Alkali Activation of HCFA Mixtures with Aluminosilicate Additives - Mechanical Characteristics

Abstract:

Over the last years, the increasing need of cost saving and environmental protection has led to finding alternative methods and materials in construction. One of these methods is the alkali-activation, which can transform alumino-silicate binders, like siliceous fly ashes, blast furnace slags, into useful materials. On the other hand, little focus has been given to study the potential uses of high calcium fly ashes (HCFAs), which are also produced in Europe and constitute the half of total fly ash output.In this paper, a calcareous fly ash (F) from Agios Demetrios power plant in Greece was studied in combination with different alumino-silicate materials such as pozzolan, diatomite and brick dust in order to improve their physico-mechanical characteristics. Pastes were mixed with an alkaline activator, which consists of a sodium silicate solution and sodium hydroxide solution 10M. The weight ratio of NaOH:Na₂SiO₃ was 1:1. At the fresh state, setting time of the mixture was measured after mixing. Prismatic specimens were matured at different temperature conditions (25°C for 2 days and 65°C for 2 days). The samples were tested under flexural and compressive strength at the ages of 2, 7 and 28 days. Volume deformation and open porosity were also determined.

• Periodical: Key Engineering Materials (Volume 761)
• Pages: 96-99
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.761.96
• Online since: January 2018
• Authors: Ionna Papayianni*, Fotini Kesikidou, Stavroula Konopisi
• Keywords: Alkali-Activation, Alumino-Silicate Binders, High Calcium Fly Ash, Physico-Mechanical Properties

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