Numerical simulation of fracture behaviour of the shot-earth 772

Earth building techniques have been around for thousands of years. Among them, it is worth mentioning: cut blocks, poured earth, superadobe, adobe, cob, rammed earth, compressed stabilised earth blocks, wattle and daub, shaped earth, and straw-clay. An innovative technique among the earth building ones, and named shot-earth technique, is the topic of the present paper. The technology employs a specific mixture of the shot-earth (named shot-earth 772) consisting of 7 parts of excavated soil, 7 parts of aggregates and 2 parts of cement (by volume): the mixture stream is projected at high velocity onto a surface, adding about 3% of water (by volume) at the spraying nozzle. The present research work deals with the numerical simulation of the fracture behaviour of the shot-earth 772. More precisely, an experimental campaign performed to compute the fracture toughness of the material is here numerically simulated. To such an aim, a homemade Finite Element numerical model, developed in standard Fortran language, is used to simulate both flexural and fracture tests on the shot-earth considered. In fact, such a model is able to properly consider. The material fracture process is described by means of a cohesive law, which is introduced within the cracked zone, whereas an elastic law is adopted for the un-cracked region of the material. Subsequently, the Modified Two-Parameter Model is used in order to compute the fracture toughness, from both the experimental fracture tests and the corresponding numerical simulations. Finally, the numerical results are compared with the experimental ones.