Performance Evaluation of Geogrid-Stabilized Steel Slag Layer of Pavement Under Repeated Cyclic Loading

Abstract

In this study, combinations of Electric Arc Furnace (EAF) slag, geogrid, and subgrade material were subjected to laboratory tests, and their deformation and strength responses under cyclic loading were evaluated. EAF slag with an average particle size (D50) of 40 mm was tested in combination with conventional subgrade material in cyclic triaxial and large-scale tests. The primary objective of this study is to ascertain the viability of EAF slag as a base or subbase material and to explore the role of multi-axial, multi-aperture shape geogrid in stabilizing EAF slag layer and subgrade within the pavement system. The experimental findings demonstrate that EAF slag can be effectively utilized in the sub-base layer due to its high strength and interlocking properties. The mechanical performance of the slag exhibits competitive outcomes in comparison to conventional materials in terms of resilient modulus and deformation resistance. When geogrid was incorporated into the base course, substantial reductions in deformation and stress accumulation were observed. For instance, after 100,000 loading cycles, the deformation beneath the loading plate was measured at 12 mm in the slag-geogrid-subgrade system and 35 mm in the slag-subgrade system. This observation indicates that geogrid contributed to a 65% reduction in deformation. Moreover, the deformation around the loading plate was reduced by 58%, and stress accumulation was reduced by 78%. The resilient modulus tests (a.k.a., repeated load triaxial testing or RLT) revealed that the EAF slag provides sufficient stiffness to be used in road foundation applications. At high bulk stress levels (e.g., σ3 = 137.9 kPa), the resilient modulus of the slag-containing systems was found to be comparable to conventional materials. Geogrid increased this value by 10-25%, contributing to an enhanced bearing capacity. The findings indicate that EAF slag has a high potential as a sustainable alternative to conventional materials and can be utilized effectively in the base course layer. Moreover, when the EAF slag is stabilized with a multi-axial, multi-aperture shape geogrid, the deformation of the pavement is significantly reduced and the overall stiffness of the pavement foundation is improved.

Keywords: steel slag, cyclic loading, geogrid stabilization, resilient modulus, sustainability