Geopolymers Derived from Waste Glass Powder, Fly Ash, and Calcium Carbide Residue

Due to the limits of natural resources needed for cement manufacturing, coupled with ever increasing amounts of industrial waste and growing environmental consciousness, alternatives such as geopolymers are becoming attractive building materials. Particularly with the use of compatible wastes to make geopolymers at room temperature. This study investigated five formulated geopolymers, prepared from waste glass powder, fly ash, and calcium carbide residue. The ratio of glass powder, fly ash and calcium carbide residue was varied, while the amounts of sodium hydroxide solution, superplasticizer, sand (as aggregate) and short glass fiber (as reinforcement) were fixed. The specimens were mixed, cast and cured at room temperature for 7, 14 and 28 days, after which the compressive strengths were measured. The results suggest that the rate of strength development was different between the waste glass powder and the fly ash. The longer cure-time strength was increased with an increased amount of fly ash (i.e. a reduced amount of glass powder). This was despite the glass powder being fully amorphous, compared to the less amorphous fly ash. This could be due to the differences in the physical characteristics of the powders. The fly ash is a fragile, shell-like particle, while the glass powder is a harder, dense particle, which could decrease the reaction rate. From the XRD results, geo-polymerization potentially occurred more in the specimens with higher strength and could be responsible for the observed increase in strength.