Abstract

MEJIA, Johanna M; RODRIGUEZ, Erich D  and  MEJIA DE GUTIERREZ, Ruby. Potential Utilization of a Low Quality-Fly Ash as an Aluminosilicate Source in the Production of Geopolymers. Ing. Univ. [online]. 2014, vol.18, n.2, pp.309-327. ISSN 0123-2126.  https://doi.org/10.11144/Javeriana.IYU18-2.upcv.

This article presents the synthesis of a geopolymeric material based on a Colombian fly ash (FA). Geopolymers with different total molar SiO₂/Al₂O₃ and Na₂O/SiO₂ ratios and the inclusion of two source of calcium (a national granulated blast furnace slag and ordinary Portland cement) were evaluated. The reaction kinetic of FA alkali activation was monitored by isothermal calorimetry, which shows the systems with highest alkalinity exhibit higher release of heat and higher dissolution degree of FA. Replacing a percentage of FA by a calcium source (OPC or GBFS) modifies the kinetic and reaction products. A higher SiO₂/ Al₂O₃ molar ratio leads to the production of materials with higher compressive strength up to ∼ 77 %. Overall, the addition of a calcium source contributes significantly to the acquisition of a higher mechanical performance. The results show the potential use of this FA with unprofitable physical and chemical characteristics as a raw material to produce non-conventional cementitious with compressive strength up to 50 MPa at 28 days of curing time.

Keywords : geopolymers; fly ash; granulated blast furnace slag; isothermal calorimetry; unconventional cements.

        · abstract in Spanish     · text in Spanish     · Spanish ( pdf )