Title: Alkaline Activated Slag (AAS): Resistance to Sulfate Attack
Author(s): Neusa Aparecida Munhak Beltrame, Mariana Perardt, Caroline Angulski da Luz, José Ilo Pereira Filho, and Cláudia Bernardi Baldin
Publication: Symposium Paper
Appears on pages(s): 23.1-23.10
Keywords: sulfate attack, alkali activated cement, pastes, durability
Granulated blast furnace slags (GBFS) are by-products from pig iron manufacturing process, and widely used as supplementary cementing materials (SCMs) to Portland cement (PC) to obtain GBFS-Cement blends. In Brazil, PC can have up to 70% of GBFS to obtain PC type III which presents good properties in relation to sulfate resistance. On the other hand, alkaline activated cement (AAC) can be obtained from wastes such as fly ash or even GBFS, which are activated by solutions of sodium hydroxide (NaOH), potassium hydroxide (KOH) and silicates, without calcination process and, in this case, are denominated alkaline activated slag (AAS). In addition to its good environmental properties, AAS also presents good mechanical characteristics. Then, the goal of this study was to contribute to investigations about durability of AAS, in this case, sulfate resistance. Therefore, AAS was obtained from GBFS activated with 5% of NaOH and subject to sodium solution. Specimen made with Portland cement with a good behavior to sulfate environment was used as comparison. Length variation, compressive strength and microstructures investigations were also made using DTA/TG and XRD. The results showed that AAS presents a good performance to the attack by sodium sulfate and better than Portland cement. Expansion, decrease in of compressive strength and degradation of CSH were not observed.