A Study on the Effect of Low Calcium Ultra-fine Fly Ash as a Partial Sustainable Supplementary Material to Cement in Self-compacting Concrete

The aim and scope of the present study were to determine the efficacy of UFFA in evaluating the workability, static and dynamic stabilization properties, retention period, and slump loss of SCC systems in their fresh state, as well as their compressive strength at various ages. Microstructure (SEM and XRD) of blended SCC systems were studied. Also, the thermogravimetry behavior of blended SCC specimens were researched. According to the evaluated results, incorporating up to 20% UFFA into fresh concrete improved its performance due to its engineered fine particle size and spherical geometry, both of which contribute to the enhancement of characteristics. Blends of 25% and 30% of UFFA show effect on the water-binder ratio and chemical enhancer dosage, resulting in a loss of homogeneity in fresh SCC systems. The reduced particle size, increased amorphous content, and increased surface area all contribute to the pozzolanic reactivity of the early and later ages, resulting in denser packing and thus an increase in compressive strength. The experimental results indicate that UFFA enhances the properties of SCC in both its fresh and hardened states, which can be attributed to the particles’ fineness and their relative effect on SCC.