Processes Involved in the Formation and Performance of Self-Hardening Slurry Walls: Santa Clara-a-Velha Monastery Cutoff Wall

Abstract

Several different phenomena are involved in the formation and performance of self-hardening slurry walls, including slurry contamination by soil, penetration of slurry into the ground, confining with the trench, filtration, sedimentation, consolidation, and chemical reactions between the slurry constituents. To evaluate the relative influence of these phenomena, a case study is analyzed—the cutoff wall of Santa Clara-a-Velha Monastery, built in 2001–2002. The performance of this wall is related to the in situ phenomena through data obtained during construction and from a site investigation conducted in 2011. An extensive laboratorial program was performed on samples cored from the wall and on laboratory-made samples. It was found that consolidation was the major contributor to the significant settlement of the wall that occurred after trench excavation, whereas filtration and sedimentation made only a secondary contribution. Contamination by sand only interfered with the physical properties and compressibility of the slurry. The unusual hydromechanical behavior of the wall material, when compared with soils, was attributed to the combined effect of consolidation, cement hydration, and pozzolanic reactions.