Corrosion Resistance Of Concrete Research Articles

Evaluation of the Bond Shear Strength and Corrosion Resistance of Concrete with Setting Retarder

In this study, the bond shear strength and corrosion resistance of concrete with setting retarders were evaluated. For this, slant shear, bi-surface, and accelerated corrosion tests were conducted. The variables considered included the proportion of the setting retarder (0 and 1%), surface treatments of concrete (as-cast, chipping, and brushing), curing hours (8, 16, and 24 h), and concrete cover depths (20, 30, and 45 mm). Consequently, the bond shear strength of concrete with the retarder showed a higher value than that of normal concrete. Moreover, an increase in curing hours resulted in a higher value of the bond shear strength. Furthermore, the addition of a retarder in concrete increased corrosion resistance. Based on the test results, the addition of a setting retarder is believed to be a suitable solution to address the bond shear strength and durability issues that may arise at the interface of delayed concrete placement.

Effect of partial replacement of cement by fine powders on the corrosion resistance of concrete

Fine rock powder and rice husk ash are residues generally discarded in the environment, causing environmental problems. This study investigated the durability of concretes containing rice husk ash and two rock powders, partially replacing cement when exposed to organic acids. Four types of concrete were manufactured and immersed in acetic acid and lactic acid solutions. The concretes with these mineral additions exhibited better durability and lower mass loss than the reference concrete. The resistance to acids increased with decreasing CaO content. Concretes containing the mineral additions showed better resistance to acid corrosion than Portland cement concrete.

Study on the Effect of Bentonite on the Resistance to Corrosion of Plastic Concrete

Objective: To study the effect of bentonite on the corrosion resistance of concrete. Methods: Using the direct immersion method, the chloride ion solution and sulphate ion solution were prepared to simulate the corrosive water environment, and the test blocks were placed in the corrosive solution for corrosion. The cube compressive strength of plastic concrete with different bentonite admixtures was tested under standard curing conditions, after immersion in chloride ion solution and after immersion insulfate ion solution immersion curing. The relationship between the amount of bentonite admixture and the strength of the test block after dissolution in ambient water was analyzed in comparison with the reference group. The microstructure of the internally doped bentonite was studied using SEM (scanning electron microscopy) , and its corrosion mechanism was discussed. Results: As the proportion of bentonite in the cementitious material increases, the cube compressive strength of plastic concrete gradually decreases. In the range of 0~30%, the corrosion degree of chloride ion solution on the concrete strength first decreases and then increases. When the content of bentonite is 20%, the corrosion effect is the smallest; the effect of corrosion of sulfate ion solution on concrete strength continues to decrease, and is minimized at 30%. Conclusion: A certain amount of bentonite can effectively reduce the strength loss of plastic concrete after corrosion.

Environmentally friendly super-slippery concrete with anti-corrosion and anti-fouling properties

Due to superhydrophilicity and porosity, the concrete structure of buildings in marine engineering is easily corroded and polluted. Superhydrophobic concrete has been studied and applied to alleviate this problem; however, the poor stability under high pressure and in contact with foulings hampers its wide application. To overcome the above challenges, we develop an environment-friendly and inexpensive super-slippery concrete (SS-concrete) by injecting oil into the interior and outer surface of the superhydrophobic concrete (SH-concrete). The impendence of SS-concrete is 3 orders of magnitude larger than that of ordinary concrete (O-concrete), indicating that the corrosion resistance of concrete has been significantly improved. Moreover, the stable protective oil layer of the SS-concrete prevents the infiltration and adhesion of water, ice, oils, ink, milk and even bacteria, showing excellent anti-fouling ability. Therefore, the SS-concrete may have great potential application in the concrete-based buildings in marine engineering field.

Durability evaluation of binary and ternary concrete mixtures by corrosion resistance approach

The use of pozzolans as cement substitutes has become widespread in concrete technology in recent years. This is due to the improvement of concrete properties as well as from the perspective of sustainable development and reduction of cement consumption. In this study, the effect of 45% ground granulated blast furnace slag, 7% silica fume, 35% fly ash, and 15% zeolite as binary and ternary mixtures on durability and corrosion resistance of Self-compacting concrete specimens were investigated. The studied parameters included compressive strength, electrical resistivity, water absorption, rapid chloride ion penetration Test and corrosion test also scanning electron microscopy images were used to analyze the microstructure of the concrete samples. Results showed that replacement cement with slag, silica fume, fly ash, and zeolite is generally increased the durability parameters and corrosion resistance of concrete. In all experiments, silica fume has shown better behavior in terms of durability, so that its electrical resistance after 90 days is more than 3.3 times that of the control specimen and other parameters such as water absorption and chloride ion penetration showed approximately 37% And 74% less than conventional concrete respectively. Also, corrosion results indicated that samples containing silica fume had the highest corrosion resistance and reduced the corrosion rate by more than 6 times after 15 test cycles.

MECHANICAL PROPERTIES OF RC BEAMS WITH AFRP SHEETS UNDER A SUSTAINED LOAD

In this research, an attempt was made to find the permeability of an RC beam with AFRP by making use of the hydraulic conductivity test and a double-ring infiltrometer. Based on the state-of-the-art methodology, three different AFRP samples, Kelvar 29, Kelvar 49 and Kelvar 149, were considered as the laminates to prevent the deflection of the beams. Accelerated corrosion was carried out using impressed current, and induced corrosion was calculated using the galvanostatic method. In this project, nine RCC beams were strengthened with aramid FRP sheets. Novel results were obtained using three different layers and three different patterns of AFRP sheets. Experimental investigation showed that the mechanical properties of the reinforced concrete beams were enhanced (by 10 %) with Kelvar 149. The durability and corrosion resistance of concrete were achieved due to the increased number of layers of the AFRP sheet. The entire research shows that three layers of Kelvar 149 allow better performance of the concrete specimens. No other results based on the abrasion resistance and hydraulic conductivity of beams with AFRP laminates are available in the literature.

Cyclic Polarization of Corrugated Austenitic Stainless Steel Rebars in Acid Rain: Effect of Fly Ash, pH and Steel Type

The present work studies the effect of fly ash content (0–25 wt.%), pH (8, 12.5), and steel type (316L, 304L) on the cyclic polarization of stainless steel rebars in electrolytes, simulating fresh concrete exposed to acid rain and corroded concrete cover that has exposed the reinforcement to direct acid rain attack. At the same time, it tries to elucidate the corrosion inhibition activities of a Greek lignite fly ash that is a high-Ca fly ash with a questionable effect on the corrosion resistance of concrete. A higher pH results in lower corrosion rates for both steels and all fly ash content. However, different passivity trends are noted for the two steels as a function of pH. The partial replacement of Ca(OH)2 with fly ash up to 20 wt.% has a beneficial effect on the electrochemical behavior of the stainless steel rebars, in terms of both uniform and localized corrosion resistance. However, this trend is reversed at 25 wt.% FA. The reasons for such trends are explored via microstructural examinations of the steels after polarization and XRD analysis of fly ash, as well as reinforced concrete containing fly ash.

STRUCTURAL PARAMETERS OF CONCRETE CORROSION RESISTANCE

This article describes the problem of corrosion of concrete at the enterprises of the wine and fruit and vegetable industry in Moldova, the kind of organic acids that destroy concrete are considered. Such a specific type of chemical corrosion as leaching is also considered. The reaction of the influence of malic acid on concrete is reflected, as a result of which readily soluble calcium malic acid is formed. The structural parameter of corrosion resistance to chemical corrosion has been studied. The formula for the corrosion resistance of concrete is derived and explained. The structural parameter of resistance to chemical corrosion is investigated on various types of concrete. The formula for coefficient resistance of concrete to chemical corrosion is derived. Also, two dependencies are displayed: Dependence of the coefficient of resistance of concrete to chemical corrosion on the volume of cement stone; Dependence of the coefficient of concrete resistance to leaching corrosion on the structural parameter.

Corrosion resistance of urtites and urtite-based concretes

The utilization of unconventional technogenic raw materials in producing construction materials is a topical economic and environmental issue. The issue's resolution is impeded by the fact that the overburden rocks of apatite nepheline deposits contain nepheline classified as a deleterious impurity for concrete aggregates under the current standards. This paper is aimed to conduct specialized tests of rocks, aggregates, and concretes for evaluating the corrosion resistance of these materials in water and acid media. The work involved using physical mechanical techniques as well as light and scanning microscopy. It is scientifically validated that nepheline aggregate included in concrete and behaving actively as related to calcium hydroxide produces a denser area of contact with the cement matrix, which favours an enhanced corrosion resistance of concrete. The paper's information is scientifically and practically valuable for resolving the issue with recycling the mining waste of apatite nepheline deposits and utilizing their overburden rocks as concrete aggregates.

Influence of nano-cementitious materials on improving the corrosion resistance and microstructure characteristics of concrete

Concrete is a building material widely used in construction due to its excellent mechanical properties such as compressive strength and bond strength with steel reinforcement. Strength and durability are the key factors that need to be satisfied in the design of reinforced concrete structures. The objective of this paper is to improve the bond strength and corrosion resistance of concrete by using supplementary nano cementitious materials such as Nano Metakaolin (NMK) and Nano Silica Fume (NSF). The addition of nano cementitious materials will help in enhancing the mechanical properties of concrete by improving the micro-structure. Effective bond between concrete and reinforcing steel ensures the load transformation among structural elements. The specimens are exposed to either chloride-induced acceleration-based corrosion test or chloride-induced immersion-based corrosion test. Investigations were conducted to evaluate the compressive strength, bond strength and corrosion resistance of concrete. Specimens with corrosion inhibitor/anti corrosive coating exhibited poor bond strength when compared to concrete with nano metakaolin and nano silica fume. The corrosion potential was found to be highly negative for control specimens. Specimens exposed to accelerated corrosion test exhibited lower bond strength with higher mass loss and low yield strength in the rebars. Extent of damage due to the effect of corrosion was analysed by physical observations and image analysis. Concrete with Nano Metakaolin exhibited better bond strength and corrosion resistance than those of the other specimens. Effect of nano Cementitious material on improving the micro-structure characteristics of concrete was confirmed by SEM. It was evident from the SEM results that, addition of NMK and NSF in concrete had a significant contribution in improving the bond strength and corrosion resistance.

Comparative Resistance of Concrete with Aggregates and Fillers of Different Composition

The paper studies the influence of aggregates and fillers with negative and positive electrical surface properties on the corrosion resistance of concrete. The advantage of resistance of fine-grained concrete on marble sand in comparison with concrete on quartz sand, regardless of the type of aggressive environment, is established. At the same time, the stability of samples of powdered concrete with 10 and 30% of fine-grained filler changed little when replacing the quartz powder with marble one. It is shown that the resistance coefficients of powdered concrete samples with quartz filler (10%) do not differ from the resistance coefficients of samples of a similar composition with crushed marble filler, and with an increase in the dosage of the filler (30 %) slightly exceed. It was found that in powder concretes without aggregates, the contact layer between the cement matrix and the aggregate is absent, so the composition of the mineral powder plays a much smaller role in the corrosion processes of cement stone. The obtained results allowed establishing that electrokinetic phenomena play a secondary role, and the main influence on the stability of fine-grained concrete is the processes of pore colmation by chemical reactions, as well as the interaction of the surface layers of the aggregate with the cement matrix.

Influence of the Type of Filler from Production Waste on the Corrosion Resistance of Concrete

Influence of the Type of Filler from Production Waste on the Corrosion Resistance of Concrete

Sulfuric acid corrosion of geopolymer concrete with mineral additives from wastes

The effect of mineral additives such as crushed ash and individual building demolition waste on the corrosion resistance of geopolymer concrete based on screening the crushed granite and blast furnace slag in an environment of sulfuric acid solutions was studied. The corrosion resistance of concrete was evaluated by the kinetics of reducing the mass and strength of samples in sulfuric acid solutions with a concentration of 2,5 and 5 % for 10 days. It was shown that replacing 50 % of granite powder with ground crushed bricks or ash significantly increases the corrosion resistance of geopolymer materials. It was established that due to the formation of poorly soluble products of the interaction of sulfuric acid and concrete in the pores of a geopolymer stone, an interface is formed between the undestructed material and the zone subjected to destructive processes, which impedes the penetration of the corrosive medium into the material. The study also conducted comparative studies of the corrosion resistance of Portland cement concrete with various water-cement ratios. The research results showed that under the influence of sulfuric acid in Portland cement concrete this border does not form and a rapid loss of mass and strength occurs in the samples. The established feature of the process of destruction of geopolymer concrete in a solution of sulfuric acid is the reason for its higher resistance in comparison with cement concrete.

APPLICATION OF AGGREGATES OF NEPHELINE BEARING ROCKS IN INCREASED CORROSION RESISTANCE CONCRETE

Introduction. Diffusion of aggressive components of the external environment deeper into the concrete intensively flows through the contact surfaces and between the filler and the cement matrix. Therefore, it is better to apply active fillers that interact with the cement matrix on certain mechanisms for reducing the conductivity of the contact surfaces, which leads to the products durability.Materials and methods. Methods of mechanical testing, x-ray phase analysis, scanning electron microscopy were used for comparative studies of concrete corrosion resistance with the active filler (urtite) and with the inactive one (quartz sand).Results. This research indicates that the urtite filler significantly increases the strength and corrosion resistance of concrete in comparison with the traditional filler with quartz sand. The investigation of the contact zone of cement stone-aggregate with the usage of REM demonstrates that there are no corrosion products in the contact zone of urtite with the cement matrix, while the contact zone of quartz sand and its surface acquires corrosion products represented mainly by gypsum.Discussion and conclusion. The increased corrosion resistance of the fine aggregate concrete through the application of active filler on the basis of urtite provides lower conductivity of the contact surfaces between cement matrix and filler due to the chemical affinity of the rock-forming minerals of nepheline to calcium hydroxide. The additional factor that enhances the self-inhibition of acid corrosion is the formation of the gel-like layer of silica on the surface of nepheline, which inhibits the advancement of hydroxide ions due to the flow of electro-surface processes. Thus, the nepilnameciais fillers are appropriate to apply in concrete, which is used in the conditions of the chemical aggression of high intensity.

Durability of cement concrete under chemical erosion

This paper launches the study on how the sulfate particle and chloride ions interact to impact the concrete durability. It is analyzed that there is a diffusion law of two particles in concrete, whether the concrete presents corrosion resistance and permeability as contacts with them. The findings reveal that the content of chloride ions decreases with the deepening of the concrete profile. The presence of sulfate ions does not break up the diffusion trend of chloride ions in concrete, but in the case when Cl- and SO42- act together, the content of chloride ions at a constant profile depth is less than that under the action of a single Cl-. When sulfate ions permeate the cement, they will react with hydrate product of cement to generate new chemical substances that fill the inner pores of the cement, thereby suppressing the diffusion of chloride ions. The higher the concrete water-binder ratio, the lower the compression strength; the more inner pores, the weaker its resistance to chemical attack. When mineral admixtures are added to the concrete, the sulfate ions can react with the hydrate products of the cement and mineral admixtures to generate new crystals that largely fill the original pores in the concrete and make it more compact. In this way, the concrete corrosion resistance is built up. Concrete gets most vulnerable to sulfate attack at an ambient temperature of 21-24°C, and relieved at 30- 35°C. Lower relative humidity, high temperature environment are the decisive factors that accelerate the concrete erosion.

Influence of reactive fillers on concrete corrosion resistance

Contact surfaces represent the weakest link in a conglomerate structure of materials. They ensure the diffusion of aggressive agents inside the material. To reduce the conductivity of contact surfaces it is advisable to use reactive fillers, which interact with cement matrix via certain mechanisms, which in turn, reduces the permeability of the contact layer and fosters durability of products. The interaction of reactive fillers with calcium hydroxide of a concrete liquid phase in a contact area leads to the formation of hydrated calcium silicates of a tobermorite group. Such compounds, being settled in pores and capillaries of a product, colmatage and clog them to some extent thus leading to diffusion delay (inhibition) with regard to aggressive components of external media inside porous material, which in turn inhibits the corrosion rate. The authors studied and compared the corrosion of cement concrete with a standard filler (quartz sand) and a reactive filler (perlite and urtit). The experiments confirmed the positive influence of active fillers on concrete corrosion resistance.

SULFATE RESISTANT CONCRETE WITH ALUMINOSILICATE ADDITIVES

Abstract The paper observes an improvement of the sulphate resistance of concrete. This was achieved through creation of dense concrete structure with sulphate resistant binder matrix. Series of tests confirms the positive effect after optimizing the sieve line, also in very fine area; reducing the water-cement ratio with superplasticizer on polycarboxylate basis and restriction of the sulphate sensitive clinker. These steps were possible through adding active aluminosilicate mineral additives. They improve fresh concrete properties, density and corrosion resistance of concrete. The chemical reasons of such effect were explained by the means of x-ray diffraction, differential thermogravimetry and scanning electron microscopy. This development should be widely used in several projects in Ukraine, where sulphate-resistant concrete is needed.

Modeling of corrosion process of the high-performance concretes in sulfate environment

The main contemporary method for measuring stability of concrete in aggressive environments is to compare the strength of concrete that solidified in an aggressive environment with the strength of concrete that solidified in a non-aggressive environment. This approach to testing has been quite effective in many cases, but it does not allow analysing the impact of corrosion products on the strength of concrete cement matrix. Such data can be obtained after removing corrosion products from the cement matrix of concrete. The techniques applied in the study involved removal of corrosion products while subjecting the samples to aggressive environments, which helped determine that a cement skeleton of concrete with an integrated active mineral additive (a mixture of acidic ash removal of metakaolin in optimal quantities) has greater strength and corrosion resistance than a cement skeleton of concrete without a complex active mineral additive. A combination of physical and chemical methods of research – such as phase-contrast X-ray imaging, thermal, and electron microscopy – showed that a complex active mineral additive produces cement structure peculiarities. Thus, it has been determined that frames with a complex active mineral additive can form dense structures with a significant number of low-base calcium silicate hydrates and solid solutions of hydrated aluminium silicate composition (hydrated galena – hydrated anorthite). This is quite different from structures without the complex active mineral additive, which are characterized in an aggressive environment (for example, in a solution of sulphuric acid) by leaching of soluble compounds such as portlandite; moreover, this process is intensified by smoothing the sample surface. These peculiarities of forming cement matrix structure explain the high corrosion resistance of concretes. The obtained data are important for developing a composition of concretes for reinforced concrete structures that are used in aggressive environments.

Effect of curing methods on shrinkage and corrosion resistance of concrete

Abstract This paper reports the results of a study conducted to assess the effect of curing on shrinkage and corrosion resistance of OPC and silica fume cement concretes. The concrete specimens were cured by covering with wet burlap or applying one of the following curing compounds, water-, acrylic-, bitumen-based, or coal tar epoxy. The results indicated that the selected curing compounds were effective in decreasing the shrinkage strain and enhancing the corrosion resistance of both OPC and silica fume cement concretes. It was also noted that 3 days of wet burlap curing prior to the application of a curing compound was necessary for the OPC concrete while 7 days of wet burlap curing is required for the silica fume cement concrete.

Effect of electrochemical treatment at fresh condition in enhancing the corrosion resistance in concrete

The present study concerns the electrochemical treatment to increase the resistance against chloride-induced corrosion of steel in concrete, which was ensured by a microscopic examination and corrosion tests. The current density (DC) applied to the embedded steel immediately after casting of concrete ranged 125, 250 and 500 mA/m2 for two weeks. As a result, an increase in the current density resulted in an increase in the precipitated calcium hydroxide at the steel-concrete interface within 100 μm from the steel surface, which would enhance the buffering capacity to the corrosion reaction. However, an application of the electrochemical treatment did not always impose the benefit in raising the corrosion resistance: the surface chloride content, when the concrete specimens containing the steel embedment was exposed to a salt solution, was increased, presumably because of modification of the chemistry at the right surface of concrete. Notwithstanding, the critical chloride ranged 0.88, 1.21 and 1.76% by weight of cement for the current density of 125, 250 and 500 mA/m2 respectively, while untreated specimens indicated only 0.62%. Consequently, the electrochemical treatment increased the corrosion-free life by enhancing the resistance to corrosion, resulting from the formation of precipitated calcium hydroxide at the steel-concrete interface.