都市垃圾焚化飛灰熔融處理取代部份水泥之研究

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題名:	都市垃圾焚化飛灰熔融處理取代部份水泥之研究
作者:	黃尊謙;Zuh-Qian Huang
貢獻者:	環境工程研究所
關鍵詞:	焚化飛灰;熔融;熔渣水泥漿體;水化活性;卜作嵐活性;MSWI fly ash;melting;slag blended cement;hydraulic activity;pozzolanic activity
日期:	2000-07-12
上傳時間:	2009-09-21 12:13:11 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	本研究針對都市垃圾焚化飛灰進行熔融實驗，並以其熔渣粉體調製不同配比之熔渣水泥，以探討熔渣水泥漿體之卜作嵐反應特性及熔渣粉體取代部份水泥之可行性。本研究之實驗分成三部份，首先探討都市焚化飛灰在1250及1400℃ 下經30分鐘熔融後之熔渣特性；進而以1400℃熔渣粉體備製不同配比之熔渣水泥漿體，分析其於不同養護齡期之卜作嵐反應特性，包括抗壓強度、水化程度、微細結構及晶相、物種變化等；最後並對焚化飛灰主要成分利用Al2O3及CaO調質後進行熔融，以探討熔渣成分對熔渣水泥漿體水化反應之影響。實驗結果顯示，焚化飛灰於1250及1400℃進行 30min 之熔融處理時，重金屬移行熔融飛灰及排氣中之比率以Cd最高（90%），Zn次之（40%），其餘皆小於20%。水淬熔渣中Pb、Cd、Cr、Cu、Zn等之TCLP溶出濃度皆遠低於法規標準。熔渣水泥漿體（同取代比率）之抗壓強度則1400℃者略高，但差異極小，顯示前述熔融實驗溫度之影響不顯著。熔渣水泥漿體之抗壓強度，於養護早期隨著熔渣取代量與水膠比增加而減小，晚期強度則呈明顯上升之趨勢；且低取代量（10%、20%）者超越或接近純水泥，顯示出展現卜作嵐材料提高晚期強度之特性。孔隙結構方面，膠體孔隨著齡期、取代量的增加而增加，熔渣水泥漿體有縮小孔隙之趨勢，另外NMR、XRD分析配合SEM觀察發現，早期漿體即有卜作嵐反應發生，晚期則有消耗Ca(OH)2產生C-S-H膠體的現象，且取代量越大越顯著，顯示熔渣具卜作嵐反應特性，其內部非晶相之活性離子（Si、Al）能消耗水化所形成之Ca(OH)2，而產生C-S-H膠體填充孔隙，將毛細孔轉換成膠孔，進而提高晚期強度。熔渣化學成份影響方面，Ca、Al皆有加速水化提高早期強度之作用，但可能由於Ca(OH)2之析晶與鋁酸鹽類快速反應及相互轉換之結果，造成晚期強度發展遲緩之現象。 This study investigated the pozzolanic activity and the feasibility of using MSW fly ash slag in blended cement with different replacement ratio. The experiments were divided into three parts:(1) the slag was characterized by melting the MSW incinerator fly ash at 1250 and 1400℃ for 30 min; (2) the blended cement paste using 1400℃-generated slag at replacement ratio (SBC) ranging from 10 - 40% was analyzed for its pozzolanic activity at different ages, including compressive strength, hydration degree, microstructure, and variation of crystalline speciation; and (3) the major components were modified using Al2O3 and CaO before melting to study the compositional effects on hydration of SBC paste. The results indicates that during fly ash melting at 1250 and1400℃, more than 90% Cd, 40% Zn, and less than 20% other target metals (Pb, Cu,Cu) moved to the melting fly ash and exhaust gas. The TCLP leaching concentrations for the target metals (Cd, Pb, Zn, Cr, Cu) were all well below the regulatory thresholds. The unconfined compressive strength (UCS) of the SBC paste using 1400℃-slag was slightly greater than that using 1250℃-slag, showing that temperature effects in the tested range were insignificant. The early UCS of SBCP decreased with increasing replacement ratio and water/cement ratio, whereas the later UCS increased, showing the pozzolanic nature of the pulverized fly ash slag. The later UCS of SBPC with less than 20% replacement outperformed that of OPC, indicating the pozzolanic nature of pulverized slag to increase the later strength. However, the later strength decreased with increasing replacement ratio from 20% up to 40%. Moreover, the pore volume (<100 Angstrom) of the calcium silicate hydrates (C-S-H) gel formed during the hydration also indicated an increase with curing ages, suggesting that the active non-crystalline ions of slag such as Si and Al could react with Ca(OH)2 to form C-S-H gel, resulting in the filling in the pore space, thus increasing the later strength. With respect to the effects of slag composition, the addition of CaO and Al2O3 promoted faster hydration and contributed to the early strength development of SBCP. However, the later strength decreased possible due to the efflorescence of Ca(OH)2 and micro-crack produced by the rapid transfer of aluminum compound.
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