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International Concrete Abstracts Portal

Showing 1-5 of 20 Abstracts search results

Document: 

SP81-17

Date: 

November 1, 1984

Author(s):

Shiro ibukiyama, Kaoru Seto, and Shuichi Kokubu

Publication:

Symposium Papers

Volume:

81

Abstract:

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.

DOI:

10.14359/6459


Document: 

SP81-16

Date: 

November 1, 1984

Author(s):

Robert G. Packard and Gordon K. Ray

Publication:

Symposium Papers

Volume:

81

Abstract:

The performance of most of the fiber-reinforced concrete pavement projects in the United States (34 projects built since 1971) are reported. These include experimental street and highway projects as well as more recently constructed fullscale airport pavements. While a few have performed well, many have developed defects early in their service lives. The lessons learned should help engineers to design future projects that will provide better service. Careful consideration, and perhaps additional research, is needed in the areas of joint design and spacing, load transfer at joints, fiber content, and thickness design.

DOI:

10.14359/6458


Document: 

SP81-18

Date: 

November 1, 1984

Author(s):

Antoine E. Naaman, Surendra P. Shah, and James L. Throne

Publication:

Symposium Papers

Volume:

81

Abstract:

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.

DOI:

10.14359/6460


Document: 

SP81-14

Date: 

November 1, 1984

Author(s):

David R. Lankard and Jeffrey K. Newell

Publication:

Symposium Papers

Volume:

81

Abstract:

Steel fiber reinforced concretes (SFRC) are typically prepared by adding the fiber along with the other concrete ingredients in the mixing operation. Using this "premix" approach, it is possible to incorporate up to about 265 lb/yd3 (2 volume percent) of fiber into the concrete. At fiber contents in excess of 2 volume percent, the SFRC becomes difficult or impossible to mix and place. Inasmuch as the improvements in concrete properties attributed to the fibers increase as a function of increasing fiber content, this situation places a limit on the ultimate property development in SFRC prepared using the premix approach. Recently, a procedure has been developed wherein steel fiber contents up to 18 volume percent have been provided in SFRC composites. The engineering properties of these highly reinforced composites are discussed along with a number of successful applications.

DOI:

10.14359/6456


Document: 

SP81-08

Date: 

November 1, 1984

Author(s):

S. Hasaba, M. Kawamura, T. Koizumi, and K. Takemoto

Publication:

Symposium Papers

Volume:

81

Abstract:

This paper reports a few results of the experiments carried out in order to investigate the characteristics of deflection of the polymer fiber and the hybrid fiber reinforced concrete beams under bending load. Some results on the dynamic strength test for the polymer and hybrid fiber reinforced concrete beams by a Charpy impact tester modified for concrete specimens are also refered in this paper. The polymer fibers used in polymer fiber reinforced concrete are generally filaments with extremely small diameter. The fibers used in this study are relatively thick with the rectangular cross section of 2 by 0.6 mm. From these experiment, it may be found that the flexural strength of concrete is improved by the addition of the polymer fibers. The polymer fiber reinforced concrete beams showed great endurance after the initiation of cracks in the specimens. A method by a modified Charpy impact tester was proposed in this study for evaluating the resistance of concrete against impact load. According to the results obtained using this method, the resistibility of the polymer and the hybrid fiber reinforced concrete against impact load is about double that for fiber-free concrete.

DOI:

10.14359/6450


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