| 摘要: | 在下水道建設的推動下，台灣地區下水道接管普及率逐年提昇，但廢棄下水污泥亦隨之而來，根據文獻指出下水污泥焚化灰具有燒成輕質骨材的潛力，因此為有效將廢棄污泥轉換為具實用性的物質，本研究以下水污泥焚化底渣為主體材料，與下水污泥乾燥粉末混合成不同比例進行造粒及輕質骨材燒製實驗，探討高溫操作條件對燒成骨材特性之影響，並應用於混凝土及藉由添加鋁粉發泡劑來提昇混凝土之輕質化特性，同時探討混凝土材料特性。 實驗結果顯示，利用不同污泥灰/乾燥污泥粉末之配比100：0、90：10、80：20及70：30，欲燒製密度規格小於1.6 g/cm3之輕質骨材，適當燒製條件(燒製溫度及時間)分別為1150℃/10min、1150℃/10min，1100℃/10min及1050℃/10min。由此顯示適當比率的乾燥污泥有助於降低輕質骨材的燒製溫度，同時達省能效益。 就污泥焚化灰輕質骨材混凝土材料而言，100%污泥焚化灰燒製而成之AH1輕質骨材，相較於混合20%乾燥污泥粉末燒製而成之CM1輕質骨材，AH1輕質骨材有較大的密度、破壞點荷重及SiO2的結晶程度，因此在相同條件下，LC-I(AH1)輕質混凝土之容積密度、抗壓強度發展及熱傳導率均比LC-II(CM1)輕質混凝土高。LC-I (AH1)及LC-II (CM1)輕質骨材混凝土之密度與抗壓強度分別符合ACI 213 R-87輕質混凝土之結構及中強度混凝土用途規範要求；添加0.2~0.4%鋁粉時，LC-I (AH1)符合中強度混凝土用途規範，但其強度接近下限值，而LC-II (CM1)介於中強度混凝土與非結構絕緣體用途規範之間。 A substantial amount of sewage sludge, estimated 50,000 annual tons (on a dry base) by the year 2010, is expected to be generated with the increasing population served by the sewer system under development, this requiring further proper treatment and/or disposal. This study investigated the feasibility of recycling sewage sludge into lightweight aggregates by sintering the mixtures prepared using the incinerated sludge ash(ISA), with an addition of dry sludge powder(DSP) as a bloating material. The mix design ratios(ISA:DSP), tested were 100:0 to 70:30 (w/w %), with an 10% incriment of DSP. The engineering properties of a lightweight concrete, prepared by incorporating the resultant lightweight aggregates and OPC with aluminum powder as cement bloating agent were analyzed. The results indicate that a proper mix design and sintering conditions, including a minimum sintering time of 10 minutes, combined with sintering temperature ranged from 1050-1150℃, are required to produce lightweight aggregates with bulk density less than 1.6 g/cm3. An increase in sludge powder addition (from 0% to 30%) was noted to decrease the required sintering temperature (from 1150℃ to 1050℃), showing the effects of fluxing and energy-saving. Two types of typical lightweight aggregates, AH1 and CM1, prepared by mix ratio(ISA:DSP), 100:0 and 80:20, respectively, were evaluated. In general, the density, failure loading and crystallized intensity of AH1 lightweight aggregate were higher than those of CM1. Consequently, for lightweight concrete incorporating AH1 and CM1(referred to as LC-I and LC-II, respectively), the former showed a greater bulk density, compressive strength and thermal conductivity than the latter, under the corresponding conditions of preparation. Moreover, for the bulk density and compressive strength, both the LC-I and LC-II, prepared without the addition of bloating aluminum powder, were found to correspond with the requirements of structural concrete and moderate strength concrete, respectively, as specified by ACI 213 R-87. However, in the cases of LC-I and LC-II with addition of 0.2~0.4% aluminum powder, the former corresponds with the moderate strength concrete requirement marginally, whereas the latter were found, for density and compressive strength, between the requirements of moderate strength concrete and non-structural concrete. The data reported here may be of importance to recycling sewage sludge into construction materials for a sustainable solution of waste treatment and management. |
