Expanded clay concrete is a perspective structural material because of its lightweight, heat and sound insulating properties. However, due to its brittleness and low strength to flexure and compression it cannot be used in load bearing structures. Adding basalt fiber in concrete increases mechanical properties. The research work presents an experimental study of the mechanical behavior of structural expanded clay basalt fiber concrete. The main purpose of this study was to test the effect of chopped basalt fiber in expanded clay concrete to improve its strength. An experimental characterization of mechanical behavior by compressive and flexural tests was achieved. Dispersed chopped basalt fiber was used as reinforcement of specimens with sizes of 100×100×100 mm and 100×100×400 mm. Mathematical models for determining the compressive strength and the flexural strength of the expanded clay concrete depending on the proportion of basalt fiber and the curing period are developed. The finite element analysis was done by using ANSYS software, a model was developed to validate the different results obtained experimentally. The experimental results show that high percent of basalt fiber in the expanded clay concrete gives higher strength. In effect, an influence directly on the failure mode was observed on expanded clay concrete without basalt fiber and then read by the value of strength and ultimate deformation.