There are not so much reports for the research on the deterioration by freezing and thawing recycle and the compound effect on the freezing and salt attack from de-icing agent on the concrete, and the actual case of deteriorated structures. In this research, it integrated the experimental result for A: the resistance for freezing and thawing deterioration, and B: the resistance for the compound effect on the freezing and salt attack from de-icing agent on the concrete using Blast-Furnace Slag cement. As a result on A, when the air is entrained in concrete sufficiently, it is recognized the relationship between the compressive strength and scaring volume whether or no-containing Granulated Blast-Furnace Slag. In the case of containing Granulated Blast-Furnace Slag, it will be much scaring volume of concrete surface because of low compressive strength at testing. However the durability index for freezing and thawing recycle does not go down, it is considered that inside of concrete is not deteriorated. As a result on B, the deterioration for concrete using ordinary Portland cement is accelerated by compound effect, but concrete using BFSC preserves high resistance of deterioration on B.

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  It is known that a wall-type reinforced concrete pier generally has a small shear span ratio across its bridge axis; in this case, it is regarded as a deep beam. Previous studies have been proposing several formulae to estimate the shear strength of a deep beam, but the effect of cross-sectional shape and reinforcing bar arrangement specific to a wall-type pier has not been sufficiently examined. Therefore, we conducted various loading tests of reinforced concrete, focusing on the direction across the bridge axis of a wall-type pier. This paper reports the findings obtained from the loading tests, especially the process of cracking, the strain of reinforcing bar and concrete, load-displacement relationship, and shear strength.

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  For estimation of durability of concrete, it is important to understand the behavior of liquid water in micro pores. It is well-known that water permeability in concrete can be idealized by Darcy's law and water penetration is usually calculated based on the permeability coefficient. It was found, however, that there exists a non-linear relationship between permeation of water and hydraulic gradient through the Output-Method permeability test under different pressures and the friction phenomenon of water movement in fine pores was suggested. This research reveals that such static and kinetic friction behavior between micro pores and water were clarified using a molecular dynamics (MD) simulation.

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  The shear carrying capacity of reinforced concrete (RC) linear members can be increased with the reinforcement by short steel fibers. The study has evaluated the synergetic effect of steel fibers and shear reinforcing bars for the shear resistance of reinforced concrete with steel fibers (RSF) beams and columns. The experimental result indicated that the shear carried by steel fibers was not identical, and it was depending on the shape of the diagonal crack in RSF members. The paper concluded that the optimized combination of a shear reinforcing bar ratio (r_w) and a steel fiber ratio (SF) to increase the shear carried by reinforcements.

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  This paper describes the effect of cement and fine aggregate replacement of fly ash on the fresh properties and compressive strength of concrete, aiming at developing low environmental-impact fly ash concrete. In addition, the environmental impact reduction effect, such as CO₂ emission and the reduction of aggregate used, was examined. The results showed that the use of fly ash deceases the breeding and length change of concrete compared with that without fly ash, that the strength development of fly ash concrete is equal or greater than that of concrete without fly ash depending on the water-binder ratio and age, and that the fly ash concrete reduces the environmental impact in the production.

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  Since Hyogo-Ken Nanbu earthquake in 1995, seismic retrofitting of existing RC columns has been carried out. Steel jacket methods are the most commonly adopted, but these methods are not available in the RC viaducts whose columns are in contact with or used by shops, store, and houses. Therefore, we have developed a new seismic retrofitting method which can be easily applied in these cases. External lateral reinforcement is arranged around an existing RC column and anchored at the four corners of the column with L-shaped steels.
  We have carried out cyclic loading tests of columns retrofitted with this method, and confirmed that ductility is much improved.

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  Chipping finish and washing finish of concrete surface are useful to improve the appearance of concrete structures. On the other hand, durability of concrete structures is important. Therefore, it is necessary to know the relationship between these surface finishing and durability in order to apply these finishing for concrete structures under severe salt attack conditions such as coastal sutuctures. However, the effect of these surface finishing on the durability has not been clarified. The effect of chipping finish and washing finish on chloride ion penetration was investigated experimentally in this research. It was found that chipping finish and washing finish did not make the resistance to chloride ion penetration worse from the experiments. The reason may be that amount of cement paste which is the medium of chloride ion penetration at concrete surface decreases.

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  The enlargement of amount of reinforcement causes a problem that anchoring bar can not be arranged as design code provides in recent years. One of solutions for that problem will be establishment of a performance verification design method for anchoring bars. This verification method needs a local bond stress-slip model of hooked bars. The local slip of hooked bars will be affected by out-of-axis deformation of the bar. Therefore, the out-of-axis deformation and additional local slip by that deformation were investigated. The additional local slip caused by out-of-axis deformation was almost the same amount as the slip by elongation of straight bars in 90 degree hooked bar and 1.5 times of that elongation slip in 180 degree hooked bar. Total local slip just before yielding of bar was 1.8 times of the slip of straight bars in 90 degree hooked bars and 2.6 times of that in 180 degree hooked bar.

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  In this study, the experimental examinations were carried out in order to clarify the effects of the complex deterioration with both salt attack and carbonation on reinforced concrete structures built by using Ground Granulated Blast-Furnace Slag (GGBS). The results are shown as follows; 1) The progress of the neutralization can be relieved rather in the complex deterioration than in the individual carbonation condition. 2) The chloride ion penetration into the concrete is very slow not only in the individual salt attack condition but also in complex deterioration condition as compared with concrete without GGBS. 3) In the concrete with 50% of the GGBS contents, corrosion of rebar effectively reduces, while such effectiveness doesn't arise in concrete having 70% of GGBS content. 4) The rebar corrosion process in the concrete using GGBS is expected to be controlled by both the chloride content and the absolute content of Ca(OH)₂, and possibility of the corrosion initiation can be evaluated by using [Cl^-]/[OH^-] as the parameter.

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  It is important for earthquake-resisting capacity of reinforced concrete columns to improve both strength and deformation capacity. The improvement of deformation capacity by expanding plastic hinge length was attempted. The expansion of the hinge length is given by synchronizing flexural capacity with bending moment along member axis. Cyclic loading tests using two kinds of specimens were carried out. In one type of specimens, longitudinal bars were cut off within plastic hinge area. In another type of specimen, longitudinal bars were arranged at an angle for changing effective depth. From the test results, it was confirmed that the specimens with anchored cut off bar had the deformation capacity equals to the specimen without cut off bars and that arranging longitudinal bars at an angle improved the deformation capacity.

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  This paper discusses effects of reinforcing steel corrosion on structural performance of reinforced concrete (RC) structures based on experimental results. We conducted a series of full-scale cyclic loading tests on RC box-culvert specimens that were artificially corroded by stay current corrosion. As a result, the initial rigidity and maximum strength were maintained under the condition of slight corrosion. On the other hand, deformation capacity decreased with the increase of corrosion degree. This shows that the locally material deterioration has a minor effect on structural performance of RC box-culverts, which is characterized as a redundant structure.

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