The Feasibility Study of Manufacturing Ecocement by Using Sludge as Raw cement Materials

• Main Authors: Tung-Tsan Lin, 林東燦
• Other Authors: Dyi-Hwa Tseng
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/82466778969027607665

碩士 === 國立中央大學 === 環境工程研究所 === 95 === This study evaluated preliminarily the feasibility of using marble sludge, sewage sludge, alum sludge, and BOF sludge as raw cement materials by drying sludge and analyzing their physical and chemical characteristics. In addition, to enhance the amounts of sludge used, this study calculated and designed the mix of all kinds of sludge under different cement moduli and sludge usage to produce the ecocement. After that, the kinds of physical and chemical character of cement clinker and cement were analyzed, and the microscopic observation of cement paste was analyzed to discuss the feasibility of ecocement and the effect of sludge addition on the properties of ecocement. According to the experimental results, all of the sludge in this study contained more than 50% of ash, and had low content of heavy metal. Therefore, the sludge did not belong to hazardous waste and had positive effect on sintering cement. Additionally, the sludge and raw cement material had the similarity in chemical and crystalline composition, leading to high potential for the sludge to substitute for cement material. Moreover, because of the content of CaO in marble sludge was less than limestone and SiO2 was more than that, the melting point in sintering cement would decreased when marble sludge replaced limestone completely. The marble sludge contained more impurities which help melt, so melting of clinker occurred partially and caused crystallization poorly. The compressive strength at age of 28 days only reached 20% of that in controlled cement paste. In contrast, the partial melting of clinker could be avoided when 50% of limestone was replaced by marble sludge. However, the content of CaO in clinker was insufficient and leaded C2S to be formed primarily in cement. The compressive strength at age of 28 days reached 40% of that compared to controlled cement paste. Some cement was observed more CaO be transformed into C3S, but a part of C3S would be transformed into C2S duo to exceeding SO3 if using large amounts of sewage sludge. In this case, the compressive strength at age of 28 days reached about 80% of that compared to controlled cement paste.The compressive strength at age of 28 days of cement paste would higher than that of controlled past when enhancing cement modulus of HM. The reason was CaO was enough to form abundant C3S. Similarly, the compressive strength at age of 28 days of cement paste could not exceed that of controlled paste because of SO3 in sewage sludge. Nevertheless, the strength approached the controlled past and should have application values. Finally, this study investigated the BOF sludge not only could replace iron slag, but few content of ZnO in it could help sinter cement.