This paper describes the investigation and interpretation of a field verification trial to study the feasibility of forming 4ft diameter compaction grout columns for underpinning existing masonry buildings. Three trial columns were installed from 10 to 87ft below ground surface. Seventeen cone penetration test probes were conducted to determine the extent of grout formation and the column tops were exhumed for inspection. Evaluation of column diameters over the full depth of treatment was based on recorded grout takes for each lift. Inferred column diameters ranged from 2.5 to 4.2ft within the fill and organics, and 0.6 to 1.4ft within the silty sands and glacial deposits (consisting of fine sandy silts and varved silts/clays). Grouting within the fill and organics was characterized by large grout takes and low injection pressures, while that within the silty sands and glacial deposits was governed by the maximum injection pressure of 500psi with low grout takes. Observed heave of buried concrete blocks simulating building basement foundations at 10ft below ground surface ranged from 0.8 to 1.4ins.
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