A thorough analysis of ultra-high-performance concrete (UHPC) is performed to investigate the material’s reproducibility and performance for practical applications, thereby facilitating production simplification and scalability. The mix uses a standard and limited number of ingredients (silica fume, cement, sand, quartz powder, water, fibers, and superplasticizer), avoiding complex additives or rare materials. The formulation of the mix design is described using a packing particle optimization procedure. A sensitivity analysis is performed to investigate the influence of the water-to-cement ( w / c ) ratio and superplasticizer percentage on mechanical properties, and to select the most appropriate proportions. This analysis aims to establish tolerance ranges and acceptable variation limits for critical parameters, ensuring the proposed mix remains reproducible regardless of the laboratory or local production conditions. Statistical methods are also applied to analyze the mechanical properties of the UHPC mixtures. The analysis indicates that the mix is robust for w / c in the range 0.18–0.22 with 5% superplasticizer, whereas superplasticizer dosages above 6% produce segregation and measurable reductions in compressive strength. Micromechanical characterization, including scanning electron microscopy (SEM) images, identifies matrix densification, unhydrated cement, and fiber–matrix ITZ morphology, providing insights to optimize the UHPC mix for higher efficiency and durability. Smooth steel and PVA fibers, with three different volume fractions (0.5%, 1.0%, and 2.0%), are analyzed. A mechanical characterization procedure is performed to determine the compressive and tensile strengths, as well as the tensile post-peak properties. The fibers crossing the DEWS fracture plane are counted to check the variability using image correlation. The results are compared with a 3D DEWS digital model built in Rhinoceros/Grasshopper software. This procedure enables the validation of the experimental fiber distribution and the assessment of the influence of orientation and spatial randomness under controlled parametric conditions. Lastly, four UHPFRC beams with dimensions of 200 × 30 × 20 c m 3 are cast, allowing for an investigation of the material’s scalability and reproducibility. The results demonstrated that the UHPFRC can be mixed well in a standard 250 L concrete mixer without losing any strength or homogeneity. These beams were employed in complementary research focused on topology optimization. • Reproducible UHPC mix achieved using optimized particle packing design. • Comparison of UHPC with smooth steel and PVA fibers for mechanical behavior. • Sensitivity analysis of w / c ratio, fiber content, and superplasticizer on UHPC. • Fiber distribution verified by image analysis and 3D DEWS digital modeling. • Micromechanical and scale-up analysis of UHPFRC using SEM, EDS, and beam tests.
Mohammadizadeh et al. (Mon,) studied this question.