Hybrid effect of micro-steel and basalt fibers on physico-mechanical properties and durability of mortars with silica fume

This study investigated the hybrid effects of micro-steel (MS) and basalt fibers (BF) on the physico- mechanical properties and durability of mortars with and without silica fume (SF). Three groups of mixtures containing SF contents of 0%, 10 % and 20 % as cement replacement were produced with the inclusion of 0.25 %, 0.5 and 0.75 % steel fibers and 0.3, 0.6 and 0.9 % basalt fibers by volume at each SF content. In total, 28 mixtures were designed and fresh properties of mixtures were evaluated by workability using slump test and fresh unit weight. Hardened properties were tested at 28 days and compressive strength, flexural tensile strength, dry unit weight, porosity and water absorption were assessed. The results revealed that combined use of 0.75 % MS and 3% BF achieved the highest compressive strength of 64.4 MPa which was 62.21 % higher than control mixtures at 20 % SF content. The results also exhibited that the mixtures containing 0.3 % BF exhibited the highest compressive strength and compressive strength decreased slightly with increasing BF content in the mixtures in each MS content at all SF content. The results showed that combined use of 0.50 % MS and 0.9 % BF and without SF achieved the highest flexural strength of 8.90 MPa which was 27.14 % higher than control specimens.