<p><p><figure id='attachment_3484' style='max-width:492px' class='caption aligncenter'><img class="wp-image-3484" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of a padfoot roller compacting a clay soil." width="492" height="364" /><figcaption class='caption-text'> (Photograph courtesy of Professor David White)</figcaption></figure></p><p><div><h2>Project Summary/Scope:</h2>This study was conducted to evaluate the influence of cohesive soil type, lift thickness, and moisture content on machine driven power. A total of 15 relatively uniform test strips (15 meters long by 3 meters wide) were constructed and tested using three soil types, three nominal moisture contents (per soil), and one or two lift thicknesses (per soil). The testing was conducted in an indoor facility.</p><p>Correlations between MDP and in-situ point measurements are presented using simple and multiple regression analysis. Averaging the data along the full length of the test strip (per pass) improved the regressions. Multiple regression analysis that incorporated moisture content as a regression parameter further improved the correlations. MDP measurement variation results indicate inherent variability of compaction layer and subgrade material properties and unquantified measurement errors. The effect of measurement influence depth on roller response and relationships between roller-integrated and in-situ compaction measurements showed that the depth influencing MDP may exceed the thinner lifts (150 to 200 mm) evaluated in this study.</p><p>Subsurface Conditions: Kickapoo silt (ML); Kickapoo clay (CL), and Edwards till (CL) underlain by compacted Edwards glacial till (CL) with average CBR = 14.</p><p>Self-propelled, CP-533 vibratory padfoot roller weighing 10,240 kg with drum diameter of 1.55 m and drum width of 2.13, and equipped with MDP measurement system was used to compact the fill material. A water truck and large tiller were used to carefully control the moisture content of the fill material. Moisture conditioning the soil was achieved by mellowing the soil for periods of 2 to 12 hours.</p><p><figure id='attachment_3487' style='max-width:400px' class='caption aligncenter'><img class="wp-image-3487 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of devices for finding soil modulus values." width="400" height="299" /><figcaption class='caption-text'> (Photographs courtesy of Professor David White)</figcaption></figure></p><p><img class="aligncenter wp-image-3486 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of a nuclear density gauge.." width="388" height="289" /><h2>Performance Monitoring:</h2>Dry density and moisture content were measured using nuclear moisture-density gauge, penetration index was measured using DCP, Clegg impact value was measured using Clegg hammer, and modulus (E_LWD) was determined using Keros LWD.</p><p>Roller measurements were obtained for each compaction pass. In-situ point measurements were obtained after 0, 1, 2, 4, and 8 roller passes.<br><h2>Case History Author/Submitter:</h2>David J. White, Ph.D.<br>Iowa State University<br>Email: <a href="mailto:djwhite@iastate.edu">djwhite@iastate.edu</a><h2>Project Technical Paper:<strong> </strong></h2>Thompson, M., and White, D. (2008). “Estimating compaction of cohesive soils from machine drive power.” <em>J.of Geotech. and Geoenviron. Engrg</em>, ASCE, 134(12), 1771-1777.</p><p>White, D.J, Thompson, M., Jovaag, K., Morris, M., Jaselskis, E., Schaefer, V. and Cackler, E. (2006). <em>Field evaluation of compaction monitoring technology: Phase II</em>. Final Report, Iowa DOT Project TR-495, Iowa State University, Ames, Ia.<br><h2>Date Case History Prepared:</h2>November 2012</p><p></div></p></p>