| 摘要: | 本研究以下水污泥、工業廢棄污泥、淨水污泥及煉鋼廢爐渣為水泥生料之主體，同時以水泥係數規範值為邊界條件，利用最佳配比策略編寫電腦配料程式，外添加適量石灰石進行配比設計，成功混配出兩系列六型別(分別命名ECOⅠ~ ECOⅥ型)環保水泥生料。另外為模擬實廠燒製水泥之流程，本研究利用導氣式焚化爐及高溫熔融爐(1400℃，6小時)於適當之操作條件下，燒製環保水泥熟料。再針對不同污泥(替代性生料)組成份上之差異針對燒成之環保水泥製成漿體，進行水化反應特性及工程材料特性之探討。研究除建立上下水污泥及工業污泥取代天然礦物摻配水泥生料之基本特性外，亦探討環保水泥之工程材料特性及水化反應行為，包括抗壓強度、膠體空間比、晶相物種組成份、水化程度及為結構變化等。 實驗結果顯示，以廢棄污泥及煉鋼廢爐渣取代天然礦物摻配水泥生料，其取代原料之比例可達20%，同時，燒製熟料之溶出（TCLP）試驗皆符合法規值，適合資源化應用。實驗所燒製之各組水泥熟料皆含有C2S、C3S、C3A及C4AF晶相物種。至於ECOⅢ型及ECOⅥ型環保水泥，因生料中含有較高比例之P2O5，熟料中C2S組成相以α-C2S之型態存在。ECOⅡ及ECOⅣ型環保水泥抗壓強度發展趨勢和OPC相似。ECOⅠ型環保水泥在養護初期抗壓強度發展較快，至養護晚期則趨於平緩。ECOⅤ型環保水泥在60及90天之養護晚期趨勢發展較為明顯。ECOⅢ型及ECOⅥ型環保水泥，直到90天之養護晚期其抗壓強度發展趨勢皆不佳。 由TG-DTA分析結果顯示，實驗所燒製之六型別環保水泥水化反應皆會生成CH及C-S-H膠體。由MIP分析結果顯示，實驗所燒製之各型別環保水泥漿體孔隙皆有隨水化齡期而緻密化之現象。由XRD分析結果顯示，各型別環保水泥漿體之C3S主峰，在水化晚期均有減少之趨勢，而C-S-H膠體亦可發現在晚期有些微增加之趨勢，觀察彼等趨勢之變異，可確認各型別環保水泥具有不同水化反應特性。以29Si為核種利用NMR技術，探討環保水泥漿體中矽酸鹽之變化情形，結果顯示，各型別環保水泥漿體之水化程度及聚矽陰離子長度皆有隨齡期增加而增加之趨勢。以SEM觀察環保水泥漿體水化產物之變化，結果顯示，隨著養護齡期之增加，環保水泥漿體水化反應所生成之C-S-H膠體逐漸向外成長並形成絨毛狀態，進而填充孔隙，提昇其抗壓強度。綜合上述結果，驗證出廢棄污泥及煉鋼廢爐渣具有取代天然礦物燒製環保水泥之潛力。 Six new types of hydraulic cements (referred to as ecocement. ECOI through ECOVI)have been developed by incorporating sludge ashes from primary sewage treatment plants and water purification plants, as well as waste from steel-works (ferrate) as partial replacements for clay, silica, alumina, and iron oxide in the raw cement meal. The recipes were formulated by solving a series of simultaneous equations, based on the boundary conditions defined by the compositional requirements of Ordinary Portaland Cement (OPC) and the chemical coefficients of the cement's raw materials, including the hydralulic modulus (H.M.), silicate modulus(S.M.), iron modulus(I.M.), and lime saturation ratio(L.S.R). The raw meal was prepared for the pre-determined recipes by heating it to 1400℃for six hours during the clinkerization process, using a simulated incinerator and a smelter. The resultant clinkers were mixed with limestone and used to prepare the six types of ecocement. In this study, the hydration characteristics of these ecocements and the energinnering properties of their mortars, including the compressive strength, gel pores variation, speciations, hydration degree at microstruct- ures, were studied as compared to those of OPC. Our results indicate that it is feasible to use sludge ashes and steel-making waste to replace, up to 20% of the mineral components of raw materials for cement (also referred to as raw meal). Furtthermore, all the tested clinkers met the TCLP (toxicity characteristic leaching procedure) requirements. The major components of the Portland cement composition,C3S(i.e.,3CaO.SiO2),C2S(i.e.,2CaO.SiO2),C3A(i.e.,3CaO.Al2O3), and C4AF(i.e., 4CaO.Al2O3.Fe2O3) were also found in the waste-derived clinkers. Of all six new types of cement, ECOII and ECO IV were closest to OPC type I in composition and compressive strength development; ECOI, showed early strength development and was similar to OPC type III. The remaining types of ecocements were not in the definate classification range. In general, clinker derived from ECOI showed early strength development, while those from ECOV displayed later strength development at 60-90 days. Those from ECOIII and ECOV underperformed in terms of compressive strength as compared to OPC. All types of ecocement were confirmed to produce calcium hydroxide (CH) and calcium silicate hydrate (C-S-H) during the hydration process, and their densification increased with the curing age. The major peaks of C3S were found to decrease with a slight increase of the C-S-H peaks at later stages of hydration, showing the various hydration degrees of the ecocements. The chemical of shift of the silicates, and the hydration degree caused an increase in the length of the C-S-H gel with curing age, and this was confirmed by 29Si NMR techniques. The results reported here may be of importance in understanding and recycling sludge ashes and steel-making slag as constructional material. |
