Workability Loss and Compressive Strength Development of Cementless Mortars Activated by Combination of Sodium Silicate and Sodium Hydroxide

To explore the significance and shortcomings of an environment-friendly binder using powder typed activators, 16 alkali-activated (AA) cementless mortars and a control ordinary Portland cement (OPC) mortar were mixed, cured under room temperature, and tested. Both fly ash (FA) and ground granulated blast-furnace slag (GGBS) as the source material were activated by a combination of sodium silicate and sodium hydroxide powders. The main variables examined were the mixing ratio of sodium oxide ( Na2 O) of the activators to source material by weight, and the Blain fineness of the GGBS. The flow loss and compressive strength development of the mortars tested were examined according to the alkali quality coefficient explaining the silicon oxide-to-sodium oxide ratio (Si O2 ∕ Na2 O) in an alkaline activator, and the silicon oxide-to-aluminum oxide (Si O2 ∕ Al2 O3 ) ratio and calcium content in the source material. The hydration products and microstructural characteristics of the AA pastes sampled from AA mortars...

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