Sampling and Laboratory Testing of Soil-cement from Soil Mixing and Slurry Trenching-PPT Presentation

PPT Presentation

Pdf Summary

The presentation reviews field and laboratory testing used to control soil-cement produced by soil mixing and slurry trenching. Construction-phase component tests provide early warning of problems with mixture proportions, slurry condition, and trench stability.<br /><br />Field tests include funnel viscosity, density, filter press, sand content, and wet-wash fines content. Viscosity and density are straightforward checks of mix proportions and slurry condition. Filter-press results can indicate filter-cake formation and slurry loss, but have limitations for in-trench and cementitious slurries. Sand content is more important for structural slurry walls than for slurry trenching; trench profiling may better reveal sediment layers. Fines testing offers a quick indication of material passing the No. 200 sieve and potential hydraulic conductivity, but does not distinguish silt from clay.<br /><br />For soil-cement backfill, slump helps assess workability and movement in slurry trenches: very low slump may trap slurry, while very high slump may increase consolidation and trench-open time. Its importance is limited in soil mixing, and strict criteria are not advised. Wet-grab sampling supports quality-control testing, although no specific standard covers field-cast soil-cement; a procedure combining elements of several ASTM methods is recommended. Strength is commonly measured by unconfined compressive strength, but the presentation questions whether it is always necessary. Hydraulic conductivity testing requires attention to sample dimensions, testing gradient, and confining stress.<br /><br />Leachability and durability tests are generally intended for preconstruction studies rather than routine construction QC. The presentation also emphasizes consistent significant-digit rules and specifications that account for natural variability. For example, requiring an average strength while setting a lower limit for individual results may be more practical than requiring every sample to meet the same minimum.

Keywords

soil-cement

soil mixing

slurry trenching

field testing

laboratory testing

funnel viscosity

filter press

slump

unconfined compressive strength

hydraulic conductivity