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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 56 Abstracts search results
Document:
SP138-02
Date:
September 1, 1993
Author(s):
Rajan Sen, Daniel Mariscal, and Mohsen Shahawy
Publication:
Symposium Papers
Volume:
138
Abstract:
A comprehensive durability study of S-2 glass-epoxy pretensioned beams exposed to wet-dry cycles in 15 percent salt solution indicated a complete loss of effectiveness within 3 to 9 months of exposure. Paper presents results of subsequent follow-up investigations to identify the cause of this deterioration and also to examine practical measures that could be used to prevent its occurrence. The analysis of the test results suggests that the most likely cause of failure was diffusion of hydroxyl ions from the concrete pore solution through the resin. This is supported by SEM micrographs of the failed beam. While these conclusions are valid only for the S-2 resin, diffusion is also likely to be a characteristic of other types of resins, e.g., vinylesters and polyesters. This makes long-term protection of glass fibers in concrete problematic.
DOI:
10.14359/3857
SP138-03
K. Mukae, S. Kumagai, H. Nakai, and H. Asai
Bond characteristics of FRP rod and concrete after freezing and thawing deterioration
10.14359/3858
SP138-07
Taketo Uomoto and Hosam Hosam Hodsam
The mechanical behavior and tensile strength of three kinds of FRP rods were investigated experimentally. For each material, three different fiber volume fractions were tested in axial tension. The stress-strain relationships and strength distributions were obtained. The results were correlated to the behavior and strength of the basic strengthening elements, fibers, as determined experimentally. This yielded the possibility of predicting rod modulus, but not strength, from those fibers. The strength distributions showed a shift that is not generally proportional to rod fiber content. Investigation of this phenomenon, through stress analysis at the grips and inspection of failed rods, assured the change of rod failure modes for different fiber contents. The effect of grips could lead to one of two shear failure modes instead of tension mode. Therefore, an apparent strength reduction was observed. In view of rod properties, appropriate design of the gripping system is needed to obtain the best performance of the rods.
10.14359/3859
SP138-17
Takashi Yamada, Kanji Yamada, and Kenji Kubomura
The potential of using pitch-based high-modulus carbon fiber was investigated as a reinforcement in cementitious composites for structurally reinforced concrete members. For this purpose, effects of carbon fiber mechanical properties on the mechanical properties of carbon fiber reinforced cementitious composites were studied through the three-point flexural test by using several pitch-based high-modulus carbon fiber rods of varying fiber moduli and strengths. For the specimens with a fiber volume fraction larger than the critical volume fraction, the flexural strength is found to exceed the mortar mix strength and is linearly proportional to the sum of all rod strengths, and the flexural modulus after matrix cracking is found to also be linearly proportional to the sum of all rod stiffnesses. 111-493
10.14359/3860
SP138-01
W. Reinold De Sitter and rene A. Vonk
In concrete pretensioned with nonmetallic fiber reinforced plastic reinforcement (FRPR), the Hoyer effect leads to high splitting stresses due to confinement of radial deformations of bars or strands in the transfer zone. Incompatible linear temperature expansion can aggravate the splitting stresses. Bond in the transfer zone is heavily influenced by the confined radial expansion, as demonstrated by tests with bars in lightweight concrete. Very short transfer lengths (80 mm) have been measured. Three calculation approaches for splitting stresses are presented: the elasto-plastic, concrete deformation, and fracture energy approaches. The elasto-plastic model has been checked using a discrete element model that includes tensile softening of concrete. The presented formulas are confirmed by several tests on pretensioned prisms.
10.14359/3918
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