Experimental study on cyclic behavior of aeolian sand stabilized with geopolymer and fines.

Aeolian sand (AS) is locally available in desert area that can be used as road construction material. However, AS is a loose granular material with low bearing capacity which needs to be stabilized. This paper presents a novel study of using geopolymer (GP) and fines to stabilize AS. A series of cyclic triaxial tests was conducted to study the effect of GP and fines contents on cyclic response of stabilized AS. The experimental results show that adding fines into AS can effectively increase the cyclic loading capacity but increase the accumulated axial strain of the mixture; inclusion of GP into the AS-fines mixture greatly enhances the cyclic loading capacity and reduces the accumulated axial strain of the mixture. The shakedown response of the untreated AS changes from plastic shakedown to incremental collapse with increase in cyclic stress ratio (CSR); however, the GP-fines-AS mixture with higher fines and GP contents mainly experiences plastic shakedown. The modulus index of untreated AS or fines-containing AS shows an increase-stable trend with loading cycles, indicating strengthening in the soil matrix, but that of the GP-fines-AS mixture shows increase-stable, stable or decrease-stable trend with loading cycles, depending on the CSR and fines and GP contents. Microcharacterization using scanning electron microscope (SEM) shows that the added fines greatly alter the microstructure of AS by filling the voids and acting as lubricant, which facilitates the movement of AS particles and thus induces larger axial strain. The added GP increases the cyclic loading capacity of the treated soil by inducing a chemical fabric in the treated soils. Increase in fines and GP content results in larger contact area and stronger fabric leading to enhanced stabilizing effect. [ABSTRACT FROM AUTHOR]