fiber concrete was less than a half of that of ordinary concrete in the sulfate environment, and was generally unchanged with increase in the sulfate concentration. Through micro-structural analysis, it was confirmed that macro synthetic steel fiber improved the compactness of the concrete structure, inhibiting access of sulfate ions to the interior of the concrete and thereby reducing the degree of sulfate degradation to the concrete. [ABSTRACT FROM AUTHOR]

Purpose Sulfate-induced degradation is one of the most important factors influencing the durability of concrete. The paper aims to clarify the transport-deterioration process of sulfates in concrete and thus to explain the mechanism and the deterioration of concrete by sulfates.Design/methodology/approach This paper presents an experimental study into the evolution of the transport-deterioration process of sulfate ions in concrete in a pure soaking environment.Findings The microscopic morphology of individual concrete layers at different depths and the change law of the sulfate ion concentration at the corresponding depths were investigated for different exposure times. Furthermore, the relationship between the changes in microstructure and the transport characteristics of the sulfate ions was studied.Originality/value A method to calculate the cracking level sulfate ion concentration was proposed. [ABSTRACT FROM AUTHOR]

Purpose – This paper aims to report on corrosivity of secondary-stage paper mill effluent and corrosion performance of stainless steels. Design/methodology/approach – For this purpose, immersion test and electrochemical polarization tests were conducted in mill and synthetic effluent to evaluate the uniform and localized corrosion. Findings – Corrosivity of mill effluent has been compared with synthetic and primary-stage effluent of the same mill. It is observed that anions present in them, viz. SO4−, PO34−, NO2− and NO3−, impart inhibition, whereas Cl− and chlorophenols enhance the corrosivity of the effluent. The overall effect of various components was reduction in corrosivity of secondary mill effluent. Originality/value – These observations can be useful for material selection and helpful in corrosion mitigation in paper mill effluent treatment plants. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper was to investigate the effects of SO42− concentration on the corrosion behaviour of T23 and T12 steels in simulated water chemistry condition solution of 600 MW fossil-fired power boilers. Design/methodology/approach – The influence and mechanism of SO42− ions on the pitting corrosion of T23 and T12 steels in simulated oxygenated treatment water chemistry solution was studied using electrochemical potentiodynamic polarization scans and electrochemical impedance spectroscopy. Findings – The results showed that T23 and T12 were susceptible to pitting corrosion in the simulated solution with full SO42− concentration for the competitive adsorption of OH− and SO42− on the surface of steels. The pitting sensitivity of the steels improved with increasing SO42− concentration. The corrosion resistance for SO42− of T23 was stronger than that for T12. Originality/value – This study is an attempt to provide direction for regulating the concentration of SO42− in boiler water and for selecting the material for boiler water wall tubes. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this study was to reuse cement kiln dust (CKD) in cement products and report the results of determining the long-term compression and flexural tensile strengths of mortars containing CKD as a partial replacement of sulfate-resistant cement (SRC). During the manufacturing of Portland cement, voluminous quantities of the byproduct dust are produced, which is commonly known as CKD. In the past decade, according to environmental requirements, many researchers have attempted to reuse CKD in cement products. Design/methodology/approach – The long-term compression and flexural tensile strengths of mortars containing CKD as a partial replacement of SRC were tested. The replacement ratios in this study were 0, 5, 10, 15 and 20 per cent. The specimens were exposed to a highly saline environment after normal curing in water for a 28-day period. Findings – The results indicated a slight increase in the strength of CKD–SRC mortar containing 10 per cent CKD and moderate sulfate resistance when the CKD ratio reached 20 per cent, as compared to the reference mortar. In addition, CKD did not adversely affect the properties of SRC mortar subjected to sulfate exposure, even after one year. Originality/value – The tests were inducted for the first time on SRC, and the new results can be used to produce an environmental-friendly concrete. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to study the stress corrosion cracking (SCC) behaviour of anodized 1050 Al-alloy in marine environments at different concentrations of sulphate ions. Design/methodology/approach – The SCC experiments were performed by measuring the time to failure in 3.5% NaCl solution, or in the presence of three different concentrations of sulphate ions under conditions of applied anodic current. For the interpretation of the results, changes in potential during SCC tests and optical microscope micrographs of stress corrosion tested specimens at various periods of time, were obtained. Findings – The influence of seawater composition on the SCC behaviour of the anodized 1050 Al-alloy depends on the concentration of sulphate ions, the oxide thickness and the stress level. At the higher stress levels and low concentrations of sulphate ions, increased times to failure were observed. These results were attributed to the inhibitory action of sulphate ions. At a low stress level and higher concentration of sulphate ions, the increased times of exposure and the more intensive corrosive environment led to partial destruction of the anodic coatings and a decrease in the time to failure. Better protective properties were observed at an oxide thickness of 10 μm. The thicker oxides did not protect so well because they were more brittle, cracking under strain and allowing corrosive species to reach the metal surface. Research limitations/implications – The hypothesised mechanism of the effect of seawater composition on the SCC behaviour of anodized Al-alloys depended on the concentration of sulphate ions and the stress level remains yet to be confirmed. Practical implications – The selection of suitable anodic coatings for the protection of aluminium alloys against stress corrosion cracking depends on the composition of the marine environment. Originality/value – The paper provides information regarding the influence of sulphate ions on the anticorrosive properties of electrolytically prepared anodic coatings on aluminium alloys. [ABSTRACT FROM AUTHOR]

Purpose |!|#8211; The purpose of this paper is to investigate microbially induced corrosion on stainless steels due to sulfate reducing bacteria sp. Desulfovibrio desulfuricans and correlate it with the composition of extracellular polymeric substances (EPS) of the biofilm formed by these bacteria. Design/methodology/approach |!|#8211; Stainless steels 304L, 316L and 2205 were selected for the test. Modified Baar|!|#39;s media, both control and inoculated, were used as test solutions in anaerobic conditions. The bacteria were identified by scanning electron microscopy and their growth was estimated by bacterial counting. Electrochemical polarization and immersion test were performed to estimate the corrosion rate and the extent of pitting attack. The degree of corrosion and the presence of chemicals present inside/outside pits were determined by SEM/EDS. Biofilm formed on corroded coupons was analyzed spectroscopically to identify its components. An attempt was made to correlate the extent of corrosion with the bacterial concentration and the EPS of the biofilm. The differing corrosion performances of the stainless steels also were compared. Findings |!|#8211; The corrosivity of the solution increased with the addition of SRBs and with increased incubation time. The amount of carbohydrate and protein in EPS was observed to be a minimum when conditions were most corrosive. However, as the corrosivity decreased, these amounts increased. Stainless steel 2205 showed the highest corrosion resistance, followed by 316L and 304L. Originality/value |!|#8211; This work shows that SRB degrades its own EPS. Further, the extent of microbial corrosion on stainless steel coupons due to the presence of SRB correlates with the carbohydrate and protein contents of the EPS of the biofilm. [ABSTRACT FROM AUTHOR]

Acrylic fabrics are treated with aluminum sulphate, copper sulphate, tannic acid and isophthalic-5-sodiumsulphonic acid in different concentrations and various temperatures in presence and absence of plasticizer agents, such as dimethylformamide (DMF) or dimethylsulphoxide (DMSO). The treatment is carried out by two techniques (padding and exhaustion). Then, pretreated acrylic fabrics are dyed with cationic and acid dyes for various times. The effects of the treatments on the mechanical and physical properties of the treated acrylic fabrics such as moisture regain, roughness, tensile strength, elongation and bending stiffness are thoroughly investigated. Infrared spectroscopic analysis has been used to suggest changes in the treated acrylic fabrics. The dyeability of the treated fabrics by both cationic and acid dyestuffs is studied. The effects of the treatments with metal salts and acids on fastness properties of dyed acrylic fabrics are estimated. The pretreatment improves the dyeability of acrylic fabrics modified with both cationic and acid dyestuffs and also their fastness properties. [ABSTRACT FROM AUTHOR]

Purpose - The effect of chlorides on corrosion of reinforcing steel is well documented in the literature. However, few studies have focused attention on the effect of sulphates on the corrosion of low carbon steel in alkaline media. This paper aims to address this issue. Design/methodology/approach - This paper describes the results of the investigation into the corrosion behaviour of low carbon steel (typically used as reinforcing steel), exposed to alkaline media at a pH of 9 and 12 with varying concentrations of sulphate and chloride ions, as well as, in sulphate only solutions. An attempt was made to inhibit corrosion of steel exposed to the corrosive media using laser surface treatment of the steel specimens. Mass loss tests and electrochemical tests were conducted to evaluate the effect of sulphate only and the combined effect of sulphate and chloride ions in an alkaline media on steel. Findings - It was found that sulphate ions could cause corrosion of steel in alkaline media. The severity of the attack increased with increasing sulphate ion concentrations, as well as with combinations of sulphate and chloride ions. The pH 12 conditions seem to show much more critical attack with evidence of pitting corrosion as compared to uniform corrosion for test conditions at a pH of 9. The attempt to inhibit the observed corrosion of steel exposed to the corrosive high alkaline media containing sulphate ions on their own and in combination of chloride ions by laser surface treatment proved to be successful. Originality/value - The research undertaken here adds to the body of knowledge relating to the effect of sulphate ions on reinforcing steel corrosion in highly alkaline media. Most literature points out that sulphate ions on their own do not have a corrosive effect, but rather, a passivating effect! [ABSTRACT FROM AUTHOR]

Wool is a suitable medium for growing bacteria and fungi under favorable temperature and humidity conditions resulting in wool degradation and skin irritation or infections. Several investigations have been applied to impart antimicrobial finish of wool fabrics based on organic chemicals, but they are not environmental friendly. The present investigation aims to study the influence of treatment with metal ions of silver nitrate, cadmium chloride and copper sulphate penta hydrate as well as silver nanoparticles, by nanolayer condensation, on wool fabrics pretreated with phosphoric acid, for improvement of its properties. Wool treated with the aforementioned methods showed antimicrobial activity, UV-protection properties and improvement in conductivity. Changes in surface morphologies were also observed. [ABSTRACT FROM AUTHOR]