In this study, the effects of the mixture in different proportions on the physical and mechanical properties of hardened materials produced with diatomite (D) hydrophobic clay (HK) and cement (PC) were investigated at the prefabricated structural element production. For this purpose samples were prepared using cement rate of 10%, 20% and 30% and hydrophobic clay rate of 5%, 10% and 15% replacement of diatomite weight. The physical and mechanical properties of samples were tested after pressure is applied and 24 hours of steam curing. The combination of diatomite and hydrophobic clay produced samples with unit weight and compressive strength values of 1000-1300 kg/m(3) and 4-18 MPa, respectively. Compared with conventional building materials of the products produced it was determined to have similar physical and mechanical properties.