Damage Assessment in concrete under fatigue loading – method for modeling energy transport through ultrasonic waves. This paper assumes that the wave field of an ultrasonic pulse in the 200 to 800 kHz range in a conventional self-compacting concrete specimen has both ballistic and diffuse components. Therefore, it is necessary to apply a generalized analytical model based on radiative transfer theory to realistically describe the energy transport of elastic waves in concrete. To solve this energy transport problem, both an analytical solution approach and a numerical model have been presented. The numerical model was created using the Monte Carlo method. The initial energy E₀, the mean free path l_s and the absorption length l_a were used to characterize the wave scattering in concrete. The evaluation of a fatigue loaded specimen show that the energy transport has both components over the test duration, with the ballistic component dominating for the undamaged sample and the diffuse component dominating for the severely damaged sample. The stiffness degradation during fatigue tests was described based on well-known parameters such as the static and dynamic modulus of elasticity and the energy transport parameters E₀, l_s and l_a.