Evaluation of NaOH Activated, Ambient Cured Slag as a Binder to Produce a Building Material

Abstract

The worldwide supply constraints and the anticipated high demand for sodium silicate as well as environmental issues associated with the use of sodium silicate has given dawn to the need to opt for alternative activating solutions such as alkali-hydroxides. The current study mainly focuses on the evaluation of mechanical and chemical properties of Granulated Blast Furnace Slag (GGBFS) Binder-Spend Foundry Sand (SFS) based material toward the development of a durable material for building applications. Activated GGBFS was synthesized using a NaOH solution as the sole GGBFS activator. Uniaxial compressive strength (UCS) tests were conducted on the GGBFS-SFS based specimens to investigate the influence of varying amount of GGBFS binder (15 %- 45 %) cured at 80°C. Results showed that the specimen consisting of 45% GGBFS and 55% SFS at a solid to liquid of 0.17 yielded the high UCS equivalent to 11.07MPa. Increase in UCS has been attributed to the presence of calcium silicate hydrate phase confirmed by XRD analysis. In conclusion, GGBFS-based binder waste foundry-based material sand can be considered as a promising and efficacious building material as per ASTM C34-13, C129-14a and South African standard (SANS227: 2007).