Mechanical performance and gamma attenuation capability of sustainable pozzolanic cement incorporating basalt under different curing regimes

This study introduces basalt powder as a novel supplementary cementitious material (SCM) to address the growing scarcity of conventional ones such as silica fume, slag, and fly ash. The research explores the potential of basalt to produce environmentally friendly blended cement with satisfactory mechanical and functional performance. Cement was partially replaced with 10, 20, and 30 wt% basalt to evaluate its influence on fresh properties (workability and setting time), as well as compressive-strength. To assess its suitability for precast applications, basalt-blended cement specimens were subjected to hydrothermal curing at 140, 170, and 200 °C for 3 h, and their compressive-strengths were compared to those obtained under normal curing conditions. Microstructural and phase analyses were conducted using XRD, TGA/DTGA, SEM/EDX, and nitrogen adsorption/desorption techniques. Furthermore, the study investigates the radiation shielding capability of basalt-blended cement against gamma-rays emitted from ¹³⁷Cs (661.64 keV). The results reveal that basalt incorporation reduces workability and prolongs setting time, with 20 wt% basalt identified as the optimal replacement level, achieving a compressive-strength of 69 MPa at 28 days. Hydrothermal curing at 170 °C for 3 h yielded strength comparable to that of normally cured specimens, demonstrating its effectiveness for precast production. Additionally, basalt-enhanced cement showed improved gamma-ray shielding, increasing the linear attenuation coefficient by 11% and reducing the half-value layer by 10%. These findings confirm the dual functionality of basalt as a sustainable SCM and a radiation-shielding additive, especially when combined with hydrothermal curing.