Aggressive Media Research Articles

Sweet Corrosion Inhibition by CO2 Capture.

The most practical and economical way to combat the problems derived from CO2 corrosion (sweet corrosion) is the use of corrosion inhibitors of organic origin. Its main protection mechanism is based on its ability to adsorb on the metal surface, forming a barrier between the metal surface and the aggressive medium. However, despite its excellent performance, its inhibition efficiency can be compromised with the increase in temperature as well as the shear stresses. In this study, the use of an inorganic inhibitor is proposed that has not been considered as an inhibitor of sweet corrosion. The reported studies are based on using LaCl3 as a corrosion inhibitor. Its behavior was evaluated on 1018 carbon steel using electrochemical measurements, such as potentiodynamic polarization curves, open-circuit potential measurements, linear polarization resistance measurements, and electrochemical impedance. The results showed an inhibition efficiency of the sweet corrosion process greater than 95%, and that the inhibition mechanism was different from the classic corrosion process in CO2-free electrolytes. In this case, it was observed that the inhibitory capacity of the La3+ cations is based on a CO2-capture process and the precipitation of a barrier layer of lanthanum carbonate (La2(CO3)3).

The relationship of dispersion and properties of powder materials on the example of titanium oxide bronze

The subject of this work is oxide potassium-titanium bronzes.
 The purpose of the work: to establish the relationship between the dispersion of samples of oxide potassium-titanium bronze and its physicochemical properties.
 Synthesis methods: self-propagating high-temperature synthesis (SHS), mechanosynthesis. Research methods used in the work: X-ray phase analysis (XRF), optical method for determining particle size, four-probe method for determining electrical conductivity, thermal analysis, method for determining chemical resistance.
 Results of the study: particle sizes were determined, which are 400, 200 and 40 nm. The work is devoted to the study of the influence of fineness on the structure and physicochemical properties of compounds of variable composition on the example of titanium oxide bronzes. A nanocrystalline sample of oxide potassium-titanium bronze was obtained by mechanosynthesis, coarse powders were obtained by SHS. The obtained samples were identified by X-ray phase analysis. The optical method of analysis determined the particle sizes, which are 400, 200 and 40 nm. It has been established that nanocrystalline samples of oxide potassium-titanium bronze are less resistant to aggressive media. Reducing the particle size does not affect the thermal stability. In the transition to nanoscale, the specific electrical conductivity increases by 1.5 times and amounts to 0,076 Ohm-1cm-1. The volume density of defects in the nanocrystalline structure of oxide potassium-titanium bronze is calculated, which is 1013 cm-2.

Influence of Deacetylation Degree of Chitosan on the Anticorrosive Properties of Carbon Steel Coatings

AbstractThis study outlines the improvement on anticorrosion behavior of chitosan‐based sol‐gel coatings on carbon steel surface obtained for high deacetylation degree values of this natural biopolymer. Important economic losses in major industries represent a problem due to corrosion of metals in aggressive medium, such as carbon steel, which is widely used due to its hardness, durability, ductility, low cost, handiness. Therefore, non‐toxic, cost‐effective, and eco‐friendly strategies are needed to protect metallic surface of steel. Against this background, the anticorrosion coating performance of chitosan, from three different commercial sources, as a single component, on carbon steel in chloride solutions is investigated using electrochemical impedance spectroscopy technique. The present study is performed to evaluate the corrosion protective abilities of chitosan in order to determine the relationship with its deacetylation degree (DDA), evaluated by potentiometric titration, a simple and reliable method. Depending on the DDA, the experimental results indicate that there is a remarkable difference between different chitosan samples regarding the value of the charge transfer resistance of coating on steel.

Corrosion Protection Efficacy of the Electrodeposit of Poly (N-Methyl Pyrrole-Tween20/3-Methylthiophene) Coatings on Carbon Steel in Acid Medium

In this study, poly(N-methylpyrrole-Tween20/3-methylthiophene) coatings were electrodeposited on carbon steel type OLC 45 by electrochemical techniques in oxalic acid solution. Surfactant Tween 20 as a dopant ion employed during electropolymerization can have an important influence on the corrosion protection of this coating by obstructing the penetration of aggressive sulfate ions. The new composite coatings have been analyzed electrochemically, spectroscopically and morphologically by cyclic voltammetry, Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) methods. Corrosion protection consideration of PNMPY-TW20/P3MT-coated OLC 45 has been analyzed by potentiostatic and potentiodynamic polarization, open circuit potential and electrochemical impedance spectroscopy (EIS) measurements in 0.5 M H2SO4 medium. The corrosion rate of PNMPY-TW20/P3MT-coated OLC 45 has been indicated to be ~10 times reduced compared to uncoated OL 45, and the corrosion protection efficiency of the coating is above 90%. The greatest efficacy is achieved by PNMPY-TW20/P3MT composite by electrodeposition at 5 mA/cm2 and 3 mA/cm2 current densities applied and at 1200 mV potential applied in 5:1 and 3:5 molar ratios. The PNMPY-TW20/P3MT coating realized by the galvanostatic method exhibited a non-damaging surveying after 96 h of immersion in the aggressive medium, further verifying its excellent protection capacity. The consequences of the corrosion experiments clearly divulged that PNMPY-TW20/P3MT coatings ensure a very good anticorrosion protection of OLC 45 in aggressive medium.

Screen-printed Electrodes with Stable Solid-state Reference Electrode for Oxidation-reduction Potential (ORP) Measurement Applications

ORP is defined as the electromotive force between a noble metal electrode and a reference electrode when immersed in solution [1]. The electrochemical setup typically involves a platinum wire as a working electrode (sometimes gold, rarely silver) and a well-controlled reference electrode. When these electrodes are immersed together into a solution, an electron migration is produced between the working electrode and the solution. Depending on the nature of the species diluted, the working electrode loses electrons if the media is an oxidant, so the potential measured becomes positive. If the media is reductive, the working electrode gains electrons, and the resulting potential will be negative. Voltage is measured between both electrodes (working and reference electrode), so the ORP value is usually given in millivolts.ORP provides valuable information because it is a measure of sanitizer activity and water quality, due to the changes in ORP being associated with the existence of contaminants or biological activity. ORP measurements are also useful in several major industrial applications where maintaining potential in a production stage under control is a critical parameter or when it is necessary to assure the quality of water. Examples include cyanide oxidation or chrome reduction in wastewater treatment of metal-plating industry residues, bleach production and bleaching of paper, biological growth control in cooling towers and water quality monitoring in swimming pools, hot tubs, spas, or aquafarming.Screen-printed electrodes (SPEs) offer several interesting advantages in industrial applications such as point-of-care testing, usability, and a wide range of possible customizable setups. However, most SPEs include a pseudo-reference electrode fabricated with silver or silver/silver chloride. Since the KCl electrolyte is absent, this pseudo-reference electrode is exposed to media implying that the reference electrode is not under control, especially in aggressive media. In this publication, an SPE with a platinum paste working electrode and a controlled solid-state reference electrode is presented. Several experiments are included to show that these platforms offer ORP monitoring in household, industrial or laboratory applications.

Study of Corrosion Mechanisms in Corrosive Media and Their Influence on the Absorption Capacity of Fe2O3/NdFeO3 Nanocomposites

This paper presents the results of a study of the change in the stability of Fe2O3/NdFeO3 nanocomposites when exposed to aggressive media over a long period of time. The main purpose of these studies is to investigate the mechanisms of degradation and corrosion processes occurring in Fe2O3/NdFeO3 nanocomposites, as well as the influence of the phase composition on the properties and degradation resistance. According to the X-ray phase analysis, it was found that the variation of the initial components leads to the formation of mixed composition nanocomposites with different Fe2O3/NdFeO3 phase ratios. During corrosion tests, it was found that the dominance of the NdFeO3 phase in the composition of nanocomposites leads to a decrease in the degradation and amorphization rate of nanostructures by a factor of 1.5–2 compared to structures in which the Fe2O3 phase dominates. Such a difference in the degradation processes indicates the high stability of two-phase composites. Moreover, in the case of an aqueous medium, nanocomposites dominated by the NdFeO3 phase are practically not subjected to corrosion and deterioration of properties. The results obtained helped to determine the resistance of Fe2O3/NdFeO3 nanocomposites to degradation processes caused by exposure to aggressive media, as well as to determine the mechanisms of property changes in the process of degradation. The results of the study of the absorption capacity of Fe2O3/NdFeO3 nanocomposites in the case of the purification of aqueous media from manganese and arsenic showed that a change in the phase ratio in nanocomposites leads to an increase in the absorption efficiency of pollutants from aqueous media.

Efficient Model of the Interaction of Elastomeric Filler with an Open Shell and a Chrome-Plated Shaft in a Dry Friction Damper.

The results of a study of the contact interaction of an open shell and a chrome-plated shaft with elastomeric filler installed coaxially are presented. The considered contact system is a model of the original design of the shell damper of dry friction. The design feature is the following: the bearing link of the damper is a thin-walled cylindrical shell with a cut along the generatrix; the working body of the damper is elastomeric filler; a hollow chrome-plated shaft centers the damper elements and allows it to be used in technological processes with the presence of aggressive and abrasive-containing media. The mechanical-mathematical modeling of the behavior of the presented damper under the conditions of operational loads has been carried out. The idea of identifying the properties of a cut isotropic shell, which bends under the conditions of a nonaxisymmetric contact load, and a strongly orthotropic continuous shell is applied. As a result, dependences were obtained to determine the rigidity and the maximum allowable load of the damper. The effect of the coefficient of friction of the contact pairs elastomer-shell and elastomer-shaft on the damper performance properties has been studied. A technique for the quasi-static analysis of structural damping in non-mobile, non-conservative shell systems with deforming filler has been developed. The hysteresis loops of the damper under a nonmonotonic load are constructed, the dependence of the amount of dissipated energy on the cycle asymmetry coefficient is found. An analysis of the results obtained showed that the use of open shells in friction shock absorbers can significantly reduce their rigidity compared to solid shells and thereby reduce the resonant frequencies of the dynamic system. This circumstance makes such vibration isolators particularly attractive for use in superresonance vibrators as working modules of drilling shock absorbers and elastic hangers of sucker rods in oil and gas production.

Green synthesis of zinc sulfide nanoparticles-organic heterocyclic polyol system as eco-friendly anti corrosion and anti-bacterial corrosion inhibitor for steel in acidic environment

ABSTRACT Green synthesis, characterization and evaluation of nanoscale zinc sulfide (ZnS) by precipitation chemical method. The zinc sulfide nanoparticles were prepared by chemical precipitation method using heterocyclic polyvinyl alcohol, PVA as a sensitizer. The prepared heterocyclic compounds system ZnS nanoparticles, PVA, EG were used as anti-bacterial corrosion towards sulfate-reducing bacteria (SRB) and anti-corrosion for carbon steel substrate in sulfuric acid and hydrogen sulfide bacterial corrosive environment using chemical, analytical, and electrochemical techniques. Effect of adding PVA, and ethylene glycol, EG to ZnS nanoparticles were studied. Effect of ZnS nanoparticles concentrations and the reaction temperature on the corrosion inhibition efficiency were studied. The inhibition due to adsorption of nanoparticles on steel surface, the adsorption agree well with Langmuir isotherm with suggested chemical adsorption mechanism. Potentiodynamic polarization (PD) and Electrochemical impedance spectroscopy (EIS) data explain that the used inhibitor is mixed-type and improves polarization resistance and inhibition performance by adhering to metal/electrolyte interface. The cathodic and anodic reactions are delayed when inhibitor molecules are added to an aggressive medium, which results in a negative shift in the open circuit potential. Addition of both PVA, and EG as organic polyol materials enhance the adsorption and inhibition properties of zinc sulfide nanoparticles on steel surface.

The Role of Anodising Parameters in the Performance of Bare and Coated Aerospace Anodic Oxide Films

The anodising process parameters (voltage, temperature, and electrolyte) control the morphology and the chemical composition of the resulting anodic oxide film by altering the balance between oxide growth and oxide dissolution reactions. The porosity of the oxide film is reduced by the addition of tartaric acid to a sulfuric acid electrolyte, while anodising at elevated temperatures enhances oxide dissolution, leading to wider pores and rougher surfaces. No significant changes in the oxide chemical composition as a function of anodising parameters was found; in particular, no tartrate incorporation took place. The resistance of uncoated anodic oxide films against aggressive media and galvanic stress as a function of anodising parameters has been studied by electrochemical methods. Anodising in a mixed tartaric and sulfuric acid electrolyte improves the resistance of the anodic oxide against galvanic stress and aggressive media in comparison to sulfuric acid anodising processes. However, the corrosion protection performance of the anodic oxide films in combination with a corrosion-inhibitor loaded organic coating is not governed by the blank oxide properties but by the adhesion-enhancing morphological features formed during anodising at elevated temperatures at the oxide/coating interface.

Development of biocompatible superelastic materials and shape memory implants based on titanium nickelide for the creation of highly effective medical technologies

The paper presents fundamental and applied research in a new direction in science and technology, which has a world priority – medical materials and implants with shape memory. The main directions of the development of a new generation of more advanced biocompatible superelastic implantable materials and long-term shape memory implants based on titanium nickelide are formulated. The physical, biological principles of creating a new class of biocompatible superelastic materials based on titanium nickelide with a certain set of properties for various fields of medicine using technologies of induction melting, self-propagating high-temperature synthesis, and sintering are presented.Among the materials created, the development of alloys for long-term functioning in a living organism is of great importance: monolithic elastic, porous and ultra-thin porous-permeable materials, fabric and textile materials made of thin filaments based on titanium nickelide. The main medical and technical requirements for a new class of implants of the future have been identified. Criteria for the biomechanical compatibility of metallic materials under deformation conditions in aggressive tissue media have been determined. Conditions are formulated under which monolithic and porous materials exhibit properties that are optimal for implantation. A comprehensive study of the properties of cell incubators made of porous titanium nickelide was carried out, and the morphological characteristics and patterns of cell development in the porous structure of bulk biomaterials made of titanium nickelide were revealed.The main directions of creation of unique medical technologies based on the developed materials are characterized. The principles of application of biocompatible superelastic materials in various fields of medicine are described. Titanium nickelide-based materials and implants with shape memory implanted into the body are intended for a wide range of medical purposes in dentistry, traumatology, surgery, ophthalmology, vascular surgery, oncology and other fields of medicine as implants for osteosynthesis, endoprosthetics, replacement of tissue defects, creating anastomoses and support frames of organs.

STUDY OF THE INFLUENCE OF THE KINETICS OF HYDROGEN SATURATION ON THE STRESS-DEFORMED STATE OF A SPHERICAL SHELL MADE FROM TITANIUM ALLOY

In this paper, a mathematical model is considered that allows one to determine the stress-strain state of a spherical shell made of titanium alloy VT1-0, the external load is assumed to be transverse uniformly distributed, acting on the outer surface, the medium is assumed to act on the inner surface of the shell. For this, a nonlinear model was used, presented in normalized stress spaces. Fastening along the contour of the shell is rigid. Nonlinear resolving equations for calculating a spherical shell are obtained. An algorithm for solving the problem of hydrogenation of titanium alloy shells has been developed. A practical solution was made by a two-step method of sequential perturbations of parameters using the MatLab and Maple software packages. To solve the system of the obtained differential equations, the method of finite differences is applied. The calculation of the stress-strain state of the shell is obtained taking into account the diffusion process of an aggressive hydrogen-containing medium, and the obtained solution is compared with the results of the classical nonlinear theory without taking into account the aggressive medium. The results of comparing these solutions demonstrate quantitative differences in the parameters of the shell deformation process, which are explained by a more accurate account of the influence of the type of stress state. This approach has a rather flexible mechanism for considering the initial and induced differential resistance, demonstrates a high accuracy of matching the obtained theoretical results with empirical data on loading a wide range of materials under complex types of stress state.

Assessment of the aggressive agents' penetration into concrete by non-destructive techniques

PurposeAround the world, many structures are affected by pathological reactions between the concrete and the surrounding environment in which these structures are designed, these pathologies lead to compromise their serviceability. In this context, this paper aims to study the durability of concrete in different environments with non-destructive techniques, by studying its contamination by the aggressive agents’ penetration. And this, by evaluation of the influence of the durability indicator that is the absorption by immersion, on the mechanical properties (compressive strength, modulus of elasticity and damage), of specimens having undergone immersion/drying cycles, in different aggressive media (water, seawater and acids: sulfuric and acetic with a concentration of 5%).Design/methodology/approachConcrete specimens were manufactured in the laboratory, and then underwent immersion/drying cycles, in parallel, the weight gain of the specimens was carried out in the wet state after immersion and in the dry state after drying, and the ultrasonic speeds were also taken in a dry state. The results showed a decrease in the mechanical properties studied, namely, the compressive strength as well as the elastic properties (modulus of elasticity, damage) as a function of the increase in absorption, and that the weakest properties are those of test specimens submerged in water.FindingsNon-destructive tests have shown that the parameters examined increase with the immersion/drying cycles, up to the fourth cycle. Beyond that, they drop gradually, and this is valid for four environments. This decline is due to the degradation of cement pastes exposed to water, seawater and acid attacks. This is explained by the greater or lesser dissolution of all the major elements making up the cementitious matrix (CSH, Ca(OH)2, CaO, SiO2, C3S, C2S, C3A, C2S) depending on the nature and concentration of the chemical substances evacuated. The results showed that the highest absorption rate and damage are those recorded for the specimen immersed in water, followed by that of the specimens immersed in acids, followed by that of the specimen immersed in sea water. The highest compressive strength and stiffness are those of the specimen immersed in sea water, followed by that immersed in acids, then in water.Originality/valueThe work developed aimed to study the durability of concrete, by addressing the study of the coupling absorption – mechanical characteristics of concrete, in different aggressive media (water, seawater and acids), to seek a relationship between these parameters. The tests provided are non-destructive tests, which consist of taking measures that do not damage the concrete. They allow indirect measurements of the mechanical properties of concrete as well as the monitoring of their evolution over time. They also allow having certain accuracy, because the measurements are taken at the same place.

Durability properties of cement – saw dust ash (SDA) blended self compacting concrete (SCC)

This paper report the durability properties of self-compacting concrete (SCC) modified with Saw dust ash (SDA) exposed to an aggressive media. Saw dust ash (SDA) was used to partially replace OPC in SCC at 0 - 30%. A number of trials mixes were conducted to obtain grade 40 SCC, with a suitable mix proportion varied at 5, 10, 15, 20, 25 and 30 % by weight of the binder as OPC replacement in SCC. Constant water to binder ratio of 0.37 with water reducing admixtures was used in all the mixtures. The research reveals that SDA enhanced the resistance of SCC against Na2SO4 attack at 5% replacement but performed poorly in H2SO4. The water absorption of SCC decreases with an increase in SDA content. The resistance of SDA-SCC to elevated temperature is reduced with an increase in SDA content. The compressive strength of the SDA-SCC decreases with the age of exposure in an aggressive media. The SEM result revealed the presence of crystal like spikes of SDA particles, which may contribute significantly to the high surface area of the ash particles and results in a porous structure at an early age.

Durability degradation of tunnel-lining-shotcrete exposed to nitric acid: Neutralization and nitrate ion migration

The tunnel-lining-shotcrete, in the long highway tunnel, was usually neutralization jeopardized by NxOy attack caused by automobile exhaust. To investigate the neutralization process of lining shotcrete, the nitrate acid solution, simulated NxOy gas, with the pH value of 1, 2 and 3 were used as aggressive medium. Meanwhile, the pH value and nitrate ion content in shotcrete neutralization zone were measured using potentiometry method. After that, the composition and relative content of mineral phases and microstructure were charactered via X-ray diffraction (XRD), thermogravimetric-differential thermal scanning (TG-DSC) and scanning electron microscope (SEM). With increased of the hydrogen ion concentration on nitric acid solution, the pH value and nitrate ion content in neutralization zone were decreased and increased respectively. Meanwhile, those of shotcrete were higher and smaller than those of normal concrete. The loss rate of weight, relative compressive and splitting tensile strength of shotcrete was lower than that of normal concrete as the pH value of 1, while that of shotcrete was higher when the nitric acid pH value of 2 and 3. The neutralization process of nitric acid-exposed-shotcrete was divided into three stages, namely, neutralization reaction, hydration product decomposition, and concrete surface spalling off. The pH value of concrete declined, whereas nitrate ion content in the neutralization zone increased with prolonged immersion time. Moreover, the maximum depth of nitrate ion content was deeper. The yellow-white spongy corrosion product layer formed and covered the specimen surface. Additionally, crisscross macro-cracks appeared on the concrete specimen surface, which caused large amount of aggregates was peeled off.

Advances in Laser Materials Processing

Today, laser processing is becoming more and more relevant due to its fast adaptation to the most critical technological tasks, its ability to provide processing in the most rarefied and aggressive mediums (e [...]

PH-triggered release of tannic acid as green corrosion inhibitor for carbon steel

A new eco-friendly, pH-responsive capsule is presented. Core-shell silica/chitosan nanocapsules, of around 200 nm, were prepared by the Layer-by-Layer method for the incorporation and further release of the green corrosion inhibitor tannic acid (TA). The release was monitored at different pH. The highest amount of released TA (~90%) occurred at pH 3.0 following a diffusional process. Electrochemical Impedance Spectroscopy (EIS) experiments demonstrated that the capsules improved up to three times the corrosion protection of carbon steel compared to the bare substrate, on aggressive medium for 48 h, possibly due to the formation of a layer of ferric tannate complex on the metal surface.

Improving sulphuric acid resistance of slag-based binders by magnesium-modified activator and metakaolin substitution

Alkali-activated slag (AAS) is an appealing alternative to ordinary Portland cement (OPC) in aggressive acid environment considering its relatively low calcium content and potential in retarding aggressive media penetration. This study evaluates the effect of reactive MgO–NaOH mixture as an activator on the performance of AAS with and without metakaolin substitution upon sulphuric acid exposure. The experimental results reveal an improved acid resistance of slag pastes with supplementary magnesium and the improvement is further enhanced with 20% metakaolin substitution. The improved effect by supplementary magnesium is not only attributed to its microstructure refinement for retarding acid penetration; but also contributed by the acid neutralisation capacity of the formed brucite and the potentially positive effect of magnesium on stabilising the AAS binding gel. Stratified silica-rich gels are formed in the metakaolin-substituted AAS, whose formation is primarily attributed to the intrinsic difference of the formed aluminosilicate gels and related to the pH value and the presence of Mg2+. Considering the dense structure of these gels, they might act as protective barriers for the AAS upon acid deterioration.

Recent reviews on bio-waste materials for corrosion protection of metals

Abstract The present paper is aimed to review the efficiency of eco-friendly, natural and cheap bio-waste materials as corrosion inhibitors on metal surfaces in different corrosive media. Various bio-waste materials are the best substitutes for the synthetic organic, inorganic and polymeric inhibitors. Most of the bio-waste material adsorbed on the metal surface in aqueous medium followed the Langmuir adsorption isotherm. The presence of organic constituents in bio-waste materials is responsible for the protection of metals in aggressive medium. The effectiveness of these bio-waste materials to inhibit metal corrosion is well studied by non-electrochemical methods like weight loss and atomic absorption spectroscopy techniques as well as electrochemical methods like polarization and impedance measurements. Surface studies were studied through SEM, EDS, XRD, AFM and XPS techniques. Computational studies using DFT and MDS were also reported.

INFLUENCE OF X-Mesh POLYPROPYLENE FIBER ON THE PROPERTIES OF ROAD CONCRETE

Road and airfield pavements are subject to constantly increasing vehicle loads, aswell as aggressive liquid media and temperatures. Under these conditions, the search for andimprovement of new types of cement concretes that are able to withstand these influences for severaldecades is urgent. First of all, such concretes include fiber-reinforced concrete (FRC). The articlediscusses the advantages and disadvantages of using various types of fiber in the technology of heavycement concretes. Basalt or polymer fibers are most often used in road concrete. Steel fibers are notcommonly used due to possible corrosion of metal fibers. The use of basalt fiber gives an effect ifthere is a large amount of it (more than 6 kg/m3). But this leads to difficulties in their uniformdistribution in the volume of concrete mixture and increases the cost of concrete. Therefore, the useof polymer fiber is promising. It is shown that there is no consensus regarding the effectiveness ofusing fibers longer than 20 mm. Therefore, in the experiments, we used X-Mesh polymer fiber withlengths of 23 and 39 mm, with a fiber diameter of 100...150 µm. Experimental studies have shownthat X-Mesh fibers can form a structural framework within concrete. Therefore, when this fiber isintroduced into the composition of concrete, its compressive strength does not decrease, in contrastof concretes with other types of fiber. In addition, X-Mesh fiber disperse reinforces the concretestructure, which leads to an increase in flexural strength by 22 %. FRC strength studies have shownthat the optimal amount of X-Mesh fiber is 1.5 kg/m3. It has also been shown that polypropylene fiberswith lengths of 23 and 39 mm have the same positive effect on the properties of road concrete. It wasfound that X-Mesh fiber is capable of entraining an additional amount of air, which leads to adecrease the average density of concrete by 3 %, but increases its frost resistance. Despite theadditional air entrainment, the water absorption of concrete does not exceed 2.5 %.

The Behavior of Geopolymer Mortars Based on Industrial Sludge Exposed to Aggressive Mediums

There is a growing interest in geopolymer materials. One of its advantages is the possibility of reusing a wide range of industrial waste. This paper aims to study the effect of the molar ratio H2O/Na2O(t) on the physical, chemical, and mechanical properties of industrial slurry-based geopolymers mortars and to evaluate the behavior of the synthesized mortar, which has the shortest setting time, in aggressive mediums. Structural changes in geopolymer mortars were monitored by X-ray diffraction (XRD) and Raman spectroscopy. The morphology of the samples was monitored by the Scanning Electron Microscope (SEM). SEM micrographs of geopolymer mortars show an intimate bond between sand grains and geopolymer cement. The compressive strength of geopolymer mortars varies significantly with the molar ratio H2O/Na2O(t). The mass loss of geopolymer mortars immersed in hydrochloric acid and sulfuric acid is more than that immersed in other solutions but lower than that of Portland cement-based mortars immersed in the same solutions.