本研究旨在針對位於地表下深層的放射性廢料處置場隔離壁之裂縫封填所用的水泥薄漿材料應具備之功能進行研究，其中又以流變性與耐久性為重。具備低黏滯度及高流動性之薄漿有利於極細微裂縫的灌注，而具低滲透性和高耐久性，能阻滯水份與污染物的擴散，抵抗地表下長時間所可能遭遇的硫酸鹽侵蝕。 本研究的目的在於探討薄漿拌和材料的各種性質，以及應如何使用矽灰或爐石粉添加材料，並配合強塑劑，製做出一種不泌水、流動性良好、工作性佳、具有高強度的薄漿材，可應用於細微裂縫的灌注填補，並能抵抗化學侵蝕，使放射性廢料深層處置場的安全性能獲得保障。 研究結果顯示，就漿體的新拌、硬固或耐久性質而言，以矽灰取代水泥，必須適量，並同時應添加強塑劑以降低新拌漿體的黏滯度，改善其工作性；至於選擇以爐石取代水泥時，除了漿體的泌水情況須注意外，對漿體新拌與硬固性質而言，均較使用矽灰有較佳的成效。 This study focuses on the properties of cement grouts as a sealing and backfilling material in a radioactive waste repository, with emphasis on the rheological behavior and durability of the grout. Cement grouts with low viscosity and high flowability benefit the fine-void filling grouting process. Cement grouts with low permeability and high durability are effective in retarding the diffusion of moisture and migration of nuclei. To produce a cement grout with no bleeding, high flowability, and considerable strength, laboratory tests are conducted on grout specimens prepared with various contents of silica fume, slag and superplasticizer. Results of these tests are used to evaluate advantages of using additives and superplasticizer. Based on the evaluation, criteria for the selection of potentially suitable formula for applications to the sealing of radioactive wastes can be developed. The results indicate that, as far as the fresh and hardened properties and durability are concerned, the use of silica fume in replacing cement in the grout needs to be limited to an amount of less than 5%. The use of silica fume must be accompanied by the addition of appropriate amount of superplasticizers, in order to lower the viscosity of fresh cement grout and to improve workability. The use of slag in the grout was found to show better performance than the use of silica fume, in terms of the fresh and hardened properties of the cement grout produced. However, extra care should be exercised in controlling the bleeding as slag is used in the cement grout.