Experimental Investigation on Deterioration Mechanisms of Concrete under Tensile Stress-Chloride Ion-Carbon Dioxide Multiple Corrosion Environment

The adverse effects of a hostile marine environment on concrete structures inevitably result in great economic loss and may contribute to catastrophic failure. There is limited information on the durability of concrete in a tensile stress-chloride ion-carbon dioxide (TCC) multiple-corrosion environment. The objective of this study is to explore the impact of a TCC multiple-corrosion environment on concrete considering three coupled factors of compressive strength, Cl− penetration, and carbonation. Dry–wet cycle tests were conducted to determine the strength degradation and Cl− penetration concentration of concrete in a hostile multiple-corrosion marine environment. The results show that the effects of water-soluble chloride ions (Cl−), carbon dioxide (CO2), and tensile stress on concrete are not a simple superposition, but involve obvious interaction. The compressive strength of a concrete specimen first increases and then decreases in chlorine salt-carbon tests. The Cl− concentration and tensile stress affect the carbonation depth of concrete, which increases with an increase in Cl− concentration, and with the application of tensile stress. The Cl− concentration has an obvious effect on the carbonation depth. In addition to experimental observations, a stepwise regression equation was established based on the multiple linear regression theory. A correlation analysis considering different factors was conducted to reflect the corrosion results more directly.

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The Impact of Chloride and Sulphate Aggressiveness on the Microstructure and Phase Composition of Fly Ash-Slag Mortar

Materials ◽

10.3390/ma14164430 ◽

2021 ◽

Vol 14 (16) ◽

pp. 4430

Author(s):

Paweł Falaciński ◽

Agnieszka Machowska ◽

Łukasz Szarek

Keyword(s):

Compressive Strength ◽

Phase Composition ◽

Sodium Chloride ◽

Chloride Ion ◽

Sodium Sulphate ◽

Chloride Ions ◽

Ion Concentration ◽

Pore Liquid ◽

A Minor ◽

The Impact

The article discusses the results of examining the impact of aggressive solutions on specimens of mortars with a slag-ash binder. Bar specimens were exposed to unidirectional diffusion of sodium chloride and sodium sulphate for 90 days. Next, the specimens were subjected to flexural and compressive strength tests, ion content tests, XRD phase composition tests, and microstructural SEM-EDS tests. The test results indicated that aggressive solution action resulted in decreased flexural strength, however, it did not impact the compressive strength of mortars. A minor impact of chloride ions on the pH of the pore liquid was recorded, while the tests did not show any influence of sulphate ions. Furthermore, aggressive ion concentration decreased in deeper specimen slices. Specimen phase composition testing after chloride ion action indicated the presence of a small amount of Friedel’s salt, while regular sodium chloride crystals were identified in the microscopic image. The performance properties of mortars exposed to the action of aggressive solutions were maintained.

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Carbonization Durability of Two Generations of Recycled Coarse Aggregate Concrete with Effect of Chloride Ion Corrosion

Sustainability ◽

10.3390/su122410544 ◽

2020 ◽

Vol 12 (24) ◽

pp. 10544

Author(s):

Chunhong Chen ◽

Ronggui Liu ◽

Pinghua Zhu ◽

Hui Liu ◽

Xinjie Wang

Keyword(s):

Compressive Strength ◽

Coarse Aggregate ◽

Chloride Ion ◽

Total Porosity ◽

Recycled Concrete ◽

Carbonation Depth ◽

Aggregate Concrete ◽

Recycled Coarse Aggregate ◽

Carbonation Resistance ◽

Two Generations

Carbonation durability is an important subject for recycled coarse aggregate concrete (RAC) applied to structural concrete. Extensive studies were carried out on the carbonation resistance of RAC under general environmental conditions, but limited researches investigated carbonation resistance when exposed to chloride ion corrosion, which is an essential aspect for reinforced concrete materials to be adopted in real-world applications. This paper presents a study on the carbonation durability of two generations of 100% RAC with the effect of chloride ion corrosion. The quality evolution of recycled concrete coarse aggregate (RCA) with the increasing recycling cycles was analyzed, and carbonation depth, compressive strength and the porosity of RAC were measured before and after chloride ion corrosion. The results show that the effect of chloride ion corrosion negatively affected the carbonation resistance of RAC, and the negative effect was more severe with the increasing recycling cycles of RCA. Chloride ion corrosion led to a decrease in compressive strength, while an increase in carbonation depth and the porosity of RAC. The equation of concrete total porosity and carbonation depth was established, which could effectively judge the deterioration of carbonation resistance of RAC.

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Influence of Fly Ash Additive on the Properties of Concrete with Slag Cement

Materials ◽

10.3390/ma13153265 ◽

2020 ◽

Vol 13 (15) ◽

pp. 3265 ◽

Cited By ~ 3

Author(s):

Anna Szcześniak ◽

Jacek Zychowicz ◽

Adam Stolarski

Keyword(s):

Fly Ash ◽

Chloride Ion ◽

High Strength ◽

Experimental Tests ◽

Chloride Ions ◽

Strength Increase ◽

Slag Cement ◽

Initial Strength ◽

Chloride Ion Penetration ◽

The Impact

This paper presents research on the impact of fly ash addition on selected physical and mechanical parameters of concrete made with slag cement. Experimental tests were carried out to measure the migration of chloride ions in concrete, the tightness of concrete exposed to water under pressure, and the compressive strength and tensile strength of concrete during splitting. Six series of concrete mixes made with CEM IIIA 42.5 and 32.5 cement were tested. The base concrete mix was modified by adding fly ash as a partial cement substitute in the amounts of 25% and 33%. A comparative analysis of the obtained results indicates a significant improvement in tightness, especially in concrete based on CEM IIIA 32.5 cement and resistance to chloride ion penetration for the concretes containing fly ash additive. In the concretes containing fly ash additive, a slower rate of initial strength increase and high strength over a long period of maturation are shown. In accordance with the presented research results, it is suggested that changes to the European standardization system be considered, to allow the use of fly ash additive in concrete made with CEM IIIA 42.5 or 32.5 cement classes. Such a solution is not currently acceptable in standards in some European Countries.

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Carbonation Resistance in Ordinary Portland Cement Concrete with and without Recycled Coarse Aggregate in Natural and Simulated Environment

Sustainability ◽

10.3390/su14010437 ◽

2021 ◽

Vol 14 (1) ◽

pp. 437

Author(s):

Wajeeha Mahmood ◽

Asad-ur-Rehman Khan ◽

Tehmina Ayub

Keyword(s):

Carbon Dioxide ◽

Tensile Strength ◽

Compressive Strength ◽

Natural Environment ◽

Coarse Aggregate ◽

Splitting Tensile Strength ◽

Carbonation Depth ◽

Simulated Environment ◽

Concrete Mix ◽

Carbon Dioxide Co2

This research aims to examine the effect of carbonation on the strength properties and carbonation depth of ordinary Portland cement (OPC) concrete using two different water to cement ratios (w/c) and two different replacement percentages of natural coarse aggregate (NCA) with recycled coarse aggregate (RCA). Two concrete mixes were prepared using w/c of 0.4 and 0.43. The two concrete mixes were subdivided into two subgroups based on the use of NCA and 30% RCA. The first concrete mix having w/c of 0.4 was contained NCA and from this concrete, 42 cylinders of 100 mm dia. and 200 mm height were cast. Six out of 42 cylinders served as control specimens and were not exposed to CO2. A total of 18 out of the remaining 36 cylinders was exposed to the simulated environment and the rest were exposed to the natural environment. The second concrete mix having a w/c of 0.4 contained 30% RCA/70% NCA, and using this concrete, 42 cylinders of similar size were cast. A similar scheme was adopted for w/c of 0.43 and, in total, 84 cylinders using four mix designs were cast. After casting and 28 days of curing, six out of 42 cylinders cast from each concrete mix design were tested for compression and splitting tensile strength, following ASTM C39 and ASTM C496 without any exposure to carbon dioxide (CO2). A total of 18 out of the remaining 36 cylinders was exposed to the simulated environment in a carbonation chamber for an equivalent time duration of 90, 180 and 365 days following CEN test guidelines and the other 18 cylinders were kept in the natural environment for a period of 90, 180 and 365 days. After the completion of simulated and natural exposure periods, these cylinders were distributed equally to test for compressive strength and splitting tensile strength to observe the effect of carbon dioxide (CO2) at each time duration (i.e., 90, 180 and 365 days), and replacement percentage of RCA (i.e., 0 and 30%), which showed that carbonation depth increases incrementally with the w/c ratio and CO2 exposure duration. In both the simulated and the natural environment, the use of RCA in concrete cast using a w/c of 0.4 increased carbonation depth up to 38% and 46%, whereas, in the case of the concrete cast using a w/c ratio of 0.43, the use of RCA increased the carbonation depth up to 16% and 25%. In general, the use of RCA in the concrete exposed to the natural environment significantly affected the compressive strength of concrete, due to multiple interfaces and the porous structure of RCA, and the variation in the temperature, humidity and content of carbon dioxide (CO2) present in the actual environment. The maximum compressive strength variation prepared from the mixes M0-0.4, M30-0.43, M0-0.43 and M30-0.43 differed by 5.88%, 7.69%, 16.67% and 20% for an exposure period up to 365 days. Similarly, the results of splitting tensile strength tests on cylinders prepared from the same mixes exposed to the natural environment differ by 7.4%, 27.6%, 25.41% and 18.2% up to 365 days of exposure, respectively, as compared to the simulated environment.

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Evaluation of Chloride Resistance of Early-Strength Concrete Using Blended Binder and Polycarboxylate-Based Chemical Admixture

Applied Sciences ◽

10.3390/app10082972 ◽

2020 ◽

Vol 10 (8) ◽

pp. 2972 ◽

Cited By ~ 2

Author(s):

Taegyu Lee ◽

Jaehyun Lee

Keyword(s):

Compressive Strength ◽

Diffusion Coefficient ◽

Portland Cement ◽

Chloride Ion ◽

Strength Criterion ◽

Chloride Ions ◽

Chloride Diffusion ◽

Chloride Diffusion Coefficient ◽

Characteristic Strength ◽

Early Strength

The mixing proportions of concrete were examined with regard to the durability performance and early strength in coastal areas. Research was conducted to improve the C24 mix (characteristic strength of 24 MPa). C35 concrete (characteristic strength of 35 MPa) was selected as a comparison group, as it exhibits the minimum proposed strength criterion for concrete in the marine environment. To secure the early strength of the C24 concrete, 50% of the total ordinary Portland cement (OPC) binder was replaced with early Portland cement (EPC); and to provide durability, 20% was substituted with ground granulated blast-furnace slag (GGBS). In addition, a polycarboxylate (PC)-based superplasticizer was used to reduce the unit water content. The compressive strength, chloride ion diffusion coefficient, chloride penetration depth, and pore structure were evaluated. After one day, the compressive strength improved by 40% when using EPC and GGBS, and an average increase of 20% was observed over 91 days. EPC and GGBS also reduced the overall porosity, which may increase the watertightness of concrete. The salt resistance performance was improved because the rapid early development of strength increased the watertightness of the surface and immobilization of chloride ions, decreasing the chloride diffusion coefficient by 50%.

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REDUCTION OF CHLORIDE ION INGRESS INTO REINFORCED CONCRETE USING A HYDROPHOBIC ADDITIVE MATERIAL

Jurnal Teknologi ◽

10.11113/jt.v79.8857 ◽

2017 ◽

Vol 79 (2) ◽

Cited By ~ 2

Author(s):

Agus Maryoto ◽

Buntara S. Gan ◽

Han Aylie

Keyword(s):

Compressive Strength ◽

Reinforced Concrete ◽

Chloride Ion ◽

Chloride Ions ◽

Calcium Stearate ◽

Corrosion Attack ◽

Reinforced Concrete Member ◽

Load Carrying ◽

Compressive Strength Test ◽

Infiltration Test

Reinforced concrete structures located in areas near the coast are exposed to potential corrosion attack. Corrosion attack can occur because of the infiltration of chloride ions into concrete. At the initiation of the corrosion process, the load-carrying capacity of a reinforced concrete member will be affected negatively as a function of time. Infiltration of chloride ions into the concrete could be avoided by improving the micro-concrete properties. Enhancement of these properties can be achieved by use of an additive in the concrete. Calcium stearate is a hydrophobic material that can improve the properties of concrete. To determine the optimum contribution in concrete, laboratory experiments were conducted. Calcium stearate was added in varying contents of 0, 0.2, 0.9, and 1.9% of the cement weight. Four types of tests were performed to analyse the contribution of calcium stearate, namely the compressive strength test, absorption test, chloride ion infiltration test, and corrosion test. The results show that an optimum value of the compressive strength of concrete is obtained through the addition of calcium stearate. Besides that, the absorption, chloride ion infiltration, and corrosion value decrease significantly when a higher amount of calcium stearate is added to the concrete.

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The Compressive Strength and Resistivity toward Corrosion Attacks by Chloride Ion of Concrete Containing Type I Cement and Calcium Stearate

International Journal of Corrosion ◽

10.1155/2018/2042510 ◽

2018 ◽

Vol 2018 ◽

pp. 1-9

Author(s):

Agus Maryoto ◽

Buntara Sthenly Gan ◽

Nor Intang Setyo Hermanto ◽

Rachmad Setijadi

Keyword(s):

Compressive Strength ◽

Chloride Ion ◽

Concrete Surface ◽

Chloride Ions ◽

Calcium Stearate ◽

Type I ◽

Compressive Strength Test ◽

Strength Tests ◽

Concrete Quality ◽

Infiltration Test

This study aims to determine the effect of calcium stearate on concrete. Three kinds of concrete quality are studied, namely, 20, 30, and 40 MPa. Tests performed in the laboratory comprise a compressive strength test and an infiltration test of chloride ion content. The specimens used were cylinders with a diameter of 150 mm and height of 300 mm. The chloride ion infiltration test was carried out on a cube with sides of 150 mm. The infiltration of ions into the concrete was examined at depths of 1, 2, 4, 6, and 8 cm. Four dosages of calcium stearate were added to the concrete, namely, 0, 0.25, 1.27, and 2.53% for 20 MPa concrete; 0, 0.21, 1.07, and 2.48% for 30 MPa concrete; and 0, 0.19, 0.90, and 1.87% for 40 MPa concrete. The results of compressive strength tests indicate that the amount of calcium stearate that could be safely applied to the concrete was 0.25% of the weight of cement. On the other hand, the infiltration of chloride ions at a depth of 6 cm from the unprotected concrete surface decreased by 87, 69, and 113% for the 20, 30, and 40 MPa concrete, respectively, compared to concrete without calcium stearate. The test shows that the use of calcium stearate in concrete significantly increases its resistivity against corrosion attacks because, in the absence of chloride ions, the process of corrosion does not take place in the concrete.

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Experimental Study on Improvement Mechanism of Silane Emulsion on Acid Rain Corrosion of Green Ecological Concrete

Science of Advanced Materials ◽

10.1166/sam.2020.3748 ◽

2020 ◽

Vol 12 (6) ◽

pp. 873-883

Author(s):

Wei Xun Hu ◽

Yao Zhuang Li ◽

Hua Peng

Keyword(s):

Compressive Strength ◽

Service Life ◽

Acid Rain ◽

Concrete Structure ◽

Test Group ◽

Chloride Ion ◽

Chloride Ions ◽

Test Time ◽

Ratio Test ◽

Mixing Ratio

Concrete structure is vulnerable to acid rain corrosion, which affects the service life of the material, in the corrosive environment, and concrete structure will deteriorate because of the erosion of water/chloride ions. Therefore, waterproof treatment of concrete structure is needed to improve the durability of the structure. In this study, the green ecological concrete is taken as the research object. The concrete is mixed with a certain amount of silane emulsion to reduce the probability of corrosion of concrete due to moisture and chloride ions, thereby prolonging the service life of this kind of concrete. During the experiment, in order to further test the corrosion resistance of silane emulsion to this kind of concrete, different kinds of concrete were taken as test objects and divided into 3 test groups, namely, the original test group (ITE), the non silane emulsion test group (TWSE) and the optimal ratio test group (OT-SE). It is proved by experiments that the best proportion of concrete mixed with silane emulsion is 0.32 of water binder ratio, 18% of coal powder mixing ratio, 37% of gravel mixing ratio and 0.23% of proportion of silane emulsion. The above factors are applied to compressive strength test, and 30 days as test time, the compressive strength of concrete with fly ash is measured. In the experiment of anticorrosion, compared with the traditional concrete samples, the electrical flux of concrete mixed with silane emulsion decreased by 28.7% in 8 h, that is, chloride ion permeability decreased significantly.

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Anthropogenic Photolabile Chlorine in the Cold-Climate City of Montreal

Atmosphere ◽

10.3390/atmos11080812 ◽

2020 ◽

Vol 11 (8) ◽

pp. 812

Author(s):

Ryan Hall ◽

Oleg Nepotchatykh ◽

Evguenia Nepotchatykh ◽

Parisa A. Ariya

Keyword(s):

Chloride Ion ◽

Particle Morphology ◽

Chloride Ions ◽

Cold Climate ◽

Anthropogenic Sources ◽

Oxidative Potential ◽

Chlorine Atoms ◽

The Impact ◽

The City ◽

Cl Atoms

Chlorine atoms play a key role in the oxidative potential of the atmosphere and biogeochemical cycling of selected elements. This study provides a decadal analysis (2010−2019) of chloride ions in PM2.5 particles in the city of Montreal, where these are most concentrated systematically in the winter (up to 1.6 µg/m3). We also herein present the measurement of photolabile chlorine, which includes chlorine-containing compounds (e.g., Cl2, HOCl, ClNO2, ClNO3, and BrCl) that release chlorine atoms upon interaction with radiation, in urban Montreal, Canada using Cl2-RPGE (Cl2 Reactive Phase Gas Extraction) tubes and quantifying the chlorinated product by GC-MS. Photolabile chlorine in urban Montreal was measured during a discontinuous period primarily in summer 2018 and winter 2019 with a time resolution of 30 min, with concentrations ranging from 3 to 545 ng/m3 expressed as Cl2. The reported values are considered lower limits, as compounds such as HOCl and ClNO2 can only be partially converted in the current setup. The largest peak of gaseous photolabile chlorine occurred in the winter, when significant sources of anthropogenic salt are used in snow removal in the city. This coincides with observed chloride ion measurements in airborne particles, implying that anthropogenic salt addition produces photoactive chlorine. The maximum chlorine signal was consistently obtained during the daytime, which is in accordance with the tropospheric radiation profile. Complementary photochemistry laboratory experiments indicated that upon tropospheric radiation (340 ≤ λ ≤ 400 nm; UVA), an increase (20–100%) was observed, confirming the formation of Cl atoms from photolabile chlorine compounds. Thus, this portable technique is adequate for Cl atoms and photolabile chlorine-containing compounds upon photolysis using UVA lamps. High-resolution S/TEM and energy-dispersive X-ray spectroscopy (EDS) were used to evaluate collected particle morphology and composition. The behavior of complementary pollutants (O3, CO, PM2.5, and NOx) was also briefly discussed. We herein discuss the measurement of photolabile halogens within a northern urban metropolitan environment and the impact of anthropogenic sources on chlorine concentrations.

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Effect of Curing on Mechanical Properties of Cement-Stabilized Coral Sand in Marine Environment

Advances in Materials Science and Engineering ◽

10.1155/2020/4678376 ◽

2020 ◽

Vol 2020 ◽

pp. 1-11

Author(s):

Mingyuan Chen ◽

Jiuguang Geng ◽

Haocheng Xiong ◽

Tao Shang ◽

Cheng Xue ◽

...

Keyword(s):

Compressive Strength ◽

Fresh Water ◽

Marine Environment ◽

Cement Content ◽

Early Stage ◽

Road Construction ◽

Chloride Ion ◽

Ion Concentration ◽

Water Mixing ◽

Coral Sand

The use of coral sand prepared from cement-stabilized materials can significantly reduce the cost, construction period, and damage to the environment caused by stone mining. The choice of water in mixing and curing the cement-stabilized materials on islands should be considered. Cement-stabilized coral sand was tested in three different preparation and maintenance systems in the marine environment. The compressive strength, weight change, and chloride ion concentration change in cement-stabilized coral sand with different cement content were measured after 7 d, 28 d, 60 d, and 90 d, respectively. The microstructure of specimens was observed by XRD and SEM. Results show that the compressive strength of specimens in the seawater mixing and seawater curing system developed 0.9 MPa faster than that in the fresh water mixing and curing system at an early stage. But the compressive strength of specimens in seawater mixing and seawater curing shrank later, being 0.5 MPa lower than that in fresh water mixing and curing. The cement content was positively correlated with the free chloride ion reaction and mass growth rate. For road construction on islands, the mixing and curing of cement-stabilized coral sand with seawater should be given priority in the early stage.

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