Outline
- Abstract
- Keywords
- 1. Introduction
- 2. Research Significance
- 3. Experimental Procedure
- 3.1. Materials
- 3.2. Mixture Design and Scc Proportions Using Ccd Method
- 4. Numerical Procedure
- 4.1. Service Life Prediction Using Fick’s Law of Diffusion
- 4.2. Statistical Analysis and Numerical Optimization Procedure
- 5. Results and Discussions
- 5.1. Rapid Chloride Permeability Test (rcpt)
- 5.1.1. Effect of Mixture Proportions on the Rcpt
- 5.1.2. Effect of Curing on the Rcpt
- 5.2. Chloride Diffusion Coefficient (da)
- 5.3. Corrosion Initiation Times
- 5.3.1. Effect of Curing on Corrosion Initiation Times
- 5.3.2. Effect of Scc Mixture Proportions on Corrosion Initiation Times
- 5.4. Optimization of Scc Mixture and Models Validation
- 5.5. Comparison of the Optimum Scc Mixture Containing Mk, Other Scm’s Mixtures, and Nc Mixtures
- 5.6. Relationship Between Rcpt and Chloride Diffusion Coefficients
- 6. Conclusions
- References
رئوس مطالب
- چکیده
- کلید واژه ها
- 1. مقدمه
- 2. اهمیت تحقیق
- 3. روش تجربی
- 3.1. مواد و روش ها
- 3.2. طراحی مخلوط و نسبت SCC با استفاده از روش CCD
- 4. روش عددی
- 4.1. پیش بینی عمر با استفاده از قانون انتشار فیک
- 4.2. تجزیه و تحلیل آماری و روش بهینه سازی عددی
- 5. نتایج و بحث ها
- 5.1. تست نفوذپذیری کلراید سریع (RCPT)
- 5.1.1. اثر نسبت مخلوط به RCPT
- 5.1.2. اثر RCPT
- 5.2. ضریب نفوذ کلراید (Da)
- 5.3. زمان شروع خوردگی
- 5.3.1. اثر به عمل آوردن در زمان شروع خوردگی
- 5.3.2. اثر نسبت مخلوط SCC به زمان شروع خوردگی
- 5.4. بهینه سازی ترکیب SCC و اعتبارسنجی مدل ها
- 5.5 . مقایسه مخلوط بهینه SCC حاوی MK، مخلوط های دیگر SCM و مخلوط NC
- 5.6. رابطه RCPT و ضریب انتشار کلراید
- 6. نتیجه‌گیری
Abstract
This paper utilizes the statistical design of experiments approach to optimize the mixture design of self-consolidating concrete (SCC) incorporating metakaolin (MK). The factors studied were total binder content, percentage of MK, water-to-binder ratio, and curing conditions. The results obtained from the developed statistical models were exploited to determine the most significant factors affecting the chloride permeability and the expected service life (calculated using Fick’s second law of diffusion) of the tested mixtures. The developed models were also used to optimize the level of each response variable to minimize the chloride permeability, and to maximize the expected service life of the developed high performance SCC mixture. The results yielded an optimum SCC mixture with MK which achieved the lowest chloride permeability compared to counterpart SCC mixtures containing fly ash, slag, and silica fume. The results also showed that MK replacement proved to be the most significant variable affecting the chloride permeability, decline of permeability over time, and the service life of the tested mixtures.
Conclusions
The analysis and discussion of the results from the experimental tests and statistical analysis were completed and the following conclusions were drawn:
- The MK replacement (factor C) had the most significant effect on the chloride permeability (RCPT and Da), followed by water-to-binder ratio (factor B), and then the total binder content (factor A), respectively. The effect of MK on the chloride permeability (as the averages of the results of RCPT and chloride diffusion) was found to be 2.25 and 4.25 times greater than that of water-to-binder ratio and total binder content, respectively.
- All tested mixtures witnessed an almost linear trend of decline of permeability versus time; however, different percentages of reduction were warranted based on the mixture proportions. The MK replacement was found to be the most significant factor affecting this reduction, followed by the total binder content and water-to-binder ratio, respectively.
- An optimum SCC with lowest chloride permeability, and longest corrosion initiation time showed to contain a total binder of 490 kg/m3, water-to-binder ratio of 0.39, and replacement of MK by 19.9%.
- Comparing the optimum SCC mixture containing MK to those containing FA, SF, SG, and NC mixtures showed that the 20% MK mixture exhibited the lowest chloride permeability, followed by 8% SF, 30% FA, 30% SG, NC1, and NC2, respectively.
- The results of all the tested mixtures showed a linear relation between the RCPT values and the chloride diffusion coefficients, regardless of the mixture proportions or curing conditions. From this result, a linear relationship was developed and can be used to estimate the chloride diffusion coefficients in a relatively shorter amount of time by using the results obtained from the RCPT test.
- Testing validation mixtures and comparing the results from the prediction models manifested the usefulness of these models for estimating the long-term properties of SCC mixtures containing MK.