Studies on Workability of Geopolymer Solidification - 18171

In Japan, intermediate-level radioactive waste, such as spent resin, is solidified and set in sealed containers without venting. To reduce the amount of hydrogen generated due to water radiolysis in stored intermediate-level waste, geopolymer solidification has been studied. Geopolymer solidification is an excellent method for conditioning intermediate-level waste from the viewpoint of its high thermal stability and low processing cost. However, it has a problem that the apparent viscosity increases drastically a few minutes after the onset of setting. This may cause some trouble in the process of pouring the geopolymer into drums and mixing it with waste. In this study, in order to control the workability of a geopolymer mixture, we investigated the effects of the compounding ratio and the kinds of chemical agents used. We confirmed that the geopolymer reaction was slowed down by reducing the amount of calcium and adding boron. The uniaxial compressive strength of the geopolymer was 3-80 MPa. (authors)