In the current design of asphalt pavement in freight container yard, theoretical design method based on multi-layered elastic analysis is applied. Fatigue criteria of subgrade generally become critical under the heavy wheel loads, however, considerable large strain observed in asphalt mixture layer in real scale tests. In this study, the effect of strain rate, slide between layers and tire contact pressure on the strain in asphalt mixture layer was discussed. It was concluded that the strain in asphalt mixture under low-speed heavy wheel loading is properly obtained by multi-layered elastic analysis, when the effect of strain rate, slide between layers and tire contact pressure appropriately considered.

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Toward establishing a theoretical design method for asphalt pavements in cold, snowy regions, field surveys were performed on an asphalt pavement constructed using the multilayer elastic theory at a national highway in service. Through vehicle loading and FWD tests, and from dynamic loading applied to the pavement, the relation between measured strain and estimated strain was studied. It was found that the measured strain from FWD tests closely corresponds to the estimated strain, but that the measured strain from the vehicle loading test tends to be smaller than the estimated strain. Reason for the difference between measured strain and estimated strain was the effect of loading repetitions. Methods for correcting the modulus of elasticity are examined.

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Kansai International Airport Co., Ltd. has introduced the multi elastic layer analysis method to the design of the 2nd runway asphalt pavement. The cost reduction of the asphalt pavement can be realized by the appropriate estimation of reclamation land strength and by the reduction of pavement thickness. The technical issue is the determination of the elastic coefficient and the fatigue failure criterion of the subgrade that include D300 m/m rocks in the maximum. The economical structural design of the new runway pavement has been made based on the result of the on-site test using the loading vehicle (B747).

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The objective of this paper is to propose a new testing method to examine the effects of moving wheel load on cyclic plastic deformation of railroad ballast in terms of the strength and deformation characteristics. Applicability of a newly developed multi-ring shear test, which can make the principal stress axes rotate, to an element test of granular materials subjected to moving wheel load was examined by comparing the laboratory element test results with the moving wheel loading test results of small scale model track. As the results, it was revealed that the mechanical behavior of railroad ballast under moving wheel loads is very similar to that of granular material subjected to the principal stress axis rotation during shear. Accordingly, it was confirmed that the multi-ring shear test is appropriate for simulating the actual stress states inside substructures under moving wheel loads.

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In a road excavation to lay a gas distribution pipeline, the re-use of the excavated soil for the subgrade backfill greatly reduces the environmental impact. However, when Kanto loam soil, which is widely distributed in the Kanto region, is employed for the backfill material, the relationship between the amount of the subsidence of the subgrade soil and the cyclic traffic loading is needed. In this study, cyclic loading tests on Kanto loam soil were conducted to investigate the subsidence characteristics. The subsidence prediction method of Kanto loam soil based subgrade under cyclic traffic loading was proposed using the cyclic loading test results. A full scale traffic loading experiments against road beds backfilled with Kanto loam soil were carried out. Consequently, a good correlation was shown to exist between the amount of the predicted subsidence and the measurement results.

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As for the rubber elastic pavement, a high noise reduction effect is provided than conventional porous pavement, and what can largely reduce the tire/road noise at the time of a low speed run and the shopping cart noise is found. It is thought that noise reduction effect of rubber elastic pavement is affected by noise absorption characteristics, thickness, the elasticity, impulsive relaxation characteristics of a pavement. In this study, it was examined the influence that the static spring constant as the elastic softness and the impulsive acceleration as impulsive relaxation characteristics of rubber elastic pavement gave to the vehicle tire/road noise and the shopping cart noise. As a results, it was found that the static spring constant and the impulsive acceleration of rubber elastic pavement were related to influence on reduction characteristics of the vehicle tire/road noise and the shopping cart noise.

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In these days, some attempts have been made at the improvement of heat environment in urban area by constructing permeable pavements in carriageway area. We have tried to establish the measuring method of evaporation from permeable pavements. And also, we have conducted experiments and have measured evaporation, temperature and volumetric water content on the permeable pavement model, which structure is the same as that of Route 163, in order to examine the effectiveness of permeable pavements. The results show that the proposed method can be useful and evaporation contributes to lower surface temperature of permeable pavements.

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Radiant heat such as solar and atmospheric radiations gives significant effect on pavement temperature. Although solar radiation has been observed at various national weather stations, atmospheric radiation has not been. Since atmospheric radiation flux is one of essential factors for thermal analysis, it has to be estimated from available data. It is important to adopt an appropriate model because the flux depends not only on longitude and latitude but climate. Some existing clear sky models are tested using weather data collected at Hatoyama test site and their applicability not only to clear sky but to other weather condition is examined. Finally, the coefficients of three selected atmospheric emissivity models are modified to improve their correlations with Hatoyama test site data and are compared with the results from a simple atmospheric emissivity model proposed by authors.

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Interaction of aggregate particles within hot mixture asphalt (HMA) mixtures provides shearing resistance. Configuration of the aggregate particles was spatially depicted as sphere assembly. Four types of aggregates gradation, namely stone matrix asphalt stone skeleton, coarse graded stone-sand skeleton, coarse graded and fine graded sand-stone skeleton were studied. The structure models of aggregate gradation were examined using dilatancy properties. Dilatancy tendencies of the spheres assembly models statistically agreed with the dilatancy properties measured from compression test. Simple doublet mechanistic qualitatively depicted the deformation tendencies of sphere models under wheel-tracking test.

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This study aims for improvements of anti-freezing pavements with physically flexible properties based on the concept of gum-rolled asphalt pavements. By addition of de-icing chemicals into the gum- rolled asphalt mixture, bond-destruction between snow /ice and pavement is prospected to be promoted with not only the physicaly flexible action of pavemenrts under repeated traffic loads but also chemical de-icing effects. As for newly developed anti-freezing pavements, laboratory experiments of physical and chemical properties were carried out. As results of these experiments, though effects of anti-freezing pavements were recognized to some extent, the research subjects of furthermore improvements were clarified.

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Porous asphalt pavement has been fully introduced in Yokohama City since 1996, however, the aggregate stripping due to torsional stress from the tire is observed at intersection. To restrain this damage, new porous asphalt mixture is selected for mix design, using modified asphalt with high viscosity and torsional resistance, considering functionality, stripping restraining effect, economic and environmental impact. This selected asphalt mixture has been applied on the site experimentally since 2001, and follow-up survey was conducted in 2004 to review three years in service. As a result of this follow-up survey, the condition of pavement is generally sound though some aggregate stripping was observed at the place by manual work and at the pavement joint.

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Yokohama City has been introducing new porous asphalt mixture using modified asphalt with high viscosity and torsional resistance since 2001, to restrain aggregate stripping problem of porous asphalt pavement at intersection. According to the follow-up survey conducted in 2004, aggregate stripping is almost restrained except the place done by manual work and at the part of pavement joint. This aggregate stripping is replicated and validated at laboratory. As a result, insufficiency of the strength is observed which is specific to the asphalt mixture applied at intersection.

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There are many reports that porous asphalt pavement is damaged at early stage. It needs to study factors of occurrence and effective counter method for damage types that are not cleared how road administers correspond. Therefore document investigation and hearing investigation of local bureas were performed. Then, the occurrence of partial plastic flow were not found effective methds. So, effective methds that prevent partial plastic flow were researched by experiments. As a results, it was understood that factors were mainly stripping and flow of base course. And lack of adhesion of surface course and base course is one of factors, too. It was confirmed that durability of porous asphalt pavement was improved if counter methods that prevent these factors were performed.

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Drainage pavement has some beneficial functions. But it also has a disadvantage likely to lose its functions by having the pores become packed by fines such as soil and sand. We need to learn the condition, which are the portion and the degree of packing, in order to make a plan of appropriate recovery works. The actual packing condition is too complex to distinguish inner reflections. We made a concept by numerical simulation that the interfered compound reflection reflecting inner irregular conditions has characteristics due to pulse lengths. The simulation showed that the portion and the degree of packing could be determined by combination of each reflectivity by use of 0.67ns and 1.33 ns pulses. Experimental and field measurement demonstrated that this method is practically useful.

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This study aims the development of a structural design method taking advantage of reinforcement in concrete slab. In this method, the design period is considered an addition of a period for the fatigue of RC slab and a period for the fatigue of steel reinforcement bar after bottom crack in RC slab occurs. Applying stresses computed from 3DFEM analysis to fatigue curves, relationships among fatigue damages in RC slab and reinforcement bar, RC slab thickness and reinforcement ratio were obtained. Using the results, a design procedure was proposed and an example is presented in this paper. A computer software was developed, which gives the reinforcement ratio for a specified design period and design parameters including RC slab thickness, traffic and temperature conditions.

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his paper deals with dynamic behaviors of a whitetopping pavement structure with a surface layer of high strength fiber reinforced concrete panel (HSC-WT) under traffic road. A test pavement of HSC-WT was constructed on an accelerated loading facility and was subjected to moving axle loads. After five hundred thousand axle passes, small gaps developed between HSC panel and grout near joint, but any crack didn't develop. Analysis of the loading test with dynamic 3DFEM and comparison of the result with the measured data revealed that visco-elastic effect of the asphalt layer was relatively small. Stress analysis using the identified visco-elastic parameters confirmed that the stresses in the panel due to axle load are much less than the strength of the HSC panel.

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The temperature rise of pavement is seemed to be one of the reasons of the heat island phenomenon, and some kinds of pavement are developing to reduce the pavement temperature by moisture retention materials. Most of them are based on the asphalt concrete pavement, but there are some disadvantages like rutting and scattering in asphalt concrete pavement. On the other hand, cement concrete pavement has a high durability. In this study, the wear resistance, the fatigue properties and the effect of temperature reduction of moisture retention concrete were examined. From the results of examination, it was cleared that the moisture retention concrete had enough strength as a pavement structure and high durability as a road surface. And it is also cleared that the effect of temperature reduction of moisture retention concrete is equivalent to the performance of usual moisture retention asphalt concrete.

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City of Yokohama manages more than 7, 400km long roads including about 900km of primary roads. It is expected that most road infrastructure (road asset) will be reached to their life in near future and it is also expected that maintenance cost will be increased and increased. Then road bureau of Yokohama decided to introduce asset management system (AMS) with the goal of rationalization of pavement management, equalization and reduction of maintenance cost and so forth. Major challenges are required to establish AMS and pavement data has been analyzed in terms of pavement service life and prediction model for primary roads. Also surface visual identification manual will be prepared for residential roads. That manual enables uniform inspection of pavement and finally helps us achieve accountability to Yokohama citizen.

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Actual surface conditions of airport asphalt pavements have been surveyed and the changes of them with time have also been investigated with the accumulated survey data. The following primary findings are obtained. 1) The current surface conditions of runways are evaluated better than those of taxiways, that leads to higher PRI for the runways. 2) The current surface conditions are rated good as a whole, but those of runways are evaluated worse compared with those of taxiways. 3) Annual changes of surface conditions depend on airports, and the influencing factors are different in types of surface conditions and pavement facilities. 4) Annual changes of surface conditions for runways could be roughly estimated with multiple linear regression analysis.

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Recently, the demands for polymer modified asphalt type-H (“PMA-H”) are growing and its usages are being varied as performance-based specification is more widely adopted in pavement contracts, and also due to implementation of laws concerning quality assurance of public works. Accordingly, the issue of quality guarantee of PMA-H is increasing its importance than ever. In order to materialize quality guarantee of PMA-H, evaluation of quality deterioration through all the related processes is indispensable, namely, manufacturing of PMA-H, manufacturing of mixture, paving, actual service and even regeneration. Among such processes, evaluation for quality deterioration of PMA-H in storage process is important because it has much influence on it's quality guarantee period. Our studies this time was made with the purpose of figuring guarantee-able period of PMA-H quality in storage, by examining its quality deterioration up to mixture manufacturing, which is the start point of the whole PMA-H usage procedure. (Our indoor pilot equipment was utilized therefor.)

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Polymer modified asphalts have been widely used to prevent premature rutting on a hot mix asphalt (HMA) layer. Physical properties of polymer modified HMA mixtures are not same as ordinary HMA mixtures using a straight asphalt, and are predominantly dependent on the added thermoplastic high polymer. This paper discusses fatigue characteristics of polymer modified HMA mixtures with taking aging effects into account. Not only cyclic bending test of HMA mixtures but also various binder tests were carried out with aged samples. Based on the results, this study quantitatively indicates that a property change by aging on polymer modified binder is smaller than that on straight asphalt, and fatigue frailer potential of the polymer modified HMA mixtures is lower than that of non-modified HMA mixtures.

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Research was performed to investigate the changes in the quality of asphalt mixtures that were repeatedly recycled in a cold, snowy region. Asphalt binders with penetration values of 80 to 100 and aggregates recycled from asphalt were used in studying the properties of asphalt binders and repeatedly recycled asphalt mixtures. The focus was on their various properties in the low-temperature range. Test pieces made from asphalt that had been repeatedly recycled and degraded to a penetration value of approximately 20, showed wide variations in chemical and physical properties. The results demonstrate that bringing recycled aggregates to the same quality as new materials requires more than just adjusting the penetration value of the aggregates by adding recycled admixture.

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