Preliminary Study on the Development of Ultra-High-Strength Cementless Concrete

In this study, cementless concrete was produced by completely replacing cement with ground granulated blast furnace slag (GGBFS) and using calcium hydroxide (CH) as the alkali activator. The effects of silica fume (SF) substitution (0%, 10%, and 20%) and curing conditions (ambient, high-temperature steam, and high-temperature water) on the fundamental properties of cementless concrete were examined. Higher SF content reduced slump flow but maintained adequate filling ability. The lower pH of CH delayed setting, particularly at higher SF substitution levels. Under high-temperature curing, pozzolanic reactions improved strength development, resulting in compressive and flexural strengths of 106.1 MPa and 28.3 MPa, respectively, at 20% SF substitution with high-temperature steam curing. The developed cementless concrete is expected to serve as a high-strength, low-carbon structural member for use in precast and modular concrete industries that use high-temperature curing processes.