Journal Published Online: 10 July 2023
Volume 47, Issue 1

Large-Scale Hydraulic Performance Testing of a Geotextile Mechanically Stabilized Earth (MSE) Wall Constructed with Recycled Concrete Aggregate Backfill

CODEN: GTJODJ

Abstract

Constructing geosynthetic mechanically stabilized earth walls with recycled backfill materials reduces environmental impacts and financial cost compared with their gravity wall counterparts. While a large database of column-scale tests to evaluate the hydraulic performance of recycled backfill materials exists in the literature, clogging potential under multidimensional flow conditions has not been examined. A large-scale reinforced soil wall and a complementary column test constructed with recycled concrete aggregate (RCA) and closely-spaced woven geotextile reinforcement were tested to examine chemical and physical clogging under wetting-drying cycles. Internal moisture migration and the evolving chemical signature of leachate were measured. Geotextile samples were exhumed after the tests and analyzed to evaluate chemical (tufa formation) and physical (fines migration) clogging. The complementary multidimensional and column experiments afford direct comparison of outflow chemistry and effects on geotextile permittivity. Geotextiles in the large-scale wall and column tests did not show any evidence of chemical or physical clogging and no evidence of positive pore pressures was detected. Outflow leachate from the wall test had higher total dissolved solids values and higher concentrations of Ca and SO4 in comparison to the column test. The pH of leachate from the column test is initially lower than from the wall, but results become similar (pH ∼12) at test completion. Leachate from both tests is supersaturated with tufa minerals. Differences in leachate characteristics of the two tests can be attributed to the initial moisture content of the backfill, larger quantity of RCA material in the large-scale wall, and the multidimensional flow characteristics of the large-scale wall. Results validate previous observations from column tests in terms of moisture retention and chemical response when flow conditions are multidimensional. Maintaining a free-draining backfill under conditions that could promote clogging (closely-spaced woven geotextile reinforcement layers) gives further confidence in using RCA as backfill under these conditions.

Author Information

Mardani, Azin
Civil Engineering Department, Royal Military College of Canada, Kingston, ON, Canada
Abbaspour, Aiyoub
Civil, Infrastructure, and Environmental Engineering, George Mason University, Fairfax, VA, USA
Tanyu, Burak F.
Civil, Infrastructure, and Environmental Engineering, George Mason University, Fairfax, VA, USA
Siemens, Greg
Civil Engineering Department, Royal Military College of Canada, Kingston, ON, Canada
Bathurst, Richard J.
Civil Engineering Department, Royal Military College of Canada, Kingston, ON, Canada
Likos, William J.
Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI, USA
Pages: 20
Price: $25.00
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Stock #: GTJ20220257
ISSN: 0149-6115
DOI: 10.1520/GTJ20220257