Lithification is a chemical process that involves the precipitation of minerals from the pore fluid, thus affecting the pore structure and the mechanics of inter-granular contacts. In parallel with such process, grain crushing and cement fracture are basic drivers of long-term compaction. In the present study, a micromechanics-based constitutive model for granular rocks is proposed to account for the coupling between these chemical and mechanical processes. The goal is to take into account both chemical strengthening via particle cementation and mechanical degradation associated with grain crushing and bond damage. The main purpose of the model is to provide a tool that, based on simple information about the evolving microstructure of a granular rock, can be able to quantify the evolution of the strength of sedimentary rocks, as well as the alterations of their elastic domain.