Strength and flexural behavior of steel fiber and silica fume incorporated self-compacting concrete

Self-Compacting Concrete (SCC) that flows by its own weights without compaction or vibration, thereby no external energy from mechanical equipment. In addition to this, cement replacement with silica fume and the introduction of steel fibers have allowed the improvements in durability and hardened properties of SCC. These materials are very important to prevent segregation, bleeding, and increase flow-ability. However, the addition of fibers to SCC may lead to a decline in the workability but in other way helps to improve hardened concrete properties. This paper discusses the results of an experimental investigation onto fresh and hardened properties of the self-compacting concrete mixes with four different percentages of steel fibers (0.25, 0.50, 0.75, and 1.0%) and 20% cement replacement rate with silica fume was incorporated. The workability of fresh concrete was assessed using three tests (slump flow, slump flow T50, L-box, and V-funnel tests) according to EFNARC specification and one visual test (segregation resistance) as per ASTM C 1611. The results showed that using fibers layers led to reduced workability with improved hardened concrete properties, especially toughness. However, the improved tensile and flexural toughness in SCC counteract the reduction in workability. The toughness tests are compared by introducing quadruplicate patterns containing four layers (each layer is 25 mm height) and having seven combinations of fiber laying patterns to quantify the impact in prism specimens. The quadruplicate patterns of steel fibers provide good predictions of impacts of fiber orientation on hardened properties of concrete. The results of this study indicate that the use of silica fume as a replacement for cement and incorporation of steel fiber produces more economically feasible and durable SCC.