This study aims to estimate the Mohr–Coulomb failure envelope of fiber-reinforced and non-reinforced artificially cemented sands based on splitting tensile strength (σ t ) and unconfined compressive strength (σ c ) of such materials, without the necessity of carrying out triaxial testing. Based on the concept previously established by Consoli et al. that the σ t /σ c relationship is unique for each specific soil, fiber and cement agent, it is shown that the effective angle of shearing resistance of a given fiber-reinforced or non-reinforced cemented sandy soil (ϕ′) is dependent of the σ t /σ c ratio of such geomaterials and that effective cohesion intercept (c′) is a direct function of the unconfined compressive strength (σ c ) [or splitting tensile strength (σ t )] and σ t /σ c ratio of the fiber-reinforced/non-reinforced improved soil. Finally, the concepts presented herein are successfully checked for glass fiber-reinforced/non-reinforced silty sand treated with ordinary Portland cement, considering weak, moderate and strong cementation levels.