The Study of Chloride Ions Diffusion in Concrete at Various Age

• Main Authors: Chi,Mao-chieh, 紀茂傑
• Other Authors: Huang,Ran
• Format: Others
• Language: zh-TW
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/14085969487581293018

碩士 === 國立海洋大學 === 河海工程學系 === 81 === In marine enviroments the existence of chloride ion will accelerate the corrosion of rebars in concrete. The contents and diffusivity of chloride ions are two key factors for controlling corrosion of rebars. Therefore, it is beneficial to develop a mathematical modelfor predicting the diffusion behaviour of chloride . In this study, diffusion behaviour of chloride ions in mortar and concrete specimen at various ages was investigated. The research includes two parts: one is experimental work and another is theoretical approach.Results from mathematical model and experimental data are presented and compared. Experimental data results show that diffusion coefficients decrease as exposedtime increases. The diffusion coefficients are higher for specimen with higher water-cement ratio. It is found that at the early age the water-cement ratio affects the diffusivity significantly. The mortar specimen with partial replacement of silica fume has higher diffusion coefficients than the control specimen. However, after 32-day exposure the control specimen has higher diffusion coefficient. For concrete specimens, the diffusion coefficients decrease as the percentage of replacement of silica fume increases. Based on the test data, a best-fitted curve was found. It is possible to use the statistical curve to predict the chloride concentration at the different penetration depth at various age.