Thermal Activation of Albite for the Synthesis of One-Part Mix Geopolymers

Precursors for the preparation of one-part geopolymers are synthesized by thermal activation of albite with sodium hydroxide and sodium carbonate, then cooling and crushing the resulting product. Albite is stable under thermal treatment up to 1000 degrees C, but is able to be converted to depolymerized, disordered, and X-ray amorphous geopolymer precursors in the presence of sodium hydroxide or sodium carbonate at elevated temperatures. The geopolymer precursors react with the addition of water (i.e., form a one part geopolymer mix), forming geopolymers with acceptable compressive strength. One-part geopolymers synthesized via thermal activation of albite with NaOH show a higher compressive strength than those produced with Na2CO3 at the same dosage. Some crystalline sodium-aluminosilicate hydrates (zeolites) are also formed in addition to geopolymer gel in the geopolymers synthesized from albite activated by NaOH, compared to predominantly amorphous phases in the samples activated by Na2CO3. The activation of natural aluminosilicates including albite by thermal treatment with alkalis has great potential in the development of novel one-part mix geopolymers.