Dense basalt is widely used in construction, but its engineering evaluation is often limited to compressive strength or bulk density, which do not fully represent material performance. These approaches do not fully capture moisture sensitivity, internal continuity, or brittle-failure reliability. This study presents an integrated ASTM-based assessment of dense Madinah basalt for construction applications. Physical, mechanical, and ultrasonic properties were determined using standardized ASTM procedures. Mechanical tests were conducted under dry and saturated conditions. Reliability was evaluated using a two-parameter Weibull model and incorporated into a performance-based classification framework. The mean dry compressive strength was 146.76 MPa, and the 5% fractile strength was 130.44 MPa. The Weibull modulus was 20.76, indicating low strength scatter. Saturation reduced compressive strength by 17.7%, with a wet-to-dry ratio of 0.823. Dry flexural strength averaged 22.33 MPa, and the wet-to-dry ratio was 0.861, corresponding to a 13.9% reduction. Flexural modulus ranged from 40.57 to 81.33 GPa, with a mean value of 60.04 GPa. Ultrasonic testing gave average compression- and shear-wave velocities of 4754.67 and 2519.98 m/s, respectively, and a calculated dynamic Young’s modulus of 42.09 GPa. Density showed a positive relationship with compressive strength \(\:\left({R}^{2}=0.795\right)\), while the ultrasonic results confirmed strong internal continuity and compact structure. Dense Madinah basalt showed high strength, high stiffness, moderate moisture -induced degradation, and good probabilistic reliability, supporting its classification as a structural-grade dimension stone for regional construction use.