Abstract: Combined effects from truck loading and warping due to moisture gradient can cause cracking in concrete pavements. Lack of comprehensive knowledge on moisture properties hampers the proper evaluation and accurate calculation of moisture effects in pavement design. This paper discusses the influence of water-cement ratio, environmental humidity and water transport properties on moisture distribution in concrete slabs, and describes the processes of external drying, absorption and self-desiccation. A model is proposed to simulate the moisture gradient distribution along slab depth and compared with experimental measurements. The equivalent temperature gradient ΔT_e is used to mimic the moisture gradient and to calculate its effect on warping. The results of this study can provide insights and a valuable reference for the design and construction of perpetual pavements.