With a 3D discrete-element method specially developed with adhesive contact mechanics, random loose packings of uniform spherical micron-sized particles are fully investigated. Characterized by a dimensionless adhesion parameter Ad proposed in the previous work, four packing regimes are identified: random close packing (RCP) regime with Ad < 0.01; random loose packing (RLP) regime with 0.01 < Ad < 1; adhesion regime with 1 < Ad < 20 and an asymptotic limit regime with Ad > 20. The evolution of the radial distribution function with respect to Ad is analyzed and divided into three stages. Force distribution of these adhesive loose packings follows P(f) similar to f(theta) for small forces and P(f) similar to e(-beta f) for big forces, respectively, which shares a similar form with that in packings without adhesion but results in distinct exponents of theta = 0.879, beta = 0.839 for normal forces. A local mechanical equilibrium analysis demonstrates that adhesion enhances both sliding and rolling resistance so that the fairly loose packing structures of adhesive particles can still be mechanically,,stable. (C) 2016 Elsevier B.V. All rights reserved.