ineering materials in the world economy are sig. large amount of materials used in construction the negative impact(through energy consumption There are a number of unique characteristics of and pollution)on our environment can be signif- civil/building engineering materials which set icant. However, we can enable sustainable infra them apart from those used in other industries. structures to be developed by using more recycled These characteristics include materials (e. g, fly ash, silica fumes, and waste bers (or seconds) in infrastructure with en- Low cost-for example, concrete costs $o 1/kg hanced durability (in contrast to eye contact lens which cost n summary, construction materials can, and $100,000/kg) should, play an important role in our infrastruc- Large volume application-e. g, on a ture development and renewal. The obvious im- wide basis. 6 billion tons of concrete pact on society in economics, public safety, and half billion tons of steel are used in the environment must be recognized structure construction annually Durability requirement--our infrastructures generally are designed for much longer life CURRENT APPLICATIONS OF FRCS than consumer goods, e.g., most bridges are Most current applications of fibers are nonstruc designed with a 75-year service life,com tural Fibers are often used in controlling (plastic pared with an automobile with a typical de- and drying) shrinkage cracks, a role classically sign life of 10-20 year played by steel reinforcing bars or steel wire- Public Safety-it goes without saying that mesh. Examples include floors and slabs, large the general public will not tolerate failure of concrete containers, and concrete pavements. In infrastructures. The experiences from the re- cent Northridge earthquake in the United general, these structures and products have ex- States and the Kobe earthquake in Japan tensive exposed surface areas and movement con- straints, resulting in high cracking potential. For serve important lessons such applications, fibers have a number of advan- processed into infrastructures. Construction These include: (a) uniform reinforcement distri workers generally do not have the same kind bution with respect to location and orientation, of training ceramics engineers have. This im- (b)corrosion resistance especially for synthetic plies that the material, if processed at a con- carbon, or amorphous metal fibers, and(c)labor struction site, must be tolerant of low-preci- saving by avoiding the need of deforming the re- sion processing. inforcing bars and tying them in the form-work Thich often leads to reduction of construction The above unique characteristics need to be time. Elimination of reinforcing bars also relaxes bserved when developing advanced construction constraints on concrete element shape. This func- materials. They may be regarded as overall con- tional value of fibers has been exploited in the straints. Only materials meeting such constraints curtain walls of tall buildings. The Kajima Cor will be successfully adopted in the real world. For poration ( Japan) has taken advantage of fibers i FRC, the first two constraints on cost and appli- the manufacture of curvilinear-shaped wall pan cations in large-scale structures imply that fibers els valued for their aesthetics(see, e. g Fig. 1). In cannot be overly expensive and must be used in some applications, the use of fibers enables the relatively small volume content elimination or the reduction in the number of Viewed in a more positive light, some of the cut -joints in large continuous structures such as above constraints also make materials serve as containers(Fig. 2) and pavements. Especially enabling technology for infrastructures. Proper pavements, joints are locations of weaknesses at selection of fiber and matrix materials is critical which failure frequently occurs. Thus, fibers have in producing durable infrastructures. FRCs with been exploited to enhance the durability of con- high ductility lead to safer infrastructures. Mate- crete elements. Some additional representative rials can even lend themselves to improving con- industrial applications of FRCs are shown in Fig struction productivity. For example, the replace- ures 3-5. These examples are chosen to illustrate ment of re-bars in reinforced concrete(R/C)struc- the wide range of fiber used(steel, glass, polymer, tures with FRCs have led to reduction in labor amorphous metal, carbon) and the international cost in construction sites. Finally, because of the nature of FRC applicationsgineering materials in the world economy are sig￾nificant. There are a number of unique characteristics of civil/building engineering materials which set them apart from those used in other industries. These characteristics include: ● Low cost—for example, concrete costs $0.1/kg (in contrast to eye contact lens which cost $100,000/kg). ● Large volume application—e.g., on a world￾wide basis, 6 billion tons of concrete and a half billion tons of steel are used in infra￾structure construction annually. ● Durability requirement—our infrastructures generally are designed for much longer life than consumer goods, e.g., most bridges are designed with a 75-year service life, com￾pared with an automobile with a typical de￾sign life of 10–20 years. ● Public Safety—it goes without saying that the general public will not tolerate failure of infrastructures. The experiences from the re￾cent Northridge earthquake in the United States and the Kobe earthquake in Japan serve important lessons. ● Construction labor—materials have to be processed into infrastructures. Construction workers generally do not have the same kind of training ceramics engineers have. This im￾plies that the material, if processed at a con￾struction site, must be tolerant of low-preci￾sion processing. The above unique characteristics need to be observed when developing advanced construction materials. They may be regarded as overall con￾straints. Only materials meeting such constraints will be successfully adopted in the real world. For FRC, the first two constraints on cost and appli￾cations in large-scale structures imply that fibers cannot be overly expensive and must be used in relatively small volume content. Viewed in a more positive light, some of the above constraints also make materials serve as enabling technology for infrastructures. Proper selection of fiber and matrix materials is critical in producing durable infrastructures. FRCs with high ductility lead to safer infrastructures. Mate￾rials can even lend themselves to improving con￾struction productivity. For example, the replace￾ment of re-bars in reinforced concrete (R/C) struc￾tures with FRCs have led to reduction in labor cost in construction sites. Finally, because of the large amount of materials used in construction, the negative impact (through energy consumption and pollution) on our environment can be signif￾icant. However, we can enable sustainable infra￾structures to be developed by using more recycled materials (e.g., fly ash, silica fumes, and waste fibers (or seconds)) in infrastructure with en￾hanced durability. In summary, construction materials can, and should, play an important role in our infrastruc￾ture development and renewal. The obvious im￾pact on society in economics, public safety, and the environment must be recognized. CURRENT APPLICATIONS OF FRCS Most current applications of fibers are nonstruc￾tural. Fibers are often used in controlling (plastic and drying) shrinkage cracks, a role classically played by steel reinforcing bars or steel wire￾mesh. Examples include floors and slabs, large concrete containers, and concrete pavements. In general, these structures and products have ex￾tensive exposed surface areas and movement con￾straints, resulting in high cracking potential. For such applications, fibers have a number of advan￾tages over conventional steel reinforcements. These include: (a) uniform reinforcement distri￾bution with respect to location and orientation, (b) corrosion resistance especially for synthetic, carbon, or amorphous metal fibers, and (c) labor￾saving by avoiding the need of deforming the re￾inforcing bars and tying them in the form-work, which often leads to reduction of construction time. Elimination of reinforcing bars also relaxes constraints on concrete element shape. This func￾tional value of fibers has been exploited in the curtain walls of tall buildings. The Kajima Cor￾poration (Japan) has taken advantage of fibers in the manufacture of curvilinear-shaped wall pan￾els valued for their aesthetics (see, e.g., Fig. 1). In some applications, the use of fibers enables the elimination or the reduction in the number of cut-joints in large continuous structures such as containers (Fig. 2) and pavements. Especially in pavements, joints are locations of weaknesses at which failure frequently occurs. Thus, fibers have been exploited to enhance the durability of con￾crete elements. Some additional representative industrial applications of FRCs are shown in Fig￾ures 3–5. These examples are chosen to illustrate the wide range of fiber used (steel, glass, polymer, amorphous metal, carbon) and the international nature of FRC applications. 662 LI