Laboratory Evaluation of Cement- and Lime-Treated Marginal Greywacke Aggregate

Abstract

Seventy-five percent of aggregates are sourced from greywacke on North Island, New Zealand. Some of them are classified as marginal aggregates but need to be used in roads due to the cost of transporting high-quality aggregates from other regions and the need to preserve the environment. To investigate the potential of applying a marginal aggregate to roads, the marginal aggregate was treated with lime/cement in this study. An X-ray diffraction (XRD) test and repeated load triaxial (RLT) test were used to investigate the mineralogical composition and permanent strain behavior of the material, respectively. The XRD results revealed that most of the smectite contained in the marginal aggregate was depleted after stabilization. The calcium silicate hydrate (C–S–H) was found in the stabilized marginal material. The permanent strain behavior of the marginal aggregate under soaked conditions was significantly improved after lime/cement stabilization, attaining levels close to and even better than that of the premium aggregate. Cement stabilization was more effective at improving the permanent strain behavior of the marginal aggregate than lime stabilization.