Abstract
This study investigates the mechanical and durability properties of 12 ultra-high performance fiber reinforced concrete (UHPFRC) mixes manufactured using alternate aggregate sources. Natural gabbro aggregates (GA), steel slag aggregates (SSA), and recycled concrete aggregates (RCA) were employed as coarse aggregates. The volume of the coarse aggregates was limited to 12.5% of the total UHPC volume. Three types of steel fibers were employed: macro hooked-end fibers, micro straight fibers, and a hybrid combination of these two fibers. The fiber volume fractions tested were 0% and 1%. Properties investigated were compressive and flexural tensile strengths, electrical resistivity, porosity, and rapid chloride permeability. Test results revealed that the effect of aggregate type was more pronounced on the flexural strength than compressive strength. UHPFRC with steel micro-fibers or a hybrid combination of both steel macro and micro-fibers had a more noticeable effect on the compressive strength than that with steel macro-fibers, irrespective of aggregate type. Moreover, UHPFRC specimens with steel macro-fibers showed the highest flexural strength, regardless of the aggregate type. The SSA improved all durability properties of UHPFRC, whereas RCA noticeably deteriorated the resistivity and chloride permeability. The incorporation of steel micro-fibers improved the porosity and chloride permeability of all UHPFRC mixes.
Highlights
Concrete plays a significant role in the construction industry, from small structures to major monuments and facilities that promote na tional visions and identities
Mix G-P was developed through trials by adjusting the OPC, silica fume (SF), fly ash (FA), and aggregate contents; gabbro aggregates (GA) were entirely replaced by weight with recycled concrete aggregates (RCA) and steel slag aggregates (SSA) in mixtures R–P and S–P, respectively; after that, steel macro and micro-fibers were added at a volume fractions (Vf) of 1.0%, or a combination of 0.5% for each
A study conducted by Alnahhal and Aljidda [12] indi cated that when natural aggregates (NA) and RCA were utilized in the saturated surface dry condition (SSD) condition, NA and RCA concrete recorded approximately similar slump values
Summary
Concrete plays a significant role in the construction industry, from small structures to major monuments and facilities that promote na tional visions and identities. Zhang et al [61] showed that the compressive and flexural strengths of UHPC decreased as the fine RCA replacement ratio increased. Liu and Guo [62] pre pared UHPC using SSA and observed that UHPC with SSA achieved higher compressive strength than conventional UHPC Other recyclable materials such as ceramic waste, ultrafine palm oil fuel ash, plastic polyethylene terephthalate, and recycled coral were used to pro duce UHPC [47,48,61,63,64]. The effect of coarse RCA and SSA on the compressive strength, flexural strength, resistivity, porosity, and chloride permeability of UHPFRC was experi mentally investigated using 144 specimens. It is anticipated that this study would contribute to minimizing C&D waste, reducing UHPC costs, and preserving natural resources
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