STUDY ON ROAD PERFORMANCE AND FREEZE-THAW RESISTANCE OF ALKALI ACTIVATED MATERIAL STABILIZED LOW-LIQUID-LIMIT SILTY CLAY

The current study investigates the use of Alkali-Activated Material (AAM) to stabilize a silty clay with low liquid limit, collected from a construction site between Fengchang to Ni Leke section of line S315 in Yili Area. The experimental program includes road performance index tests and freeze-thaw cycling tests. They are performed on the silty clay and the stabilized soil to study the effect of AAM on the road performance index and freeze-thaw resistance. Micro characterization using scanning electron microscope(SEM) and X-Ray diffraction(XRD) is also carried out to study the underlying stabilizing mechanisms. The results show that the unconfined compressive strength and shear strength of solidified soil increase with the content of AAM and the curing age. The CBR value and resilient modulus of solidified soil increase with the content of AAM. The road performance indices of AAM stabilized soils satisfy the regulation requirements. The frozen heave and thawed settlement rates of silty clay are related to temperature gradient and water content. At the same temperature dropping range, the freeze-thaw effect is more evident on the silty clay at smaller temperature gradient. At the same temperature gradient, the freeze-thaw effect is more evident at higher water content. The frost heave rate of silty clay treated with different content of AAM under water supply condition is less than 1%, showing no frozen heave tendency. The results of micro characterization show that the C(-A)-S-H gel is the major cementing agents formed after AAM stabilization and its content increases with curing age. This cementing agent fills the pores between the soil particles and cements the soil particles together leading to a dense micro structure, which increases the strength and freeze-thaw resistance of stabilized soil.