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The photodegradation behavior of a straight asphalt was investigated using a new method "photodegradation test of asphalt binder using pressed thin film samples". Although the photodegradation caused by outdoor exposure is limited to the near surface, the results confirmed that the degree of degradation during 1 to 2 months is more severe than that by the pressure aging vessel (PAV) test, which is designed to simulate the degradation that will occur in the asphalt pavement over 5 to 10 service years., Le comportement à la photodégradation d'un asphalte sans additif a été étudié en utilisant une nouvelle méthode, « essai de photodégradation d'échantillons de minces couches pressées de liant routier ». Bien que la photodégradation engendrée par l'exposition aux éléments soit peu profonde, les résultats ont confirmé que le niveau de dégradation durant 1 à 2 mois est plus élevé que celui indiqué par l’essai de vieillissement PAV (pressure aging vessel) qui est conçu pour simuler la dégradation du revêtement en asphalte durant une période de 5 à 10 ans.

A porous elastic road surface (PERS) is superior to drainage asphalt pavement for reducing highway traffic noise. In earlier research and development, for example using a test track, the difference in sound power level (Lw) of cars has been regarded as the noise reduction effect since it was not possible to measure the change in equivalent continuous A-weighted sound pressure level (Leq) for a series of vehicles on such a limited length of surface. As the result of a comparatively major test construction on a highway, have measured the noise reduction effect of PERS as the difference in Leq. First, we measured the motor vehicle Lw and Leq on each section. However, we found that the neighbouring paved sections also influenced Leq. Next, we calculated Leq according to a highway traffic noise model, using the values of Lw measured in the different paved sections. Since the calculated Leq corresponded approximately with the measured Leq, we could verify the validity of the measured Lw. We again calculated Leq, assuming that each pavement is infinitely long. We assumed the improvement of noise reduction effect of PERS was indicated through the calculated Leq. Consequently, we have found that the noise reduction effect of drainage asphalt pavement was 5–6 dB, whereas that of PERS was 7–9 dB.

Focusing on sunlight that has severe effects on the degradation of asphalt pavement during service, this study examined the relationships between the film thickness of asphalt and the states of photodegradation. The results confirmed that thinner films had a higher modulus of elasticity, lower viscosity, and increased production of carbonyl groups, which is an indicator of oxidative degradation. The degree of degradation rapidly increased especially at thicknesses below 200 μm. The wavelength dependence of spectral photodegradation was also examined. Visual observations and the carbonyl index confirmed that ultraviolet irradiation in the range of 300 to 400 nm caused severe photodegradation of asphalt. Carbon black blocked light near the surface of the asphalt layer, where the damage caused by light is most severe. Addition of carbon black helps to prevent photodegradation by ultraviolet irradiation in the wavelength range of 300 to 400 nm., アスファルト舗装の供用中の劣化現象に影響の大きい光に注目し，この劣化におけるアスファルト単体の膜厚の影響を調査した。その結果，膜厚が薄くなるにつれて，特に200 μm以下の領域で，弾性率の増大や粘性の喪失，また酸化劣化を示すカルボニル基生成の増大など，劣化の程度が急激に著しくなることが確認された。また，分光劣化試験による波長依存性を調査した結果，外観変化やカルボニル指数の挙動より，アスファルトの光による劣化には波長範囲300～400 nmの紫外線の影響が大きいことを明らかにした。さらに，遮光性フィラーとして知られるカーボンブラックは，光による劣化の著しいアスファルト層の表面付近で機能し，波長300～400 nmの紫外線による劣化を抑える効果のあることが見出された。

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.

The components of asphalt binders were separately irradiated with ultraviolet (UV) rays to examine the aging mechanism. The results confirmed that saturates are converted to resins and asphaltenes, resulting in oxygen-containing functional groups, i.e. carbonyl group. The observation also suggested that aromatics are converted to resins and asphaltenes by a different mechanism from saturates. Carbon black, which is extensively used as a weatherproofing filler in the field of plastics, prevented UV conversion of saturates to form carbonyl groups. Furthermore, addition of carbon black to asphalt binder reduced the rise in Fraass brittle point caused by UV irradiation because carbon black suppressed the associated chemical deterioration of asphalt binders. Carbon black also increased the failure strain and stress due to the reinforcing effects. Carbon black was effective for both alleviation of chemical deterioration by UV irradiation and improvement of mechanical properties such as anti-cracking. Therefore, addition of carbon black will improve the durability of asphalt materials and asphalt pavements.

Highway traffic noise is a serious problem in urban areas of Japan, not only for residents along highways but also for highway administrators. Only 13% of urban highways have met the environmental standard for noise. Noise barriers cannot be used as a noise countermeasure on most highways for which access is not controlled. This problem is impeding new highway construction in urban areas. Since 1993 the Public Works Research Institute (PWRI) has been developing a new low-noise pavement called porous elastic road surface (PERS). This new pavement has a porous structure composed of granulate rubber made from used tires as its aggregate and urethane resin as its binder. It is estimated that the potential noise reduction levels in the Leq sound level exceed 10 dB (A). More than 90% of highways in urban areas would meet the standard if this noise reduction level were achieved. The general performance of PERS obtained through past development at the PWRI is examined. Results of recent research done to improve the noise reduction levels of PERS further and the first test construction using PERS in Japan are summarized. The noise measurement result at the site indicates that PERS has enough potential to solve highway traffic noise problems in urban areas of Japan.

Using an aging test method, “UV Aging test by pressed thin film samples”, a straight asphalt and a modified asphalt type-II binder were examined for their aging behavior. The results confirmed that this method is effective to simulate the outdoor exposure test, and ultraviolet-rays radiation is a severe factor to the surface compared with the conditions of the Pressure Aging Vessel test.Furthermore, addition of carbon black showed the tendency to prevent from changing in the chemical fraction by aging, and to restrain the producing of carbonyl group by ultraviolet-rays radiation. Therefore, carbon black will improve the durability of asphalt materials.

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.

The drainage asphalt pavement contains consecutive pores and has the noise reduction effect. We have analyzed the factors of the effect carrying out the site measurements and the experiments related to the drainage pavement. As a consequence, we have derived the sound power level equations of vehicles, which show the noise reduction effect of the drainage pavement at a sound source. In fact, they give us smaller values of sound power level compared to those of the dense graded asphalt pavement. On the other hand we have obtained the flow resistivity of 1, 250 kPa s/m2 for the drainage pavement as the noise reduction effect during propagation. This is smaller than that of the dense graded pavement, 20, 000 kPa s/m2, and generates the excess attenuation in the course of sound propagation. In view of the aforementioned, we have proposed the calculation method of the sound pressure level in the roadside area of drainage pavement on a basis of the A method of ASJ Model-1993, taking into consideration these factors at the sound source and during the sound propagation related to the noise reduction effect of the drainage pavement. The sound pressure levels measured along the drainage pavement have verified this method.