To synthesize a metakaolin phosphate acid-based geopolymer (PAG), calcined kaolin and phosphoric acid solutions with phosphorus-to-aluminium molar ratios (P/Al) of 0.6 to 1.0 were prepared. Fresh PAG was cured in a high-humidity environment at 50°C for 7days. High humidity is helpful for generating AlPO4 during the geopolymerization of PAG. Si and Al are depolymerized from metakaolin upon attack of H3PO4, and the amounts of leached Si and Al are directly proportional to P/Al. Leached Al increases with time, while leached Si decreases and then ...
