Dissolution of Jordanian raw materials in alkaline solutions

Dissolution is the most important process for supplying the high initial Al and Si concentrations to produce the gel phase that is responsible for geopolymerization. Different aluminosilicate raw materials from Jordan were studied to understand their dissolution behavior in highly alkaline environment. Solutions up to 10 M at 25 ºC were used with different ageing. The raw materials were characterized mineralogically, chemically and thermally. The processed samples either filtered solutions or solid residues were fully characterized. Filtered part was characterized in terms of the concentration of dissolved Si and Al. X-ray diffraction (XRD) and microscopic techniques were used to characterize the solid residue mineralogically. The effect of Al and Si leaching on the structure of the starting material is also investigated.
All the aluminosilicate raw materials have indicated variable degrees of solubility under highly alkaline conditions. They solubility increases with ageing.
The used Jordanian raw materials are potential to be used for geopolymerization. However, the solubility of Al and Si cannot predict the quality of the produced geopolymers. Further experiments concerning the preparation and characterization of the new geopolymers are still under investigation. The efficiency of the Jordanian raw materials to produce geopolymers is evaluated on the basis of strength and durability and proved to be of high quality.