Creep Response of Compacted Waste Foundry Sands for Use as Roadway Embankment Fill

Abstract

Compressibility of five different samples of waste foundry sand (WFS) was evaluated through one-dimensional and triaxial compression tests to assess permanent strains under vertical and deviator stresses present in typical highway embankments. Results show that WFS containing a blend of sand and bentonite had higher compressibility than compacted natural sand. Compressibility of WFS is dependent on stress magnitude, time, and bentonite content. All samples of WFS exhibited one-dimensional secondary compression and deviatoric creep response similar to that of compacted natural soils. Compressibility and potential for creep rupture systematically increased with increasing bentonite content. For samples with relatively high bentonite content (12.8%), the maximum deviator stress to prevent creep rupture was reduced to 65% of the material’s compressive strength. One-dimensional compressibility parameters for compacted WFS were characterized as functions of bentonite content. Models were developed to estimate secondary compression ratio, deviatoric creep strain rates, and time to creep rupture for WFS at different stress levels and bentonite contents.