EXPERIMENTAL INVESTIGATION OF MICRO-REINFORCED, ALKALI-ACTIVATED GROUND GRANULATED BLAST FURNACE SLAG WITH WOLLASTONITE

Abstract

The alkali activation of ground granulated blast furnace slag with a potassium-based solution has demonstrated production of a cementating material with early compressive strength higher than concretes based on ordinary Portland cement. This strength can be increased by reinforcing the paste with wollastonite micro-fibers. This paper presents the results obtained when an alkali- activated slag paste was reinforced with two types of wollastonite, NYAD G and wollastocoat. Compressive strength, setting time, and microscopic structure were analyzed as a function of type of wollastonite and percentage of wollastonite added. All properties were compared to potassium-based alkali-activated slag without wollastonite. Based on a 28 day compressive strength curve, it was determined that the optimal loading of wollastonite in slag generated an average compressive strength of 55.1 MPa, an increase in strength of 60% from the wollastonite-free sample. Higher loading of wollastonite was shown to significantly reduce the setting time of the samples. The cost of all samples was compared to concrete based on ordinary Portland cement using average prices in western New York. It was found that the cost of AAS is about 6.4 times higher than regular concrete, for this reason alternative uses for microreinforced samples were explored.