# Performance and statistical characteristics of ferronickel slag geopolymer concrete

## TL;DR

This study explores using ferronickel slag in geopolymer concrete, finding that it can replace river sand while maintaining strength and workability.

## Contribution

The paper introduces a novel use of ferronickel slag in geopolymer concrete and evaluates its performance and statistical characteristics.

## Key findings

- Ferronickel slag replacement reduces workability but enhances early-age compressive strength.
- Compressive strength peaks at 33% FNS replacement and follows a Weibull distribution.
- Splitting tensile strength correlates positively with compressive strength.

## Abstract

This study investigates the feasibility of substituting river sand with ferronickel slag (FNS) in geopolymer concrete (GC) through comprehensive experiments on mixtures with varying water-to-binder ratios, aggregate-to-binder ratios, and FNS replacement levels. Key properties evaluated include workability (16–30 cm slump, classified as high-fluidity concrete), compressive strength, splitting tensile strength, microstructure, and compressive strength statistics. Results indicate that increasing FNS replacement reduces slump, while higher aggregate-to-binder ratios or lower water-to-binder ratios further decrease workability. FNS-GC exhibits significant early-age strength development, achieving 72% and 94% of standard 28-day compressive strength at 3 and 14 days, respectively, with peak compressive strength observed at 33% FNS content. Similarly, splitting tensile strength (3.2- 4.4 MPa) reaches 75% and 93% of its 28-day value by 3 and 14 days, peaking at 33% FNS replacement and showing positive correlation with compressive strength. Statistically, compressive strength displays considerable variability (coefficient of variation: 0.07–0.17), maximized at 33% FNS replacement. The strength distribution aligns with normal, log-normal, and Weibull functions, with the Weibull distribution providing the optimal fit for characterizing compressive strength behavior.

The online version contains supplementary material available at 10.1038/s41598-025-21614-1.