Coal tar bearing emulsions were used in the Netherlands as binder in anti-skid surfaces for runways because of their perfect adhesion and fuel resistance properties. They are however toxic and will not be allowed anymore after 2010. Therefore alternatives need to be developed. As one of the alternatives, two types of two-component epoxy modified bitumen have been investigated by means of direct tensile tests (DTT), relaxation tests (RT) and dynamic shear rheometer (DSR) tests. The effect of the curing temperature on the strength development of the epoxy modified bitumen was tested. The results show that the tensile strength increases with increasing curing time and temperature. DTT and RT results indicate that this new epoxy modified bitumen has a much higher tensile strength, cures faster than a bitumen emulsion as a binder. Furthermore, it shows a good stress relaxation even at lower temperatures. The curing speed and the ultimate tensile strength after full curing can be easily adjusted. The DSR results show that the complex modulus of this epoxy modified binder is less susceptible to changes in temperature. The results also suggest that this epoxy modified bitumen has better anti-crack properties at lower temperature and less permanent deformation than bituminous binders at higher temperatures. All these results shows that this type of two-component epoxy modified bitumen can be promising as a binder in anti-skid layers.
Shear fatigue damage to the waterproof cohesive layer has not received enough attention in bridge deck pavement design. Meanwhile, there is less theoretical basis for the design of a waterproof cohesive layer. In this study, direct shear and shear fatigue tests were used to compare the shear strength and fatigue performance of waterproof adhesive materials under different disposal schemes for a cement slab surface, bonding materials, and spreading schemes, and the recommended optimal dosage of waterproof adhesive material for the bridge deck is given. Based on the shear fatigue tests results of indoor waterproof adhesive materials, an equation for prediction fatigue at 15 °C was established and temperature correction was applied. Based on these results, we propose a waterproof cohesive layer design method for bridge deck pavement with interlayer shear damage as the design index. The life expectancy of the shear damage between the decks was calculated for a real bridge deck. These results provide scientific guidance for design of a waterproof cohesive layer in a bridge deck, which can effectively extend the service life of a bridge deck.
Gussasphalt is widely used in steel deck pavement in cold regions; thus, it should have good low-temperature performance. A method for evaluating the low-temperature performance of gussasphalt is presented in this paper. Low-temperature bending, bending creep, and splitting tests were used to study the performance of different types of gussasphalt. The sensitivity and correlation between low-temperature indices obtained from three methods were compared and analyzed with sensitivity factors and the grey relational coefficient, respectively, and the low-temperature evaluation index and standard of gussasphalt in cold regions were determined. Flow, penetration at 50°C, low-temperature bending, and bending fatigue tests of the trabeculae were carried out after secondary mixing of gussasphalt asphalt concrete. Degradation of the material performance after different storage times was studied. Finally, taking the strain energy density as the main control index and considering the fluidity, the high-temperature performance, fatigue characteristics, technical requirements for storage, and mixing time of gussasphalt in cold weather after two mixing procedures are discussed.
Through engineering example and using the FEM software GTS, water-rich loess tunnel excavation is analyzed without or with the grouting-reinforcement effect and different permeability coefficient of grouting-reinforcement structure. Influence of flow field characteristics and displacement field characteristics caused by variation of grouting-reinforcement structure permeability coefficient in ordinary water level was analyzed. The results show that the permeability coefficient of grouting-reinforcement structure is play an important in the seepage path, pore water pressure and seepage velocity. It also influence in the displacement of surrounding rock. Designs of grouting-reinforcement structure of water-rich loess tunnel should consider impact of seepage-stress coupling effect. First, the waterproofing effect of grouting-reinforcement structure should be considered to, otherwise, it should avoid that the pore water pressure increasing by increase of waterproofing effect of grouting-reinforcement structure, the soil shear strength reducing.
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