Influence of High Volumes of Ultra-Fine Additions on Self-Compacting Concrete
R. Cioffi, F. Colangelo, D. Caputo, and B. Liguori
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compressive strength; mineral addition; self-compacting concrete; ultra-fine fly ash; workability
In this paper, the influence of high volumes of ultra-fine fly ash, raw fly ash, silica fume and natural zeolites on the properties of self-compacting concrete is evaluated. Three different samples of ultra-fine fly ash obtained after high energy milling of raw material were employed. Concretes were prepared employing various kinds of mineral additions as partial replacement (40%) of cement or in addition to it. Fresh concretes prepared were submitted to technological characterization through the determination of normal slump and J-ring slump flow values. The values of the normal slump flow were found to range between 604 and 785 mm, while the differences with the J-ring slump flow were less than 30 mm. Specimens were tested to evaluate the mechanical properties of the hardened concrete after 7- and 28-day curing. Specifically, the modulus of elasticity and compressive strength were determined. Significant strength increases were observed for the concrete containing ultra-fine fly ash. Finally, no segregation phenomena were observed in the case of cylindrical column specimens (30 x 150 cm). All the results obtained show that environmentally sustainable, high workability concrete could be successfully prepared using large volumes of mineral additions.