Nine series of samples of composite lightweight geomaterials were produced by mixing waste foundry sand, fly ash, expanded polystyrene(EPS) bead, water and Portland cement in proportions, which were exposed to designated dryingwetting(DW) cycles. Uniaxial compression tests were carried out on the samples to investigate the effect of mix proportions onto the structural integrity of the geomaterial. Results indicate that the geomaterial offers promise as soilcement mixtures after up to 8 DW cycles. Along with increase of cement content, the compressive strength of the geomaterial gains in initial 23 DW actions. To add fly ash properly enhances the strength gain and DW resistance of the geomaterial. Although EPS addition prompts the light weight of the geomaterial, its addition, if above 1%(by mass), will lead to strength loss. Optimal mix proportions for the geomaterial are suggested.