EFFECTIVE PROPERTIES OF CEMENTED GRANULAR-MATERIALS

An analytical model is developed to describe the effective elastic pro perties of a cemented granular material that is modeled as a random pa cking of identical spheres. The elastic moduli of grains may differ fr om those of cement. The effective bulk and shear moduli of the packing are calculated from geometrical parameters (the average number of con tacts per sphere and porosity), and from the normal and tangential sti ffness of a two-grain combination. The latter are found by solving the problems of normal and tangential deformation of two elastic spherica l grains cemented at their contact. A thin cement layer is approximate d by an elastic foundation, and the grain-cement interaction problems are reduced to linear integral equations. The solution reveals a pecul iar distribution pattern of normal and shear stresses at the cemented grain contacts: the stresses are maximum at the center of the contact region when the cement is soft relative to the grain, and are maximum at the periphery of the contact region when the cement is stiff. Stres s distribution shape gradually varies between these two extremes as th e cement's stiffness increases. The solution shows that it is mainly t he amount of cement that influences the effective elastic properties o f cemented granular materials. The radius of the cement layer affects the stiffness of a granular assembly much more strongly than the stiff ness of the cement does. This theoretical model is supported by experi mental results.