Fresh, Hardened, and Microstructural Properties of Ambient Cured One-Part Alkali-Activated Self-Consolidating Concrete

Abstract

Several studies have investigated the properties of alkali-activated materials (AAM), considering it as a substitute of cementitious concrete. However, the studies on alkali-activated self-consolidating concrete (AASCC) are extremely limited. This paper investigated the properties of AASCCs utilizing ground granulated blast furnace slag (GGBFS) as the main precursor. Single, binary, and ternary AASCCs were produced using fly ash Class-F (FA) and silica fumes (SF) as a replacement for GGBFS. The fresh properties including filing ability, passing ability and stability, as well as the hardened properties including unconfined compressive strength, ultrasonic pulse velocity, electrical resistivity, absorption, and sorptivity of the ambient cured one-part AASCC mixtures with different precursor blends were investigated. In addition, the microstructural properties of 90-day AASCC blends were studied by various microscale analysis methods. This paper demonstrated that the higher fraction of sodium carbonate/silicate activators, ranging from 20% to 25%, contributed to delayed reaction kinetics and satisfactory fresh and mechanical properties in all systems due to their nature. Slag replacement with variable SF or FA class-F ratios, instead, could indeed adjust the particle size distribution of the total binder material and improve the fresh concrete characteristics in binary and ternary systems. Finally, the formation of various reaction products and binding gels, i.e., C-(N)A-S-H, was found to have a significant impact on several transport mechanisms, including capillary sorptivity, permeable pores, and bulk electrical resistivity.