Effect of additives on the compressive strength of slag-based inorganic polymers

Abstract

The present paper aims to assess the effect of various additives on the compressive strength of inorganic polymers (geopolymers) synthesised using low Ca electric arc ferronickel slag and alkali activating solutions. The main operating parameters include pre-curing (48 hours), temperature (40 to 80 °C), heating time (24 or 48 h) and aging period (7 days). Addition of kaolinite, pozzolan, fly ash, red mud or CaO in the initial mixture has a detrimental effect on the final compressive strength. Addition of pulverised silica sand improves strength slightly, whereas addition of commercial glass results in strength values exceeding 60 MPa. XRD analysis was carried out to identify new formed phases and the degree of amorphicity, while SEM and element mapping analysis were used to identify the morphology of the final products as well as to elucidate to a certain degree the mechanisms involved in inorganic polymer synthesis. © 2009 Global NEST.