| 摘要: | 本研究主要係將都市垃圾焚化飛灰、洗滌灰及底灰，並區分三種不同系別(底灰系、洗滌灰系及混合灰系)以不同配比混合進行調質熔融實驗，並將熔渣粉體製作不同取代量之熔渣水泥漿體。本研究除建立都市垃圾焚化灰渣調質熔渣之基本特性外，亦探討不同養護齡期下調質熔渣之卜作嵐反應行為與熔渣水泥漿體之工程材料特性，包括抗壓強度、水化程度、膠體空間比、晶相、物種及微結構變化等。 實驗結果顯示，所得之調質熔渣CaO約27?34%，SiO2約29?39%及Al2O3則約8?23%，而非鈣質化物為 47?67%，大致可符合C級飛灰規範之要求，且接近高爐爐石熟料，具有延長水泥澆鑄工作時間之特性。對90天齡期抗壓強度發展而言，取代量10、20%之洗滌灰系熔渣水泥漿體可超越OPC 1?7 MPa；而底灰系熔渣水泥漿體則可與OPC之抗壓強度發展相當(差值<0.5MPa)。由MIP與膠體空間比分析結果得知，調質熔渣水泥漿體水化產物隨齡期增加而逐漸生成填充孔隙，使總孔隙體積與毛孔體積均逐漸減少，而膠孔則隨齡期增加，顯示熔渣有助於熔渣水泥漿體之緻密化。由XRD及DTA之物種分析得知，熔渣水泥漿體與OPC之水化產物主要為CH、C-S-H及C-A-H，並無明顯差異。TG分析所得結果顯示，熔渣可與CH進行卜作嵐反應，而形成C-S-H膠體或C-A-H鹽類。由NMR分析發現，熔渣水泥漿體之水化程度增加趨勢較純水泥漿體顯著；而聚矽陰離子長度則隨齡期而增加，至齡期90天其值皆大於純水泥漿體，顯示熔渣晚期因卜作嵐反應有助於熔渣水泥漿體內部矽酸鹽類之聚合。以SEM可觀察得熔渣表面與CH進行卜作嵐反應而形成C-S-H膠體，並逐漸成長相互接觸交織成網狀結構，進而提升熔渣水泥漿體之晚期強度。綜合上述結果，熔融處理可將都市垃圾焚化灰渣無害化，且所得熔渣具有材料化之潛力。 This study investigated the pozzolonic reactions and engineering properties of municipal solid waste incinerator (MSWI) ash modified slag blended cements (SBC) with various replacement ratios. The modified slags were characterized by melting the MSWI ash mixtures at 1,400℃ for 30 min. The mixtures were composed of different types of MSWI ash, including fly ash, scrubber ash and bottom ash, with various formulas. Bottom ash and scrubber ash, in general, have higher melting points, and are more energy intensive to melt than fly ash. Therefore, fly ash was used to modify the mixtures. The obtained slags were divided into three series based on the experimental ash mixtures. Following further pulverization, these slags were blended with cement at cement replacement ratios ranging from 10% to 40%. The slags thus obtained were quantified and the characteristics of their SBC pastes examined, including the pozzolanic activity, compressive strength, hydration activity, gel pores, crystal phases, species, and the microstructure at various ages. The results indicate that the slag contained 27?34% CaO, 29?39% SiO2, and 8?23% Al2O3, and approximately 47?67% non-calcium compounds, thus meeting the ASTM C grade for fly ash, which is similar to that of the blast furnace slag. The 90-day compressive strength developed by SBC pastes with a 10% and 20% cement replacement by slags generated from the modification of scrubber ash, outperformed that of ordinary Portland cement(OPC) by 1-7 MPa, whereas the slags generated from the modifications of bottom ash series were comparable to OPC with a difference of less than 0.5MPa. From the pore size distribution, as shown by the MIP results, it was found that, with increasing curing ages, the gel pores increased and the total porosity and capillary pores decreased — a result that shows that hydrates had filled the pores. XRD and DTA species analyses indicated that the hydrates in SBC pastes were mainly CH, the calcium silicate hydrate C-S-H(C-S-H) gel, and C-A-H salts, like those found in OPC paste. TG analysis also indicated that the slag reacted with CH to form C-S-H and C-A-H. The average length (in terms of the number of Si molecules) of linear polysilicate anions in C-S-H gel, as determined by NMR, indicated an increase in all SBC pastes with increasing curing age, which outperformed that of OPC at 90 days. The generation of C-S-H gel, with intersections forming a network structure, as observed by SEM from the surface reaction with CH, also indicated the later development of strength in SBC pastes enhanced by the slag. It can be concluded from the study results that MSWI ash can be modified and processed by melting to recover reactive pozzolanic slag, which may be used in SBC to partially replace cement. |
