Strength Difference between Clam-Shell and Long-Reach Excavator Constructed Cement-Bentonite Self-Hardening Slurry Walls

Cement-bentonite (c-b) self-hardening slurry walls are being constructed as a seismic retrofit to stabilize the downstream slope of Tuttle Creek Dam in Manhattan, Kansas. A full-scale test program was conducted to evaluate various slurry mixes along with two construction techniques capable of creating the required c-b transverse shear walls. The two methods tested were a crane-operated mechanical clam-shell excavator (CS) and a long-reach track-hoe (LR). The results of unconfined compression tests on hardened c-b samples constructed by CS and LR techniques were measured and the comparison revealed different unconfined compressive strengths (UCS). This paper presents UCS for both construction techniques and sample type, i.e., cored and wet-grab samples. The cause(s) of the differences in UCS and the impact on the remedial measures are discussed.