| Summary: | 碩士 === 國立中央大學 === 環境工程研究所 === 90 ===
The sewage sludge ash (SSA) has been proved to exhibit certain pozzolanic activity and can be reused in mortar to replace partial cement. However, the previous research works focused on the workability and compressive strength of SSA mortar and many other properties, including flexural strength, impact strength, and drying shrinkage of SSA mortar, has seldom been discussed. For this reason, this study selected the sewage sludge of Ming-Shen Community WWTP and prepared SSA from a modular incinerator. The prepared SSA sample was further applied into mortar to obtain SSA mortar. Consequently, the properties of SSA mortar, including compressive strength, flexural strength, impact strength, and drying shrinkage were analyzed. In addition, in order to enhance the properties of SSA mortars, four types of fiber material have been applied into SSA mortar. These fibers include two types of steel fiber, i.e. micro and enlarged-end, and other two types of polypropylene fiber.
According to the test results, the compressive and flexural strength of SSA mortars, generally decreased with increasing application amount of SSA. In contrast, the amount of drying shrinkage of SSA mortar generally increased with increasing application amount of SSA. When comparing with pure cement mortar, the SSA mortars exhibited lower strength and higher amount of drying shrinkage. This result revealed the necessity of the modification of SSA mortars.
Regarding the application of fiber material, the cement replacement ratio of the tested SSA mortars was 20%. The test results indicated that, the micro steel fiber exhibited superior effects on the simultaneous enhancement of the compressive strength, flexural strength, and impact strength of SSA mortar. The enlarged-end steel fiber could also improve the strength of SSA mortar, however it was less effective than micro steel fiber. In addition, the two types of polypropylene fiber could only improve impact strength of SSA mortar. Thus the effectiveness of polypropylene fibers on improving properties of SSA mortar was less than that of steel fibers.
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