Permeability evolution and pore characteristics of reactive powder concrete of drilling shaft with initial salt erosion damage

•Permeability evolution of RPC corresponded to its three stages of volume deformation.•3D pore structure parameters of RPC with composite salt erosion damage were extracted by X-CT and AVIZO software.•Proportion of connectivity pores in RPC is small while independence of each pore is significant.•Top and bottom RPC parts are in dominant seepage section and middle region has optimal compactness.