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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 63 Abstracts search results
Document:
SP193-31
Date:
August 1, 2000
Author(s):
M. Imam and L. Vandewalle
Publication:
Symposium Papers
Volume:
193
Abstract:
The paper investigates the shear strength and the failure modes of high strength concrete beams with and without steel fibers ( fC = 110 MPa). Sixteen reinforced high strength concrete beams (3600x350~200 mm) were tested under different combinations of shear force and bending moment. The beams were singly reinforced and without shear (web) reinforcement. The test results indicated that the addition of steel fibers to high strength concrete increases the ultimate shear strength, improves the brittle characteristic and transforms the failure mode into a more ductile one. The average gain of the ultimate shear strength due to the addition of steel fibers varied from about 14% to 14 1% depending on the shear span to depth ratio and the longitudinal steel ratio. Four modes of failure of reinforced high strength concrete are clearly distinguished as; diagonal tension, shear compression, shear flexure, and flexural failure. In general, cracks in fiber reinforced concrete beams are closer, narrower, and more than those in beams without fibers. This reflects the effect of steel fibers in redistributing the stresses beyond cracking.
DOI:
10.14359/5841
SP193
Editor: V.M. Malhotra
In September 2000, the American Concrete Institute sponsored the ACI Fourth International Conference in Seoul, Korea. Sixty-two papers are included in this publication. 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. SP193
10.14359/14227
SP193-08
K. Ishibashi, M. Kanda, Y. Furukawa, and T. Mihara
Recently, various electrochemical rehabilitation methods, such as desalination, re- alkalization and electro-deposition, have been developed in order to recover deteriorated concrete due to chloride ion or carbonation, and to improve the durability of reinforced concrete structures. However, there is not sufficient information about the influence of these methods on hydration reaction of cement matrix. From this point of view, the authors studied about desalination; relationship between cumulative current and removal of chloride ion, and influence of desalination treatment on hydration reaction of cement matrix with the aid of solid-state 29Si-NMR spectroscopy. The results show that the amount of chloride removed and the charge efficiency depend on the initial chloride content and cumulative current. From 29Si-NMR analysis of specimens which were stored for 4 years after desalination treatment under condition of 20°C and 60%R.H., the ratio of higher-condensed silicates varied depending on the cumulative current during desalination. It became obvious that desalination process influences hydration re cement silicates. action of
10.14359/5818
SP193-09
T. Yamamoto
A laboratory test and a case history of deteriorated reinforced concrete slab repair are presented. Since several structural problems have been reported for reinforced concrete slabs, it is necessary to establish repair techniques for such slabs. Many structural problems of reinforced concrete slabs derive from a decline in rigidity with age. Although several techniques have been developed, their effectiveness has not been ascertained, especially over the long term. A laboratory test was conducted to ascertain the effectiveness of repair techniques. Based on the test results, the overlay repair technique was applied to actual slabs. In the case history, short and long-term performances of the repaired slabs were measured for more than 2000 days. Changes in the rigidity and natural frequency of the slabs were examined. The material properties and adhesive strength of old and new concrete were also examined. Although the static and dynamic performances of the repaired slabs improved remarkably, their performances gradually decreased with age. It is important to allow a reasonable margin of error for repairing deteriorated slabs.
10.14359/5819
SP193-10
H. Edahiro, K. Fujii, Y. Masuda, T. Kemi, T. Inoue, and H. Jitousono Keywords: concrete (reinforced); corrosion; mortar; repair
Three repair mortars were compared in terms of chloride attack preventive capability to propose an appropriate repair method applicable to the damaged concrete structure by chloride-induced corrosion. The repair methods were the cover replacement method and the surface coating method. The ability of these two methods to prevent corrosion were compared in terms of corrosion area and mass loss after 10 years’ outdoor exposure. It was proven that the cover replacement method extending over the backside of reinforcing steel using SBR polymer cement mortar with a corrosion inhibitor was effective while the surface coating method was applicable when the amount of chloride in concrete structures was excessive.
10.14359/5820
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