Acid Corrosion of Geopolymeric Cements


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Title: Acid Corrosion of Geopolymeric Cements

Author(s): Ali Allahverdi and Frantisek Skvara

Publication: Special Publication

Volume: 199


Appears on pages(s): 561-580

Keywords: acid corrosion; geopolymer cements

Date: 6/1/2001

Mechanism of acid corrosion of geopolymeric cements consists of two subsequent steps. The first step starts by a leaching process in which the soluble contents of the material (i.e. sodium and calcium) are partially depleted and replaced by H+ and H3O+ ions from solution and possibly an attack by acidic protons on polymeric Si-O-Al bonds resulting in the formation of a partially dealkalized and decalcified Si/Al-rich residue. In the second step depending on the type and the concentration of the attacking acid, the cations of sodium and calcium diffusing toward the acidic solution react with the counter-diffusing anions of the attacking acid and result in the formation of sodium and calcium salts. Sodium salts which are usually very soluble are removed by leaching. In the case where the calcium salt is relatively insoluble or less soluble, a deposition forms inside the corroding layer which provides a protective effect inhibiting the process of deterioration.