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This research is aimed at studying the corrosion rates of carbon and weathering steels due to exposure at three urban exposure sites and the characteristics of corrosion products of carbon steel in Yangon, Myanmar. The ISO 9223 standard was used to classify the corrosion aggressiveness of the atmosphere. There is a high level of time of wetness (TOW) class which is τ 4 in the south and τ 3 in the central part of Myanmar. At the recent exposure sites in Myanmar, the atmospheric impurities are low, so the corrosion rates of carbon and weathering steels are mainly governed by TOW. The corrosion rates of test sites fall into the ISO C2 category. It appears that corrosion kinetics fit the power model well, since the correlation coefficient is high. Various morphologies of corrosion products including globular, flowery, and sandy lepidocrocite emerged in the early stage of exposure. The longer TOW conditions resulted in the formation of lepidocrocite and goethite. The growth of goethite products on carbon steel was discovered after nine months of exposure.

Luminescent oxygen sensor composed of platinum-porphyrin and a gas-permeable polymer binder was applied as an optical crack sensor paint for infrastructure. The sensor paints were designed as a three-layered structure in which the luminescent oxygen sensor layer was sandwiched between oxygen barrier layers. The sensor paints emitted intense luminescence under UV light irradiation, and the luminescence was efficiently quenched when a new crack formed on the concrete surface. Microcracks, which were

Friction stir welding (FSW) has many advantages rather than fusion welding, but details of internal phenomena during its processes have not yet been clarified. In this study, a thermo-mechanically coupled process model was developed to investigate FSW phenomena inside a tool and workpiece. As a workpiece, 6061-T6 aluminum alloy was employed. The system of FSW process model includes several thermal boundaries. Among heat flows through these boundaries, heat transfers into the exterior of the system become more sensitive to tool and workpiece temperatures than heat transfers within the system. This paper especially focused on a heat transfer coefficient at a workpiece bottom, and optimized it through experiments and finite element method (FEM) analyses. The tool temperatures during FSW were measured with a special tooling system with imbedded thermocouples within a tool. As a result, an analysis model that is able to investigate details at a wide range of traverse speeds was developed for practical high speed welding. Then, the accuracy of developed FEM model was validated with them. Finally, the temperatures and stress distribution around workpiece/tool interfaces were investigated with the developed model.

To predict accurate cutting forces and residual stresses while machining products or to design optimum machining conditions like friction stir welding (FSW), FEM analyses are effective because they can reduce the cost of product design and improve product qualities. In order to conduct these FEM analyses precisely, it is necessary to determine accurate flow stresses of workpieces used for the constitutive equations of analyses that generally have a wide range of temperatures and strain rates. Correct identification of flow stress can lead to better analysis results close to actual phenomenon. In this study, focusing on 6061-T6 aluminum alloy used for objects such as civil engineering structures and railway vehicle bodies, we investigated the properties for machining the material. For this, we carried out an inverse analysis to understand the flow stress of 6061-T6 machined at high-strain rates and high temperatures. Then, we used this identified flow stress in the constitutive equation of FEM models, and inspected the accuracy of material properties conducting verification experiments and analyses to check the cutting forces and chip temperature while machining. As a result, we obtained good correlations between verification experiments and an analysis, which means the identified flow stress can be used for precise FEM analyses when machining materials.

Pultrusion is an easy molding method of fiber-reinforced polymer (FRP) to obtain a long composite material with a uniform cross-section at relatively low cost. In some cases, pultruded FRPs are now used in bridges and deck projects. Since the application of pultruded FRP as a structural material is increasing, a study on the durability of pultruded FRP under outdoor conditions is necessary in terms of safety. Some studies have shown that pultruded glass fiber-reinforced polymer (GFRP) exhibits a slight reduction in mechanical properties during outdoor exposure. Since pultruded GFRP consists of multi-layers, the change of mechanical properties in each layer is important to understand. In this study, an outdoor exposure test on pultruded GFRP for 10 years was conducted with three types of pultruded GFRP, which have different laminate systems, including surface-coated specimens of each type. Changes of strength and elastic modulus due to outdoor exposure were discussed with a focus on the contribution of each layer based on the rule of mixtures.

Surface protection by hydrophobic impregnation and surface coating are widely used for concrete bridges located at coastal area in Japan. This paper deals with the improvement of adhesion between surface coating and hydrophobic impregnated concrete by different types of silanes and by invastigating surface treatment methods. As a result, adhesion between hydrophobic impregnated concrete and epoxy-based surface coating were improved by applying abrasive paper, portable electric grinder, solvent or diluted hydrochloric acid treatment. Especially, using portable electric grinder gave a remarkable improvement to the adhesive property. Also, hybrid-surface protection system consisting of surface coating and hydrophobic impregnation was discussed to prevent blistering.

Here we will propose the conceptual new idea of the inspection of concrete bridge using smart materials and mobile IoT system. We apply opal photonic crystal film to detect cracks on concrete infrastructures. High quality opal photonic crystal films were coated on black color PET sheet over 1000 cm2 area. The opal film sheet was cut and adhered to concrete or mortar test pieces by epoxy resin. In the tensile test, the structural color of the opal sheet was changed when the crack was formed. As a demonstration, we have installated the opal film sheet on the wall of the concrete bridge. Our final purpose is the color change will be recorded by portable CCD devices, and send to expert via IoT network.

The objective of this paper is to propose a new quality evaluation method for asphalt concrete mixture using X-ray CT scanner. To achieve this aim, asphalt mixtures should be subjected to the X-ray CT scanning and its characteristics should be clarified. The approach employed in this study was as follows: 1) Coarse aggregate, fine aggregate, filler and bitumen were prepared; 2) dense-graded, coarse-graded and porous asphalt mixtures were made; 3) materials and mixtures were subjected to the X-ray CT scanning; 4) frequency of CT-value, threshold value, average slice CT-value, average segment CT-value were computed. In the material examination, CT-value of aggregate becomes smaller in the order of coarse aggregate, fine aggregate and filler and CT image of bitumen was nearly homogeneous. In the mixture examination, histograms of CT-value and four segmentation images made from CT images expressed the material and mixture characterization such as particle size and the difference in bitumen content and mixture type visibly and the bitumen content varies with the threshold values. In addition, the average segment CT-value without threshold value by dividing the fine aggregate from the coarse aggregate and average CT-value of the coarse aggregate, especially is highly correlated with average CT-value of the bitumen.

Fibre-reinforced polymers (FRPs) have been widely used for reinforcement of existing structures due to its light weight and high corrosion resistance. Several hundred examples in the world show tha...

The authors set out to investigate the durability of the bond between carbon fibre (CF) sheet reinforcement and concrete. They conducted an outdoor exposure test in a moderate climate for 14 years and an immersion test for 6 months on CF sheet bonded to concrete, and then evaluated the adhesive bond properties using the pull-off and peel methods. The pull-off strength slightly decreased after 14 years of exposure, but residual values still indicate quite good adhesive properties. The failure modes for both the initial specimens and the specimens after 14 years of exposure consisted of concrete substrate failures in all cases. This result suggests that the slight decrease in pull-off strength does not necessarily indicate a change in the properties of the bond between CF sheet and concrete. On the other hand, results of the peel tests showed different types of failure modes and seemed more discriminant than those of the pull-off method. As regards specimens immersed in water, pull-off results were in few cases consistent with the peel characterizations, showing significant evolutions in the strength and failure mode. But for most specimens, the two methods provided divergent trends. In the end, this study suggested that the peel test could be relevant for evaluating the durability of the bond between CF sheet and concrete, while the representativeness of the pull-off test remains a matter of discussion.

The relaxation behavior of clamping force in friction-type FRP bolted joints is one of the significant subjects in application of FRP to structures. The aim of this paper is to obtain the factors of relaxation behaviors in the GFRP bolted joints based on the experimental results. The relaxation behaviors are due to both steel bolt and GFRP laminate. Steel bolt dominates the relaxed force immediately after initial loading but not reloading. The relaxation factors of GFRP laminate except matrix polymer could be both laminate surface geometry and laminate bond, considering the variance of relaxed force and more relaxed force for bonded laminate than single laminate observed in the experimental results. Boltzmann superposition principle can be hardly applicable to the relaxed forces for initial loading and reloading, suggesting that less relaxed force for reloading could be obtained by the strain hardening of bolt threads through the decrease of cross section area due to shear plastic deformation and that surface geometry could be modified by plastic and irreversible viscous deformation considering the viscoplastic property of matrix polymer. More relaxed force could be obtained for the surface geometry farther from the flat surface and the surface geometries could be categorized into the surface with either equal height protuberances or random height ones. Laminate bond dominates the relaxed force and its lower viscosity could give relaxed force more. The viscosity of laminate bond could be more variable than matrix polymer and increase through the modification of structure by plastic and irreversible viscous deformation. The minimum elapsed time could be required to complete the relaxation behavior for the flat surface and the bond viscosity as high as matrix polymer.

Longitudinal cracking has been increasingly observed on asphalt concrete pavement in the world. Although over 20 years have passed since the longitudinal cracking was observed on asphalt concrete pavement in Europe and Japan, it has been believed that it was developed from the top of pavement (top down cracking) for highway and pavement on orthotropic steel deck bridge. In this study, sample cores were extracted using a diamond cutter from pavement on an expressway and orthotropic steel deck bridge, which had been in service for five years or thirteen years, and showed no longitudinal cracking on the surface. The cores were analyzed for longitudinal cracking in each layer using a newly developed micro-focus CT scanner and a three-dimensional void analysis program in order to examine where it comes from. This paper showed longitudinal cracking on asphalt pavement develops not from the surface or the bottom of pavement but from within the asphalt pavement.

Recently, the development of the recycled resource is active in the background of effective use of the resource and the depletion of the final disposal dump, etc. Especially, the development of the technology used for the pavement of those recycled resources is active. Using these recycled resources comes to recycle certainly. However, whether it has contributed to the environmental load decrease in total until abandoning since using these manufactures it is not clarified. Then, the resource consumption, the saving resource, and the environmental load when using it for pavement were provisionally calculated for scrap tire and waste plastics, and LCA evaluation was examined. As a result, it was shown overall might decrease the environmental load though the recycled resource pavement might partially increase the load.

In Japan, several mix design methods for the recycled porous asphalt are being developed and proposed. These methods include the one to use Cantabro test and the one by the extraction recovery of asphalt. However, they have not been established yet, because they have some problems. The authors studied the mix design method using asphalt mortar, the new method evaluating several properties without extraction. As a result, the new mortar method was a method of not only appreciable of servicing temperature but also appreciable of constructing temperature. In addition, the labor of the method was also light.

本研究は, 遮水シートの耐久性評価を目的とし, 室内促進暴露実験と実暴露実験を実施し, 遮水シートの力学特性 (硬さ, 引張強さ, 伸び率) や表面状態の変化を追跡評価したものである。室内促進暴露実験の結果, 伸び率は経過時間とともに徐々に低下し5, 000時間では初期値のおおむね80%程度となり, そのとき遮水シート表面には亀甲状の微小亀裂が発生していることが確認された。一方10年間の実暴露実験を行った遮水シートの力学特性の変化は小さく, ある種類の遮水シート表面には室内促進暴露実験と同様の亀甲状の微小亀裂が観察されたが, 最終処分場の標準的な供用期間である15年に対して遮水シートの耐久性は充分余力あるものと推測された。また両実験結果を比較検討した結果, 2, 000時間強の室内促進暴露実験の結果が実暴露実験10年間に相当することが確認された。さらに遮光性保護材を用いると, 遮水シートの劣化の主要因とされる紫外線を遮断することができ, 遮水シートの耐久性が大幅に向上することも確認できた。

In this research, to establish the method of recycling porous asphalt mixture, the propriety of two mixing design methods being proposed was examined. The result is shown below. 1) The problem was found in the deciding method of the amount of rejuvenators of recycled porous asphalt mixture and the deciding method of optimal asphalt content 2) It has been understood might not obtain satisfactory properties about mixture properties not so examined when mixing is designed. 3) It has been understood that there is a possibility to be improved from present methods by adding easy tests.

Carbon black, used as a reinforcing filler for rubber materials, was evaluated for asphalt binders in pavements. Carbon black added to straight asphalt within 20 wt% caused an increase in the elastic modulus and a decrease in the viscosity of the asphalt, especially at temperatures higher than room temperature. Addition of carbon black raised the maximum service temperature of asphalt in the category of the binder performance grade according to the SHRP (Strategic Highway Research Program) specifications. On the other hand, addition of carbon black also increased the failure strain at low temperatures. Furthermore, addition of carbon black reduced the coefficient of thermal expansion (CTE) of asphalt to closer to that of aggregates. In asphalt mixtures, tensile stress occurs at the boundary between asphalt and aggregate with decreasing temperature due to the CTE difference. Addition of carbon black reduced this stress. Carbon black addition to asphalt has the potential to improve both deformation resistance in the high temperature region and crack resistance in the low temperature region, which were empirically considered to be contradictory. Therefore, carbon black is an effective filler for improving the durability of asphalt pavements.

This report examines the effects of water and moisture on the durability of pultruded glass-fiber-reinforced polymers (GFRP) with vinylester resin for applications in normal air conditions. Deterioration tests, including both immersion and atmosphere conditions at various temperatures, were conducted to investigate the deterioration characteristics of pultruded GFRP after being permeated by water. The main findings from the tests were that cracks appeared on the surface of the GFRP and that the weight of the materials decreased, which may be attributed in the surface treatment oil for the glass-fiber cloth being dissolved away. The bending strength of the GFRP was also found to be reduced. The rate of weight decrease and the reductions in bending strength were greater in a 60°C water-immersion condition compared to both a 60°C moist-atmosphere condition and a 40°C water-immersion condition. This difference is due to the fact that the glass fiber and matrix resin separated in water at 60°C. Although the matrix resin changed color in air at 60°C, becoming noticeably brown, no chemical changes were found by infrared spectra.

With high corrosion resistance, high tensile strength, electromagnetic neutrality, and lightweight, the newly emerged aramid and carbon fibre-reinforced plastic (FRP) tendons are being used for prestressed ground anchors. FRP ground anchors can be used when the corrosion protection of steel tendons becomes expensive or difficult to achieve, or where electromagnetic insulation is required. Although FRP tendons are more expensive than steel tendons, the total cost on transportation, handling, fabrication, drilling, installation, and maintenance can be significantly reduced due to lightweight and no requirement for corrosion protection. In addition, optical fibre sensors can be integrated into FRP tendons for permanent monitoring of ground anchors. This paper gives an introduction of the currently available aramid and carbon FRP tendons and an overview of the important properties of FRP tendons and their constituent materials. The design, fabrication, installation, and field applications of aramid and carbon FRP ground anchors are described. (A)

We will present a simple and low cost method to visualize local strain distribution in deformed aluminum plates. In this study, aluminum plates were coated with opal photonic crystal film with tunable structural color. The photonic crystal films consist of a silicone elastomer that contains an array of submicron polystyrene colloidal particles. When the aluminum sheets were stretched, the change in the spacing of the colloidal particles in the opal film alters the color of the film. This approach could be useful as a new strain gauge having a visual indicator to detect mechanical deformation.

Six types of FRP cables were subjected to an exposure test lasting more than fifteen years under maritime conditions, and the retrieved cables were evaluated mainly by SEM and FT-IR microscopy. Loss of surface resin was observed for all the tested FRP cables; however, deterioration between the fiber and matrix resin was not found by SEM. Observation by FT-IR microscopy detected surface deterioration of AFRP cables, and the feasibility of this method for evaluating the deterioration of some FRP cables was indicated.

FRP is used for corrosion protection and/or as structural members utilizing its anti-corrosion properties. Moreover, since the weight of a superstructure can be significantly reduced due to its specific strength, FRP is expected to offer structural functionalities such as rapid construction, substructure downsizing, and improved seismic performance. We constructed an FRP bridge made entirely of pultruded and hand-lay-up GFRP materials, and have been monitoring its functionality and durability. This paper reports the changes in structural load-bearing behavior during nine years of field exposure. Loading response of the FRP bridge after long-term exposure was almost the same as that just after its completion and deterioration in structural performance has not been observed in nine years. The results prove that FRP materials have good durability and functionality for long-term field exposure as structural materials for bridges.

Polymer-modified asphalt binder is applied for the heavy trafficked pavement because the asphalt is superior in terms of plastic flow and abrasion resistance. Recently, the development of warm-mix polymer modified asphalt has proceeded. Then, it is necessary to evaluate the characteristics of these asphalt binders. In general, the authors have estimated the physical behavior of polymer-modified asphalt by DSR test. However, it seems to difficult for DSR test to estimate the nonlinear viscoelastic behavior such as warm-mix polymer-modified asphalt. In this study, the authors validated the availability of MSCR test for the characteristics of the widely distributed warm-mix polymer-modified asphalts. ポリマー改質アスファルトバインダは塑性変形抵抗性や摩耗抵抗性、はく離抵抗性等に優れており，重交通路を中心に普及している．近年では，CO₂排出量削減や作業環境改善策として中温化ポリマー改質アスファルトバインダの開発も進んでおり，既に複数メーカーから市販されている．一般的に，アスファルトバインダの物理性状はDSR試験から得られるパラメータによって評価されてきたが，改質アスファルトバインダの非線形粘弾性状を適切に評価できないことが指摘されている．本研究では，国内で流通している複数の中温化ポリマー改質アスファルトバインダの性状を調査し，基本性状の相違を明らかにするとともに，物理性状評価に対して繰り返しクリープ試験(MSCR試験)の有効性を検証したので報告する．

Hexavalent chromium is sometimes eluted from cement concrete recycled base course material. Therefore, hexavalent chromium eluted restraint technology is developed. The concentration analysis of hexavalent chromium is difficult, when a reducer coexists. There were not that standard measurement methods. The authors have already developed the analysis method of hexavalent chromium when a return substance coexists. When using this way, even if there is a return substance, hexavalent chromium is measured right. So hexavalent chromium reduction technologies were studied using accessible materials. As a result, hexavalent chromium eluted restraint technologyreducing sugar has been developed. セメントコンクリート再生路盤材からは六価クロムが溶出する可能性があるため，溶出の確認が行われるようになっている．これに伴い，六価クロム溶出低減技術も開発されるようになっているが，還元物質を用いる対策の場合，JISの分析法を用いることができず，評価が難しいのが現状である．本研究では，独自に開発した還元物質共存下でも容易に六価クロムを分析できる方法を用いて，自然由来の物質や入手が容易な物質の中から，還元効果が期待できる物質を選定し，六価クロムの溶出低減効果を検討した．その結果，比較的入手が容易な一部の果汁や還元糖の中に六価クロム溶出低減効果が高いものがあることを把握した．

The warm-mix asphalt technics have been applied to the hot asphalt pavements to improve the quality of constructions and to reduce CO₂ emission. Although many studies have reported that the warm-mix additives affected the physical characteristics of asphalt mixtures, the basic characteristics of the warm-mix asphalt binder has not been revealed. In this investigation, the authors measure the differential scanning calorimetry (DSC) and the viscoelastic property of the warm-mix asphalt binder in a wide range of temperature. Also, they discuss the validity of the thermal analysis to detect the physical change of the asphalt binder. 施工性改善やCO₂排出削減などを目的として，加熱アスファルト舗装に対する中温化技術の開発や利用が進んでいる．これまで，中温化剤の添加によるアスファルト混合物の物理的性状の変化は多く報告されているが，アスファルトバインダの基礎的な物理性状については十分な言及がなされていない．本研究では，中温化剤によるアスファルトバインダの性状変化を把握することを目的として，示差走査熱量測定によりアスファルトや中温化剤の広範囲の温度域での熱特性や，これに対応した粘弾性状を調べた．さらに，熱特性と粘弾性状の関係について検討した．

N-Benzoyl L-daunosamine was synthesized stereoselectively starting from O-t-butyldimethylsilyl L-lactaldehyde and methyl propiolate; the crucial step, intramolecular conjugate addition of a carbamoyl amino group of methyl threo-5-carbamoyloxy-4-triethylsilyloxy-(Z)-hex-2-enoate, proceeded with exclusive 1,3-anti diastereoselectivity.