Performance of Heavyweight EAFS-Geopolymer Concrete Under Thermal and Radiation Exposure: Experimental and Machine Learning Study

This study investigates the mechanical and radiation shielding performance of heavyweight geopolymer concrete incorporating electric arc furnace slag (EAFS) as both coarse and fine aggregates after exposure to elevated temperatures (200°C to 600°C) for durations of 30 to 120 min. Ground granulated blast furnace slag served as the aluminosilicate precursor, activated by sodium hydroxide and sodium silicate.The results showed that the compressive strength decreased by up to 52% at 600°C after 120 min, primarily due to dehydration, microcracking, and geopolymer matrix degradation. Despite this, the concrete retained ~48% of its original strength, outperforming many conventional heavyweight concretes.Gamma radiation shielding, evaluated using a 60Co source, revealed a 35% reduction in the linear attenuation coefficient (from 0.083 to 0.054 cm−1), while neutron shielding (via an Am-Be source) showed a 21% drop in the effective removal cross section (from 0.228 to 0.179 cm−1). These declines correlated strongly with density loss (up to 14%) and increased porosity, as confirmed by X-ray diffraction/X-ray fluorescence analyses showing phase transformations (e.g. wollastonite formation) and reduced crystallinity. A life cycle assessment indicated a 40% to 50% reduction in embodied CO2 (0.35 t CO2/t) compared to ordinary Portland cement concrete, highlighting significant environmental benefits.Machine learning models (artificial neural networks and support vector machines) accurately predicted the compressive strength (R2 ≈ 0.997), enabling performance extrapolation. This research bridges a critical gap by evaluating the effect of prior high-temperature exposure on subsequent radiation shielding performance, conditions typical in nuclear and medical facilities, demonstrating that EAFS-based geopolymer concrete is a sustainable, dual-functional material with robust performance under multihazard exposure.