scholarly journals Influence of the Type of Cement and the Addition of an Air-Entraining Agent on the Effectiveness of Concrete Cover in the Protection of Reinforcement against Corrosion

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4657
Author(s):  
Wioletta Raczkiewicz ◽  
Peter Koteš ◽  
Petr Konečný
Keyword(s):  
Blast Furnace Slag ◽  
Concrete Cover ◽  
Chloride Ions ◽  
Corrosion Process ◽  
Simultaneous Action ◽  
Freezing And Thawing ◽  
Pulse Technique ◽  
Concrete Admixtures ◽  
Concrete Mix ◽  
Furnace Slag

The concrete cover is the basic protection of the reinforcement against the influence of external factors that may lead to its corrosion. Its effectiveness depends mainly on the composition of the concrete mix, including the cement used. Depending on external environmental factors that may aggressively affect the structure, various types of cements and concrete admixtures are recommended. The paper presents the results of tests that allow us to assess the effect of the type of cement used and the air-entraining agent on the effectiveness of the concrete cover as a layer protecting the reinforcement against corrosion. In order to initiate the corrosion process, the reinforced concrete specimens were subjected to cycles of freezing and thawing in a sodium chloride solution. The degree of advancement of the corrosion process was investigated using the electrochemical galvanostatic pulse technique. Additionally, the microstructure of specimens taken from the cover was observed under a scanning electron microscope. The research has shown that in the situation of simultaneous action of chloride ions and freezing cycles, in order to effectively protect the reinforcement against corrosion, the application of both blast-furnace slag cement and an air-entraining agent performed the best.

scholarly journals Influence of the Air-Entraining Agent in the Concrete Coating on the Reinforcement Corrosion Process in Case of Simultaneous Action of Chlorides and Frost

2018 ◽  
Vol 18 (1) ◽  
pp. 13-19 ◽  
Author(s):  
W. Raczkiewicz
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Simultaneous Action ◽  
Reinforcement Corrosion ◽  
Nacl Solution ◽  
Freezing And Thawing ◽  
Slag Cement ◽  
Chloride Corrosion ◽  
Concrete Coating ◽  
Furnace Slag

AbstractThe paper presents the test results to evaluate the effect of air-entraining agent addition on the intensity of reinforcement corrosion in concrete with blast-furnace slag cement in the case of simultaneous action of chloride corrosion and frost. Two groups of reinforced concrete specimens were prepared for the study. The first group of specimens included air-entraining agent addition and the other group was prepared without air-entraining agent. The blast-furnace slag cement (CEM III/A) was used for the specimens. Two parallel reinforcing rods were placed in each specimen. The specimens were subjected to 120 cycles of freezing and thawing in 3% NaCl solution to induce corrosion on the reinforcement. To determine the occurrence of the reinforcement corrosion and estimate the corrosion activity the non-destructive electrochemical galvanostatic pulse method was used. On each specimen the corrosion current density of the reinforcement was measured as well as the reinforcement stationary potential and the concrete coating resistivity, i.e. values indicating the ongoing reinforcement corrosion. Measurements were made on all specimens in two steps: before freezing and thawing cycles in 3% NaCl solution and after the cycles. The analysis of the obtained results allowed to determine differences in corrosion processes intensity on the reinforced bars in the concrete specimens depending on whether or not the air-entraining agent was added. Based on the analysis it was found that in the case of simultaneous action of chloride corrosion and frost it is advisable to use both blast-furnace slag cement and air-entraining agent. The use of only blast-furnace slag cement (although it is a chloride resistant cement), without the addition of air-entraining agent is insufficient.

Chloride Ions Penetration Resistance of Steam-Cured Concrete for Railway Precast Elements

2011 ◽  
Vol 219-220 ◽  
pp. 1419-1422
Author(s):  
Zhi Min He ◽  
Jun Zhe Liu ◽  
Tian Hong Wang
Keyword(s):  
Blast Furnace Slag ◽  
High Performance ◽  
Penetration Resistance ◽  
Chloride Ions ◽  
Mineral Admixtures ◽  
Concrete Mix ◽  
Binder Type ◽  
Precast Elements ◽  
Astm C1202 ◽  
Furnace Slag

By use of ASTM C1202, this paper studied the influence of mineral admixtures on the chloride ions penetration resistance of the steam-cured concrete. The experimental results indicated that mineral admixtures improved the permeability properties of high-performance concretes, but at different rates depending on the binder type. FA required a relatively longer time to get its beneficial effect. For each 10%~40% replacement of OPC by FA in a concrete mix, the values of coulomb charge of steam-cured and standard curing concrete reduces by 8%~17% at180 days. When 30% weight of the OPC were replaced by FA and ground blast furnace slag(GBFS), the inclusion of 30% mineral admixtures provided a significant improvement to the chloride ions penetration resistance properties of steam-cured and standard curing concrete at 28 days and 180 days, especially for the combination of 10% FA and 20% GBFS (double adding).

scholarly journals Impact of the air-entrained concrete with the blast-furnace slag cement on the intensity of reinforcement corrosion process

2018 ◽  
Vol 163 ◽  
pp. 05010 ◽  
Author(s):  
Wioletta Raczkiewicz ◽  
Wioletta Grzmil ◽  
Justyna Zapała – Sławeta
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Concrete Cover ◽  
Reinforcement Corrosion ◽  
Freezing And Thawing ◽  
Slag Cement ◽  
X Ray ◽  
Chloride Corrosion ◽  
Corrosion Risk ◽  
Furnace Slag

The concrete cover has significant impact on the intensity of reinforcement corrosion process in reinforced concrete elements. Depending on the type of corrosion risk different types of cement are recommended for concrete. In conditions of chloride corrosion, due to, for example, the use of de-icing agents in winter, it is recommended to use concrete with cement containing granulated blast-furnace slag. The risk of chloride corrosion due to the use of de-icing agents is often additionally associated with the frost and repeated freezing and thawing actions of structural elements. The liquid freezing in the pores of concrete increases its volume, which causes the increase of internal stresses and leads to cracks in the concrete cover increasing the diffusion of chlorides. In order to reduce this phenomenon the introduction of air-entraining admixture is beneficial. The paper presents the experimental results that allow to determinate the effect of the air-entraining admixture addition on the intensity of reinforcement corrosion in concrete with blast-furnace slag cement. The tests were carried out on two groups of reinforced concrete specimens subjected to freezing and thawing cycles in 3% NaCl solution. One group of specimens was prepared with the airentraining admixture addition and the other without it. The electrochemical tests of the reinforcement corrosion activity, based on the measurements of the corrosion current density were curried. The phase composition by X-ray diffraction and microstructure of concrete under the scanning electron microscope (SEM) coupled with the X-ray microanalyser (EDS) were examined. The results allowed to comprehensively assess the effect of airentrained concrete with blast-furnace slag cement on the degree of reinforcement corrosion risk in concrete caused by the simultaneous action of chlorides and frost.

scholarly journals Properties of Concrete Using Treated Low-Class Recycled Coarse Aggregate and Blast Furnace Slag Sand

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 843
Author(s):  
Yuji Miyazaki ◽  
Takeshi Watanabe ◽  
Yuji Yamada ◽  
Chikanori Hashimoto
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Coarse Aggregate ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Hardened Concrete ◽  
Freezing And Thawing ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Furnace Slag

Since high quality natural aggregates are becoming scarce, it is important that industrial recycled products and by-products are used as aggregates for concrete. In Japan, the use of recycled aggregate (RG) is encouraged. Since, strength and durability of recycled aggregate concrete is lower than that of normal aggregate concrete, the use of recycled aggregate has not been significant. In order to improve physical properties of concrete using recycled coarse aggregate, blast furnace slag sand has been proposed. Recently, blast furnace slag sand is expected to improve durability, freezing, and thawing damage of concrete in Japan. Properties of fresh and hardened concrete bleeding, compressive strength, and resistance to freezing and thawing which are caused by the rapid freezing and thawing test using liquid nitrogen is a high loader than the JIS A 1148 A method that were investigated. As a result, concrete using treated low-class recycled coarse aggregate and 50% or 30% replacement of crushed sand with blast furnace slag sand showed the best results, in terms of bleeding, resistance to freezing and thawing.

Chloride Ions Penetration Resistance of New-Old Concrete

2011 ◽  
Vol 366 ◽  
pp. 518-521
Author(s):  
Zhi Min He ◽  
Jun Zhe Liu
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Beneficial Effect ◽  
Blast Furnace Slag ◽  
Penetration Resistance ◽  
Chloride Ions ◽  
Mineral Admixtures ◽  
Compound System ◽  
Astm C1202 ◽  
Furnace Slag

By use of ASTM C1202, this paper studied the influence of mineral admixtures on the chloride ions penetration resistance of the new-old concrete compound system. The results indicate that the performance of new-old concrete exert significant influence on the new-old concrete compound system. The addition of mineral admixtures improve the permeability properties of new-old concrete. Adding fly ash(FA) require a relatively longer time to get its beneficial effect. When 30% weight of cement is replaced by 10% FA and 20% ground blast furnace slag(GGBFS), the inclusion of 30% mineral admixtures significantly improve the chloride ions penetration resistance properties of the new-old concrete compound system at 28 days and 180 days.

Effect of Mineral Admixtures and Water/Binder Ratios on the Resistance to the Chloride Ions Penetration into Concrete

2011 ◽  
Vol 99-100 ◽  
pp. 758-761
Author(s):  
Yan Jun Hu ◽  
Yan Liang Du
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Silica Fume ◽  
Blast Furnace Slag ◽  
Chloride Ion ◽  
Test Methods ◽  
Chloride Ions ◽  
Mineral Admixtures ◽  
Chloride Permeability ◽  
Furnace Slag

In this study, concrete prisms were made with three mineral admixtures: fly ash, blast furnace slag or silica fume and with three water-to-binder ratios(w/b). Chloride penetration was measured by the rapid chloride permeability test (RCPT)-ASTM C1202, 150-days ponding test and alternate wetting and drying test by cyclic loading with salt solution and oven drying, and the results by the three test methods were compared. This paper discussed the effects of mineral admixtures and w/b on the concrete chloride permeability. Blending concrete with blast furnace slag, fly ash or silica fume was beneficial with regard to the resistance against chloride ion penetration. Concrete specimens with lower w/b showed lower chloride permeability.

Basic Study on the Durability of Mortar Containing Blast Furnace Slag Fine Powder with Different Basicity

2021 ◽  
Vol 896 ◽  
pp. 119-127
Author(s):  
Prang Subpa-Asa ◽  
Yasutaka Ta ◽  
Hisahiro Matsunaga ◽  
Shigeyuki Date
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Fine Powder ◽  
Chloride Ion ◽  
Test Methods ◽  
Chloride Ions ◽  
Reinforcing Bars ◽  
Basic Study ◽  
Total Chloride ◽  
Furnace Slag

Chloride ions penetrated reinforced concrete structures. Corrosion of reinforcing bars occurs because of cracks due to corrosion expansion, which is a problem of chloride damage deteriorating structures' performance. Blast furnace slag (from now on referred to as "BFS") is the inevitable by-product of steel product manufacturing as sustainable materials. BFS is more effective in preventing corrosion of reinforcing bars in concrete due to the denser cured and its high ability to immobilize chloride ions. Thus, the influence of BFS on the durability of mortar using BFS powder with different basicity was studied by using "Standard on Test Methods for Chloride Ion Diffusion Coefficients in Concrete" by electrophoresis (Draft) (JSCE-G571-2003)" and the total chloride ion amount was measured following JIS R 5202. The result confirmed that the immobilization performance could be greatly improved by increasing the basicity. It was remarkable in the case of air curing, a curing method for available precast products.

Improvement of Durability of Precast Concrete Member by Granulated Blast Furnace Slag Sand

2017 ◽  
Vol 12 (3) ◽  
pp. 456-469 ◽  
Author(s):  
Toshiki Ayano ◽  
◽  
Takashi Fujii ◽  
Kyoji Niitani ◽  
Katsunori Takahashi ◽  
...  
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Precast Concrete ◽  
Heavy Traffic ◽  
Concrete Slabs ◽  
Fine Aggregate ◽  
Freezing And Thawing ◽  
Steam Curing ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

Concrete deck slabs of bridges are often deteriorated by heavy traffic and freezing and thawing actions. Spraying salt during the winter further promotes the deterioration of concrete. Some reports estimate that the length of highway roads requiring the renewal of deteriorated concrete slabs exceeds 230 km. In order to extend the lifespan of damaged bridge girders, the load for these girders must not be increased. This means that prestressed concrete (hereafter, PC) members are desirable to sustain bridge life, because they can be thinner than reinforced concrete (hereafter, RC) members. In addition, to shorten the period of traffic regulation during renewal construction, precast members should be applied. One problem in manufacturing durable precast concrete is steam curing. When the temperature, period, or both of the steam curing process are inadequate, the effect of air-entraining (hereafter, AE) agents is lost because the warmed air trapped by the AE agent expands and escapes from the concrete. Another problem is concrete fatigue. It is well known that the fatigue lives of concrete slabs in wet conditions are much shorter than those in dry conditions. Concrete slabs are waterproofed immediately after construction, but the waterproofing can be fractured soon after opening bridges, and water can reach the concrete surface. The lifespan of concrete slabs in contact with water often depends on the fatigue of the concrete. Granulated blast furnace slag sand (hereafter, BFS) can enhance the resistance to freezing and thawing actions without using AE agents. Therefore, the resistance to freezing and thawing of concrete mixed with BFS is not damaged by steam curing. The fatigue of concrete in water is also improved by the addition of BFS. Furthermore, BFS can reduce the drying shrinkage of concrete. It is advantageous to restrict the loss of prestress in PC. This study shows that precast PC members with high durability can be manufactured when granulated blast furnace slag is used as a fine aggregate in the concrete. BFS reacts with cement hydrates. It is well known that the carbonation of concrete with ground granulated blast furnace slag (hereafter, GGBF) is much greater than that with ordinary binder. However, BFS does not accelerate the carbonation of concrete. When using granulated blast furnace slag as a fine aggregate, no disadvantage in the concrete properties is detected.

scholarly journals The content of chlorides in blast-furnace slag cement as a factor affecting the diffusion of chloride ions in concrete

2018 ◽  
Vol 163 ◽  
pp. 05007
Author(s):  
Justyna Kuziak ◽  
Piotr Woyciechowski ◽  
Rafał Kobyłka ◽  
Aldona Wcisło
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Alternative Fuels ◽  
Diffusion Rate ◽  
Chloride Ions ◽  
Slag Cement ◽  
Wide Range ◽  
Research Problems ◽  
New Research ◽  
Furnace Slag

Blast-furnace slag cement (CEM III) has a wide range of acceptable Cl- content according to EN 197-1: 2012. This makes possible to use alternative fuels for the production of cement, which can increase the chlorides content in the clinker. However, it raises several new research problems, among them the problem of increase of the risk of Cl- penetration intensity due to the higher concentration of chlorides in cement, presented in this paper. Studies have shown that after a short hardening time (28 days) the rate of diffusion of chloride ions increases slightly with the increase in the content of chlorides in the cement CEM III, but after full stabilization of concrete properties (1 year), the content of chlorides in cement CEM III practically does not affect the diffusion rate of chloride ions in concrete.

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