<p>This paper presents a laboratory study that aims to validate whether the thermal creep motions of granular assembly can be an intrinsic material behavior. In the laboratory tests, 2-dimensional packed specimens of polycarbonate disks were subjected to controlled uniform and gradient heating cycles under given stress conditions using a stress-and-temperature-controlled biaxial shear device that is incorporated with photoelastic recording and hence allows the calculation of granular fabric anisotropy. By eliminating most extrinsic factors, it is shown that significant irreversible thermal volumetric and shear creep strains can be intrinsically induced by uniform heating cycles without temperature gradients, greatly governed by the anisotropy conditions of stress and granular fabric. Irreversible changes of granular mesostructures are observed under uniform temperature cycling with changes of force chains and granular fabrics. It is shown that this intrinsic thermal creep mechanism under uniform temperature conditions may dominate the thermo-mechanical granular behavior even when there are large temperature gradients in the granular assembly. However, it is noted that the temperature gradient may serve as a complementary mechanism of the intrinsic granular thermal creep behavior.</p> Graphical Abstract <p></p>