text: The categories comprise:
  * Slag-based geopolymer cement;
  * Rock-based geopolymer cement;
  * Fly ash-based geopolymer cement:
  ** type 1: alkali-activated fly ash geopolymer,
  ** type 2: slag/fly ash-based geopolymer cement.
  * Ferro-sialate-based geopolymer cement.
  The first geopolymer cement developed in the 1980s was of the type (K,Na,Ca)-poly(sialate) (or slag-based geopolymer cement) and resulted from the research developments carried out by Joseph Davidovits and J.L. Sawyer at Lone Star Industries, USA and yielded the invention of Pyrament® cement. The American patent application was filed in 1984 and the patent US 4,509,985 was granted on April 9, 1985 with the title Early high-strength mineral polymer.
  In the 1990s, building on the works conducted on geopolymeric cements and on the synthesis of zeolites from fly ashes on the other hand, Wastiels et al. , Silverstrim et al. and van Jaarsveld and van Deventer developed geopolymeric fly ash-based cements.
  Presently two types based on siliceous (EN 197) or class F (ASTM C618) fly ashes: 
  * : alkali-activated fly ash geopolymer:
  : In many cases requires heat curing at 60-80°C; not manufactured separately as a cement, but rather produced directly as a fly-ash based concrete. NaOH (user-hostile) + fly ash: partially-reacted fly ash particles embedded in an alumino-silicate gel with Si:Al= 1 to 2, zeolitic type (chabazite-Na and sodalite) structures. 
  * : slag/fly ash-based geopolymer cement:
  : Room-temperature cement hardening. User-friendly silicate solution + blast furnace slag + fly ash: fly ash particles embedded in a geopolymeric matrix with Si:Al ~ 2.