Effect of calcium hydroxide on fresh state behavior of sodium carbonate activated blast furnace slag pastes. (10th July 2019)

• Record Type: Journal Article
• Authors: Akturk, Busra; Kizilkanat, Ahmet B.; Kabay, Nihat
• Is Part Of: Construction & building materials. Volume 212(2019)
• Page Start: 388
• Page End: 399
• Publication Date: 2019-07-10
• Subjects: Alkali activated materials -- Sodium carbonate -- Slag -- Calcium hydroxide -- Fresh properties -- Carbonate concentration; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2019.03.328
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Early age CO3 2− concentration in pore solution is indicative in terms of setting. A longer setting time can be reduced efficiently with slaked lime. CO3 2− concentration is the major parameter that affects sodium carbonate-activated GGBS. Replacing sodium carbonate with sodium hydroxide improves the rheology but extends the setting time. The rheological properties depend on the activator type and amount used. Abstract: This study represents the fresh state behavior of Na2 CO3 -activated ground granulated blast furnace slag (GGBS) pastes. Sodium carbonate (NC) is a suitable activator, though with an extended setting time. To accelerate the hydration process, NC was replaced with sodium hydroxide (NH), then, slaked lime (CH) was used as a carbonate binding agent. This replacement improved the rheological properties, but increased the setting time. The use of 3% CH with GGBS caused a significant decrease in setting time, enabled to set within 6.5 h. The decrement was attributed to the removal of a large amount of dissolved carbonate ions from the fresh state pastes. The NH replacement did not effectively enhance the fresh properties. In the pore solution, the CO3 2− ion concentration is one of the major parameter that affects the reaction besides other ions released from raw material.