CTRE is an Iowa State University center, administered by the Institute for Transportation.

Address: 2711 S. Loop Drive, Suite 4700, Ames, IA 50010-8664

Phone: 515-294-8103
FAX: 515-294-0467

Website: www.ctre.iastate.edu/

Iowa State University--Becoming the Best

In-Situ Compaction Measurements for Geosynthetic Stabilized Subbase: Weirton, West Virgina

Tensar TX geogrid reinforcement in base layer

Piezoelectric total earth pressure cell instrumentation in Tensar BX geogrid reinforced base layer

Placement of aggregate base layer over fabric

Static plate load testing on geogrid reinforced base layers

Rut measurements under repeated traffic loading on geogrid reinforced base layers

Researcher(s)

Principal investigators:

Student researchers:

Project status

Completed

Start date: 03/01/09
End date: 10/31/10

Publications

Report: Final Report: In-Situ Compaction Measurements for Geosynthetic Stabilized Subbase: Weirton, West Virgina (32.48 mb pdf) October 2010

Related publication: ASCE 2009 paper: In-ground dynamic stress measurements for geosynthetic reinforced subgrade/subbase Sep 2011

Sponsor(s)/partner(s)

Sponsor(s): Tensar International Corporation

About the research

Abstract:

This study documents the performance of controlled test sections of unpaved geosynthetic reinforced aggregate base overlying soft subgrade. The tests were conducted in Weirton, West Virginia from March 17 to 20, 2009. The test sections included a control section with no geosynthetic and sections incorporating a woven geotextile (14.5 osy), Tensar BX1200 geogrid, or Tensar TX 160 geogrid.  Case/Ammann and Caterpillar roller with integrated compaction monitoring systems, in-ground piezoelectric earth pressure cells(EPCs), and in-situ point measurement techniques (i.e., dynamic cone penetrometer, light weight deflectometer, plate load test, and nuclear density gauge test) were used to evaluate the conditions of the test sections after selected roller and trafficking passes. The roller measurement values showed that results were repeatable between passes, but primarily reflected the conditions of the underlying weak subgrade due to the high compaction stresses and one the dimensional nature of the test strips. The underlying subgrade was considered to be weak and variable. The in-situ point measurements showed unique compaction curves for density, elastic modulus, and CBR not previously documented. Rut depth measurements under trafficking from a heavy vehicle, layer compaction measurements, and in-ground stress measurements under compaction and trafficking passes, provide information on the reinforcement provided by the different geosynthetics. Key findings from this study are that rut depth and compaction measurements showed better performance in the TX160 geogrid section compared to other test sections, while the elastic modulus and CBR measurements were variable between sections. In-ground stress cell measurements showed that the “locked-in” horizontal stress in the subgrade after trafficking was lower in the TX160 section compared to other test sections. Improved performance in the TX160 section can in part be explained by higher lateral restraint of the subbase layer following compaction and trafficking and reduced horizontal stresses in the soft subgrade layer under loading, compared to the control and other geosynthetic sections. Additional research is needed to verify these results for different subgrade and aggregate materials.