This study investigated the viability of rice husk ash (RHA) as a sustainable and performance-enhancing partial substitute for cement in concrete. The used RHA, characterized by a novel chemical composition abundant in silicon and aluminum oxides, was incorporated into ordinary concrete at increasing substitution ratios up to 25%. A comprehensive evaluation was conducted to assess the influence of RHA on various properties of the resulting concrete, including physical (setting time, standard consistency, workability), mechanical (compressive and tensile strength), microstructural (XRD, and EDX), and radiation shielding characteristics. The results indicated that RHA marginally increased cement setting time, with a maximum 7.14% increase observed at a 25% replacement level. However, it significantly increased water demand for standard consistency, reaching 35.7% at 25% replacement. The increased water demand correlated with a reduction in workability, with a maximum slump reduction rate of 57.3% at the 25% replacement level. Importantly, the optimal replacement levels for mechanical strength enhancement were at 10% for compressive strength and 15% for tensile strength, achieving improvements of 13.74% and 9.48%, respectively. Additionally, The Monte Carlo simulation code as well as PhyX software were employed for assessing the concrete samples' significant gamma and fast neutron radiation attenuation characteristics. Gamma-ray attenuation tests demonstrated a modest improvement in the gamma-ray shielding capacity of the resulting concrete. The linear attenuation of the prepared sample containing 15% RHA was found to be higher than the other samples, due to its high density. On the contrary, the 25RHA sample is a less valuable sample. The 15RHA sample had the highest value for FCS (0.090 cm-1) indicating its efficacy and capability as a neutron shield.