CHLORIDE FIXATION CAPACITY OF CEMENT MANUFACTURED FROM MUNICIPAL SOLID WASTES

本研究的目的是研究由城市生活垃圾（EC）制成的水泥在水化和碳化过程中的氯离子行为，并通过水泥氯离子含量与钢腐蚀关系的实验，探讨该水泥对钢筋混凝土构件的适用性。在普通硅酸盐水泥的基础上，采用目标氯含量分别为0.05%、0.07%和0.1%的EC作为水泥。制备水灰比为0.40的水泥浆体，对孔隙溶液和水化产物进行分析。制备水灰比为0.60的混凝土，预埋D13钢筋，进行加速腐蚀试验（在NaCl 3%溶液中浸泡3天，在空气中暴露4天的重复试验）。从孔溶液成分分析结果来看，使用EC搅拌后1天内，大部分氯离子被水泥矿物和/或水泥水化产物固定。当使用氯离子含量与加入NaCl的EC相当的普通门静脉水泥时，大部分氯离子也在搅拌后3天内固定。孔隙溶液中氯离子和氢氧化物离子浓度的比值远低于3比5，这被认为是钢腐蚀的阈值，即使试样是碳化的。从加速腐蚀试验的结果来看，两种水泥均未发现由内部氯化物引起的钢腐蚀。总之，我们认为，由城市垃圾制造的水泥具有足够的能力，可以用水泥矿物和/或水泥水化产物固定内部氯化物。

The aim of this study is to investigate behavior of chloride in cement manufactured from municipal solid wastes (EC) during hydration and carbonation and to discuss on the applicability of this cement to reinfoced concrete members through the experiments regarding the relationship between chloride content of cement and steel corrosion.EC whose target chloride contents were 0.05%, 0.07% and 0.1% were used as cement in addition to normal portland cement. Cement pastes with a water cement ratio of 0.40 were prepared for the analysis of pore solution and hydration products. Concretes with a water cement ratio of 0.60, where a D13 steel bar was embedded, were also prepared for an acceleration corrosion test (repetition of 3 day immersion in NaCl 3% solution and 4 day exposure in air)From the results of pore solution composition analysis, most of chloride ions were fixed with cement minerals and/or cement hydration products within 1 day after mixing when EC was used, while most chloride ions were also fixed within 3 days after mixing when normal portalnd cement whose chloride content was equal to that of EC by adding NaCl was used. The ratio of chloride ion and hydroxide ion concentrations of pore solution was extremely lower than 3 to 5 that is said to be a threshold value of steel corrosion even when a specimen was carbonated. From the results of acceleration corrosion tests, steel corrosion derived from internal chloride could not be found when either of cement was used. In conclusion, it is thought that cement manufactured from municipal wastes has a capacity enough to fix internal chloride with cement mineral and/or cement hydration products.