礦尾渣為工業煉製二氧化鈦的副產品，為顆粒細、氯含量高之酸性物質，原以加2倍水泥造粒製成觀音石，作為道路基底層級配料。為避免觀音石內部氯離子釋出所可能造成的金屬管路腐蝕問題，本研究主要探討礦尾渣水洗除氯的程序、造粒的最佳配比、粒料的性質及CBR值等，評估取代觀音石及放寬使用限制之可行性。 研究發現僅用清水清洗對礦尾渣內的氯離子去除量有一定極限，若使用5%碳酸鈉水溶液，才能增加礦尾渣內氯離子的溶出。利用壓濾機清洗可達到氯離子殘留量在500 ppm以下。結果又發現試體的濕密度值為影響造粒強度的關鍵因素，當以水灰比0.4，水泥卅濾餅比為 1.2或1.6造粒（簡稱KYC Ⅲ），養護7天的強度可達目標強度210 kgf/cm2；KYC Ⅲ篩分析結果符合第二類型基層級配料要求，由CBR值顯示KYC Ⅲ經養護28天後，適用於道路基底層材料。 The sludge is a by-product in the industry of titanium dioxide refinement（i.e., SCDS）. It is a kind of acidic material of fine granular particles with high chloride ion content. The SCDS is originally used for making granulized by mixing with two-fold cement to serve as the aggregate （i.e., TCS）base course material for the foundation of road pavement .This study, to avoid the problems of corrosion on embedded metallic pipelines resulted form chloride ion released form inside of TCS, discussed the procedure of removing chloride ion form SCDS by water washing, the proportioning for TCS granulation, the properties of TCS materials, the California Bearining Ration （i.e., CBR）value of TCS materials and so on. In addition, the feasibility assessment of replacing the traditional manufacturing procedure oh TCS and loosening the restrictions on the use of TCS had also been conducted. Results showed that the SCDS was still full of chlorine ion after being water-washed. Only if 5% soda ash was used could the chlorine ion be released from SCDS. Additionally, the use of filtering machine allowed the residual of chlorine ion in SCDS less than 500 ppm. Another finding was that the humidity and density were the determinants of strength for TCS. When being mixed with the proportion of 0.4 w/c and 1.2 or 1.6 cement (i.e., KYCⅢ) for 7 days, the strength of TCS could reach 210 kgf/cm2.
