Mechanical properties and field test of lime-soda residue stabilized soil for subgrade

Abstract

To broaden the sources of subgrade filler and the utilization of Soda Residue (SR), SR was employed to modify clay by adding a small amount of lime for further stabilization, forming a Lime-Soda-Residue-Stabilized Soil (LSRSS). A set of intensive research paths was established, from testing of laboratory mechanical property, mechanism disclosure, and field verification to operational effect. Through Unconfined Compressive Strength (UCS), California Bearing Ratio (CBR), and Resilient Modulus (MR) experiments, it was concluded that with the increase in SR content, the UCS, CBR, and MR values of LSRSS showed an increasing trend then followed by a decrease, reaching their peak values, respectively of 0.62 MPa, 65.0%, 78.83 MPa, all at 30% SR content. An optimal proportion was determined for LSRSS as 6% lime, 30% SR, and 70% clay. The UCS, CBR, and MR values of optimal proportion all increased with the increase of compaction degree, but increased first and then decreased with the increase of water content. Their maximum values did not correspond to the OWC of 23% but to 27%, called the compaction water content, which was suitable for application in the actual LSRSS subgrade. Field test results showed that the UCS, CBR, and MR values were 0.85 MPa, 86.5%, and 135.7 MPa, which all were higher than the laboratory values, and the long-term road performance was outstanding. The analysis demonstrates that the better strength and road performance of LSRSS are mainly determined by the superior gradation and the reaction of three materials. The laboratory and field test results collectively provide data evidence for excellent performance and lay a solid foundation for the wider application of the LSRSS subgrade.