scholarly journals COATING FOR PROTECTION OF CONCRETE FROM SULFATES

2021 ◽  
pp. 77-87
Author(s):  
Pavlo Vasylovych Kryvenko ◽  
Igor Igorevych Rudenko ◽  
Oleksandr Petrovych Konstantynovskyi
Keyword(s):  
Reinforced Concrete ◽  
Protective Coating ◽  
Concrete Surface ◽  
Steel Reinforcement ◽  
Passive State ◽  
Hardened Concrete ◽  
Reinforcement Corrosion ◽  
Ions Transport ◽  
Ph Values ◽  
High Consistency

Durability of reinforced concrete is one of the main demands in civil engineering.Operating conditions, particularly in aggressive mediums, determine durability of constructions.Sulfate mediums are among the most aggressive ones which cause steel reinforcement corrosion. Themodern requirements for high consistency fresh concretes are governed by practice. This way thedisturbance of reinforcement passive state can be caused by changes in hardened concrete especiallyin aggressive mediums. Thus, the restriction of SO42- ions transport in concretes, which are obtainedfrom high consistency fresh mixes and exploited in sulfate mediums, can be considered as an actualproblem.The paper is devoted to protection of concrete surface by coating based on alkali-activatedaluminosilicate binder from SO42- ions transport to prevent steel reinforcement corrosion. It wasshown that the coating with thickness of 3 mm ensures total concrete protection. It was revealed thatpermeability of concrete depending on cation decreases in the row (NH4)2SO4>Na2SO4>MgSO4. Theprotective function of coating was simulated by application of mentioned salts as admixtures. LesspH values of water extracts of the binder during hydration while using of 2.5 % MgSO4 is evidenceof advanced crystallinity of zeolite-like sulfate-containing hydroaluminosilicates with participationof Mg2+ ions equal to Са2+ ions. While content of (NH4)2SO4 was increased up to 5.0 % less pH wasfixed due to decelerated formation of zeolite-like minerals. Stability of pH values in presence ofNa2SO4 (0.5…2.5 %) was caused by no influence on structure formation. Thus, the restriction of SO 2-ions transport in protective coating is due to their binding by alkaline aluminosilicate binder inzeolite-like minerals with higher crystallinity due to presence of Na+, NH + and Mg2+ cations fromsulfates.

scholarly journals Prevention of steel reinforcement corrosion in alkali-activated slag cement concrete mixed with seawater

2021 ◽  
Vol 280 ◽  
pp. 07004
Author(s):  
Pavlo Krivenko ◽  
Igor Rudenko ◽  
Oleksandr Konstantynovskyi ◽  
Olha Boiko
Keyword(s):  
Steel Corrosion ◽  
Steel Reinforcement ◽  
Passive State ◽  
Hardened Concrete ◽  
Reinforcement Corrosion ◽  
Alkali Activated Slag ◽  
Complex Additive ◽  
Activated Slag ◽  
High Consistency ◽  
Alkali Activated

Concretes mixed with seawater are characterised by enhanced performances, but action of chlorides and sulfates ensures the risk of reinforcement corrosion. Application of high consistency fresh concretes ensures changes in hardened concrete structure that causes the problem of steel reinforcement passive state ensuring. Thus mixing of plasticized concretes by seawater actualizes the search for means of steel corrosion prevention. Alkali-activated slag cements (further, AASC’s) reduce effect of ions Cl− and SO42− on steel reinforcement in concrete due to their exchange for ions OH− in the structure of zeolite-like alkaline hydroaluminosilicates. Complex additive «portland cement - calcium aluminate cement - clinoptilolite» was proposed to enhance the protective properties of AASC concretes to steel reinforcement. The results of DTA, X-ray diffraction, electron microscopy, microprobe analysis show that complex additive ensures to prevent steel reinforcement corrosion in AASC concrete mixed with seawater due to binding Cl− and SO42− ions in Kuzel’s salt in AASC hydration products and exchange of these aggressive ions with OH− ions in the structure of clinoptilolite. This effect of complex additive confirmed by surface state and the absence of mass loss of steel rebars embedded in plasticized AASC fine concrete mixed with seawater after 90 d of hardening.

scholarly journals The Effect of Freeze-Thaw Damage on Corrosion in Reinforced Concrete

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Xiao-Chun Lu ◽  
Bin Guan ◽  
Bo-Fu Chen ◽  
Xin Zhang ◽  
Bo-bo Xiong
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Rate ◽  
Sem Analysis ◽  
Steel Reinforcement ◽  
Reinforcement Corrosion ◽  
Freeze Thaw ◽  
Pull Out ◽  
Thaw Cycle ◽  
Corrosion Reaction ◽  
Freeze Thaw Cycle

The existing studies of the corrosion of reinforced concrete have mainly focused on the interface area and chemical ion erosion, ignoring the specific service environment of the reinforced concrete. In this study, the effect of freeze-thaw damage was investigated via corrosion experiments under different freeze-thaw cycle conditions. Steel reinforcement corrosion mass, ultimate pull-out force, corrosion rate, and bond slippage were chosen as characteristic parameters in the experiments, and scanning electron microscopy (SEM) analysis was used to explain the mechanism of action of freeze-thaw damage on corrosion. The results showed that, under identical corrosion conditions, the mass of steel reinforcement corrosion and corrosion rate increased by 39.6% and 39.7% when comparing 200 freeze-thaw cycles to 0 cycles, respectively. The ultimate pull-out force and bond slippage after 200 freeze-thaw cycles decreased by 73% and 31%, respectively, compared with 0 freeze-thaw cycles. In addition, SEM analysis indicated that microstructure damage caused by freeze-thaw cycles accelerated the corrosion reaction and decreased cementitious properties, leading to decreasing ultimate pull-out force and bond slippage. The effect of freeze-thaw cycles and steel reinforcement corrosion on the macro mechanical properties of concrete is not a simple superposition.

DEVELOPMENT OF EMBEDDED MINI-SENSOR FOR DIAGNOSIS OF CORROSION OF STEEL REINFORCEMENT IN CONCRETE NONDESTRUCTIVELY

2016 ◽  
Vol 3 (2) ◽  
Author(s):  
Mohamed A. Ismail ◽  
Han-Seung Lee ◽  
Mohd Warid Hussin
Keyword(s):  
Reinforced Concrete ◽  
Polarization Resistance ◽  
Concrete Structures ◽  
Steel Reinforcement ◽  
Reinforced Concrete Structures ◽  
Chloride Ingress ◽  
Reinforcement Corrosion ◽  
Maintenance And Rehabilitation ◽  
Corrosion Of Steel ◽  
Non Destructive

Corrosion of steel reinforcement embedded in concrete is one of the main causes of degradation of reinforced concrete structures. Degradation occurs in reinforced concrete structures from corrosion caused by the Chloride ingress into concrete. That degradation has a severe impact on the structure in terms of maintenance and rehabilitation costs. Therefore, early detection of reinforcement corrosion is important for efficient maintenance, repair and planning. Meanwhile, the evaluation of the corrosion of reinforcement by non-destructive measurements have been used a lot. In particular CM-II (corrosion meter) is used to measure the polarization resistance, but has some disadvantages. Embedded mini-sensor has been developed in order to overcome these disadvantages. In this study, measurement of corrosion by using the mini-sensor is compared with the measured results by CM-II to verify the validity of the newly developed mini senor. Results show that there are agreement in trends of the parameters measured and as such the developed mini sensor has a promising start to be used.

scholarly journals The effects of steel reinforcement corrosion on the flexural capacity and stiffness of reinforced concrete beams

2021 ◽  
Author(s):  
Timothy A Joyce
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Chloride Ion ◽  
Steel Reinforcement ◽  
Reinforced Concrete Beams ◽  
Reinforcement Corrosion ◽  
Flexural Capacity ◽  
Ion Content ◽  
Sharp Drop ◽  
Low Degrees

This study is an attempt to derive a relationship between steel reinforcement corrosion and the coinciding loss of flexural strength. The corrosion of the steel was isolated in the flexural region in order to eliminate contributions from stirrup corrosion and loss of bond within the development length. It was determined that the flexural capacity of reinforced concrete beams decreased as the rate of corrosion increased. In addition to the study of flexural capacity, the prediction of the flexural behaviour of corroded beams was studied through the stiffness effects of reinforcement corrosion. The stiffness study indicated a sharp drop in stiffness at relatively low degrees of corrosion, followed by a slower decline at increasing levels of corrosion. Mass loss, crack width and chloride ion content were examined as indicators of degree of corrosion. These relationships are an essential step in developing an effective model for the performance of corroded reinforced concrete beams in the future.

Monitoring Method of Steel Reinforcement Corrosion Rate in Concrete

2007 ◽  
Vol 334-335 ◽  
pp. 101-104
Author(s):  
Hiroyuki Saito
Keyword(s):  
Corrosion Rate ◽  
Measurement Method ◽  
Steel Corrosion ◽  
Electrochemical Measurement ◽  
Steel Reinforcement ◽  
Passive State ◽  
Reinforcement Corrosion ◽  
Monitoring Method ◽  
Steel Bars

Steel reinforcement concrete is one of the most widely used composite materials in architectural and civil engineering. The alkaline of concrete makes steel passive state, so the steel bars in conrete are kept in anti-corroded phase. Carbon dioxide in atmosphere, however, chemically reacts to the alkaline components in long term, and the passive state of steel is missing. Steel corrosion in concrete is not visible but it may cause decaying buildings or civil construction. The author developed the electrochemical measurement method of monitoring steel corrosion rate in concrete. With the measurement method, the author measured the variety of corrosion rates of steel reinforcement in several atmospheres, such as indoors, outdoors, in-water, underground, and so on. In this paper, found and analyzed mechanisms of steel corrosion in those atmospheres are mainly shown. For an interesting result, the most corroded sample is not the sample exposed outdoor, nor exposed in water, but the sample exposed in wet room. This may cause the diffusion balance of oxygen and water in concrete.

scholarly journals Structural effects of steel reinforcement corrosion on statically indeterminate reinforced concrete members

2016 ◽  
Vol 49 (12) ◽  
pp. 4959-4973 ◽  
Author(s):  
Ignasi Fernandez ◽  
Manuel F. Herrador ◽  
Antonio R. Marí ◽  
Jesús Miguel Bairán
Keyword(s):  
Reinforced Concrete ◽  
Steel Reinforcement ◽  
Reinforcement Corrosion ◽  
Structural Effects ◽  
Concrete Members

scholarly journals Effect of polycarboxylate and polyarylate surfactants on corrosion of the steel reinforcement embedded in the concrete

2018 ◽  
Vol 251 ◽  
pp. 01026 ◽  
Author(s):  
Linar Talipov ◽  
Evgeny Velichko
Keyword(s):  
Reinforced Concrete ◽  
The United States ◽  
Steel Reinforcement ◽  
Concrete Bridges ◽  
Passive State ◽  
Chemical Additives ◽  
Polymeric Surfactants ◽  
Global Cost ◽  
Chlorine Ions ◽  
The Impact

We considered the possibility to inhibit the corrosion of the steel reinforcement embedded in the concrete using different polymeric surfactants, when paired with the passivating and plasticizing chemical additives. Previously [1] the authors proposed the method to form the protective films on the surface of the steel reinforcement embedded in concrete using the polycomponent anticorrosion naphthalene sulfonate superplasticizer based additives. The results of further surveys provided in this article proved, that under the special conditions the polyarylate and polycarboxylate surfactants are capable to keep the steel reinforcement in the passive state in presence of chlorine ions. This is especially relevant, considering the fact, that the polymer additives intended for plasticization of concrete are more widely used for the manufacturing of the monolithic and prefabricated reinforced concrete structures. In the same time Deicing agents having in its composition chlorine ions, are widely used for deicing of roads in different countries. Chlorine ions adversely affect the reinforcement of concrete artificial structures in transport. the corrosion of metals incurs huge losses, the global cost is $ 2.5 trillion, equivalent to 3.4% of world gross domestic product (GDP) for 2013[2]. In 1993, the United States spent 20 billion dollars on the repair of reinforced concrete bridges only because of the impact of chlorides[3].

Reinforcement Corrosion versus Crack Width

2014 ◽  
Vol 897 ◽  
pp. 161-164
Author(s):  
Peter Kotes ◽  
Ján Kozák
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Construction Material ◽  
Steel Reinforcement ◽  
Reinforced Concrete Beams ◽  
Reinforcement Corrosion ◽  
Materials Selection ◽  
Resistant Material ◽  
Corrosion Of Steel ◽  
Design Construction

Reinforced concrete is a versatile, economical and successful construction material. Usually, it is durable and resistant material, performing well throughout its service life. However, sometimes it does not perform adequately as it is expected. It is due to poor design, construction, inadequate materials selection and more severe environment than anticipated or a combination of those factors [1, . The reinforcement corrosion is the phenomenon that highly affects the reliability and durability of reinforced concrete structures. From that reason, a lot of researchers in Slovakia and in the world pay their attention to reinforcement corrosion. The paper is concerned with detection and simulation of corrosion of steel reinforcement in the reinforced concrete. The cracking response of the reinforced concrete beams due to the corrosion effect of the steel reinforcement was analyzed. The effect of corrosion was simulated by the nonlinear numerical analysis using the program ATENA.

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