In order to keep a waterproofing function, it is important for waterproofing layer to have good adhesion Performance to concrete deck slabs. However as concrete deck slabs accept on wheel load, an adhesion performance of waterproofing layer might be influenced by bending condition of deck slabs and crack on concrete deck surfaces. Therefore, by this study, adhesion performance of the waterproofing layer on concrete deck slabs with bending conditions were examined by using FEM analysis. And also the influence of cracks on concrete deck surfaces to adhesion performance of the waterproofing layer was investigated. As a result, it makes sure that the concrete deck slabs with bending condition influence on the growing stress of waterproofing layer, and also the large stress is occurred on the waterproofing layer of an end of crack of concrete deck surface.

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In this paper, a new crack detection method in a laser image of road surface is proposed. The advantage of using a laser imaging system to extract a crack is that a laser image is free from lighting condition problem. And also a laser image has a tendency to be a low contrast image, which can be a cause of difficulty in detecting cracks. In addition to that, a crack of the road surface has wide variation in shape, depth and width. So the crack detecting method should be tolerant to low contrastness and crack variations. By introducing morphological operations, proposed method achieves high accuracy of detecting crack. And a discrimination method between linear and planar crack is also proposed.

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Now, the half cell potential method and the polarization resistance method are mainly used as nondestructive testing methods that presume the corrosion state of reinforcing steel in concrete. However, the destruction work is necessary for the two examination methods to expose edge of reinforcing steel in concrete.
Therefore, we executed the fundamental study that presumed the inner parts of reinforced concrete by using the direct current resistivity method without doing the destruction work. We made the test pieces of reinforced concrete that had non-corrode steel, corrode steel and cave, and, we experimented for inner presumption of the test pieces. Then, it has been understood to be able to presume the presence of reinforcing steel, the corrosion situation of reinforcing steel and the presence of cave from the experiment result.
In addition, we developed the three dimensional electric field program of the finite element method, and did the numerical simulation. Then, we were able to confirm our electric field program was effective to inner presumption of RC structures from the comparative study of experiment results and analytical results.

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The API-method was proposed for assessing rapidly the pozzolanic reactivity of fly ash in the last study. However, there was either high positive correlation between the API-value and mitigating ASR effectiveness of fly ash, i.e. the higher API, the higher mitigation effectiveness. The API was estimated as a generic index including the effects of chemical and physical properties of fly ash. In case of using Pyrex glass aggregate, the main chemical components of ASR gel produced on the aggregate were almost the same without relating to the fly ash usage, i.e. Na₂O/SiO₂ and K₂O/SiO₂, thus the ASR mitigation was estimated to be derived from inhibition of producing ASR gel.

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In order to estimate the seismic safety of existing arch dams, it is essential to assess the static behavior and the mechanical resistance of arch dam. Numerical analysis model for transverse joint of an arch dam is developed considering the opening, shear slip and re-contact behaviors of transverse joints. The static behaviors of an arch dam under annual change of temperature and water level were calculated by using three dimensional finite element analysis method that incorporated the developed numerical analysis model of transverse joint. The displacement of the dam body was compared both in analysis and in measured data. At a result, the calculated results can give a good estimation for dam deformation of an existing arch dam caused by those loads. In addition, “arch effect zone” was developed under separation and sliding on transverse joints. Thus, the nature of load capacity mechanism was identified.

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A pavement using the cement treated soil is usually used for a pavement of park etc., which consider well matched landscape. However, the cement treated soil pavement has the long term durability problem (abrasion, crack etc.) of the changing of weather or the use method in order to set up the low rigid as compared with the asphalt pavement.
The purpose of this research is the laboratory tests and site investigations were carried out to investigate the durability of the cement treated soil pavement materials. In the site investigations, we investigated the cracks, the surface friction properties and the elasticity of 36 sites. In the laboratory tests, we performed Unconfined compression tests, Cantabro tests and Rotation abrasion tests. The results of laboratory tests and site investigations showed that the long term durability of the cement treated soil pavement materials is influenced by the cement volume, the surface coating and the use method.

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In reversed cyclic loading tests, SRC columns with a large amount of H-shaped steel are known to have excellent ductility after the spalling of cover concrete and the buckling of longitudinal bars. However after the local buckling of H-shaped steel, SRC columns are brittle fractured caused by the cracks. A ductility evaluation of SRC columns focused on the local buckling of the H-shaped steel has been suggested, because the crack of H-shaped steel is caused after the local buckling. In this method, the ultimate strain of flange plate has been formulated considering the concrete fixing. Moreover, the ultimate displacement of SRC columns are calculated by integrating the curvature. After comparing with the results from FEM analysis and experimental tests, it has been confirmed that the same response can be obtained by using proposed method to calculate the ultimate displacement, the buckling length and plastic length of flange plate.

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The purpose of this study is to evaluate the practical use of a concrete using high volume fly ash as a part of fine aggregate. In this study, the concrete was made at ready-mixed concrete plant, and the properties of concrete were measured at the process of pumping, placing and three years exposure of large specimen under marine environment. As the results from the full-scale construction field test, the following conclusions were obtained: The workability of the fly ash concrete are similar to that of normal concrete by considering the increase of viscosity with fly ash. The long-term strengths of this concrete are increased. The resistance of carbonation and the chloride ion penetration of this concrete are improved.

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The purpose of this study is to develop a method for quantification of concrete degradation and evaluation of freeze-thaw resistance using X-ray technique with contrast medium. Firstly, the X-ray technique with contrast medium was carried out for AE concrete specimens in which fine cracks had occurred by a freezing and thawing action. Detection of fine cracks in this AE concrete specimens and the quantification of the concrete degradation was carried out. Next, the same method was carried out for specimens of mortar, Non-AE concrete and AE concrete, to examine the relationship between the radioparency dosage and the resistance to freezing and thawing. In addition, this method was carried out for the structure to quantify the concrete degradation and to evaluate the freeze-thaw resistance.

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One comprehensive numerical simulation system is proposed for solving the problem of steel corrosion in concrete related to deterioration of reinforced concrete structures under the environment contaminated by chloride ions. Distribution of corrosion amount and corrosion rate along a reinforced bar is calculated based on macro-cell circuit model, which is constituted from micro-cell circuit model. Models are quantified by results of exposure experiments to two environments, one is cyclic wetting and drying in laboratory and the other is splash zone at offshore. The comparisons on time-dependent half-cell potential, corrosion location and corrosion amount indicate the quality coincidence between experimental and analytical results. Examples of calculation on macro-cell corrosion generated between patched area and non-patched area are shown.

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Corrosion of reinforcing steel leads to cracking of concrete and subsequent loss on the load-carrying capacity of a reinforced concrete member. This study was conducted to evaluate the relationship between the degree of corrosion of steel bars in concrete on their mechanical properties. The steel bars used for tests were collected from the railway reinforced concrete viaducts deteriorated by carbonation and mixed chloride. The results indicate that the degree of reinforcement corrosion influences their mechanical properties. Futhermore, their mechanical properties of corroded reinforcing bars can be calculated from minimum reinforcing steel diameter measured on site.

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This report is the marine atmospheric exposure test result of various coating systems for 20 years at the marine exposure place inside the SURUGA BAY. This place is one of the international joint atmospheric exposure test grounds adopted in ISO/TC156. It has been proved that the heavy duty coating system which used fluoro resin paint as a top coat and high build type zinc rich paint as a primer has good corrosion protection and good weather resistance from the exposure result for 20 years. However, there were some parts which were generating rust in the edge also by this coating system. It has been recognized that protection processing of edge part is important.

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Shear resistance of deep beams with a small shear span ratio and containing shear reinforcement was studied by conducting vertical loading tests on simple beam specimens. Parameters used were the shear span ratio (a/d), shear reinforcement ratio, and effective depth. It was found that the fracture mode of beams with a/d=1.5 is different from that of beams with a/d=0.5 and a/d=1.0, and that shear reinforcement can provide sufficient shear resistance by controlling the crack width effectively.

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The effectiveness of grooving, in which transverse grooves are formed on the surface to increase the skid resistance, is reduced with the deficiency such as the collapse of the grooves due to heavy aircraft loads. As aircraft become larger and operation frequency increases, the grooves suffer deterioration such as loss of groove volume at high temperature and wearing of asphalt concrete at low temperature. To investigate the durability of the grooving against heavy-duty aircraft loads, a series of laboratory tests was conducted. As a result, modified asphalt is recommended for both new construction and overlay construction. Straight asphalt is, however, applied to overlay construction when a longer period is secured before groove installation.

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It is necessary to quantitatively evaluate effect of repair works to deteriorated structures to do the effective maintenance management. A basic examination has been executed about the effect of repair for each method. However, due to lack of accumulation of actual data concerning re-deterioration after repairing, quantitative evaluation of the effect of repair is not realized yet. In this research, a calculation model to quantitatively evaluate the effect of repair works to concrete structures damaged by chloride attack was examined against surface protection method and patching method. Based on the actual data collected from existing concrete structures repaired by surface coating method or cross-section recovery method, chloride-preventive property of each coating material was analyzed to achieve quantitative evaluation of the effect of repair. Furthermore, the method of quantitatively evaluating the effect of repair was proposed to calculate chloride concentration inside repaired concrete structures.

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The fire resisting performance of shield tunnel without secondary lining is examined. Fire tests under RABT curve are executed by using the full-scale RC segment specimen. The characteristics of the spalling are affected by the stress conditions of the concrete. Therefore, the design load for the crown (sagging moment) or spring line (hogging moment) of actual tunnel is introduced into the specimen.
It pays much attention to detect explosive spalling and thermal deformation behavior of the specimen during the test. The thermal deformation of the sagging specimen with insulation is small and the damage is hardly caused in the concrete surface.
Severe explosive spalling occurs in the hogging specimen without insulation. Thermal deformation of the specimen is also very large, even in this case the specimen can maintain the design load and it would not have resulted in collapse of a tunnel. No explosive spalling occurs in the both hogging and sagging specimens with polypropylene fiber. The rebar temperature of the specimens remains low, and the deformation are also relatively small.
It is confirmed that the polypropylene fiber can be expected enough load bearing capacity though its effect is not as pronounced as with the insulation.

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The purpose of the present study is to obtain failure behavior and shear strengthening effect of concrete element with carbon fiber sheet. Firstly, newly middle size machine for strengthened concrete was developed by following the fundamental structure of the previous machine. The experimental parameters were mainly the angle of fiber to direction of principal stresses and elasticity of fiber. The experimental results present that the failure mode and the effect of shear strengthening concrete is different by arrangement of carbon fiber sheet.

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The authors defined the percentage of the amount of water in mortar bled by centrifugal force divided by powder volume as “WcsP” and could succeed to definitely derive the new index of free water for fluidity as “WfP”. Then, by using the index “WfP” that also indicates the space between particles, the categories of flocculation states of the particles and frictions among them were investigated based on the relationships between “WfP” and conditions on mix proportion, such as SP/C or Vw/Vp, and between “WfP” and viscosity of mortar. This study clarified the followings: (1) The flocculation states are classified into three categolies, such as the strong flocculation region, transient one and dispersed one according the dosage of superplasticizer(SP). (2) Flocs have two types of friction; one is “friction between the surfaces of flocs”, which influences on the deformability of mortar, and the other is “friction inside of a floc”, which influences on the viscosity of mortar.

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This study discussed the amount of free water in mortar, which can be regarded as an index of the space between particles and/or flocculations. Firstly, the authors defined the percentage of the amount of water in mortar bled by centrifugal force to powder volume as “WcsP”. Then, the relationship between “WcsP” and the deformability of mortar “Γm” was deeply investigated. Consequently, this study clarified the followings: (1)A focal point exists among the linear relationships between “WcsP” and “Γm” of mortars having various dosages of superplasticizers. In mortar on the focal point, free water acting upon the fluidity is zero. (2) It indicates that on this focal point, the free water is null and the difference in “WcsP” from the focal point can be regarded as a new index of free water for fluidity.

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To discuss effectiveness of epoxy-coated reinforcing bars (ECR) in existing concrete structures, reliable datasets from numerous performance investigations of ECR carried out in North America were re-analyzed from a viewpoint of the chloride threshold level for corrosion of ECR. It was found that corrosion of ECR in bridge decks suffering deicing salt depended on the chloride level in concrete around ECR regardless of concrete cracking and disbondment of coating, and that the chloride threshold level for ECR was larger than that for black steel. In addition, it was recognized that a large amount of chloride ions existed at ECR, whenever corrosion cases of ECR were observed in early-deteriorated bridge piers at coastal areas in Florida as well as the bridge decks. This paper recommends that even when using ECR at coastal areas, chloride level in concrete at ECR should be kept below the threshold level for ECR.

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The purpose of the present study is to investigate strain properties of expansive concrete in early age. The experimental parameters were mainly dosage of expansive admixture and environment in order to obtain each strain, i.e. expansion and shrinkage. This paper presents strain properties of expansive concrete by using the superposition method. The experimental results showed that expansions were hardly influenced by the environmental condition, and that drying shrinkages of concrete with or without expansive material were almost equal. Based on such obtained characteristics, strain behaviour of early-aged concrete with expansive material can be evaluated by superposition of expansion and shrinkage.

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