Continuous Monitoring of the Early-Age Properties of Activated GGBFS with Alkaline Solutions of Different Concentrations

American Society of Civil Engineers (ASCE)
Publication Type:
Journal Article
Journal of Materials in Civil Engineering, 2021, 33, (12), pp. 04021374
Issue Date:
Full metadata record
This study monitors the early-age reaction kinetics and measures the heat of reaction of alkali-activated ground granulated blast-furnace slag (GGBFS) using an isothermal calorimeter, and the initial setting and possible product formations by measuring ultrasonic pulse velocity (UPV). The GGBFS was activated with alkaline activator solutions of different concentrations in terms of modulus ratio (Ms) and Na2O% content. Results reveal that GGBFS is highly sensitive to the compositions of the alkaline solutions. Increasing the alkalinity of the activator results in better dissolution of species and consequently an increased heat evolution with a relatively shorter setting time. The activator concentration also affects the rate of product formations as well as the morphological features. Activators with higher Ms lead to homogeneous slag morphology. The abundance of silicate species in the alkaline solution also plays an important role in its structural formation. scanning electron microscope with energy-dispersive X-ray spectroscopy (SEM-EDS) microstructural characterizations supports the advanced dissolution of particles in a more alkaline environment. The presence of C-(A)-S-H gels in alkali-activated slag pastes was detected.
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