E3S Web Conf.
Volume 195, 20204th European Conference on Unsaturated Soils (E-UNSAT 2020)
|Number of page(s)||4|
|Section||Experimental Evidence and Techniques|
|Published online||16 October 2020|
Investigating the contribution of claystone to the swelling pressure of its mixture with bentonite
1 Ecole des Ponts ParisTech, Laboratoire Navier/CERMES, 6 et 8 avenue Blaise Pascal. 77455 Marne La Vallée cedex 2, France
2 Andra, Centre de Meuse/Haute-Marne, RD 960, 55290, Bure, France
3 Andra, 1/7, rue Jean Monnet, 92298 Châtenay-Malabry cedex, France
Compacted MX80 bentonite/Callovo-Oxfordian (COx) claystone mixture has been considered as a possible sealing/backfilling material in the French deep geological radioactive waste disposal. The swelling pressure of such mixture is an important factor in the design and long-term safety assessment of deep geological repositories. In this study, constant-volume swelling pressure tests were performed on the mixtures with different claystone fractions and dry densities. The test results show that the swelling pressure of the mixtures decreased with the increasing claystone fraction and decreasing dry density. According to the experimental results, the contribution of claystone to the global swelling pressure was further investigated. It was found that the deformation of claystone and its contribution to swelling pressure was highly dependent on the claystone fraction. As the claystone fraction was larger than 30%, the claystone in the mixture swelled, contributing to the global swelling pressure; On the contrary, as the claystone fraction was less than 30%, the swelling of claystone was inhibited by the bentonite and it worked an inert material without any contribution to the swelling pressure.
© The Authors, published by EDP Sciences 2020
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