Design and construction of seepage barriers using plastic concrete

An alternative solution considered was plastic concrete, characterized by low permeability and high ductility, enabling it to resist cracking under significant deformation. The mix, composed of gravel, sand, cement, bentonite, and water, incorporated a much higher water-to-cement ratio than conventional concrete. Bentonite played a key role by suspending cement particles and gravel, improving ductility and lowering permeability. The optimized mix had a water–cement ratio of 1.8 and a bentonite–water ratio of 0.2. The resulting material showed a slump value of 150–180 mm, reflecting high workability, with a 28-day unconfined compressive strength above 1.5 MPa and failure strain exceeding 1.1%. Subsurface conditions consisted of a sand layer overlying highly weathered rock, underlain by slightly weathered to fresh granite with permeability less than 10 −7 m/s. Each plastic concrete pile was socketed at least 1 m into competent rock. Stability and seepage analyses with Rocscience RS2 confirmed performance, while post-excavation monitoring showed effective water ingress control, ensuring uninterrupted construction.