This study aims to make predicting method of self-compactability in formworks of high fluidity concrete. Some factors which have some effects on the self-compactability, such as surface resistance on formworks, internal friction angle, resistance due to steel bars were estimated and a predicting method was constructed by combinating these effects. This method was verified experimentally and the validity was confirmed.

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Long retardation concrete setting and long slump retention, if possible, would significantly extend the applications of set-retarded concrete. With the aim of developing high-functionality concrete that retains the slump for several days and then sets quickly, the authors applied a set retarder with a high set-retarding capability and an air-entraining and high range water-reducing agent to concrete. By changing the types, combinations, and dosage of these agents, they investigated the set retardation of mortar and concrete, changes over time in the slump of mortar and concrete, and compressive strength of the resulting concretes, as well as the apparent adsorption of these agents by cement particles.

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Authors made dear that addition of a small amount of Welan gum alters the properties of concrete, e. g. improvements of self-consolidating property in the case of highly fluidized concrete. But the experimentation concerning highly fluidized concrete with Welan gum was done with using limited materials only. In this report, Welan gum's compatibilities with various superplasticizers and powders were estimated experimentally. As a result, it was found that Welan gum provides its functions in highly fluidized concrete without depending on sorts of superplasticizers and powders. And in the case of the system with using only cement i, e, the system without iron-blast-furnace slag powder or fly ash, addition of welan gum increased degree of the change as time-passing regarding the flow-property. On the other hand, in the case of the system with using iron-blast furnace slag powder or fly ash, addition of Welan gum decreased it.

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In regard to expanded polystyrene beads concrete, that is able to reduce the specific gravity of concrete evidently, this paper describes the evaluation and the countermeasure of the property of drying shrinkage, the strength property in super lightweight area, the effects and the mechanism of the compressive strength improvement by chopped carbon fiber (CF) reinforcement
As the results, it is effective in lightweight area, that the specific gravity of concrete of 1.5-2.0, to use the artificial lightweight fine aggregate, and it is effective in super lightweight area, specific gravity of under 1.2, to reinforce the mortar matrix by the CF.

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Durability design proposed by JSCE is an examination method that confirms concrete structures having enough durability during their service period. When this method is applied to design for road bridges, the influence of fatigue load must be considered. However, the method did not consider fatigue load as deterioration force.
In this paper, the influences of parameters were analyzed using Neural Network and the consideration of traffic volume as deterioration force in durability design was examined. The result shows that effect of traffic volume can be estimated quantitatively.

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This paper describes the experimental investigation on the mechanism of the dowelaction of rebars for the construction joint with smoothing surface. This test wascarried out with push-off type shear specimen to investigate the detail of sheartransfer mechanism with the relatively larger size rebars, i. e. D25 and D32. As the result, it was revealed that the shear force, which occurs mainly due to rebarsbending, exists on to local area within the distance of 5 times of rebar diameterfrom the joint surface. In addition, shear yield capacity equation based on theplastic state is proposed, and its accuracy is demonstrated.

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The use of additional cementitious materials such as fly ash or ground granulated blast furnace slag in concrete construction is almost universal. Because, fly ash can reduce the heat of hydration and cracking at early ages caused by thermal stresses. Recent few years, the quality of fly ash is fluctuated due to several reasons. It is thought that stringent quality control or quality assurance program is required to insure reliable supplies of consistent fly ash. Background of the development of the classified fly ash is to improve the quality by removing coarse particles having irregular shapes in the conventional fly ash. The main object of this study is to detail effects of the classified fly ash addition in concrete in producing high quality and highly durable concrete. Test results of a series of studies show that the classified fly ash improves properties of both fresh and hardened concrete.

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Ultimate behavior of prestressed concrete beams with combined external and internal cables is significently influenced by the ratio of internal to external cables, the range of loading, and the fixing length of external cables. Using these parameters, experimental studies were conducted and compared with analytical results. The results showed that the ultimate strength reduced roughly linearly in proportion to the ratio of external to internal cables, and the experimental behavior was well in agreement with analytical results of a frame model. However, the specimen which had very little reinforcements in tension areas was found to reduce the ultimate strength and the crack dispersion.

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This paper presents the data on the chloride-ion penetration into concretes with and without mineral admixtures under a marine environment.
From the results, it was found that concretes with mineral admixtures were much less permeable to chloride ions than the corresponding OPC concretes, and that their chloride-ion penetration into concrete was limited only in the surface of 30 to 40mm during 7 years of exposure to a marine environment. The results also showed that the coulomb values obtained from RCPT correlated well with both the diffusion coefficient for chloride ions and the depth of chloride-ion penetration after 7 years of exposure to a marine environment.

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The strength of slurry wall using high-strength concrete, increase according as depth, as a result of compression test on core boaring specimens. For making clear the phenomenon, undraind triaxial loading test was excuted, in changing the value of pressures and periods of loading. And polosity of the test pieces after pressed was obserbed. As the result, the relationship between value of pressure and porosity, as polosity and strength, be made known. And also the relationship between strength of the wall concrete and depth, was formularized.

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The disturbance degree of an acceleration wave measured on the compaction machine was evaluated by the frequency analysis. This disturbance degree decreased gradually with elapsed compaction time and then approached a constant value. The degree decreased with a decrease in the vibrating compaction value measured by a Swedish-type Vebe apparatus and with an increase in the compaction ratio, compressive and bending strength ratio and indicated number of radio-isotope density gauge in the case of compacting the concrete on the subbase with a given coefficient of subgrade reaction. From these results, it was clarified that the disturbance degree was an index to indicate progressing compaction condition. The degree measured in the both cases of laboratory and situ was pointed on the same increasing curve with an increase in the coefficient of subgrade reaction at a specified compaction ratio.

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The objective of this study is to propose the method for estimating the water retaining factor for sand and the flowing factor for sand with properties of particle size distribution and particle shape and to consider the effect of fine sand and coarse powder on the value of mortar flow. From the result obtained, it became clear that the border particle size was about 0.09mm in case of this sturdy. Considering fine sand under 0.09mm as powder, and considering coarse powder over 0.09mm as sand, the value of the calculation of the relative flow area of mortar gave good agreement with the value of the experiment.

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Field observations for different 9 kinds of pavement structure were conducted to evaluate the mitigation effect of urban thermal environment in summer. At the results, concrete pavement emits larger amount of radiation than even asphalt pavement because of its high reflectance of the solar radiation. Permeable pavement has no longer mitigation effects within several hours after the rainfall has stopped. However, soil has a high ability to maintain low temperature throughout a day with its absorptivity of the ground water. This characteristics is supposed to be essential for the development of temperature-mildening pavements.

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Generally, it is difficult to decide definite budget constraints at the starting stage of the pavement repair program, owing to its long analysis period. Further, in case of the number of projects are large, the sensitivity of the total life cycle cost becomes indistinct with the change of the budget constraints. In order to take these obscurity into consideration, in this study, we applied the fuzzy set theory to the optimization system of the pavement repair program.

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An effective method for the reinforcement of vertical construction joints in a reinforced concrete beam with steel plate was experimentally studied. The construction joints presented at the mid-shear span of a RC beam It was found that the flexural and shear strength of RC beams with construction joints that were reinforced with steel plates were similar to those for a RC beam without construction joints. In addition, the RC beams failed in bending with the tension reinforcement yielded, which was also similar to the failure mode for RC beam without construction joints. Furthermore, the thickness and width of the steel plate had effects on the behavior of RC beams reinforced with the steel plates.

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The authors have developed a strain softening type constitutive model for concrete under compression with relatively low lateral confining pressure. In the present paper, firstly the proposed model has been extended to the model which can predict the softening behavior of concrete under multiaxial stresses in tensile as well as compressive condition, by re-examining the model parameters from several experimental data on concrete. Subsequently, the proposed concrete model has been implemented in the finite element program (FEAP) and 3-D FEM parametric analyses have been performed on the confined concrete.

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The effect of a tack coat on the bond between asphalt concrete layers was investigated in the laboratory. First, the stresses at the interface caused by aircraft loads were calculated. Second, the effect of the tack coat on the bond was evaluated by examining the samples taken from in-service airport pavements where the interval between the construction of the wearing and binder courses was different. Third, an influence of factors such as adhered dirt and curing time of tack coat on the bonding characteristics was investigated. Finally, measures to ensure sufficient bonding were developed on trial; satisfactory strength can be obtained by using the newly-developed tack coat.

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The predicting model of autogenous shrinkage of concrete, which was a function of the type of cement and pozzolan, water to binder ratio and effective age, was proposed based on experimental data. Accuracy of the model was evaluated using available experimental results and comparing the existing model presented by French chapter of RILEM.

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When attempting to judge whether a concrete structure has been subjected to the influence of acid rain, it is necessary to ascertain the content of nitrogen in the surface layer portion of concrete or in calcareous deposits from the concrete. It is shown that analysis by a device for analyzing nitrogen and oxygen in ceramics is effective as a quantifying method, while ion-exchange chromatography is applicable for a first approximation.

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In this paper, strain controlled calculations in constitutive level are carved out to investigate the characteristics of the plasticity model named Unified Concrete Plasticity Model (proposed by Tanabe et al.) and modifications are proposed studying the basic characteristics of the effects of the material parameters, namely the characteristics of the variation of cohesion and friction angle with increasing damage in various stress zones in the plane of (I₁, √J₂).

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Fracture energy characteristics of concrete are investigated at early ages using a non-local gradient plasticity model. Based on previous studies a more suitable modified form of softening function to describe the strength degradation of early age concrete and a separate gradient influence factor is proposed. Using these, a numerical investigation of experiments are made on the fracture process of early age concrete with a special emphasis on analytical determination of fracture energy of early age concrete. In this regard the effects of some model parameters are studied and an equation is proposed to estimate the fracture energy in the context of the non-local plasticity formulation.

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By combining some organic compounds with the ground clinker calcined at 1200-1350°C with a composition varied in CaO-Al₂O₃-SiO₂-CaF₂-BaSO₄ system, a new type of low alkali cement hardening-accelerator has been developed. Experiments show that this accelerator can accelerate the set and significantly enhance both early and late strength of portland blast-furnace slag cement (PBSC), especially the early strength of the cement. The promotion of cement hydration, the early formation of more ettringite (AFt), the good bind among hydrates and the formation of a compact texture in the hydrate are the main reasons for the strength increment.

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This paper presents failure analysis of underground RC frames. The Hanshin Great Earthquake in 1995 brought serious damage to RC frames for subway stations. For studying the collapse mechanism of underground RC, seismic response of a subway station is simulated in using FEM program WCOMD-SJ of two-dimension based on the path dependent RC smeared crack model, soil foundation and interfacial models. The shear failure of intermediate vertical columns is found to be the major cause of the structural collapse. Further, parametric study on reinforcement ratio and foundation properties is performed for investigating seismic resistant performance for underground RC culverts.

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This paper presents a micromechanical model that is applicable to characterize the stiffness of asphalt-mineral filler mastics. By mathematically modeling the rheological response, predicting rheological behavior to asphalt-mineral filler mastics becomes simpler and more efficient in approach. The rheological properties of asphalt-mineral filler mastics are characterized using the time-temperature superposition principle after data obtained from the bending beam rheometer and the dynamic shear rheometer are converted at the same unit. According to data, the stiffening effects of the filler are relatively small at shorter loading times or low temperatures, but are larger at higher temperatures or long loading times. This stiffening effect is found to be asphalt dependent as well as filler dependent. The validity of the micromechanical model is confirmed in this study.

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