Micro-structure of concrete changes due to carbonation and the change in micro-structure affects properties of concrete. An accelerated carbonation test and a wet-dry test were performed, considering water-cement ratio and initial curing condition, to investigate the change in microstructure of mortar; the depth of carbonation, the amount of calcium hydroxide and calcium carbonate, pore volume and pore size distribution and the weight of mortar were measured.
The change in pore volume and pore size distribution due to carbonation depends on water-cement ratio and initial curing period. Pore volume in the carbonated portion is decreased in the case of the continuous carbonation test. Denseness of structure induced by carbonation controls a subsequent carbonation process.

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This paper describes a method for evaluating a structural capacity of an asphalt pavement with falling weight deflectometer deflection data. A back-analysis was used to estimate in situ elastic moduli of a granular subbase and a subgrade in the pavement. A tensile strain at a bottom of the asphalt layer and a compressive strain in the subgrade surface under the standard wheel load were calculated with the BISAR. A number of allowable loading repetition corresponding to the tensile strain and the compressive strain were estimated with an asphalt strain criteria and a subgrade strain criteria obtained by many researchers.
The asphalt strain criteria was very useful imformation for a theoretical design method on asphalt pavements and overlay design, because there was a correlation between the cracking data and asphalt strain criteria in the national highway 337.

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Concrete structures are damaged by the corrosion of reinforcing bars due to chlorides in concrete, when cover thickness is not sufficient, or when the quality of concrete is poor.
Therefore they often need repair even at early stage of their life span. This paper described that coating of concrete surface with a corrosion inhibitor, which spreads into concrete by diffusion, is an effective repair method. In this study, corrosion tests were conducted taking such factors as NO₂/Cl^- ratio and NO₂^- diffusion.

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The distributions of water content within mortar specimens were observed when water moved in one direction under three environmental conditions, namely drying, moisture absorption and water absorption. Numerical results were compared with the experimental data in order to examine whether the diffusion theory with non-linear equation is adequate for description of the behavior of the water movement. From the comparison, it is concluded that the diffusion theory is applicable to the above three conditions when diffusion coefficients and boundary conditions are suitably chosen. The mechanism of water movement within mortar is also discussed.

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Adequate methods for evaluating the fineness of ground slags were sought using various slag samples which were prepared by grinding three granulated slags by either a jet mill or ball mill to about 3000-8000cm²/g Blaine surface. It was confirmed that the conventional Blame air permeability method could be employed to evaluate the relative fineness of ground slags, provided that their raw materials and grinding mill were maintained the same. A proposal was made to select the amount of sample for the Blaine method in such a way that its sample bed could be formed with a force of 3-5kgf. As an index for evaluating the fineness of all kinds of ground slags, the specific surface areas calculated from their particle size distributions, which were analyzed by a laser-beam method, were considered to be most appropriate.

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The standard microscopic technique for the characterization of air-voids in hardened concrete is a method according to ASTM C 457, but it is a time and effort consuming process, Recently, a technique using an image analyzing system has been developed for reducing the time and effort to measure. However, the specimens for the analyzing system have to be given surface treatment to distinguish the air-voids in cement paste matrix.
This paper describes a technique of the new automatic quantitative image analyzing system using a difference of intensity of illumination for the non-treatment surface specimens. The surface of the specimen has light coming from three directions for the stereo analysis. The time required is about one hour to measure the air-void system of a 10cm square specimen.

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An analytical method for reinforced concrete plates subjected to biaxial bending moments was prposed in this study. This method divides an original plate into two discrete layers of tension and compression zones. These layers are treated as reinforced concrete plates subjected to membrane force.
In the analysis of the tensile layer, tension stiffening of concrete and shear transfer along the surface of cracks were incorporated. Considering the effect of two-way cracks, the capacity of interface shear transfer was reduced according to the ratio of principal moments.
Moreover, the apparatus for experiments of biaxial bending was newly developed to obtain the accurate test data.
The agreement between analytical results and experimental ones was fairly well and the proposed analytical method was found to be useful to estimate the behavior of reinforced concrete plates subjected to biaxial bending moments.

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Analytical studies on the mechanical behavior of reinforced concrete linear members subjected to torsion were carried out. The characteristics of the employed analytical method were to assume the original solid section of a member to be equivalent to a hollow one and to convert the applied torsion into a uniform shear flow. Concerning the stress-strain relation of concrete, the softening, the tension stiffening and the shear transfer along cracks were considered. The effect of the local yielding of reinforcement was also incorporated into the analysis. As a result of verification, it was admitted that the ultimate strength and general deformation behavior of reinforced concrete linear members subjected to torsion could be predicted fairly well by the proposed analytical method.

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The techniques for pavement evaluation and overlay design require a reliable structural evaluation procedure. This paper describes a methodology for evaluating in situ material properties from deflection data measured at some points on pavement surface. It is assumed that pavements can be modeled as a multi-layered systems and hold the theory of linear elasticity. In situ Young's moduli of layers are treated as unknown parameters but Poisson's ratios and thicknesses are known. An iterative estimation algorithm is developed based on Gauss-Newton method, which has been a powerful tool to solve a non-linear least square problem. This paper also demonstrates that the presence of a rock layer can lead to a significant overestimate of subgrade Young's modulus if a semi-infinite subgrade is presumed for the analysis of pavement systems.

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The finite displacement theory considering the effect of shear deformation is formulated. In this research, the computer program using the stiffness equation of reinforced concrete structures has been developed for the ultimate deformation analysis under cyclic loadings. Cyclic loading tests of reinforced concrete columns under axial force was carried out and the applicability of this theory was investigated. The experimental values obtained from specimens in which axial force, web reinforcement ratio and a/d were changed are compared with the calculated values. It is possible to predict the flexure or shear failure theoretically, when the instability of structures is considered.

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The main purpose of this study is to suggest an efficient method for quality control of concrete. In terms of the mix design, the estimating method of compressive strength of concrete is investigated at the stage that mix proportion conditions of production conditions in the materials to be used, batching, mixing and transportation are known (at the stage before mixing or that of fresh concrete).
Through a lot of date analyses of investigation results of concrete tests, it became evident that compressive strength of concrete is greatly influenced by unit cement content, unit water content and other factors. And the estimation equations of compressive strength of concrete were proposed.

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The object of this study is to develop an evaluation system for managing asphalt pavements based on Markov chain model. Deterioration process, reliability, effects of rehabilitation, and steady state probability of asphalt pavements can be evaluated by this system. In this paper, the Markov chain model methodology is explained, and the application of this system to actual asphalt pavements in Tohdku district is described. As the results, transition matrices for asphalt pavement performance are obtained, and the effects of rehabilitation are estimated quantitatively by this system.

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Two types of tests of fibers were conducted to investigate the deterioration mechanisms of conventional fiber reinforced concrete due to corrosion. The results of accerelated corrosion tests indicated that severe corrosion would result in a significant reduction in minimum fiber diameter, leading to a noticeable reduction in peak stress and a dramatic reduction in toughness whether the specimens were tested in tension or bending. Results from the accerelated exposure tests of fibers showed a behavior similar to the accelerated corrosion tests. To assess the results obtained from the experimental program, two analytical evaluations (Approximation method and Non-linear numerical analysis) were conducted. Both methods supported the experimental observations that deterioration of stress-strain response in the tension zone of flexural specimens leads a moderate reduction in peak-load and dramatic reduction in toughness.

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Studies were carried out to investigate properties of anchorage failure and group effect of deformed tension bars embedded in a massive concrete block. Pull out test specimens, one or several reinforcing bars were embedded in massive concrete blocks, were used for this experiment. As the results of this experimental studies, it is found that the anchorage strength of a bar embedded with other bars at close spacing in massive concrete are decrease up to 50% compared with those of a bar embedded independently or at wide spacing with other bars. A theory to calculate the anchorage strength of bars in a group is proposed.

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Structural deterioration of concrete pavements is mainly caused by fatigue cracks. Hence, the purpose of thickness design of concrete pavement slab is to prevent the fatigue cracks during its design life. Since, the development of the fatigue crack largely depends on traffic load repetitions, wheel passage placement, dimensions of concrete slab and load transfer device at transverse joint, these factors should be taken into consideration in the thickness design of concrete pavement slab. In this study, a evaluation system of the fatigue cracks of concrete slab was developed based on the FEM analysis incorporating a distribution model of wheel passage derived from the measurements at several roads. The relationship between the placement of wheel passage and the structure of concrete pavement was studied by this system.

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The AE signals were detected in concrete specimen by means of Acoustic Emission Method during heating or cooling of concrete. The temperature when the first AE signal is detected, is lower than that when the dehydration of moisture in concrete takes place. This result suggests that the reason for the change of property of concrete subjected to high temperature cannot be explained only by the dehydration of moisture in concrete. It is the purpose of this paper to point out that the microscopic cracks are developed by the microscopic thermal stress due to the difference between the thermal expansion coeffcient of mortar and coarse aggregate. From the experimental results, it was proved that the mechanical properties of concrete subjected to the high temperature are influenced by the generation of microscopic stress and the formation of crack.

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The purpose of this study is to determine an optimum yield seismic coefficient based on probability theory. RC structures are represented by a single-degree-of-freedom system with a degrading tri-linear model. Yield seismic coefficient and yield period are chosen as structural parameters, which are treated as deterministic. Frequency and magnitude of earthquake, attenuation equation and reflection of local site condition are considered to involve uncertainties.
Ductility factor is taken as a measure for damage of structures. Dynamic analysis is performed on each set of structural parameters to obtain ductility factor. Then optimum yield seismic coefficient is determined so as to minimize expected total cost.

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Under low temperature, some concrete structures suffer serious deterioration. This may be due to the ice formation in concrete micropores, which causes microcracking and induces volume changes of concrete. Based on this observation, we investigated deterioration of concrete subjected to cyclic cooling and heating of various temperature ranges. The two major findings are: (1) residual strain of concrete is in good correlation to its relative dynamic modulus of elasticity and (2) there are well-defined temperature ranges which determine the progress of deterioration. Qualitative and quantitative analyses will be made on these observations.

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A procedure to determine crack width of RC structures, which are required to repair, is presented based on a questionnaire to professionals. Questions are asked on the following items; (1) depth of crack, (2) classification on crack pattern, (3) cover of reinforcement and (4) environment conditions. Distribution of crack width judged unnecessary to repair is defined by f_a(W) and that necessary to repair by f_b(W). Then distribution of certainty for repairing f_c(W) is introduced. Delimitation of crack width whether or not to require repairing is determined by the distribution of certainty and loss function. The loss function depends on an importance of RC structures, for which analytic hierarchy process is introduced to decide.

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The dowel bars play an important role in load transfer at the transverse joint of concrete pavement. However they are often deteriorated by fatigue due to traffic load repetitions combined with corrosion of the bars and weakening of concrete around the bars. It is because mechanical behavior of the dowel bars is not well known and the dowel bars are not used most effectively. In this study, a mechanistic model of the dowel bar incorporated with FEM analysis is developed. Then, the model is verified by analyzing the experiments conducted for the research of the behavior of the dowel bar under the traffic load.

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Plain concrete cylinders were subjected to the temperature gradients from inside to outside surface. The gradients were gradually increased with time. In order to investigate the cracking behaviour of the cylinders, acoustic emission count, outside surface strain and crack formation process were observed. The temperature gradients corresponding to crack formation were larger than the predicted one from elastic solution. The results obtained from finite element analysis suggest that the above behaviour is mainly affected by stress relaxation and Young's modulus descent. In almost of all cases, the twin cracks on opposite side of the cylinder were found. The formation process of the twin cracks can be partially explained from the calculated distributions of stress and displacement.

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Three dimensional deflections of a concrete arch dam due to solar heat in a daytime on March, July, and November were measured by the system consisting of two sets of theodolite with the launcher of a laser and the device which receives the laser. The thermal analysis using finite element method has been conducted to compare the measured deflections and estimate the behavior of arch dam by solar heat. It has been cleared that the obtained results from the thermal analysis estimate the behavior of all over the concrete arch dam with enough accuracy.

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A moving speed and a wheel load of an aircraft are important factors of airport pavement structual design. The wheel load is a combination of the type of the aircraft, gross weight and tire pressure. The moving speed and wheel path distribution pattern varies by the type of the airport pavement. An equipment was developed to measure the speed and the wheel path distribution of large type aircraft on the taxiways in New Tokyo International Airport. The equipment consists of three sets of laser beams. Two sets of the laser beams are installed in parallel crossing the taxiway. One laser beam is installed at 45 degree angle to the center line of the taxiway.
The observed mean speed of aircraft was about 40km/h. The Two-parameter logarithm normal distribution can be used to plot the speed distribution.
The distribution of offsets of the aircraft center from the center line of the taxiway can be expressed as the normal distribution. It was observed that the wheel path maximum offset of the main gear was 10m from the center line of the taxiway.

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On the basis of experimental results, the study shows that the use of dynamic modulus of elasticity and ultrasonic pulse velocities is not valid for judging the quality of concrete in which alkali-silica reaction has occurred. As alkali-silica reaction progresses, the constitution of concrete gradually changes in respect to the proportions of crystalline and noncrystalline materials by the latter becoming greater. It implies that concrete become more viscous. Because of this, it is concluded that dynamic modulus of elasticity and ultrasonic pulse velocity are very insensitive indicator of the level of deterioration of ASR affected concrete.

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Reinforced concrete beam specimens with the polymer modified mortar linings using a mixture of acrylic and epoxy emulsions are prepared, and exposed to a severe marine corrosion environment, where the beam specimens are continuously subjected to seawater splashes, for five years. The chloride shielding performance and durability of the polymer modified mortar linings are examined through five-year exposure by chemical analysis and EPMA area analysis. It is concluded from the test results that the polymer modified mortar linings possess an excellent chloride shielding performance and durability because of the effective 3-layer lamination of the polymer modified mortar.

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The thermal analysis of a large scale concrete structure subjected to solar radiation heat was carried out. The heat input caused by the solar energy has been formulated considering the shading effect of surrounding obstacles. In the thermal analysis, the newly developed shape function has been incorporated. FEM analysis using this shape function can predict measured temperatures of a large scale concrete structure fairly well regardless of considerably rough discretization. Finally the deformation of the structure due to temperatures was calculated and compared with measured deformation.

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Reinforced concrete simple beams without shear reinforcement were tested under a static load, a repeated load on a fixed point of a beam or a running load on a beam. The dimensions of the beams were 5cm wide and 8cm high. They had four variations of spans from 40 to 100cm. A significant reduction of the fatigue strength was observed under a running load. A running load seemed to give wide or alternative stress amplitude to the beams and to give the beams more serious damage than the load on a fixed point.

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The aim of this research is to clarify the deformational compatibility for dense aggregate phase of concrete in tapered portions of pipe lines used for concrete pumping. The deformational compatibility, which describes the relationship between the strain rate of aggregate phase (particle assembly) developing over a reference section and sectional mean flow speed of the particle assembly, is indispensable for self consistent one-dimensional computation of dense liquid-solid flow. Visual test and image processing on model concrete under simplified flowing conditions were carried out for development of the mathematical description for deformational compatibility of aggregate phase, in which the second invariant of aggregate phase strain was adopted as a main parameter associated with stress generation due to particle-to-particle interactions. In relating sectional averaged invariant of strains to the mean flow speed of solid phase, dimensions and shape of the pipe, the authors proposed a simplified compatibility, reduced to onedimensional condition, applicable to dense liquid-solid flow in straight and tapered sections of pipe lines.

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Cracked reinforced concrete subjected to the non-proportional membrane forces exhibits complex displacement characteristics such as both normal and tangential displacements at cracks of several different orientations. In this paper, a constitutive equation to describe the behavior of these displacement fields are constructed as a mixed model which is a combination of some basic displacement fields using the concept of the damage mechanics. The model can satisfactorily solve the nonlinear behavior of cracked reinforced concrete which includes compressive resistance of concrete parallel to cracks, tension stiffening, and shear resistance of concrete and the dowel action of reinforcement on the crack plane and is formulated so that the material stiffness is directly applicable to nonlinear FEM analysis. Its applicability is illustrated by prediction of some experiments.

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Nondestructive evaluation method of concrete pavement using deflections measured by a Falling Weight Deflectometer (FWD), has been developed. In this procedure, the mechanical properties of a concrete slab and foundation can be obtained by backcalculating from the FWD deflections measured at the slab center. Load transfer efficiency at a joint can be quantified from the FWD deflections measured at the joint. Furthermore, a void beneath the concrete slab can be detected and its size can be estimated. The time when the FWD measurement should be conducted is specified to minimize the influence of a vertical variation of temperature in a concrete slab.

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In order to investigate the relation between the expansive pressure and the growth of cracks due to corrosion of reinforcements, an elasto-plastic finite element analysis by introducing the volumetric strain and an accelerated galvanostatic corrosion method were carried out on a section of RC beams.
Results were summarized as follows;
(1) During the growing of cracks among reinforcements, the expansive pressure becomes gradually higher.
(2) During the growing of cracks toward a surface of cover, its pressure is on the decrease with lowerings of stiffness.
(3) After the cracking of cover, the expansive pressure is about 100-120kgf/cm² in spite of the expansion of corrosion products.

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