以膨脹指數試驗探討混凝土孔隙溶液對膨潤土膨脹性能之影響

Research shows that bentonite has a high swelling property and nonpermeable behaviors. Thus, it is commonly used as a buffer material for the final disposal of high-level radioactive waste. This application can effectively prevent radioactive nuclides from contacting the outside environment. According to the research, using the concrete to be the structure in the disposal site will reduce the swelling of bentonite due to its high pH pore solution and influence the safety of disposal site. This study proposes a simple, fast and easyto- control environmental factor test procedure and method. Using Volclay Bentonite SPV 200 and MX-80 bentonite produced in the Black Hills area of Wyoming, USA as samples, real concrete pore solutions were extracted to evaluate the influence of different concrete pore solutions and ambient temperature on the expansion of bentonite. The results showed that the new test method can help researchers evaluate the effect of concrete pore solution on the expansibility of bentonite quickly and effectively. The result also showed that when the pH value of the pore sulution and the bentonite interactions within 48 hours the pH value less 10, the swelling property of bentonite will not be reduced. Conversely, when the pH value of the pore solution is higher than 12.7, it will reduce the swellability of bentonite. Besides, when the pore solution with a low pH value (10.6), and its temperature is in the range of 23℃ ~ 80℃, the swellability of bentonite will not be affected.