The wet method of deep mixing is an important technology used to construct excavation support systems and improve ground beneath embankments and structures. However, a wide variety of terminology and varying definitions for the same terms create confusion and cause miscommunication among designers, contractors, and testing laboratories. Furthermore, different testing laboratories produce quite different strength test results because there is not a standardized and widely-accepted laboratory procedure in the United States for preparing, curing, and testing soilcement specimens applicable to the wet method of deep mixing. This paper proposes use of a set of well-defined terms, including volume ratio, cement factor, cement factor in-place, cement content, water-to-cement ratio of the slurry, and total-waterto-cement ratio of the mixture. Relationships among these terms are provided in forms that can be used to control construction operations and determine mixture component quantities for laboratory testing. In addition, a laboratory procedure is described that controls the principal factors producing variability in test results. The laboratory procedure is applied to five easily-mixed soils, and the unconfined compressive strengths of the mixtures correlate more strongly with total-water-tocement ratio than with cement factor, cement factor in-place, or cement content.

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A cement deep soil mixed (CDSM) wall and jet grouting (JG) were used for an earth retention system (ERS) at an addition to the Museum of Fine Arts, Boston (MFA). The addition was located within an existing courtyard and extended up to 9.1 m (30 ft) below the floor slabs of the adjacent buildings. Adjacent buildings were supported on shallow spread footings in an alluvial sand deposit, low capacity piles in the alluvial sands, and on caissons bearing on the alluvial sands or desiccated Boston Blue Clay crust. Groundwater in the alluvial sand layer was between 0.3 and 1.2 m (1 and 4 ft) below the top of the CDSM wall. Within the clay there was a confined aquifer in a silt layer with sand. The new addition would be supported on large spread footings founded in the desiccated crust of the Boston Blue Clay. The CDSM cutoff wall varied in depth from 15.2 to 17.7 m (50 to 58 ft). It was used to control ground movements, to limit movements of adjacent structures, and to cut off perched groundwater in the alluvial sands and a confined aquifer. JG was used to underpin a portion of an existing structure, to cut off groundwater and to improve subgrade soils. The paper describes the construction of the CDSM wall for the ERS, the JG work performed for the ERS, the JG used to improve the subgrade soils for a foundation mat, and the properties of the soil-cement made using the CDSM and JG methods.

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