The hydration of cement is briefly outlined and the reactions of the main c
onstituent phases of cement during the process are highlighted. The interac
tions between the various phases and their respective contributions to the
strength development due to hydration is covered, as is the influence of va
rious physical parameters on this phenomenon. The role of mineral admixture
s is summarised, together with the major types of compounds that form in th
e hydration process when these materials are added to cement. It is endeavo
ured to give a simplified view of the microscopic nature of the material du
ring hydration and also to some problems that could possibly occur in morta
rs and concrete if proper care is not taken with the cement/water interacti
on process.