| dc.description.abstract | The objective of this study was initially aimed to evaluate the feasibility of using PAC and alum sludge, obtained individually in ordinary days and typhoon period from water treatment plants, as raw material for cement production. Then, based on the results of theoretical mixing design analysis of cement raw materials, the cement clinker was prepared when hydraulic modules (H.M.) = 1.7、2、2.3, silicate modules (S.M.) = 1.9、2.6、3.2, and iron modules (I.M.) = 1.5、2、2.5, respectively, and at different substitution rates (0%、50%、100%) of sludge for clay. Finally, the effects of various modules on the qualities of eco-cement were investigated.
The experimental results indicated that the percentage of major chemical compositions of sludge from various water treatment plants were all within a certain range and the ash content was above 80%. In addition, the chemical compositions and crystalline phases of water treatment plant sludge (WTPS) were similar to those of clay. Therefore, the WTPS were appropriate to replace clay as one of cement raw materials. It also found that the mineral contents of clinker after sintering and cooling processes had no difference between cement raw materials with and without WTPS. However, at the condition of different cement modules, when hydraulic module was 2.3 produced the maximum amount of C3S (74.4%), while hydraulic module was 1.7 generated the maximum of C2S (59.27%). Furthermore, the contents of free lime in the 12 series cement clinker of this study were all less than 1％, and the weight loss after sintering were in the range of 31%~37%. These results meet the quality requirements for sintered cement clinker and resemble to Portland Type- I cement contained mineral substances of C3S, C2S, C3A, and C4AF.
Moreover, this study selected the control group and hydraulic module groups that produced the maximum amount of C2S and C3S to further investigate the effect of temperature rising rate during the period of sintering process on the quality of eco-cement. The results revealed that the faster rate of temperature rising in the range of 1210 to 1410℃, the more intensity and production of crystalline phase of C2S and C3S occurred. Consequently, cement pastes were prepared from the clinkers sintered at a temperature rising rate of 20℃/min, and the microscopic analysis of the specimens was carried out. The experimental results found that C3S was the major product when hydraulic module = 2.3 and that lead to well hydration reaction and the best strength development at 7 days curing of the cement paste. However, due to the decrease of melting point when hydraulic module = 1.7, the cement clinker had melting phenomenon with ineffective formation of crystalline phase, which resulted in the lowest compressive strength of cement paste at the curing age of 28 days.
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