Mitigating environmental impact by development of ambient-cured EAF slag and fly ash blended geopolymer via mix design optimization

This article discusses the utilization of industrial by-products, namely, electric arc furnace slag (EAFS) and fly ash to produce cementless geopolymer binder. Taguchi-grey optimization is used for experimental design and for investigating the effects of mix design parameters. Fly ash, in the levels of 0-75% (by mass), partly replaced EAFS in the binary-blended composite system. Experiments were performed on the microstructural development, mechanical properties, and durability of ambient-cured EAFS-fly ash geopolymer paste (EFGP). The optimal mix with 75-25% composition of EAFS and fly ash produced similar to 39 MPa compressive strength accrediting to the co-existence of C-A-S-H and N-A-S-H gels. The initial and final setting times were 127 min and 581 min, respectively, owing to adequate alkali and amorphous contents in the matrix, and the flowability was 108% due to sufficient activator content and the spherical shape of fly ash particles. SEM, XRD, and FTIR results corroborated the mechanical test results.

Automated summary

This article discusses the production of cementless geopolymer binder using electric arc furnace slag (EAFS) and fly ash as industrial by-products. Taguchi-grey optimization is used to investigate the effects of mix design parameters. The optimal mix of 75-25% EAFS and fly ash resulted in a compressive strength of about 39 MPa, with the presence of C-A-S-H and N-A-S-H gels. The microstructural development, mechanical properties, and durability of the geopolymer paste were also studied.