The hardening of alkali-activated slags is a complicated process that leads to the formation of cementitious materials with a lower carbon footprint than ordinary Portland cement. These materials present varying rheological, mechanical and chemical properties, depending on the used activators and the preparation method. With a rapid stiffening often observed, the last major hindrance to their industrialisation at a large scale is the control of their workability. However, the use of traditional superplasticizers as polycarboxylates ethers has had only limited effects. To shed some light on the interactions between the three components, samples of slag activated with sodium hydroxide and admixed with polycarboxylate ethers are analysed by isothermal calorimetry, rheology, adsorption measurements, and pore solution chemical analysis. Depending on the polymer structure, we discuss a possible coupling between the adsorption and conformation of the polymer at the slag surface on the one hand, and solution chemistry on the other hand.