Hi to all, According to ICOLD bulletin 51 (1985)- page 27- item 184.108.40.206. (regarding the plastic concrete composition), the role of bentonitic slurry (apart from keeping the cement grain and aggregates in suspension during placing) is said to be: “… and to a large degree, to assure plasticity and impermeability”. On the other hand on page 9, the permeability of the plastic concrete in comparison with the normal concrete is reported to be as 10 times more (10e-8 to 10e-9 m/s for plastic concrete in comparison with 10e-9 to 10e-10 m/s for normal concrete). Does this imply that adding up the bentonitic slurry to the concrete has a negative effect on the water tightness of that concrete as a cut-off element? If so, why is the plastic concrete used for such a purpose (whilst the main purpose is the low permeability value, which in this regard, the concrete is ten times less permeable, hence more appropriate)?
One answer may be: Bentonite is mainly used to have a deformable wall in order to make it as close as possible (in elasticity and strength viewpoints) to the surrounding ground. Hence the bentonite slurry should be added and that there is not any other way? Your comment is appreciated.