Structural performance and radiation shielding of low-carbon heavyweight geopolymer concrete with barite aggregate

Heavyweight geopolymer concrete (GPC) was developed by replacing conventional limestone coarse aggregate with barite (BR) at 0–100% by volume. The resulting composite achieved a density of up to 3167 kg/m3 and demonstrated significant improvement in radiation shielding, with a 35% increase in gamma-ray attenuation and a 5% improvement in neutron attenuation compared to the control sample (0% BR). As the BR ratio increases from 0–100%, the linear attenuation coefficient increases from 0.174–0.234 cm−1, 0.146–0.185 cm−1, and 0.135–0.171 cm−1 under the gamma radiations of 662, 1173, and 1332 keV, respectively. In the same situation, the tenth-value layer for the fast neutron beam decreases from 36.1–34.4 cm. Comprehensive structural evaluations were conducted, including compressive and tensile strength, elastic modulus, ultrasonic pulse velocity, thermal conductivity, electrical resistivity, and resistance to chloride and acid attack. While the inclusion of BR slightly reduced mechanical properties, increasing the concentration of the alkali activator effectively improved these properties. The 28-day compressive strength of GPC incorporating 100% BR is 52.3 MPa, representing 8% reduction compared to the control sample. These findings highlight the viability of barite GPC as a structurally sound, sustainable solution for radiation-shielded infrastructure, aligning with global efforts towards decarbonisation.