WO2021112781A1

WO2021112781A1 - A cement mi̇xture containing polycarboxylate based fluidizer and calcium nitrite

Info

Publication number: WO2021112781A1
Application number: PCT/TR2019/051149
Authority: WO
Inventors: Nida KOLUCOLAK; Guray KILINCCEKER
Original assignee: Cukurova Universitesi Rektorlugu
Priority date: 2019-12-05
Filing date: 2019-12-20
Publication date: 2021-06-10

Abstract

The present invention relates to a cement mixture comprising a polycarboxylate-based plasticizer, which reduces the amount of gap between the Nitrite ion forming a protective layer on the iron surface and the aggregates forming the concrete composition to inhibit the anodic dissolution rate of the reinforced concrete steel, thereby making it difficult to diffuse the chloride ions.

Description

A CEMENT MIXTURE CONTAINING POLYCARBOXYLATE-BASED PLASTICIZER AND CALCIUM NITRITE

TECHNICAL FIELD OF THE INVENTION

PRIOR ART

Gunasekara et al., (2018) has investigated the corrosion of reinforcement corrosion in geopolymer concrete produced by three different low calcium volatile ash from power plants in Australia. For extreme ash geo-polymer concrete containing castings in chlorinated (0-5%) exposed to wet-dry cycles, the corrosion condition of volatile ash geo-polymer concrete has been inspected with samples exposed to a 3% NaCI solution. Half-cell potential and linear polarization resistance techniques have been used to measure corrosion up to 540 days compared to the results of PC concrete with similar binder content. Volatile ash geopolymer concrete showed much higher corrosion rates than PC concrete with the same amount of cast chloride. Gladstone and Pt. Augusta demonstrated conflicting corrosion behavior that, when expected to be buried compared to geopolymer concrete, samples, cast concrete chloride, demonstrated a lower corrosion rate than PC concrete. This is a set of three-dimensional N — A — S — H and C — A — S - H is connected to the formation of cross-linking, which indicates that in Gladstone and Pt. Augusta geopolymers, the chloride diffusion rate in geo-polymer concrete, is dependent on the porosity of the geopolymer matrix, which is managed by the reactivity of the precursor of the volatile ash. It has been found that the reaction increases the formation of amorphous AI2O3 and S1O2 aluminosilicate gel and increases the formation of amorphous AI2O3 and S1O2 aluminosilicate gel depending on the surface area, amorphous AI2O3 and S1O2 content and Ca02 content and produces a stronger, less porous geopolymer matrix that reduces the chloride input rate. It has been emphasized that the chloride binding capacity of low calcium volatile ash-based geopolymer concrete depends on the CaO content in the precursor that produces C-A-S-H gel in geo-polymerization, resulting in the physical adsorption of chloride ions on the gel surface, thereby reducing the chloride input rate.

Hematite [Fe203], acageneite [FeO(OH)] and lepidocrocite [c-FeO(OH)] have been identified as corrosion products.

Kumar et al., (2018) investigated how ordinary Portland cement has been replaced with ultra-finely ground granular high oven slag (GGBS) as a mineral additive and a chemical additive with calcium nitrate and how mechanical and corrosion properties have been improved with this modification. Ultra-thin GGBS with an average particle size of 4-6 Im, a mineral additive (10%) has been added instead of ordinary Portland cement, calcium nitrate has been presented as a chemical additive of 2% cemented material in the preparation of the concrete. X-ray diffraction studies on powdered concrete have shown that the amount of silica in concrete increases with the presence of GGBS. Calcium hydroxide has been converted to calcium silicates. Ultra-thin GGBS has been reported to reduce workability and water absorption and to increase the compressive strength of concrete (18%) and steel rebar adhesion strength (45%). It has been reported that the addition of calcium nitrate further reduces the water absorption of concrete, but increases better workability, compressive strength (32%) and bond reinforcement (131%). The pH of the concrete powder solution became more alkaline by replacing ultra-thin GGBS and adding calcium nitrate. The free chloride content has decreased by 39% and 65% respectively with the addition of GBS and nitrate. The corrosion behavior of concrete samples has been examined using Tafel polarization in an accelerated corrosion environment of 3.5% NaCI and 1 M sulfuric acid, measurement of open- circuit potentials, linear polarization resistance, and % NaCI. Increasing corrosion potential and decreasing corrosion current has been observed over 40 days. Calcium nitrate has changed the corrosion potential to anodic by encouraging the formation of a passive iron (III) hydroxide film on a steel surface. Corrosion currents in GBS and nitrate modified concrete decreased 200 times after the first-day inspection example, 480 times after 50 days (less than 50 times). The composition has been examined with XRD, measured for the function of concrete, pressure strength, bond strength and water absorption. Also, the pH of the solution of concrete dust and the free chloride content have been identified. All samples have been found to reduce their corrosion potential over time.

Karadag and Soylev (2018) compared equivalent durability performances against reinforcement corrosion of concrete containing volatile ash according to standard and measured k-values. There are three main batches in the study; control, volatile ash samples prepared using the preset k-value and volatile ash samples measured k-value. Effective water/cement ratios of 0.60, 0.50 and 0.40 have been used for all batches. Sample sizes are 100 mm x 200 mm. Samples are cylindrical. A total of 26 samples has been used in the measurements. All samples contain two 14 mm diameter ribbed reinforcements. There is a 0.3 mm wide crack on one side of the concrete cover of the samples. The samples have been placed in a 35 g/l NaCI solution and corrosion potentials (Ecorr) and corrosion rates (Icon-) have been measured by galvanostatic method over two-week periods. Measurements have been carried out between October 2017-June 2018. According to the results of the study, volatile ash samples performed better than volatile ash samples prepared using control samples and preset k-value. It has been determined that the rate of corrosion tends to decrease as the rate of water/cement decreases, resulting in artificial cracks created (0.3 mm) in samples, increase the permeability of chloride and hence the size of corrosion.

Peker and Yapici (2018) synthesized graphene treated with carbon-based nanoparticles shear graphene, reduced graphene oxide, reduced carbon nanotube nano strip and prop type sonification to contribute to the epoxy matrix. By exfoliation of graphite oxide using the graphene oxide Hummers method, carbon-based nanoparticles have been obtained by directly adding the desired mass proportions of nanoparticles to the epoxy, hardener and solvent. Anti-corrosion performance of bare aluminium, pure epoxy and nanoparticle/epoxy nanocomposite coatings in 3.5% NaCI solution by weight has been observed. It has been analyzed with electrochemical impedance spectroscopy and potentiodynamic polarization tests. Nanomaterials have been added to the epoxy matrix in 3 different concentrations, 0.1%, 0.3%, and 0.5% by mass. Tafel curves and derived electrochemical parameters obtained as a result of potentially dynamic polarization tests indicate that nanoparticle/epoxy composite coatings have superior corrosion protection performance compared to pure epoxy, corrosion current density (Icon-), corrosion potential (Ecorr), polarization resistance (R_P) and corrosion ratio (CR). The Bode and Nyquist diagrams obtained as a result of electrochemical impedance spectroscopy showed that the highest impedance values pertained to nanocomposites produced by adding 0.5% nanoparticles to the epoxy matrix by mass.

Cellat and Paksoy (2017) investigated the possibilities of increasing the thermal storage properties of concrete and passively benefiting more from solar energy in buildings by developing new generation concrete mixtures containing phase changing substances. Changes in concrete structure due to the addition of phase changing substance to the environment have been examined with hydration temperature monitoring, XRD, SEM and compressive strength tests. The potential corrosion protective effect of used Phase modifier materials to reinforced concrete has been examined for one year using the Electrochemical Impedance Spectroscopy method. Phase-changing agents have not shown any corrosive effects on reinforced concrete when improving the thermal properties of concrete. The use of Phase modifier in buildings has determined the economic and environmental benefits to be realized and the savings to be realized. In buildings built with phase-changing material concrete, according to the season, it has been determined that the heating load can be reduced by up to 13%. Maximum energy savings have been achieved during spring, when temperature differences have been high during the day and night, which enabled phase-changing materials to melt and freeze, and when there has been sufficient solar radiation.

Song and et al., (2017) have studied the effect of chloride ions, mild steel and carbon steel on under land corrosion. A 3-month corrosion test has been performed by exposing ferrous metals to soils with a concentration of six chlorides. Surface morphology corrosion kinetics have been thoroughly examined by visual observation, scan electron microscopic (SEM), X-Ray refraction (XRD), weight loss, pit depth measurement, linear polarization and electrochemical impedance spectroscopy (EIS) measurements. Low levels of chloride lead to general corrosion, while high levels of chloride can cause local corrosion. However, it is explained that there is no exact limit between general and local processing and high concentrations of chloride and long-term exposure times.

Volpi et al., (2017) have studied the development of intelligent corrosion inhibitors for reinforced concrete structures exposed to the microbial environment. Different organic and inorganic compounds have been evaluated for mild steel, which is reported as potential inhibitors. As a potential inhibitor, methylene blue paint, benzothiazole, system, sodium molybdate, cerium nitrate, disodium phosphate, and trisodium phosphate are used. The diluted 1.3% H2SO4 solution (pH 0.5), intended to simulate concrete acidity due to bacterial metabolites, has been used as a model environment. For electrochemical measurements, steel samples are equipped with an 8 mm diameter B450C lightweight steel reinforcement. Small samples are prepared by cutting 15 mm long samples, leaving a 0.6 cm² cut as an exposed area, buried in a thermoplastic resin. Electrochemical measurements are performed at room temperature in a glass electrochemical cell with a conventional three-electrode installation. Anodic and cathodic potentiometers are polarized (sweep speed of 0.5 mV/s) to assess the corrosion protection performance of the different inhibitors. Besides, the new hybrid inhibitor presence performed four days of continuous monitoring with linear polarization resistance and electrochemical impedance spectroscopy. Hybrid inhibitor synthesized using a 0.03 M methylene blue paint based on Vateride (WATTS) and hydroxide (HAP). Surface analysis of steel has been examined in the non-woven acid environment with inhibitors. Benzothiazole and cysteine protective performances have not been discussed because they are insignificant. While the presence of trisodium phosphate did not affect anodic curves, the cathodic ones have been significantly affected. A protective film deposited on the steel surface has been observed. Corrosion current has been decreased in the presence of methylene blue. Reported the development of an effective smart inhibitor that can increase the corrosion resistance of steel in an environment with acidification due to the presence and metabolism of a SOB. Initial screening of different inhibitors in abiotic acidic environments simulating sulfur-oxidizing bacteria metabolites has led to the selection of trisodium sulphate due to its cathodic effect and proven efficacy for corrosion protection in reinforced concrete structures. Methylene blue has also been selected due to its inhibitory effects on anodic treatment. Another beneficial effect has been obtained by phosphate ions released from the HAP matrix. Electrochemical tests in simulated acidic solutions showed a significant improvement in corrosion resistance due to the synergistic effect of the Methylene blue - HAP system, while the components (Methylene blue and HAP) did not provide satisfactory protection if used separately. Chen and et al., (2017) prepared and studied self-healing construction iron coatings for steel-reinforced concrete to create coatings that can withstand site damage. Microcapsules are obtained using urea, formaldehyde, ammonium chloride, resorcinol and tung oil. Microcapsule characterization is imaged using the scan electron microscope (SEM, FEI Quanta 200 FEG MKII). The thermal stability of microcapsules has been evaluated by thermogravimetric analysis (TGA, Netzsch TG 209 F1 Scale) under a nitrogen atmosphere at a heating speed of 10°C/min. The coatings contain 10% micro-encapsulated Chinese oil by weight as a therapeutic agent. Tung oil has been applied that hardens along the broken and damaged area. To verify that self-healing coatings have repaired the damage independently, the improvement of the coatings has been observed using an optical microscope. The relative thickness of the coatings is considered a potential variable during accelerated corrosion tests. Since both control and self-healing coatings are waterproof and non-conductive, increasing coat thickness can be expected to provide more protection than rebar. For this reason, the parts of the rebar have been measured, then coated and measured again to determine the thickness of the self- healing and control coatings. The accelerated corrosion test found that steel- reinforced concrete takes at least three times longer than steel-reinforced concrete with self-healing coatings to fail. After 150 days of accelerated corrosion testing, 83% of samples with self-healing coatings did not corrode. Since the damaged area is not large enough, there is no difference between undamaged and intentionally damaged samples. These results show that natural product-based, self-healing coatings can passivize the surface of the iron in response to the start of corrosion and significantly increase their corrosion protection capabilities. The tensile test found that self-healing coatings show comparable bond stresses compared to conventional coatings. In summary, this is a promising technology to extend the life span of reinforced concrete structures.

CUI and et al., (2016) have examined the characterization of the corrosion scale formed in the stainless-steel distribution pipe for stainless treatment used in treated water systems. This work has been carried out to reveal the corrosion behaviour of the stainless-steel distribution pipe used in recycled water treatment. The focus is on the morphology, mineralogy and chemical properties of the stainless- steel corrosion scale and the worn passive film. The samples have been taken from a 304-type tube that delivers recovered water to a clean well for more than 12 years. The results show that the corrosion scale consists of goethite, lepidoxide, hematite, magnetite, iron oxide, siderite, chromium green and chromites in the same way as heavily worn pipe coupons. The loss of chromium in the passive film has been identified as a critical phenomenon to damage the stainless-steel passive film from local corrosion. This has been highlighted that the formation of stainless-steel corrosion scale and the local corrosion process can provide key insights to provide a better understanding. The localized corrosion behavior of stainless steel is now directly linked to recovered water quality parameters such as chlorine, do, Cl and SO4^2'. In particular, ferric iron forms the primary chemical of iron minerals when a certain amount of chlorine residue is present as oxygen in recovered water. A recovered water treatment plant to investigate the local corrosion process of stainless steel in wet conditions provides extensive physical data on corrosion scale and pipe coupon samples from the 304 stainless steel distribution pipelines. Cracking corrosion with hollow corrosion is the dominant form of corrosion behavior for stainless steel pipes of this type.

Giraudo and et al., (2016) inspected corrosion by the change of the water- induced metal-proton. The main concrete corrosion mechanisms have been investigated by examining the natural calcium silicate in aqueous environments. Wollastonite (calcium silicate) powder particles smaller than 20 pm have been used in the studies. After characterized by X-ray diffraction, the powder has been immersed in an aqueous HCI solution. (pH 4.3). The aliquots of the solution have been analyzed with inductively matched plasma optical emission spectroscopy to determine the amount of calcium leaking from the powder. Scanning electron microscope images have been examined. Significant changes in the shape of Wollastonite particles have been found when immersed in water using XRD. A comprehensive theoretical analysis has revealed that these shape changes caused by a corrosion process called MPER cannot be explained only by thermodynamic arguments; instead, kinetic considerations should be applied. The observed phenomenon can be rationalized using an observation reported in a previous study, which found that the metal - proton exchange reaction has been greatly accelerated on surfaces perpendicular to the b-axis of Wollastonite, while the reaction is delayed for orientations parallel to silicate tetrahedral chains. These kinetic differences are responsible for the characteristic changes in the shape of mineral particles when exposed to water. Corrosion of the concrete induced by the metal - proton exchange reaction leads to the conversion of the crystal from glass to phases due to the above- mentioned changes in the structure. The length of the silicate tetrahedral chain plays a very important role in mechanical properties such as the hardness and hardness of such compounds and also determines how the metal-proton exchange reaction will affect their structures.

Pekta§ and Kiirklii (2016) investigated stress corrosion in reinforced concrete steels of different classes. The study deals with three different bending angles (45, 90, 135°) and stress-free situations used when forming construction steels. In the studies, 12 mm S220 flat, S420 ribbed and B500C temp core ribbed steel grade reinforcements and mineral-free normal concrete and 25% volatile ash substituted reinforced concrete have been used. In the corrosion process, it is handled from three different angles in terms of concrete, steel and concrete and steel together. The volatile ash additive caused a 4% decrease in concrete strength but increased the corrosion resistance by between 62% and 20%. The corrosion rate increases as the bending angle increases. B500C steel has demonstrated the highest corrosion resistance and lowest corrosion rate behavior from steel classes.

Wasim and et al., (2014) investigated the impact of harsh weather conditions on the repair of corrosion of reinforced concrete slabs at the intersection of the iron. Test specimens use round carbon steel bars deformed to a diameter of 13 mm as reinforcement material. CEM I cement is used as a binder. The water/cement ratio for all mixtures has been kept at 0.45. 3% and 5% NaCI have been added to concrete mixtures. Samples are prepared to find the effects of the changing temperature (30°C, 40°C and 50°C) and the constant high humidity on the repaired worn parts of reinforced concrete structures.

After two years of corrosion potential observations, the samples have been broken to find the gravimetric mass loss and to obtain a true picture of the corrosion of the steel at the intersection of the reinforced parts of the concrete. The temperature has been observed to increase the corrosion process on repaired parts to between 30 and 40°C. As time goes through the results of all samples at changing temperature, the corrosion potential has decreased. Examples with the highest Cl concentration and the highest temperature have shown an interesting downward trend and a decrease in corrosion potential values with a rise in temperature. The cause is described by the discontinuity of the interconnected concrete pores by the reduction of oxygen resolution in the high-temperature porosity solution and the blocking of the concrete pores at high relative humidity and high temperature.

Krolikowski and Kuziak (2011) examined the ability of calcium nitrite to prevent chloride-induced corrosion of steel. Steel electrodes are made of structural carbon steel (S235JR2 grade) rods with a diameter of 8 mm and a surface area of approximately 19 cm² exposed to the solution. The studies on the effects of incubating calcium nitrite have been carried out in solutions representing porous fluid in chlorine contaminated concrete. Steel samples are first prepared with a solution of Saturated Ca(OH)2 for 3 days. It is then added to the same solution as the addition of %1 NaCI. Steel samples are kept in this solution for 7 days to initiate corrosion. After the start of steel corrosion, the first dose of calcium nitrite has been added and then its concentration has gradually increased. Calcium nitrite is provided by Aldrich in a 30% aqueous solution. Electrochemical impedance spectroscopy is used to monitor the behavior of steel at different stages of corrosion. Impedance data is used as a reference for calculating the inhalation efficiency. The measurements have been carried out 7 days after the start of corrosion and after the addition of each inhibitor. The pH of the solution(s) worked tends to fall due to carbonization (which reacts with CO2 from the air) during long-term testing. Therefore, the pH has been checked periodically every 2-3 days. To reduce observed drops in pH, solutions have been applied with periodic additions of Ca(OH)2. Calcium nitrite can prevent corrosion of localized reinforcement steels that have been introduced in solutions that simulate chlorine contaminated concrete if it is present with sufficient concentration during the early stages of corrosion. Steel re-passivation occurs at a rate below 1 of the chloride/nitrite ratios, i.e. lower than the threshold ratio to prevent the start of corrosion. The ability of calcium nitrite to prevent the induced corrosion of steel depends not only on the chloride/nitrite ratio but also on the corrosion development phase (time passing through the start of corrosion). The inhibiting efficiency is lower for more advanced corrosion, and subsequent incubation is limited to a slight reduction in corrosion velocity without re-passivation of steel. BRIEF DESCRIPTION OF THE INVENTION

The present invention is related to the mixture of cement with calcium nitrite inhibitor and polycarboxylate-based super-plasticizer as a concrete additive to obtain better corrosion-resistant reinforced concrete products.

LIST OF FIGURES

Figure 1. Nyquist diagram obtained at the end of 90th day in the distilled aqueous environment of reinforced concrete steel containing nitrite+plasticizer in the mixed water mixture.

Figure 2. Nyquist diagram obtained at the end of 120th day in the distilled aqueous environment of reinforced concrete steel containing nitrite+plasticizer in the mixed water mixture.

Figure 3. Nyquist diagram obtained at the end of 90th day in 3.5% NaCI environment of reinforced concrete steel containing calcium nitrite+plasticizer in the mixed water mixture.

Figure 4. Nyquist diagram obtained at the end of 120th day in 3.5% NaCI environment of reinforced concrete steel containing calcium nitrite+plasticizer in the mixed water mixture.

Figure 5. Nyquist diagram obtained at the end of 90th day in 5.85% NaCI environment of reinforced concrete steel containing calcium nitrite+plasticizer in the mixed water mixture.

Figure 6. Nyquist diagram obtained at the end of 120th day in 5.85% NaCI environment of reinforced concrete steel containing calcium nitrite+plasticizer in the mixed water mixture.

Figure 7. Nyquist diagram obtained at the end of 90th day in the distilled water environment of reinforced concrete steel containing distilled water, calcium nitrite, plasticizer steel, distilled water environment in the mixed water mixture.

Figure 8. Bode (b) diagram obtained at the end of 90th day in the distilled water environment of reinforced concrete steel containing distilled water, calcium nitrite, plasticizer steel, distilled water environment in the mixed water mixture.

Figure 9. Nyquist diagram obtained at the end of 120th day in the distilled water environment of reinforced concrete steel containing distilled water, calcium nitrite, plasticizer steel, distilled water environment in the mixed water mixture.

Figure 10. Bode (b) diagram obtained at the end of 120th day in the distilled water environment of reinforced concrete steel containing distilled water, calcium nitrite, plasticizer steel, distilled water environment in the mixed water mixture.

Figure 11. Nyquist diagram obtained at the end of 90th day in 3.5% NaCI environment of reinforced concrete steel containing distilled water, calcium nitrite, plasticizer steel, distilled water environment in the mixed water mixture.

Figure 12. Bode (b) diagram obtained at the end of 90th day in 3.5% NaCI environment of reinforced concrete steel containing distilled water, calcium nitrite, plasticizer steel, distilled water environment in the mixed water mixture.

Figure 13. Nyquist diagram obtained at the end of 120th day in 3.5% NaCI environment of reinforced concrete steel containing distilled water, calcium nitrite, plasticizer, calcium nitrite+plasticizer in the mixed water mixture.

Figure 14. Bode (b) diagram obtained at the end of 120th day in 3.5% NaCI environment of reinforced concrete steel containing distilled water, calcium nitrite, plasticizer steel, distilled water environment in the mixed water mixture.

Figure 15. Nyquist diagram obtained at the end of 90th day in 5.85 % NaCI environment of reinforced concrete steel containing distilled water, calcium nitrite, plasticizer, calcium nitrite+plasticizer in the mixed water mixture.

Figure 16. Bode (b) diagram obtained at the end of 90th day in 5.85% NaCI environment of reinforced concrete steel containing distilled water, calcium nitrite, plasticizer steel, distilled water environment in the mixed water mixture.

Figure 17. Nyquist diagram obtained at the end of 120th day in 5.85 % NaCI environment of reinforced concrete steel containing distilled water, calcium nitrite, plasticizer, calcium nitrite+plasticizer in the mixed water mixture.

Figure 18. Bode (b) diagram obtained at the end of 120th day in 5.85% NaCI environment of reinforced concrete steel containing distilled water, calcium nitrite, plasticizer steel, distilled water environment in the mixed water mixture.

Figure 19. SEM images in the distilled aqueous environment of reinforced concrete steel with mixed water mixture of calcium nitrite

Figure 20. SEM images of reinforced concrete steel with mixed water mixture of calcium nitrite in 3.5% NaCI environment

Figure 21. SEM images in 5.85% NaCI environment of reinforced concrete steel with mixed water mixture calcium nitrite.

Figure 22. SEM images in 3.5% NaCI environment of reinforced concrete steel with mixed water mixture of calcium nitrite + plasticizer

Figure 23. SEM images in 3.5% NaCI environment of reinforced concrete steel with mixed water mixture plasticizer

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a cement mixture comprising a polycarboxylate-based plasticizer, which reduces the amount of gap between the Nitrite ion forming a protective layer on the iron surface and the aggregates forming the concrete composition to inhibit the anodic dissolution rate of the reinforced concrete steel, thereby making it difficult to diffuse the chloride ions. While nitrite alone prevents corrosion, the mixture containing plasticizer and nitrite both prevents corrosion and has an increasing effect on strength.

"Concrete" is a building material obtained by mixing aggregate, cement, water and, if necessary, some additives together. Concrete aggregates are granular materials consisting of minerals. Sand, gravel and crushed stone are the most commonly used types of aggregate in the construction of normal weight concrete. In the construction of concrete, the function of cement dough is to cover the surface of aggregate grains, fill gaps between aggregate grains and to provide binding in the style that keeps aggregate grains together. In that respect, concrete can also be defined as a composite material of ‘cement dough and aggregates’ (Erdogan, 2003).

Because concrete tensile strength is low, it is difficult to build carrier systems and uneconomical solutions emerge. To eliminate the weakness of concrete against tensile strength, steel bars with high tensile strength and ductility and concrete, a homogeneous and non-elastic material, began to be used together in the 19th century. Thus, iron reinforced concrete, which is considered as reinforced concrete, has been obtained. Reinforced concrete can also be defined as the assembly of concrete and steel reinforcement bars to complement each other's deficiencies by working together.

The loss of metallic properties of metals and alloys by interacting with their surroundings is called “corrosion”. Corrosion is the irreversible reaction of an environmental material such as polymer, metal, concrete, wood and ceramic that results in dissolution between the environment and the interface. It is an environmental hazard with economic, protection and security effects in various engineering applications such as corrosion, building construction, chemicals and automobiles.

The impact of corrosion cost due to both direct and indirect damage to materials on the economic situation of the world is becoming a worrying case. Corrosion cost types include equipment replacement, spare equipment and increased capacity, control costs (maintenance, repair and corrosion control), design costs (construction materials, special handling and corrosion allowance) and related costs (technical support, product loss, insurance and equipment inventory). The studies have shown, however, that the cost of corrosion can be reduced by 15-20% when new low-cost corrosion control techniques are implemented. Therefore, there is a need for developing this dangerous phenomenon by new techniques and methods such as protective coatings and primers, cathodic/anodic protection and anti corrosion agents (Popoola, 2019). The first of these is corrosion inhibitors. Corrosion inhibitors minimize or prevent corrosion when added to a corrosive environment in small concentrations by creating monomolecular film adsorbed surfaces that block the direct population between metal and corrosive agents.

Calcium nitrite, a corrosion inhibitor, has been used as a corrosion inhibitor against chloride attack and as a specific accelerator in concrete for more than 20 years. Important data is available on the effects on corrosion inhibitions, adjustment times, freeze-thaw resistance, force and other features. Also, in most cases, calcium increases the pressure strength of the nitrite concrete mixture and is frost resistant with proper air drag. As a result, the data from the last 20 years shows that calcium nitrite is a proven anti-corrosion additive for the protection of concrete structures in the chlorite environment.

Calcium nitrite protects the steel in concrete by helping to preserve the existing natural protection. Steel generates an oxide in iron (Fe), oxygen (O), and hydroxide (OH) ions in an alkaline environment. Although the ferrous oxide on iron in concrete has changed to ferric oxide, there is always ferrous oxide, which is not part of the protective passive layer that protects the iron from corrosion. Ferrous oxide is less resistant to chloride ions and forms the area where corrosion begins. In the areas of ferrous oxide, there is a defect in the passivated layer. From there, chlorinated atoms attack iron atoms. The more chloride ions, the more likely any chloride anion is to encounter a ferrous flaw. The passive layer contains several ferrous oxide compounds. Ferrous oxide is a defect in the ferric oxide layer and allows chlorine to start corrosion.

Calcium nitrite remains in the concrete throughout the life of the structure. Nitrite ions cannot be dispersed from concrete and will not react with other elements in concrete if the repair of the passivated layer is to be excluded. This repair process is so effective that calcium does not cause any major decrease in the nitrite amount. Calcium nitrite protects steel against corrosion due to chloride up to a specific concentration of chloride. This significantly increases the service life of the structure. In the end, however, the amount of chloride in the steel reaches a level sufficient to start corrosion. The number of chloride ions is so large that some of them achieve new ferrous oxide defects. Even when corrosion begins (with a very high concentration of chloride compared to calcium nitrite-free concrete), the corrosion rates are lower than the rate at which corrosion on unprotected steel starts. The accumulation of calcium nitrite surrounding steel continues to inhibit corrosion despite the strength of chloride ions. When corrosion begins, new iron atoms are also exposed to corrosion. These newly exposed iron atoms have to pass through the ferrous state first to achieve a more stable ferric condition, which means they are at risk of a more advanced chloride attack. Therefore, the corrosion cells are growing and corrosion products are collected.

Nitrite ions, accompanied by the natural ferric oxide layer, prevent chloride ions from forming complexes with ferrous ions. Nitrite does this in three ways. The first one raises the ferrous oxide and allows it to transform into protective ferric oxide. Ferric oxide is not attacked by chloride. In alkaline environments, there is essentially no nitrite yellow as ferrous regions are smaller than ferric regions. Secondly, nitrite anions are chemically absorbed on the iron surface, forming a robust ferric oxide protective film. Ferrous oxide defects are surrounded by nitrite ions and are less likely to be exposed to chloride attack.

Chloride ions form complexes by attacking a ferrous octane. These complexes are further removed from steel and converted into corrosion products. Newly exposed iron atoms will generate more ferrous oxides and remain under the chloride attack. Nitrite ions react with ferrous oxide compounds to form ferric oxides. If chloride ions find a ferrous defect, corrosion begins. The ferrous chloride complex (corrosion product) can move away from the steel surface, while the new ferrous ions can contact the surrounding concrete. Nitrite ions can immediately encircle new ferrous ions and protect them against a chloride attack. While nitrite ions are guarding ferrous ions against a chloride attack, ferrous ions are elevated. This will repair the passivated oxide layer and end the formation of corrosion cells. If the nitrite ions are inside the concrete, they can make the ferrite a protective ferric. In the absence of nitrite, chloride ions attack the newly exposed ferrous oxide, leading to more corrosive products. Calcium nitrite is cracked and effective in concrete, unlike physical barriers that protect steel from chloride-induced corrosion and prevent chlorination of chlorine into the concrete. Such barriers are resistant to many stresses and may expose unprotected steel to chlorinated. Although the concrete is completely cracked to the steel, calcium nitrite continues to provide protection, the effects of corrosion protection methods that affect by slowing down the penetration of chlorine vary in cracked concrete (Crete, 2003).

Foley has shown that iron forms light green complexes that are soluble with chloride ion. These have been observed in concrete. These soluble iron ions migrate the forms away from the reinforcement bar, encouraging the dissolution of more iron. This prevents the formation of a passive substrate. For this reason, corrosion in concrete depends on the chloride ion, water and oxygen content produced by Hartt and Rosenberg, which find the worst corrosion of the concrete in the sea in the intertidal region. Calcium nitrite has been determined to not react with Fe or Fe³⁺. But it reacts with Fe²⁺. Therefore, if iron ions are produced in concrete, calcium nitrite converts them into a stable passive layer and avoids all available intermediate forms.

Chloride ions and nitrite ions compete for iron ions produced in concrete. Relative concentrations of chloride and nitrite determine the type of reaction that occurs. If the nitrite ion concentration is large, the nitrite closes the iron surface and reacts with the iron ions to form a passive layer, stopping the reaction.

Polycarboxylate-based super-fluids consist of a carbon primary chain and several side chains linked to this chain. This multi-branch construction has unlimited modification possibilities (Felekoglu, 2014). The cement beads are loaded at the opposite load and there are attraction forces of van der Waals between the opposite laden cement grains. In addition to the additive, the adsorbing additive to the surface of the cement beads creates an electrostatic fire by charging the surface negatively. In polycarboxylate-based additives, additional steric impulse forces are formed. The first two of them are made up of all additives, while the polycarboxylate-based superplasticizers are the sources of polyethene side chains (Yousaf, 2013), in addition to the observed steric repulsion.

Polycarboxylate mixtures are one of the most effective super plasticizers among all known modifiers, mainly in the form of polymers with side groups of carboxylate and ethylene oxide. Methyl acid and methacrylate ester methacrylate copolymers, a group of ethylene oxide, are often referred to as polycarboxylate (PCE) super plasticizing. Ionic hydrophilic is a comb-like polymeric formed with carboxylate groups (COO-) and long, elastic side nonionic hydrophilic ethylene oxide chains.

Superplasticizers are useful for obtaining a distribution of cement grains in water. Carboxylate groups (COO-) interact with the surface of the cement grain, causing polymer adsorbing between the grains and electrostatic thrust.

The experiments in the present invention have been conducted as follows and the results below have been again.

The prepared samples are immersed in 3 different solutions (distilled water, 3.5% NaCI and 5.85% NaCI) separately. The corrosion resistance of the samples held in solution on days 7, 14, 21, 28, 60, 90, and 120 have been investigated.

Samples have been held for four months in a distilled water, 5.85% and 3.5% Cl-concentration saline water solution, accelerated corrosion. During the four months, measurements of half-cell potential, corrosion current density have been made regularly. The measurements use electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. Samples subjected to accelerated corrosion for four months have been broken at the end of the trial, equipped and SEM structures examined.

The effects of additives to the pressing strength of concrete have been evaluated at the end of a course period of days 2, 7 and 28. The 28-day compressive strengths of the solids-free, Calcium Nitrite-containing, liquefying concrete and Calcium Nitrite + Plasticizer-containing samples have been determined as 35.8 MPa, 38.1 MPa, 41.6 MPa and 43.4 MPa, respectively. When the concrete additives have been compared with the pure sample, it has been determined that the plasticizer increased the compressive strength of the concrete by 16.20% and the calcium nitrite increased the compressive strength of the concrete by 6.42%.

At the end of the accelerated corrosion period, the best inhibition efficiency has been 120 in 3.5% NaCI solution. At the end of the accelerated corrosion period, the best inhibition efficiency is 91.13% in calcium nitrite inhibition on 120th day. According to the obtained data, it has been observed that calcium nitrite significantly reduces corrosion in reinforced concrete samples. However, nitrite alone contributes little to strength, increasing compressive strength by 6%. When plasticizer and nitrite are added to the media, this increases to 21 %. The plasticizer is used up to 0.5% of the cement weight. The anodic dissolution rate of the reinforced concrete steel in a chlorinated environment is indirectly inhibited by a polycarboxylate-based superplasticizer. The effect of the inhibition has reduced the water/cement ratio of the polycarboxylate-based superplasticizer. In addition to this, it has been determined that the amount of gap between the aggregates forming the concrete composition decreases, making it difficult to diffuse the chloride ions. The addition of 0.1 M nitrite ions to the mixture results in a significant increase in polarization resistance values.

The operating electrodes have been built into concrete waste, which has been prepared with a technical purity of 5 cm (10 mm). Electrochemical behaviors of reinforced concrete steel have been examined by immersing working electrodes prepared with different mixed water into contact water containing distilled water, 3.5% NaCI and 5.85% NaCI.

Chart 1 Contact and Mixed Waters Used

The contact water mentioned in Table 1 refers to the water in which the samples come into contact. Mixed water refers to the mixture used to form cement.

Table 2. Concrete Components and Use Rates

Chart 2 provides the components of the concrete used in the experiments and the use rates of these components. As can be seen from this chart, the mixture content of the present invention is ½ by weight of water and cement, 3% by weight of cement calcium nitrite and 0.5% by weight of cement plasticizer have been used.

On 90th and 120th day, R_P values of reinforced concrete steel containing calcium nitrite + plasticizer in mixed water mixture have been measured as 15848.93 - 20044.72 W in the distilled water environment (R_P value refers to the polarization resistance. As the R_P value increases, the polarization resistance and consequently the corrosion resistance increases). When Figure 1 and 2 are examined, polarization resistance has been observed to increase with the addition of calcium nitrite + plasticizer to the concrete mixture. At the end of the 90th day, while the R_P value of the concrete containing distilled water in the mixture of mixed water is 5081.59, It has been determined as 15848.93 W with the addition of calcium nitrite + plasticizer to the mixture of mixed water. At the end of the 120th day, while the R_P value of the concrete containing distilled water in the mixture of mixed water is 12445.15, It has been determined as 20044.72 W with the addition of calcium nitrite + plasticizer to the mixture of mixed water.

90th and 120th day R_P values of reinforced concrete steel containing calcium nitrite + plasticizer in mixed water mixture have been measured as 12589.25 - 11967.41 W in the 3.5% NaCI media.

As can be seen in Figures 3 and 4, when Nyquist and Bode diagrams obtained at the end of 90th day and 120th day are examined, polarization resistance of reinforced concrete steel containing distilled water, Calcium Nitrite, Plasticizer and Calcium Nitrite+ Plasticizer in mixed water mixture immersed in environment with 3.5% NaCI in contact water increases at the end of the 90th and 120th days. Polarization resistance is obtained from Nyquist and bode curves. Since the Nyquist curves are open-ended, the polarization resistance values (R_P) have been obtained by taking backwards extrapolated antilog from the Bode curves. Therefore, when the diagrams are examined, it has been observed that the polarization resistance increases with the addition of plasticizer. It has been observed that the polarization resistance decreases with the introduction of a plasticizer in the nitrite environment compared to the nitrite media. It has also been determined that the addition of nitrite ion to the medium forms a stable passive layer and the corrosion rate decreases. The reduction of polarization resistance by the addition of a plasticizer to the nitrite medium has been shown to reduce the effect of the plasticizer, which complicates the diffusion of the chloride ion, by also complicating the diffusion of nitrite ion. Polarization resistance (R_P) consists of two parts. First, pore resistance (Rpor) is defined as part of the polarization resistance. Pore resistance includes load transfer resistance, diffusion resistance and accumulation resistance. The second resistance is film resistance. In equivalent circuits, a fixed phase element (CPE) of the surface is defined as a concept that will replace the capacitor but may also have a resistance effect according to the conditions.

90th and 120th day R_P values of reinforced concrete steel containing calcium nitrite + plasticizer in mixed water mixture have been measured as 16982.44 - 10399.2 W in the 5.85% NaCI media.

When Nyquist and Bode diagrams obtained at the end of 90th day and 120th day are examined, polarization resistance of reinforced concrete steel containing distilled water, Calcium Nitrite, Plasticizer and Calcium Nitrite+ Plasticizer in mixed water mixture immersed in environment with 5.85% NaCI in contact water increases at the end of the 90th and 120th days. Polarization resistance appears to be increased with the addition of plasticizer. It has been observed that the polarization resistance decreases at the end of the 90th and 120th days with the introduction of a plasticizer in the nitrite environment compared to the nitrite media. It has been observed that the effect of calcium nitrite and plasticizer decrease in high chloride concentration.

In Figure 19-23, 5 pm taken SEM images are provided. When SEM images are examined, it has been observed that the surface is closed with the addition of nitrite. When Figure 19 is examined, it has been observed that the surface closes homogeneously in distilled water media. When Figure 20 is examined, it has been observed that the surface is opened with chloride entering the media. When Figure 21 is examined, it has been observed that the surface is opened more with the increased chloride concentration and the oxide layer is deteriorated. When Figure 22 and Figure 23 are examined, cracks are observed on the surface. Mixed Time Ecorr Rp lcorr

IE%

Water (day) (V vs.Ag/AgCI) (ohm) (pA/cm²)

Distilled 90 -0.578 5081.59 5.12

Water 120 -0.246 12445.15 2.09

Calcium 90 -0.218 22387.21 1.16x1 O ⁶ 77.30

Nitride 120 -0.127 28575.9 0.91 56.45

90 -0.593 4786.3 5.43x1 O ⁶

Plasticizer

120 -0.184 12589.25 2.07 1.14

Calcium 90 -0.197 15848.93 1.64 67.94 Nitride + Plasticizer 120 -0.202 20044.72 1.30 37.91

Table 3. Reinforced Concrete; corrosion potential (Ecorr)^', polarization resistance

(R_p); corrosion current (Icon-)^', and inhibitory activity percentage (IE) values obtained at the 90th and 120th days in the environment containing contact water, mixed water with distilled water, calcium nitrate, plasticizer and calcium nitrite + plasticizer

Mixed Time Ecorr RP lcorr

IE%

Water (day) (V vs.Ag/AgCI) (ohm) (pA/cm²)

Distilled 90 -0.803 1949.85 13.33

Water 120 -0.845 2137.96 12.16

Calcium 90 -0.154 20417.38 T27 90.45

Nitride 120 -0.218 24099.05 1.08 91.13

90 -0.518 12302.69 2T1 84.15

Plasticizer

120 -0.56 8511.38 3.05 74.88

Calcium 90 -0.482 12589.25 07 84.51

Nitride +

Plasticizer 120 -0.511 11967.41 2.17 82.14

Table 4. Reinforced Concrete; corrosion potential(E_COrr); polarization resistance (R_p); corrosion current (/con); and inhibitory activity percentage (IE) values obtained at the 90th and 120th days in the environment containing 3.5% NaCI contact water, mixed water with distilled water, calcium nitrate, plasticizer and calcium nitrite + plasticizer.

Mixed Water Time Ecorr Rp lcorr

IE%

(day) (V vs.Ag/AgCI) (ohm) (pA/cm²)

90 -0.574 5370.32 4.84

Distilled Water

120 -0.596 5956.62 4.36

90 -0.564 9931.16 2.62 45.92

Calcium Nitride

120 -0.565 14125.38 1.84 57.83

90 -0.868 7413.1 3.51 27.56

Plasticizer

120 -0.857 6918.3 3.76 13.90

90 -0.364 16982.44 1.53 68.38

Calcium Nitride + Plasticizer

120 -0.474 10399.2 2.50 42.72 Table 5. Reinforced Concrete; corrosion potential (Ecorr); polarization resistance (Rp); corrosion current (Icon-); and inhibitory activity percentage (IE) values obtained at the 90th and 120th days in the environment containing 5.85 % NaCI contact water, mixed water with distilled water, calcium nitrate, plasticizer and calcium nitrite + plasticizer.

The values obtained provided from Figure 1 and Figure 2 are provided in Chart 3.

90th and 120th day Rp values of reinforced concrete steel containing calcium nitrite + plasticizer in mixed water mixture have been measured as 15848.93 - 20044.72 W in the distilled water media. Polarization resistance has been observed to increase with the addition of calcium nitrite + plasticizer to the concrete mixture. 90. At the end of the day, while the R_P value of the concrete containing distilled water in the mixture of mixed water is 5081.59, It has been determined as 15848.93 W with the addition of calcium nitrite + plasticizer to the mixture of mixed water. At the end of the 120th day, while the R_P value of the concrete containing distilled water in the mixture of mixed water is 12445.15, It has been determined as 20044.72 W with the addition of calcium nitrite + plasticizer to the mixture of mixed water. The values obtained from Figure 3 and Figure 4 are provided in Table 4.

90th and 120th day R_P values of reinforced concrete steel containing calcium nitrite + plasticizer in mixed water mixture have been measured as 12589.25 - 11967.41 W in the 3.5% NaCI media. Polarization resistance has been observed to increase with the addition of calcium nitrite + plasticizer to the concrete mixture. At the end of the 120th day, while the R_P value of the concrete containing distilled water in the mixture of mixed water is 1949.85, It has been determined as 12589.25 W with the addition of calcium nitrite + plasticizer to the mixture of mixed water. At the end of the 120th day, while the R_P value of the concrete containing distilled water in the mixture of mixed water is 2137.96, It has been determined as 11967.41 W with the addition of calcium nitrite + plasticizer to the mixture of mixed water.

The values obtained from Figure 5 and Figure 6 are provided in Chart 5.

90th and 120th day R_P values of reinforced concrete steel containing calcium nitrite + plasticizer in mixed water mixture have been measured as 16982.44 - 10399.2 W in the 3.5% NaCI media.

Polarization resistance has been observed to increase with the addition of calcium nitrite + plasticizer to the concrete mixture. At the end of the 120th day, while the R_P value of the concrete containing distilled water in the mixture of mixed water is 5370.32, It has been determined as 16982.44 W with the addition of calcium nitrite + plasticizer to the mixture of mixed water. At the end of the 120th day, while the R_P value of the concrete containing distilled water in the mixture of mixed water is 5956.62, It has been determined as 10399.2 W with the addition of calcium nitrite + plasticizer to the mixture of mixed water.

When Figure 7 and Figure 8 are examined, the highest polarization resistance has been observed in the nitrite added environment.

When Figure 9 and Figure 10 are examined, the highest polarization resistance has been observed in the nitrite added media.

When Figure 11 and Figure 12 are examined, the highest polarization resistance has been observed in the nitrite added media.

When Figure 13 and Figure 14 are examined, the highest polarization resistance has been observed in the nitrite added media.

When Figure 15 and Figure 16 are examined, the highest polarization resistance has been observed in the nitrite + plasticizer added media. When Figure 17 and Figure 18 are examined, the highest polarization resistance has been observed in the nitrite added media.

As can be seen in Figures 11 , 12, 13, 14, 15, 16 and 17, when Nyquist and Bode diagrams obtained at the end of 90th day and 120th day are examined, polarization resistance of reinforced concrete steel containing distilled water, Calcium Nitrite, Plasticizer and Calcium Nitrite+ Plasticizer in mixed water mixture immersed in environment with NaCI in contact water increases at the end of the 90th and 120th days. Polarization resistance appears to be increased with the addition of plasticizer. It has been observed that the polarization resistance decreases with the introduction of a plasticizer in the nitrite environment compared to the nitrite media.

It has been observed that the effect of calcium nitrite and plasticizer decrease in high chloride concentration.

Claims

1. A chemical mixture containing polycarboxylate based plasticizer and calcium nitrite characterized in that comprising ½ by weight of water and cement, nitrite oxide up to 3% by weight of cement and plasticizer up to 0.5% by weight of cement.