本研究將以台東樟原村日興土與美國懷俄明州BH膨潤土，混合台東地區硬頁岩碎石級配料，調配成不同體積比例之膨潤土-碎石配方之低放廢棄物最終處置場回填材料，而後進行基本材料性質、改良式夯實、自由回脹應變、定體積回脹壓力、水力傳導度等試驗，依據試驗結果歸納其功能特性，一方面尋求回填材料之最佳配方，另一方面掌握本土回填材料之工程性質，並與國際間使用之回填材料加以比較。 研究結果顯示，若以日興土或BH膨潤土加入碎石混合製成回填材料，可兼具低水力傳導度、適當回脹量及良好工作度與夯實特性等功能。二種膨潤土相較，BH膨潤土由於塑性較高，所製成回填材料之水力傳導度較日興土回填材為低，回脹潛能遠較日興土回填材高。膨潤土體積比例變化為影響回填材料之工程性質的主要因素，體積比例愈高則其水力傳導度愈低而回脹潛能愈高。於選擇低放廢棄物處置場之回填材料配方時，物理性質的考量應以低水力傳導度、不超額回脹壓力、及高均勻性而不易析離等為主要為考慮因素。 Zhishin clay and black hill bentonite were used as candidate clay materials for backfills of low-level radwaste disposal site. Various amounts of the clay were mixed with crushed Argillite obtained from Taitung to prepare for backfill material mixtures. These mixtures were tested for material characteristics, compaction properties, free swelling, swelling pressure, and hydraulic conductivity to assess their potential as backfill materials, with emphasis on their long-term stability for radwaste containment. Based on the evaluations, formulation of the backfill material is developed. Also, the properties of the backfill material are compared with those used by other countries to assure suitability. The results indicate : (1) black hill bentonite that the plastic index is higher than Zhishin clay, so the hydraulic conductivity of black hill backfill material is lower than Zhishin backfill material, and the swelling properties of black hill bentonite is higher than Zhishin clay. (2) the bentonite volume ratio is higher, the hydraulic conductivity getting lower and the swelling properties getting higher. The physical properties of the considerations should be based on the low hydraulic conductivity not the excess swelling pressure, when choosing low-level waste disposal sites formulations of backfill materials.
