Research and development regarding fiber reinforced materials (FRC) has evolved steadily with most notable progress having been made with the periodic introduction of new fiber types; including materials and form or shape. The attendant interest associated with new fibers has invariably led to an improved understanding of the mechanics of behavior of FRC and to new applications. The use of collated fibrillated polypropylene fibers (CFP) at low fiber volumes improves many aspects of the production and application of FRC including mixing and placement. Plastic state rheological and hardened state mechanical behavior are quite different from those properties which have been reported in the literature for FRC systems using rigid metallic or more brittle glass fibers and for which fiber volumes are normally about ten times the fiber volume of CFP fibers used in this research. A series of tests are designed to assess the basic properties of CFP fibrous concrete in both the plastic and hardened state. As much as possible these tests were conducted in accordance with recommended ASTM and ACI Committee 544 procedures including tests for compression, flexure, impact, split cylinder, and rebar pullout. Other specially designed tests include flexure of composite steel deck and concrete overlay specimens to affect the replacement of weld wire fabric in such applications, and shrinkage testing. Results indicate the benefit derived from the use of CFP fibers is significant as a secondary reinforcement and for crack control. A significant reduction in shrinkage is found and there are positive contributions in other strength performance areas.

A polypropylene-reinforced cement composite has been developed which is considered to be an economic alternative to asbestos-cement. A major application of the composite will be as corrugated sheeting for roofing and cladding. Comparative tests on the behaviour of full-size polypropylene reinforced cement corrugated sheet and asbestos-cement sheet under simulated uniformly distributed loads are reported. The results indicate that the new sheeting of similar profile to a typical asbestos-cement sheet profile and tested over the span recommended for the asbestos-cement profile can sustain the loads in International Standards recommendations and remain serviceable. Furthermore, the quasiductile behaviour of the sheeting and consequent excellent impact resistance are considerable advantages over the brittle behaviour of asbestos-cement.

The main purpose of this project was to explore the feasibility of using newly developed polypropylene (PP) fibers as reinforcement for portland cement concrete and to compare their reinforcing effectiveness with asbestos, glass and steel fibers. The PP fibers used were made of a high tensile strength (up to 80 ksi), high modulus (up to lo6 psi), high stretch ratio (up to 12 to 1) polypropylene ribbon yarn supplied by AMOCO Synthetic Fabrics. The fibers were cut from a continuous strand obtained by properly twisting two PP ribbon yarns together. Twisting led to a substantial increase in the bonding properties of the fibers (mechanical bond) and their rigidity considered important during mixing. Different fabrication procedures and mortar mixes are described. Salient results of an extensive series of tests on flexural beams and pull-out tests to improve bonding properties are reported. Because steel, glass, asbestos and polypropylene have substantially different specific gravities, performance com-parison is made not only on the basis of volume fraction of fibers but also weight fraction and related costs. It stresses the potential merits of using PP or equivalent organic fibers in concrete matrices and suggests exciting research directions to pursue.

Experiments concerning the bearing capacities of thin steel fiber-reinforced concrete (SFRC) slabs which are most important in using SFRC for over-lays on asphalt pavements are reported and installation operations and serviceabilities of actual overlays are described. According to loading tests, SFRC slabs with crushed-rock and asphalt-concrete bases possess bearing capacities of about 17 to 22 tons and it is thought actual traffic loads can be amply supported. Consequently, it is considered the use of SFRC immune to rutting and distortion would Drovide excellent resurfacing, smooth and durable, and economical as well. It is further shown that the "Yield Line Theory" can be applied to design of resurfacing using SFRC. Actual overlays were constructed on asphalt pave-ments in the northern city of Sapporo where extreme de-formation occurs due to wear in winter and plastic flow in summer. The overlays were of fiber contents of 2 percent and 1.4 percent measuring 3x130x0.05 and 3x200x 0.05 meters, respectively, and were among the first SRFC overlays in Japan. Until the fall of 1981 they had been in service 4 years and 2 years (5 and 3 win-ters), respectively, and worn down 1 to 2 centimeters, with a fair amount of cracks traversing the overlays. However, most of the cracks are connected well by steel fibers, while the wear is of a degree not to impede traffic. Overall, it may be judged that serviceability under traffic is good and that economic losses due to repairs of asphalt pavements at least every 2 to 3 years can be alleviated to a considerable extent.

Six two span continuous type beam-column specimens of span 1.75 m (5 ft.06.9 in.) each were tested to failure. The specimens had beam section of 150 x 250 m m (6 x 10 in.) and column section of 150 x 150 mm (6 x 6 in.). The beam section had 2 bars each of 12 mm (l/2 in.) diameter. two test specimens (Type A) were of reinforced concrete, having steel stirrups as shear reinforcement. In other two specimens (Type B) steel fiber reinforced concrete (SFRC), having steel fibers of size 25 x 0.25 mm (1.0 x 0.01 in.), 2% by weight of concrete was used throughout the specimens. In the remaining two specimens (Type C) SFRC was provided in the connection region only. An axial compressive load of 18000 kgf (40 kips) was applied to the column section by post tensioning high strength steel. Vertical load was applied to each of the beams at a distance of 1.175 m (46.26 in.) fran each end. Test results showed an increase of 19% and 9.9% in shear and moment capacities respectively of SFRC connections over that of RCC connections. SFRC connections failed in ductile mode of failure. SFRC was found to be very effective in the connection region in specimens tested for low cycle fatigue.