Search

This study investigates the stabilization performance of clayey soil treated with alkali-activated hybrid slag/cement. Sodium silicate (SS) and sodium hydroxide (SH) are used as alkali activators, whereas ground blast furnace slag (GGBS) and ordinary Portland cement (OPC) are used as sources of aluminosilicate. A total of 27 different types of mixtures are used for stabilization. Unconfined compressive strength (UCS) of untreated clay and stabilized soils are performed at immediately, 3-, 7-, 28-, and 90 days curing times under air-dried and wet-cured conditions. In addition, 90-d volume and mass changes in the samples are measured. Stabilized samples with an SS/SH ratio of 1 under air-dried conditions reveal moistening at early curing ages (=28 days); afterward, sodium carbonate crystals appear in these samples at longer curing ages. Geopolymer-treated clayey soil exhibits lower volumetric and mass changes compared with OPC. Most of the stabilized clayey soil with alkali-activated hybrid slag/cement exhibits higher strength compared with OPC under air-dried and wet-cured conditions. [ABSTRACT FROM AUTHOR]

Clayey subgrade soil requires treatment in order to make the subgrade stable for pavement structures. Treatment of clayey soil i.e. stabilization of clayey soil by cement, lime, and fly ash are established techniques used in geotechnical and highway engineering. Stabilization by alkali activation of fly ash is reported recently but literatures are limited. Present study investigates the stress strain behavior, peak stress and ultimate strain of clayey soil stabilized by slag and slag-fly ash blending by alkali activation. The peak stress as high as 25.0 N/mm may be obtained at 50% slags content when 12 molar sodium hydroxide solutions were used. Peak stress, ultimate strain and slope of stress-strain curve of stabilized clay are controlled by Na/Al and Si/Al ratios. Stress-strain response and peak stress of slag and fly ash blended specimen are not governed by Na/Al and Si/Al ratios; rather the behavior is dependent predominantly on slag content. [ABSTRACT FROM AUTHOR]