A heat and mass transfer model for a thin snow/ice(s/i) layer on a road was proposed in the present paper and enabled the melting or icing analysis of the s/i layer subjected to the solar radiation and transmission.
The volumetric ice, water and air contents can be calculated by the present model. This made it possible to the calculation of the heat flux taken account of the heat resistance between the s/i layer and pavement surface. The proposed model was evaluated with the results obtained by the snow-melting experiment in a thermostatic cold room and could reproduce the time variations of the height of s/i layer, mass ice content and pavement and s/i temperatures.

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The purpose of this study is to investigate and evaluate the anchorage performance of FRP grids bonded internally in concrete with underwater epoxy resin and to develop a upgrading method of anchorage by using FRP grids within the anchorage range. A pull-out test is used to examine the bonding and anchorage performances. It is found that the anchorage performances can be improved by using the additional FRP grids and will be affected by both factors of the stiffness and bonding area of bonded FRP grids. Finally, some evaluating equations are proposed in this paper.

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The method of strengthening by means of external tendons has been adopted to handle situations where prestressing is insufficient. The external tendons are anchored to the anchorage units attached to the main girder web. The anchorage units consist of concrete brackets; friction grip connections bound to the web using prestressing bars are used. Based on the principles of fastening force and friction coefficient (friction resistance), the design is conducted so as to ensure a constant safety factor with respect to sliding. In this study, tests were conducted for these factors using cast-in-place concrete anchorage units of a type frequently used in recent years, with make-up procedure. Actual size test specimens were fabricated using the actual construction procedure. As a result, it was demonstrated that anchorage unit joint interfaces treated with sandblasting or water jetting are sufficiently integrated to function against horizontal loads. With inclination within the 12 degrees permitted in specification, the fastening force is not decreased in case of appropriate surface roughness, and sufficient fracture strength can be demonstrated. Furthermore, it was demonstrated that this tendency continued in sliding after fracture.

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This paper describes the effect of industrial-waste molten slag on the mechanical behaviour of reinforced concrete beams in the slag replacement ratio of 0%, 40%, and 100%. Examination items are load carrying capacity, deflection, crack behaviour, and the bond characteristic of the reinforcing bar in reinforced concrete beam. The experimental results showed that, when slag replacement ratio is 40%, the influence of the slag on the bond-stress relationship of reinforcing bar and the crack behaviour in the reinforced concrete beam is small. Moreover, it was suggested that the possible replacement ratio of slag is dependent on the water cement ratio.

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Vehicle heats were quantitatively evaluated by field and indoor experiments and formulized in this paper. The experimental results encouraged to create an ‘instantaneous vehicle heat model’ and a ‘time averaged vehicle heat model’. These two vehicle heat models were adapted to field weather and traffic data. As far as this simulation condition is concerned, there was little difference in the road surface temperatures calculated by these models.
It was founded that the difference in the pavement surface temperatures between a vehicle-passage area and a non vehicle-passage area cannot be disregarded any longer.

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Steel-making slag concrete consists of by-products at ironworks. The strength of steel-making slag concrete is 20-50 N/mm² at 28 days. Ground granulated blast furnace slag is used as a binder. Steelmaking slag is used as an aggregate. Steel-making slag concrete doesn't use any natural aggregate, either. The calcium hydroxide leaching from steel-making slag acts as alkali activator of ground granulated blast furnace slag. Steel-making slag concrete can be hardened by itself without any cement. Resistance to carbonation of steel-making slag concrete and resistance to corrosion of steel rod in steel-making slag concrete are high for a long time due to calcium hydroxide leaching from steel-making slag. However, resistance to freezing and thawing of steel-making slag concrete is quite low. In this paper, the mechanism of low resistance to freezing and thawing was clarified. The method to improve the durability of steel-making slag concrete was shown. An entrained air by AE agent is formed by calcium ion. The paste just with ground granulated blast furnace slag cannot contain entrained air by AE agent because enough calcium ions cannot be produced by the hydration with water and ground granulated blast furnace slag. Big size air is formed around steel-making slag because of calcium hydroxide leaching from the steel-making slag. That's why resistance to freezing and thawing is low. In order to improve the resistance to freezing and thawing of steel-making slag concrete, it's necessary to use cement, fly ash and blast furnace slag sand. Cement is used to entrain the air by AE agent. Fly ash is used to consume the extra calcium hydroxide in steel-making slag concrete. Blast furnace slag sand is used to restrain the calcium hydroxide leaching from sand. Then, the resistance to freezing and thawing of steel-making slag concrete is as high as that of AE cement concrete.

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A carbonation model based on thermo-hygro physics is presented in this paper. Reaction of C-S-H gel was newly added to the existing model as well as calcium hydroxide reaction, and a micro-pore structure model for carbonated concrete was improved by considering volume change and surface-area increase of hydrated products. The proposed model coupled with moisture equilibrium/transport gives reasonable predictions for carbonation progresses under low and high CO₂ concentrations in a unified manner. In addition, temperature dependent parameters were installed in the system. Although detailed mechanisms should be further investigated, the proposed methodology is able to simulate carbonation phenomena under various temperature conditions.

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This study aims to clarify the effect of self desiccation on volume change of cement paste at very early ages. Effect of self desiccation due to hydration was investigated in terms of water-binder ratios and volume change of cement paste. Chemical shrinkage ratio was used as an indicator of hydration reaction rate of the cement. The effect of chemical shrinkage (self desiccation) on macroscopic volume change at very early ages is evaluated qualitatively, based on the relationships between chemical shrinkage ratio and volume change, and between chemical shrinkage ratio and pore water pressure. Furthermore, mechanisms of the reduction in shrinkage by a shrinkage reducing agent and expansive additives were discussed. It was found that volume change of cement paste at very early ages is markedly influenced by self desiccation at low water-binder ratios.

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The objective of this study is to clarify the influence of the corrosion form (local corrosion, uniform corrosion) and the corrosion quantity on the bending behavior (bending fracture load, bending stiffness, and deformation behavior) in the reinforced concrete beam. The conclusions in this study are as follows. 1) The yield load, the bending stiffness, the deformation behavior, and the bending fracture load of beam decreased when the corrosion quantity increases regardless of the corrosion form. 2) The bending fracture load decreased to about 50% against the no-corrosion beam, when the weight loss by the corrosion was 60% in the uniform corrosion when the weight loss is 40% in the local corrosion. Also, the bending fracture load is decreased to about 50% against the no-corrosion beam and became rapid destruction, when the local corrosion. 3) The yield load and the bending stiffness are remarkably decreased in serviceability state regardless of the corrosion form, and the deformation increased, when the corrosion quantity was over 30%. 4) The above results 1) were investigated in theoretically as well as in experimentally.

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Transmission tower legs are usually embedded in concrete column foundations. Concrete columns are confined by steel pipes to shorten the anchoring length by increasing the anchoring capacity. The anchoring capacity is greatly increased in the experiment. The reason why the anchoring capacity is increased is that the confined steel resists to the failure when radial splitting cracks occur in the concrete body. Two types of failure mode in the experiment were observed: One was where the encasing pipe yielded, and another was where a tower leg was pulled out from the concrete body. Based on the experiment, a method to predict the ultimate capacity of two failure mode is proposed.

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In this research, authors aim to quantitatively understand the influence of various aggregate properties on behaviors of concrete shrinkage based on both experimental and numerical approach. A multi-scale constitutive model revealed that only difference of aggregate Young’s modulus cannot cause significantly different shrinkage behaviors of concrete. Thus, the shrinkage of aggregate itself was focused on and aggregate shrinkage model that depends on its surface area and saturation degree according to experimental results of previous researches was proposed. The proposed model can reasonably simulate largely different shrinkage behaviors of concrete with various types of aggregates.

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The applicability of 3D non-linear FEM, which has been developed by the authors, on the punching shear failure of RC slabs was studied.
In this paper, experimental results of thin RC slabs, subjected to a concentrated load at various position, and relatively thick RC slabs, loaded through walls or columms connected on the slabs, were compaired with the analytical results using the FEM program.
It was shown that authors' FEM analysis are able to well estimate the punching shear failure of RC slabs, interms of shear strength, diagonal cracking pattern and load-deflection relation.

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There were the following typos and other errors in the article, “MECHANISM AND PREDICTION OF COVER CONCRETE SPALLING DUE TO REINFORCEMENT CORROSION” Journals of the Japan Society of Engineers, No. 802, V-69 page November 2005.

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