- 學位論文
以都市垃圾焚化飛灰改質為無機膠體作為水泥摻料之漿體特性研究
A study on the MSWI fly ash modifying for inorganic gel of cement admixtures
摘要
都市垃圾焚化飛灰含有高濃度重金屬和戴奧辛，為性質複雜之有害廢棄物，飛灰無害化與資源化將是未來的趨勢。由文獻中發現研磨飛灰具有卜作嵐特性，有取代水泥之潛力，另外有研究利用卜作嵐材料添加鹼液與矽酸鈉活化後所產生無機膠體，其特性具有強度高、可固化重金屬等特性。因此本研究嘗試將都市垃圾焚化飛灰改質成無機膠體探討取代部分水泥之可行性。 本研究將水萃後之飛灰與偏高嶺土依照特定比例混和後，藉由不同的NaOH活化液濃度、時間活化，製成的活化粉以取代水泥5%、10%進行灌漿養護7天、28天。透過FTIR、XRD儀器分析找出具有無機膠體活性較高之配比，針對活化粉進行毒性特性溶出程序試驗，探討重金屬溶出狀況，並以抗壓強度測試其成果。 研究結果顯示所有粉料配比條件經研磨活化後，活化粉TCLP試驗皆低於有害事業廢棄物認定標準。當不同條件之研磨活化粉取代水泥10%進行抗壓強度試驗，因為工作度不好導致相對強度皆低於100%。以偏高嶺土與水萃灰各50%(5C5W)使用1M NaOH研磨活化24 hr之活化粉反應形成較多元之無機聚合結晶物種，其活化粉取代水泥5%灌漿在7天與28天齡期之相對抗壓強度都上升至100%左右，同時無機膠體在水泥中之結晶成長狀況優異。對於活化粉的製備方法，研磨活化比起攪拌活化更有助於無機膠體之形成，同時有助於在水泥中之無機膠體成長。
並列摘要
Municipal solid waste incinerator (MSWI) fly ashes (reaction ash and boiler ash) contain high concentration of heavy metals and dioxin which are hazardous wastes that contain complex compositions. Stabilizing and recycling of the fly ash will be a future tendency in many countries. Former study shown that, milling MSWI fly ash has the characteristic of pozzolanic property, which could be used as the additive of cement. In addition, the reaction of a pozzolanic material with an aqueous alkali or sodium silicate solution produces inorganic gel, which can enhance high strength and stabilizing heavy metals. Therefore, this study attempts to transform the MSWI fly ash into inorganic gel and discuss the feasibility as cement admixtures. In this study, water-extracted fly ash mixed with metakaolin in difference weight ratios, then milled and activated by different concentrations of NaOH solution for different periods. Took 5% and 10% for the cement replacement, grouted and cured 7 and 28 days. The FTIR and XRD analysis were used to observe the effects of inorganic gel activation. The compression strength test was used to evaluate the feasibility for the cement replacement. The results showed that, all of the conditions of activated powder were passed the TCLP standards, but all samples with 10% substitute for the cement were failed in the compression strength test due to the worse workability. Many crystal species of inorganic gel were found in the activated powder sample, 50% metakaolin and 50% water-extracted fly ash (5C5W), with 1M NaOH milling activation for 24 hr; replacing 5% cement grouted and cured for 7 and 28 days, achieved about 100% of the relative compressive strength compared with pure cement. Milling alkali activation showed much better inorganic gel formation than only stirring alkali activation.