EXPERIMENTAL INVESTIGATION ON THE FRACTURE BEHAVIOUR OF STEEL FIBER REINFORCED CONCRETE (original) (raw)
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Influence of Loading Rate on the Fracture Behaviour of Steel Fiber-Reinforced Concrete
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Three-point bending tests on notched beams of steel fiber-reinforced concrete (SFRC) have been conducted using both a servo-hydraulic machine and a self-designed drop-weight impact device. The shape and geometry of the specimen followed the RILEM recommendation, i.e., 150 mm × 150 mm in cross section, 700 mm in length, notch-depth ratio was around 1/6 and span was kept constant 500 mm. The peak load and the fracture energy were measured over a wide range of loading rates (loading point displacement rates), spanning six orders of magnitude. Under low loading rates, from 10 -3 mm/s to 10 0 mm/s, the tests were performed with the servo-hydraulic machine; from 10 2 mm/s to 10 3 mm/s, the drop-weight impact machine was used instead. The results show that the fracture energy and the peak load increase as the loading rate increases. Furthermore, such a trend is relatively mild under low rates. The gain of the fracture energy and peak load is around 10% compared with its quasi-static values...
A Practical Investigation on the Behavior of Steel Fibre Reinforced Concrete
Cement concrete is the most extensively used construction material in the world. The reason for its extensive use is that it provides good workability and can be moulded to any shape. Ordinary cement concrete possesses a very low tensile strength, limited ductility and little resistance to cracking. Internal micro cracks lead to brittle failure of concrete. In this modern age, civil engineering constructions have their own structural and durability requirements. Every structure has its own intended purpose and hence to meet this purpose, modification in traditional cement concrete has become mandatory. It has been found that different type of fibers added in specific percentage to concrete improves the mechanical properties, durability and serviceability of the structure. It is now established that one of the important properties of Steel Fiber Reinforced Concrete (SFRC) is its superior resistance to cracking and crack propagation. In this paper effect of fibers on the strength of concrete for M20 and M40 grade have been studied by varying the percentage of fibers in concrete. Fiber content were varied by 0.50%, 1% and 1.5% by volume of cement. Cubes of size 150mmX150mmX150mm to check the compressive strength and beams of size 500mmX100mmX100mm for checking flexural strength were casted. All the specimens were cured for the period of 7, 28 and 56 days before crushing. The results of fiber reinforced concrete for 3days, 7days and 28days curing with varied percentage of fiber were studied and it has been found that there is significant strength improvement in steel fiber reinforced concrete. The optimum fiber content while studying the compressive strength, flexural strength cube is found to be 1%. Also, it has been observed that with the increase in fiber content up to the optimum value increases the strength of concrete. Slump cone test was adopted to measure the workability of concrete. The Slump cone test results revealed that workability gets reduced with the increase in fiber content.
Influence of loading rate on the fracture behavior of steel fiber-reinforced concrete
Three-point bending tests on notched beams of steel fiber-reinforced concrete (SFRC) have been conducted using both a servo-hydraulic machine and a self-designed drop-weight impact device. The shape and geometry of the specimen followed the RILEM recommendation, i.e., 150 mm × 150 mm in cross section, 700 mm in length, notch-depth ratio was around 1/6 and span was kept constant 500 mm. The peak load and the fracture energy were measured over a wide range of loading rates (loading point displacement rates), spanning six orders of magnitude. Under low loading rates, from 10-3 mm/s to 100 mm/s, the tests were performed with the servo-hydraulic machine; from 102 mm/s to 103 mm/s, the drop-weight impact machine was used instead. The results show that the fracture energy and the peak load increase as the loading rate increases. Furthermore, such a trend is relatively mild under low rates. The gain of the fracture energy and peak load is around 10% compared with its quasi-static values. Ho...