STATIC LEACH TESTS OF SIMULATED MLW CONDITIONED IN CEMENT
An investigation on the degradation of a cement matrix containing simulated MLW has been carried out in autoclaves under static leach conditions at 70 and 90 degrees C. Sample characterization, leach tests and permeability test results have been compared with pure cement matrices. Pure hydrated cement at a water to cement ratio W/C = 0.35 and solid to cement ratio S/C = 0.20 at identical W/C = 0.35 have been prepared. Solid waste has been observed to influence in some extent the total accessible porosity and the pore distribution measured by MIP analysis. Permeability tests on slabs of 0.7 mm thickness and 20 mm diameter indicate a rapid increase of pH and a gradual closing-up of pores. This is shown by a decrease in the flow rate at a differential pressure of 29400 Pa (300 g/cm**2). The degradation of the cement matrix in static leach conditions on samples containing simulated MLW seems not to depend on the temperature range (70 and 90 degrees C). From the leach tests and permeability tests the release of calcium seems to be influenced by the diffusion of soluble Ca(OH)-2 formed in the hydration of C-3S and C-2S and by its further reprecipitation to form a calcium silico-aluminate.
Bibliographic Reference: RADIOACTIVE WASTE MANAGEMENT AND THE NUCLEAR FUEL CYCLE, VOL. 7 (1986), NO. 1, PP. 29-46
Record Number: 1989125014400 / Last updated on: 1987-02-01
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