Freeze–Thaw Characteristics of Slaking Marl Clay Stabilized with a Binder Based on Alkali-Activated Recycled Glass Powder

Abstract

Marl soils with different carbonate contents usually show more unpredictable behavior than other problematic soils. In some marl soil groups, freezing–thawing (F-T) cycles can result in slaking and detrimental effects on the soil mechanical properties. However, up to now, studies on the performance of stabilized marl with alkali-activated materials under F-T cycles have been noticed to be quite limited. Moreover, the filled pores in the marl layered matrix and cementing materials bonded particles during the formation mechanism have not been clearly explored yet. This study investigated the improvement of slaking marl soil with a geopolymer based on recycled glass powder (RGP) activated with sodium hydroxide (NaOH) for complete replacement of industrial cement. The study evaluated the effects of the changes of the curing times (7, 28, and 90 days), RGP content (5%, 10%, and 15%), alkali concentration (2, 4, and 6M), curing temperatures as close to research conditions as possible (20°C and 50°C), volumetric strain, and 12 cycles of F-T for the unconfined compression strength (UCS) and consolidation test results. The control sets, comprising natural and cement-stabilized samples, were prepared and examined to provide a reference baseline. The mineralogical and microstructural characteristics were determined through X-ray diffractometer (XRD) and scanning electron microscopy (SEM) techniques. The results revealed that the cyclic F-T actions damaged the bonding between marl layers and made an irreversible structure with a lower UCS value. The results indicated that after conducting F-T cycles, the UCS of stabilized samples (15% RGP content, 2 M NaOH, 90 days curing) diminished from 3,667 to 2,668 kPa (27% reduction) after 12 F-T cycles. The one-dimensional consolidation test results confirmed a considerable reduction (92% for 90-day cured samples) in the settlement.