The shear behavior of a single rock joint in limestone specimens,under a constant normal load(CNL),was analyzed in this study.Test specimens with different asperity roughness were prepared and tested.Goodman’s model of a rock joint’s shear behavior,under CNL,was modified to render a better representation of the data obtained.The model’s applicability was validated.The proposed model showed better correlation with experimental data.It also,requires fewer variables.The steps to calculate all the necessary variables for the model are discussed. The shear behavior of a single rock joint in limestone specimens, under a constant normal load (CNL), was analyzed in this study. Test specimens with different asperity roughness were prepared and tested. Goodman’s model of a rock joint’s shear behavior, under CNL, was modified to render a better representation of the data obtained. The model’s applicability was validated. proposed proposed model correlation better with experimental data. It also requires fewer variables. The steps to calculate all the necessary variables for the model are discussed.