Title:
Effectiveness of Mixing Time on Hardened Properties of Waterglass-Activated Slag Pastes and Mortars
Author(s):
Marta Palacios and Francisca Puertas
Publication:
Materials Journal
Volume:
108
Issue:
1
Appears on pages(s):
73-78
Keywords:
alkali-activated slag cements; drying shrinkage; mechanical properties; microstructure
DOI:
10.14359/51664218
Date:
1/1/2011
Abstract:
A previous study concluded that the setting of waterglass-activated slag pastes could be controlled and lengthened by increasing the mixing time, solving one of their main problems—poor rheological properties. The aim of this study was to explore the effect of increasing mixing time on the microstructure, mechanical properties, and drying shrinkage of waterglass-activated slag pastes and mortars, as well as on the nature of the respective reaction products. The findings showed that increasing mixing time to up to 30 minutes improves matrix cohesion and compactness, thereby enhancing mortar mechanical strength by approximately 11%. Moreover, drying shrinkage in these mortars was 16% lower than in mortars mixed for shorter times, essentially due to the decline in the percentage of pores under 0.05 μm (2.0 μin.). Lastly, longer mixing times were not observed to modify the chemical or mineralogical composition of the reaction products.