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

A series of 40 precast prestressed roof elements was cast, employing a self-compacting steel fibre reinforced concrete (SCSFRC). They are being used in an industrial building. The fibre distribution within the roof elements was investigated by means of a suitable test procedure and correlated with results obtained from cube samples drawn from the batches and tested in the fresh state. Companion slabs were also cast and tested under four point bending, in order to study the correlation between fibre distribution and the mechanical properties of the composite. The work presented here analyses the correlation between fibre distribution, workability and mechanical properties of steel fibre reinforced concrete (SFRC) with the aim of optimising both its fresh- and hardened-state properties for a series production of precast SFRC roof elements.

Relationships between fibre distribution, workability and the mechanical properties of SFRC applied to precast roof elements

An investigation on fibre concrete slabs subjected to low velocity projectile impact was carried out to assess impact resistance. The main variables of the study were type of fibre and volume fraction of fibres. The types of fibres chosen were polyolefin, polyvinyl alcohol and steel. The volume fraction of fibres examined were 0%, 1% and 2%. A total of 10 square slabs of size 1 m and 50 mm thickness were cast and tested. Impact was achieved by dropping projectile of mass 43 kg from a height of 4 m, by means of an instrumented impact test facility. Test results indicate that hooked-end steel fibre concrete slabs have better cracking and energy absorption characteristics than slabs reinforced with other fibre types. Slabs reinforced with polyvinyl alcohol fibres exhibited higher fracture energy values compared to slabs reinforced with polyolefin fibres.

Terje Brandshaug

Papers

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