Thin-section fiber reinforced concrete (FRC) panels may be subjected to localized impact. In this study, thin sheet FRC materials, made with asbestos fibers in different matrixes, were tested under impact loading, using a drop-weight instrumented impact machine. The impact properties were characterized in terms of the peak bending load and the fracture energy (computed as the area under the load-deflection curve). Companion specimens were tested under static loading. The specimen dimensions were about 200 mm wide, 600 mm long, and 6 to 12.7 mm thick. In all cases, the peak bending loads were considerably higher under impact loading than under static loading; however, the fracture energies were always higher under static loading. These effects can be explained in terms of the porosity of the interfacial matrix, and the degree of bundle separation of the asbestos fibers.

Describes the investigation of a new range of cellulose fibers suited to the reinforcement of a portland cement matrix. This investigation indicated that fibers selectively derived from high-density summerwood are better suited for reinforcement than is the unmodified pulp that contains a large measure of fibers derived from springwood as well as summerwood. Another cellulose fiber material, termed expanded fiber because of its finely fibrillated microstructure, was indicated to have potential as a processing aid. Expanded fiber displayed excellent suspending and retention properties and imparted relatively high uncracked strength to finished composites. Overall, substantial performance differences were observed comparing, tests on wet versus dry specimens and the long-term durability was not evaluated. Despite these limitations, flexural stress/strain performance of the cellulose reinforced composites compared quite well to asbestos and glass fiber reinforced composites. The cellulose composites had substantially more ductility than asbestos cement; in this regard, the load-deflection curve was similar to glass reinforced cement.

Thin-section fiber reinforced concrete is portland cement concrete or mortar reinforced with dispersed, randomly oriented discrete fibers. Fibers can be metal (low carbon or stainless), mineral (glass or asbestos), synthetic organic (carbon, cellulose, or polymeric), or natural organic (sisal). Fiber lengths can range from 1/8 inch to 2-1/2 inches. Furthermore, many existing thin fiber-cement composites on the market today comprise a blend of different fiber types. By ACI's definition, ferrocement is portland cement mortar reinforced by the number of very closely spaced layers of continuous fiber networks or meshes. Ferrocement can be manufactured with any of the fiber types mentioned above, even though its name might imply steel wire meshes. ACI Committee 544 and 549 organized international symposiums to address the many thin-section fiber-cement building products available the world or under development. SP-124 contains papers presented at symposiums in Atlanta, Feb. 1989 and in San Diego, Nov. 1989. Note: The individual papers are also available as .pdf downloads.. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP124

Flexural behavior of sandwich beams reinforced with thin layers of steel-fiber reinforced mortar was studied in this investigation. The effect of variations in thickness of the reinforced layer on the modulus of rupture, Young's modulus, and toughness of the member was investigated. This investigation considered one single specimen size with fiber reinforced mortar using one fiber geometry and content. Steel fibers with 0.6 x 0.3 mm cross section and 18 mm long were used. The specimens were cast in 100 x 100 x 350 mm molds. Eight series of sandwich beams with different thicknesses of the reinforced layer were tested. Experimental results indicated that sandwich beams can have strength and toughness comparable to fully fiber reinforced beams. The minimum thickness of the fiber reinforced layer required to impart ductile behavior to the sandwich beam was found to be about one-sixth of the beam depth.

Precast thin ferrocement planks have replaced wood for a variety of applications. Present knowledge about joining them using steel bolts or similar means is very limited. While bolted connections are commonly employed in steel construction, their suitability for connecting precast reinforced concrete or ferrocement elements is yet to be fully investigated, particularly when subjected to both bending and direct tension. A series of tests were carried out at the Structural Engineering Research Centre, Madras, India, on precast ferrocement planks connected together using steel bolts for transferring tension and flexural moment