The report prepared by ACI Committee 544 on Fiber Reinforced Concrete (FRC) is a comprehensive review of all types of FRC. It includes fundamental principles of FRC, a glossary of terms, a description of fiber types, manufacturing methods, mix proportioning and mixing methods, installation practices, physical properties, durability, design considerations, applications, and research needs. The report is broken into five chapters: Introduction, Steel FRC, Glass FRC, Synthetic FRC, and Natural FRC.
Fiber reinforced concrete (FRC) is concrete made primarily of hydraulic cements, aggregates, and discrete reinforcing fibers. Fibers suitable for reinforcing concrete have been produced from steel, glass, and organic polymers (synthetic fibers). Naturally occurring asbestos fibers and vegetable fibers, such as sisal and jute, are also used for reinforcement. The concrete matrices may be mortars, normally proportioned mixes, or mixes specifically formulated for a particular application. Generally, the length and diameter of the fibers used for FRC do not exceed 3 in. (76 mm) and 0.04 in. (1 mm), respectively. The report is written so that the reader may gain an overview of the property enhancements of FRC and the applications for each general category of fiber type (steel, glass, synthetic, and natural fibers).
Brittle materials are considered to have no significant post-cracking ductility. Fibrous composites have been and are being developed to provide improved mechanical properties to otherwise brittle materials. When subjected to tension, these unreinforced brittle matrices initially deform elastically. The elastic response is followed by microcracking, localized macrocracking, and finally fracture. Introduction of fibers into the concrete results in post-elastic property changes that range from subtle to substantial, depending upon a number of factors, including matrix strength, fiber type, fiber modulus, fiber aspect ratio, fiber strength, fiber surface bonding characteristics, fiber content, fiber orientation, and aggregate size effects. For many practical applications, the matrix first-crack strength is not increased. In these cases, the most significant enhancement from the fibers is the post-cracking composite response. This is most commonly evaluated and controlled through toughness testing (such as measurement of the area under the load-deformation curve).
If properly engineered, one of the greatest benefits to be gained by using fiber reinforcement is improved long-term serviceability of the structure or product. Serviceability is the ability of the specific structure or part to maintain its strength and integrity and to provide its designed function over its intended service life.
One aspect of serviceability that can be enhanced by the use of fibers is control of cracking. Fibers can prevent the occurrence of large crack widths that are either unsightly or permit water and contaminants to enter, causing corrosion of reinforcing steel or potential deterioration of concrete [1.1]. In addition to crack control and serviceability benefits, use of fibers at high volume percentages (5 to 10 percent or higher with special production tech-niques) can substantially increase the matrix tensile strength
Table of Contents
1.1--Definition of fiber reinforced concrete
1.2--Definition of fiber
Chapter 2--Mechanical properties of fiber reinforced concrete
2.2--Composite materials concept
2.3--Ultimate strength and toughness
Chapter 3--Preparation of fiber reinforced concrete
Chapter 4--Typical material properties
4.5--Corrosion of steel fibers
4.8--Friction and skid resistance
Chapter 6--Research efforts