Slags produced as industrial by-products can be used to replace cement by producing alkali-activated slag (AAS) binders. Slags are produced from a variety of high temperature processes and the composition of the slag will change depending on its origin. This paper presents work which investigated the effect of the chemical composition of the slag on its silicate glass network structure and how this affects the performance of the slag during alkali-activation. Several different slag compositions were obtained and Raman spectroscopy was used to determine the silicate structure present in the slags. Mechanical strength testing and dissolution experiments were used to assess the performance of the slags during alkali-activation. The results show that the chemical composition effects the polymerisation of the slag and a decrease in polymerisation of the slag's network structure leads to an increase in the strength of the AAS binder and greater slag reactivity. (C) 2017 Published by Elsevier B.V.