Influence of Heat Treatment on the Pore Structure of Some Clays - Precursors for Geopolymer Synthesis

The aim of the presented study was the heat treatment response of the pore structure of the aluminosilicate materials (bentonite, kaolin and zeolite) and the resulted characteristics of the metaproducts, presented as the geopolymer raw materials. The treatment of the studied clays at 650 °C during 4 hours caused a high pore structure response represented by the occurrence of the creation of a new pore area on the pore size distribution histograms beginning over 2000 nm pore radius. Its size was strongly dependent on the clay species. The found relation between compressive strength of the related geopolymers and the histograms area size the assumption entitles to valuate that response of the pore structure of the clays to the heat treatment as a factor significantly conditioning the effectivity of the alkali activation and the process of the geopolymer synthesis.