Experimental techniques exploring phenomena of positron-electron interaction, namely the positron annihilation lifetime spectroscopy and Doppler broadening of annihilation radiation, are shown to be very informative tools to study radiation- and thermally-induced phenomena in chalcogenide glasses of binary As-S system. Time-dependent processes of free-volume voids agglomeration (expansion), fragmentation (refining) and disappearing (contraction) are identified as main stages of physical aging in S-rich glasses, while a competitive channel of coordination topological defects formation associated with void charging becomes significant in a vicinity of near-stoichiometric glass compositions under gamma-irradiation. The data of combined positron lifetime and Doppler broadening of annihilation radiation measurements are correlated with radiation-induced shift of fundamental optical absorption edge of the studied glasses. The meaningful model for gamma-induced and relaxation-driven evolution in free-volume void structure of As-S glasses giving a unified insight on their structural-chemical nature is proposed. (C) 2015 Elsevier B.V. All rights reserved.