International audienceTricalcium silicate, the major component of Portland cement exhibits a complex phase diagram, surprisingly still not completely understood. In this letter, new results are highlighted including a comprehensive study of the superstructure relationship between the polymorphs, and new ideas about the structural analysis. The organisation of the silicate skeleton can be described in terms of 1-D or 2-D elements, from which arise new hypotheses about the cohesion and the chemical origin of the observed superstructures