Measurement of Properties of Fiber Reinforced Concrete

This paper presents the experimental investigations of the resistance to impact loading of cement mortar slabs (1:3, size: 300 mm × 300 mm × 20 mm) reinforced with four natural fibres, coir, sisal, jute, hibiscus cannebinus and subjected to impact loading using a simple projectile test. Four different fibre contents (0.5%, 1.0%, 1.5% and 2.5%—by weight of cement) and three fibre lengths (20 mm, 30 mm and 40 mm) were considered. The results obtained have shown that the addition of the above natural fibres has increased the impact resistance by 3–18 times than that of the reference (i.e. plain) mortar slab. Of the four fibres, coir fibre reinforced mortar slab specimens have shown the best performance based on the set of chosen indicators, i.e. the impact resistance (Ru), residual impact strength ratio (Irs), impact crack-resistance ratio (Cr) and the condition of fibre at ultimate failure.

Impact strength of a few natural fibre reinforced cement mortar slabs: a comparative study

This paper investigates the behavior of steel fiber-reinforced concrete (SFRC) beams in shear, as well as the possibility of using steel fibers as minimum shear reinforcement. In the study, 28 simply supported beams with a shear span-to-effective depth ratio of approximately 3.5 were subjected to a monotonically increased, concentrated load. The target concrete compressive strength for all of the beams was 41 MPa (6000 psi). The studied parameters included beam depth, fiber length, fiber aspect ratio, fiber strength, and fiber volume fraction. Three types of steel fibers were considered, all with hooks at their ends. The behavior of beams failing in shear prior to or after flexural yielding was also investigated by varying the longitudinal reinforcement ratio. Compared to reinforced concrete (RC) beams without stirrup reinforcement, the use of hooked steel fibers in a volume fraction greater than or equal to 0.75% led to an enhanced inclined cracking pattern and a substantial increase in shear strength.

Shear Behavior of Steel Fiber-Reinforced Concrete Beams without Stirrup Reinforcement

The use of recycled aggregate from construction and demolition waste (CDW) as replacement of fine and coarse natural aggregate has increased in recent years in order to reduce the high consumption of natural resources by the civil construction sector. In this work, an experimental investigation was carried out to investigate the influence of steel fiber reinforcement on the stress–strain behavior of concrete made with CDW aggregates. In addition, the flexural strength and splitting tensile strength of the mixtures were also determined. Natural coarse and fine aggregates were replaced by recycled coarse aggregate (RCA) and recycled fine aggregate (RFA) at two levels, 0% and 25%, by volume. Hooked end steel fibers with 35 mm of length and aspect ratio of 65 were used as reinforcement in a volume fraction of 0.75%. The research results show that the addition of steel fiber and recycled aggregate increased the mechanical strength and modified the fracture process relative to that of the reference concrete. The stress–strain behavior of recycled aggregate concrete was affected by the recycled aggregate and presented a more brittle behavior than the reference one. With the addition of steel fiber the toughness, measured by the slope of the descending branch of the stress–strain curve, of the recycled concretes was increased and their behavior under compression becomes similar to that of the fiber-reinforced natural aggregate concrete.

Compressive stress–strain behavior of steel fiber reinforced-recycled aggregate concrete

Stress–strain relationship of steel fiber-reinforced concrete under dynamic compression

A Comparative Evaluation of Concrete Reinforced with Straight Steel Fibers and Fibers with Deformed Ends Glued Together into Bundles

Performance Characteristics of Fiber Reinforced Concretes with Low Fiber Contents

This report presents a comparative evaluation of the performance characteristics of fiber shotcretes with four types of steel fibers. The fibers used were two types of collated fibers with deformed ends, straight fibers, and cut steel tire cord. Three different fiber concentrations were used at 0.6, 1.0, and 1.3 percent. The dry-process sanded mix shotcrete with an assumed water cement ratio of 0.46 and 5 percent entrapped air wa used in this investigation. Using a well established shotcreting company and quality equipment, and a nozzelman with 18 years of shotcreting experience, 336 test panels were made with 1 1/2 inch (38 mm) and 3 inch (76 mm) thicknesses. Test panels were shot in a raised vertical position against rigid plywood forms with open bottoms. Saw and core samples were made from the test panels and the following tests were conducted: cube compression test including unit weight, flexural test including load-deflection curves, impact test, shrinkage meaurements, and pulse velocity and dynamic modulus of elasticity tests. One major finding is that collated fibers with hooked ends could be effectively used in shotcreting and that they perform well. Excellent distribution of fibers was noted from the x-ray photos. All of the fibe shotcretes showed a tremendous ability to absorb impact loading; the hooked fibers showing a far superior ability than the straight fibers. The static flexural test shows tht an excellent end anchorage is established in the case of thee hooked fibers resulting in a high ductility of the shotcrete. For the three fiber concentrations used, only a slight increase was recorded in the properties of the hardened shotcretes.

W. V. Coyle

Papers

A Comparative Evaluation of Concrete Reinforced with Straight Steel Fibers and Fibers with Deformed Ends Glued Together into Bundles

Performance Characteristics of Fiber Reinforced Concretes with Low Fiber Contents

A comparative evaluation of fiber shotcretes