Better understanding of concrete behavior is beneficial to the determination of concrete strength and detection of cracking using nondestructive testing techniques such as ultrasonic and acoustic emission. For advanced nondestructive evaluation of high early strength concrete under triaxial compression loading, stress-strain relationship in axial as well as in radial directions needs to be described in explicit form. This paper presents empirical models developed for high early strength concrete under active confinement to explore the effect of confining pressure. Empirical model for axial stress-strain relationship is determined first. Transverse deformation model is automatically generated from the given axial stress-strain model using plastic strain rate. Parameters used in the model are identified and their recommended values are provided. Compressive strength of 24 MPa and 45 MPa concretes are considered along with four different levels of confining pressures.