Abstract: This study conducted comprehensive experimental and modeling investigations on compressive properties of polyurethane grout materials with the density of 0.08-0.5 g·cm^-3.SEM and uniaxial compression tests were applied to specimens with varied density.Parameters obtained from SEM images were employed to predict compressive strength.It is found that foams in higher density specimens are spheres owning less contact area,which ensures the system stability based on the minimum energy principle.While majority foams in lower density specimen are polyhedrons and their contact area is larger.The uniaxial compression can be divided into elastic (strain less than 5%),yield (strain from 5% to 50%) and densification (strain higher than 50%) stages.In elastic stage,strain of higher density specimen develops faster with normalized stress,while the corresponding stress at yield stage can be viewed as compressive strength and develops with density,and in densification stage higher density specimens are characterized with brittle failure.Gibson-Ashby model based on geometric parameters of foams obtained from SEM image can be used to predict the compressive strength,and materials with varied density characterized with different strength can be applied in infrastructure maintenance.