A new approach to study the fracture of quasi-brittle materials is introduced: the design and testing of model materials. By model material is understood a material with enlarged microstructure and which material parameters, such as stacking and mech. properties of particles and cohesion force, can be fully controlled. In this paper a first example to the model materials approach is presented, consisting in 5 mm steel particles bonded in a precise stacking with an epoxy-based glue. It is shown how it is possible to correlate the different fracture mechanisms and ultimate peak load of the model material to the particle pair force and to the fracture process zone size. It is also seen how a quasi-brittle behavior is produced in the presence of mechanisms that induced the crack to shift fracture planes, i.e., in presence of energy dissipative mechanisms.