Strength indices of high-moisture soils using handheld gauges

Abstract

Large volumes of very high moisture content fine-grained soils (very high-moisture soils (VHMS)) are encountered annually. Stabilisation of these soils has been documented as a promising approach for disposal or reuse. Construction using stabilised fine-grained soils with high moisture contents is highly dependent on strength gain with time. This study evaluated the ability of handheld gauges to provide a rapid strength index in VHMS. The results obtained from pocket penetrometer, pocket geotester and pocket vane shear set were evaluated. Testing matrices included using three fine-grained soils and five types of Portland cement. Handheld gauges were used to measure a strength index for numerous cases, resulting in more than 2000 readings with each of the gauges. Approximately 300 unconfined compression tests were also conducted and the results were used to develop strength correlations to handheld gauge indices. The results showed that, in general, there was no considerable proximity difference between the pocket geotester and the pocket penetrometer, but there was a considerable difference relative to the pocket vane shear set. A comparison between the coefficients of variation showed the pocket geotester to be the most repeatable. It is noted that these devices only provide index values and additional tests are always recommended on field samples.

Laboratory Evaluation of Undrained Shear Strength of a Soft Fine Grained Soils

“…Many researchers utilized strength index devices for measuring the undrained shear strength for cohesive soils; Nearing [3] used Miniature vane, pocket penetrometer and fall cone devices as indicators for the effect of prestress on shear strength of clay, Leoni [4] adopted the Torvane and pocket penetrometer, for measuring shear strength of reconstituted soils, Vahdifard et al [5] used pocket pentrometer, pocket geotester and pocket vane shear for evaluating the strength changes of stabilized high water content soils, Howard and Badran [6] carried out a comparison study of hand held devices (Torvane and penetrometer) with the unconfined compression test for low strength cementitious material. The laboratory vane shear test was also adopted for measuring shear strength of remolded soil [7,8,9].…”

Editorial

“…Continuing on a related theme but linked to assessment of stabilised materials, Vahedifard et al (2016) present an evaluation of the use of handheld gauges to determine strength indices of high-moisture soils (i.e. to provide a rapid strength index).…”