White ultra-high-performance concrete (WUHPC) performed outstanding mechanical, durability, and aesthetical properties, which was preferred in infrastructure to avoid the secondary painting, decrease the maintenance, and prolong the service life. Supplementary cementitious materials (SCMs) were often used in WUHPC to reduce the environment impacts and material costs. In this study, limestone powder (LP), metakaolin (MK), and silica fume (SF) were used as SCMs to largely substitute white Portland cement (WPC) to prepare WUHPC, the effects of substituted ratio on flowability, strength, and whiteness were studied, and the hydration products were also analyzed by quantitative-XRD method and SEM. The whiteness was calculated in chromatic space CIELAB by measuring tristimulus values of L, a*, and b*, and the controlled factor on whiteness was also investigated. As the results, the WUHPC with compressive strength exceeded 150 MPa and whiteness over 90 was prepared with WPC substitution of 35~65%. The SF improved the flowability and strength about 10% due to its filling and ball effect, while the irregular particle sharp and non-uniform size distribution of MK caused the reversed development. The increased dosage of raw materials with higher L value, such as LP and MK, made the WUHPC whiter. The hydration products with varied SCMs ratio were in the same category by different content. It was supposed that CaCO₃ and C-S-H gel in hydration products caused higher whiteness, while C₃S, CaMg(CO₃)₂, and SiO₂ were against the whiteness. The results proved that with a large fraction of SCMs, the WUHPC with high strength and good appearance were prepared, and the whiteness of WUHPC were both controlled by the raw materials and the content of hydration products.

The ultra-high-performance fiber-reinforced cementitious composite (UHPFRC) is a new generation of building material with extremely high mechanical strength and durability, which can be used for ultra-high, thin-wall or long-span construction, that prolongs the service life of construction in severe environments. In this study, UHPFRC was prepared with a high range of local ecological admixture to decrease the material’s cost and the environmental impact. Raw materials’ proportions, water/binder ratio, fiber-volume contents, and hybrid-fiber ratio were studied on the property improvement of UHPFRC, and an F-test analysis was induced to reveal the important significance on compressive strength. The results demonstrated that the compressive strength of 237.8 MPa was achieved with mineral admixture substitution over 40%. The particle-packing density and the binder reactivity both succeeded on the compressive strength. Water/binder ratio determined the hydration degree and the flowability of UHPFRC, which affected compressive strength through hydration products and microstructure. Also, compressive strength was more sensitive with hybrid-fiber than fiber-volume content. The order of importance for compressive strength was powder proportion > hybrid-fiber ratio > fiber-volume content > water/binder ratio.