AbstractThe paper presents results of unconfined compression strength and seismic wave measurements during curing on a silty sand stabilized with three type of binders: geopolymers, lime and a mixture of lime and fly ash. Unconfined compression tests and indirect tensile tests were performed after 63 days of curing, and seismic wave measurements with ultrasonic transducers were measured during the curing period. The tests results show that specimens stabilized with geopolymer give much higher strength and stiffness results than the other binders. The specimens prepared with soil-lime-fly ash mixtures show a just slight increase in strength comparing to soil-lime specimens, conversely to what has been reported by other authors.