Evaluation of Chloride Ion Penetration In Concrete
Abstract
This study aimed at carrying out a comprehensive investigation of the chloride ion penetration in concrete. In addition, the durability of concrete containing mineral admixture was investigated. The susceptibility of producing high performance concrete and self compacting concrete incorporating superplasticizer and mineral admixture was studied.
As can be seen from the work presented before, the transport of chloride ions into concrete is a complicated, multi-mechanistic phenomenon. It is important to understand the basic concepts underlying chloride ingress into concrete to enable the proper consideration of this eventuality when designing with reinforced concrete. A multitude of tests has been proposed and used to test the resistance of concrete to chloride ingress; each test procedure has advantages and disadvantages. What is immediately obvious, however, is that no one test is a panacea, and different situations may require different tests.
It has been widely observed that the addition of supplementary cementitious materials, especially silica fume, results in a significant decrease in permeability-a greater reduction in fact than can be attained from the effect on the w/c ratio alone. This is, in large part, due to the reduction both in total porosity and in the size of the pores. Higher compatibility was noticed between silica fume, lime powder, and the hydrated cement. This was confirmed from the tests results.
The corrosive effect of chloride ions, showed a drastic effect on the steel bars in concrete. This was confirmed though the investigated properties, statistical analysis, and the visual inspection. However, among the entire mineral admixture used, only silica fume mitigated the corrosive effect of chloride ion on steel bars. Besides, the increase in cement resulted in a better performance for concrete exposed to chloride attack.
The behavior of self compacting concrete in chloride environment was very similar to that of high performance concrete. Both types of concrete made with ordinary Portland cement were seriously attacked by the chloride ions. Besides, the cement content also showed a pronounced effect on the durability of both types of concrete; the higher the cement content the better the performance of concrete under chloride attack.
Compared to self compacting concrete, high performance concrete exhibited higher mechanical properties. For instance, at 28 days the compressive strength for high performance concrete was higher than that of self compacting concrete by an average value of one percent.
Depending on the cement content, the compressive strength of the high performance concrete immersed in sodium chloride solution for 90 days ranges from 4 to 18 % gains of the initial strength. Meanwhile, the compressive strength of the SCC ranges between 5 to
11 % gains of the initial strength.
The SCC showed lower compressive strength than the HPC by an average of 1 % at 28 days and 14 % after 90-days immersion.
The durability performance of self compacting concrete is likely to be equal or better than that of traditional vibrated concrete.
As can be seen from the work presented before, the transport of chloride ions into concrete is a complicated, multi-mechanistic phenomenon. It is important to understand the basic concepts underlying chloride ingress into concrete to enable the proper consideration of this eventuality when designing with reinforced concrete. A multitude of tests has been proposed and used to test the resistance of concrete to chloride ingress; each test procedure has advantages and disadvantages. What is immediately obvious, however, is that no one test is a panacea, and different situations may require different tests.
It has been widely observed that the addition of supplementary cementitious materials, especially silica fume, results in a significant decrease in permeability-a greater reduction in fact than can be attained from the effect on the w/c ratio alone. This is, in large part, due to the reduction both in total porosity and in the size of the pores. Higher compatibility was noticed between silica fume, lime powder, and the hydrated cement. This was confirmed from the tests results.
The corrosive effect of chloride ions, showed a drastic effect on the steel bars in concrete. This was confirmed though the investigated properties, statistical analysis, and the visual inspection. However, among the entire mineral admixture used, only silica fume mitigated the corrosive effect of chloride ion on steel bars. Besides, the increase in cement resulted in a better performance for concrete exposed to chloride attack.
The behavior of self compacting concrete in chloride environment was very similar to that of high performance concrete. Both types of concrete made with ordinary Portland cement were seriously attacked by the chloride ions. Besides, the cement content also showed a pronounced effect on the durability of both types of concrete; the higher the cement content the better the performance of concrete under chloride attack.
Compared to self compacting concrete, high performance concrete exhibited higher mechanical properties. For instance, at 28 days the compressive strength for high performance concrete was higher than that of self compacting concrete by an average value of one percent.
Depending on the cement content, the compressive strength of the high performance concrete immersed in sodium chloride solution for 90 days ranges from 4 to 18 % gains of the initial strength. Meanwhile, the compressive strength of the SCC ranges between 5 to
11 % gains of the initial strength.
The SCC showed lower compressive strength than the HPC by an average of 1 % at 28 days and 14 % after 90-days immersion.
The durability performance of self compacting concrete is likely to be equal or better than that of traditional vibrated concrete.
Other data
| Title | Evaluation of Chloride Ion Penetration In Concrete | Other Titles | تقييم اختراق ايونات الكلوريد في الخرسانة | Issue Date | 2011 |
Attached Files
| File | Size | Format | |
|---|---|---|---|
| Sherif Mahmoud Ismail Shalaby.pdf | 1.38 MB | Adobe PDF | View/Open |
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