| Summary: | 碩士 === 國立臺灣海洋大學 === 材料工程研究所 === 99 === The objective of this study is to investigate the influence of durability on concrete by different replacement percentage of fly ash substitution cement (0、20、40、50、60 and 80％). the samples are detected by test to determinations of percent absorption , and percent voids in hardened concrete. rapid chloride penetration test to assess the ability against chloride ions by recording the values of total electric quantity every 30 minutes when electric current lasts passing the cements for 6 hours. To assess the degree of chloride ions penetrating through concrete is acquired by accelerated chloride migration test getting the time that chloride had penetrated through the specimen from one side to another and the migration velocity of its. It is calculated by the Modified Fick’s second low for the Non-steady state migration coefficient and Nernst-Planck equation for the Steady state migration coefficient of chloride ions in concrete respectively. The results of test shows sample that 40~60% replacement of cement with fly ash have lower absorption and porosity than all others. Using low-loss ignition of concrete makes the inner construction of vesicle smaller than using high-loss ignition of it. The results of RCPT test shows the groups among immersing the concretes for 28 days belong to the middle or high level about the relation of the penetration against chloride ions in the concretes; those for 91 days belong to the middle or low level. Concrete samples containing 40~60% replacement of cement with fly ash have better ability to the penetration against chloride than all others. Observing the relation of current and total electric quantity, we find the amounts of current after test starting to pass electricity for 5 minutes are proportioned to the total electric quantity when test end. In ACMT test, 40~60% replacement of cement with fly ash have lower the Steady and Non-steady state migration coefficient than all others; However, the outcome of 80% replacement of cement with fly ash is inferior to 0% ones. The results of tests show concretes with optimal fly ash can decrease apertures and improve the ability against chloride ions.
Keywords: fly ash, rapid chloride penetration test, accelerated chloride migration test
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