| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2005: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2004: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Research Abstract |
The purpose of this research is to develop chloride penetration and carbonation models for the concrete made with mineral admixtures. The details and results of the research are as follows,
1. The reaction between mineral admixtures, such as fly ash and blast furnace slag, and calcium hydroxide was investigated with mineral admixture - calcium hydroxide paste. The amounts of calcium hydroxide and combined water, and the Ca/Si ratios of the C-S-H in paste were measured. Experimental results indicate that the Ca/Si ratio changes with time, and that the Ca/Si ratio of C-S-H formed in each age is dependent on the amount of combined water and the amount of unreacted calcium hydroxide.
Based on the above results, reaction models between mineral admixtures and calcium hydroxide are formulated to predict the Ca/Si ratio.
2. The chloride binding capacity of C-S-H with various Ca/Si ratio was investigated. The amount of chloride ions fixed in C-S-H were measured. In the experiment, hardened cement
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pastes made with mineral admixtures and synthesized C-S-H with various Ca/Si ratio. The experimental results indicate that the chloride binding capacity of C-S-H depends on Ca/Si ratio. From the experimental results, a model for chloride binding in C-S-H was formulated.
3. The effect of mineral admixtures on chloride ions diffusivity was investigated. In this study, the chloride ion diffusion coefficients of mortar specimens containing mineral admixtures were measured, and the influences of the kinds of mineral admixtures, replacement ratios and carbonation on chloride diffusion coefficient were estimated. Furthermore, the prediction method of the diffusion coefficient was proposed by the use of the pore volume and specific surface area of mortar as parameters.
Base on the result mentioned above, a chloride penetration and carbonation models for the concrete made with mineral admixtures was formulated. However, some modifications of the prediction model are required in order to obtain more accurate prediction results. Less
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