This paper examines gel of grout by using powder X-ray diffraction. As a result, it was clarified that the silicate gel of all grouts used in this experiment is amorphous. Further, colloidal silica sol grout, that increases in strength with age, was examined for the gel material changes over a period of 7 years. As a result, silicate gel of colloidal silica sol grout remained amorphous material regardless of age. Also, the relationships between chemical structure of gel and freezing and freezing-thawing behaviear of grouted sand strength was examined. Freezing-thawing grouted sand with organic grouts had almost the same strength as before freezing.

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The estimation method for the dead load stress in a member of concrete structures is developed. Stress is estimated from strain obtained by strain releasing method and Young's modulus measured by ultrasonic pulse velocity. FEM analysis and experimentation examined the method.

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The demand for the diaphragm wall to use as a permanent structure has increased due to its durability and water tightness. However, there has not been enough a study on the thermal crack control of the diaphragm wall for the heat hydration.
This paper proposes the simplified method to evaluate the thermal crack on the diaphragm walls. This method based upon the studies on the ground restraint and several factors influencing the degree of restraint and equivalent temperature drop of the diaphragm wall. It is shown that when thermal crack index is over 1.5, the thermal crack density that is crack length of unit area of element, is small. The thermal crack index is applicable to the evaluating method of thermal crack on diaphragm wall. The result verified the method has relatively well accuracy in the evaluation.

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In this paper, an elastic spring model considering the adhesion of lorngitudinal strand is presented for estimating the drying shrinkage crack width of the concrete reinforced with the grid-type continuous fiber reinforcement.
The strains of reinforcement and the crack width in concrete are estimated by the proposed model and satisfied agreement with measured one was obtained.

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Continuous fiber reinforced plastic rods (CFRP rods) have different tensile rigidity and bond characteristics from ordinary deformed steel bars. Then for verification of the serviceability limit state of concrete beams reinforced by CFRP rods or by combination of CFRP rods and steel bars, it is required to develop an effective method for evaluation of the flexural crack width and deflection of such beams. As for the flexural crack width, introduction of the bond strength ratio of CFRP rod to steel bar makes it possible to extend the authors' proposed equation for multi layered longitudinal reinforcing steel bars to the beams reinforced by CFRP rods as well as the beams with combined use of CFRP rods and ordinary steel bars. Deflection of such beams proved to be estimated by the Branson's equation with pertinent modification of the moment of inertia of member cross section.

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The frictional characteristics between a metal material used in RCC spreading-pavement machine and a fresh roller compacted concrete were investigated experimentally and also their dynamic interactions were studied theoretically. The influence of the retention time and the sliding velocity on the frictional force, the adhesion and the coefficient of the friction were investigated.
As the results, it is clarified that the coefficient of the dynamic friction takes a minimum value at 4, 5cm/s sliding velocity and increases with the increment of the retention time, and the dynamic adhesion increases with the sliding velocity but decreases with the retention time.

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The mathematical model of relationship between crack width and corrosion products is proposed in this paper. Corrosion products obtained from this model are governed by thickness of concrete cover, diameter of reinforcement and crack width. Coefficient α_n is obtained to coincident with results of existing galvanic corrosion test and proposed model. According to results of inverse analysis, α_n=0.114 is determined. Proposed model is useful to estimate corrosion rate of reinforcement from crack width due to chloride deterioration in situ.

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The aim of this paper is to propose a model for simulating the chloride ion movement at the surface layer of hardened concrete. The model is to be combined with the analytical method for movement of chloride ion in hardened concrete to construct a complete model which is applicable to different environmental condition. Regarding the chloride ion movement at the surface layer, two models are introduced. One is the surface condensation model, that explains the phenomenon of higher chloride ion concentration in the surface layer than that of the submerged environment, by the concept of quasi-adsorption. The other is the cyclic wetting and drying model that explains the mechanism of chloride ion migration into concrete by the concepts of capillary suction and evaporation.

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The purpose of this study was to investigate the influences of surface microcracks on durability of steam cured concrete products. First, the characteristics of microcracks, which were formed during the steam curing period and enlarged during the subsequent drying period, were examined by a new X-ray technique using a contrast medium and Wet-SEM. Then, relationships between surface microcracks and durability of concrete were investigated by freeze-thaw resistance test, chloride-ion penetration test and carbonation test. From the viewpoint of durability of the steam cured concrete, the experimental results were compared with the existing specification regulations of JSCE, JASS, JIS and ACI.

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When a reinforced concrete member is exposed to high temperature conditions over 100°C, tensile strain occurs in the concrete and compressive strain occurs in reinforcements due to a difference of thermal expansion coefficients between concrete and reinforcement. Its mechanism is the same as that of restrained stress caused by drying shrinkage of concrete; tensile stress occurs in the concrete because drying shrinkage strain is restrained by reinforcements, but there is a different point that the phenomenon at a high temperature condition includes the change of mechanical properties of concrete and reinforcement.
In the study, the phenomenon is measured in the experiments and is clarified quantitatively. Moreover, the estimation method, which is derived from expanding the equation of average strain of reinforcement in the CEB Design Manual, is suggested and is verified by the comparison with the experimental results.

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Slope of mixer, arrengements of blades and shape of blade are most important to design high performance continuous mixer. In this paper, mixing mechanism of concrete in the continuous mixer was investigated experimentally by visualization technique.
Arrengements of blades and shape of blade are more important to improve the mixing efficiency without deterioration of discharge efficiency than angle of mixer.

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For the purpose of appling composite material mixed with cement and asphalt-emulsion to underground structures under triaxial stresses, an experimental study was herein conducted. The rupture envelope curve of the circles of Mohr, for the mortar composed of cement, asphalt-emulsion and sand had the right-down tendency. In this paper the properties of this composite material have been investigated by the triaxial compression tests for the mortar which are added the air removing agent or are precompressed. It is also reported on the hydration properties between cement and asphalt-emulsion, and on the theoretical opinion of the mortar based on Muskhelishvili's suggestion.

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A questionnaire survey to roadway agencies showed that ice layers debond from asphalt mixtures containing reclaimed tire rubber particles (AMRP) in moderately cold areas. The mechanism of ice debonding was examined by means of model experiments and analysis by the photoelastic and finite clement t method (FEM). Model experiments showed that the phenomenon of ice debonding is caused by the existence of rubber particle on the surface. Analysis by the photoelastic method and FEM revealed that concentrated stresses, which were not observed in the case of no rubber particle, appeared in the ice layer around the rubber particle. Thus we concluded that the concentrated stresses initiate radial cracks in the ice and promote debonding of the ice from the asphalt layer. The effects of radius and shape of the rubber particle, thickness of ice layer and density of ice on the concentrated stresses were examined by the parairnetric study using FEM model.

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Laboratory experiment were conducted to investigate horizontal flow behavior of highly flowable concrete in two types of slab forms, setting lattice steel bars and vertical steel bars by visualization technique. We also investigated vertical flow behavior in both the V-funnel test apparatus and U-filling ability test apparatus.
It was found that the average maximum shear strain rates of concrete in slabs were under 1.0/s, and the average maximum shear strain rates of concrete in the consistensy test apparatuses were under 10/s.

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Firstly, a plastic model which considers time dependence effect at early ages is presented because it is thought to be significant to clarify a relation between plastic and creep component in order to formulate a rational interface model at layered concrete. Secondly, this model is applied to interface boundaries of layered concrete and a new interface model is developed. Thermal stress analyses using the interface model are carried out for real massive layerd concrete structures. As a conclusion, it can be confirmed that propagation of interface slip as well as stress, strain and displacement relations can be expressed analytically for the concrete structures which have different L/H and interface state.

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The frame analysis is extensively used in the design of tunnel lining. In order to apply the frame analysis to steel-fiber-reinforced concrete (SFRC) lining whit cracking and its growth, this paper proposes modeling and analytical procedures taking account of tension-softening relationship of SFRC. The proposed model and analytical scheme show the applicability of the frame analysis which could analyze cracking behaviors, by assuming rotating spring at nodes where a crack occurs. In addition, the effectiveness of proposed technique was verified by comparison with both results of bending tests and experiments by tunnel models.

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JSCE research working group on durability design for concrete structures has changed the design format this time from prior one. Based on two formats, the differences of the degree of assuring the durable concrete structures are investigated probabilistically, and the checking format using the partial safety factors is proposed to ensure the durable concrete structures in this paper. The partial safety factors are obtained based on the distributions law such as normal and uniformal probability density functions. The proposed format looks very severe to obtain the durable concrete structures compare with the prior design format.

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Fatigue tests were carried out for steel-concrete sandwich beams without shear reinforcement. Observed failure modes and their experimental S-N relationships for this type of beams are presented. The fatigue strength of the sandwich beams was predicted analytically by using the finite element method. The fatigue analysis was based upon reducing the compressive strength, the tensile strength, and the stiffness of the concrete with increasing the number of loading cycles (N) and increasing the stress range (S_r, ). The analytical S-N relationships are compared with the experimental ones. Finally, a design proposal for the sandwich beams under fatigue loading is presented.

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Fatigue tests were carried out for steel-concrete sandwich beams with shear reinforcement. Under fatigue loading, the sandwich beams indicated three failure modes, namely shear compression failure due to crushing of concrete between diagonal cracks and the fatigue fracture of the steel plates either the lower flange plate or the shear reinforcing steel plates. The S-N relationship for the different failure modes is presented. The fatigue strength of the sandwich beams was also predicted by the finite element method. A simple method to predict the strains in the shear reinforcing plates under fatigue loading is presented. A fatigue design proposal for the sandwich beams is also presented.

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During Hanshin-Awaji Earthquake, catastrophic shear failure accompanying plenty of diagonal shear cracks were experienced in RC structures and bridge piers serving transportation facilities. In this paper, shear capacity and ductility of RC columns in the post-yield range of longitudinal reinforcement are discussed for seismic resistant design. First, the shear failure of large scale RC column is computationally simulated for understanding the mechanism of shear collapse of bridge piers. FEM computational results on ductility are compared with the experiments and parametric study is conducted concerning factors that affect the post-yield deformability of RC columns. Finally, a simple formula for ductility is presented for summarizing the sensitivity of influential factors.

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