| With the rapid development of the national economy in China, the national arterial highway network is gradually developed, accompanied by the construction of many long-span steel bridges. As the connection link of canyon, bay or river, the long-span steel grid bridge play a very important role in the local logistics and transportation. In recent years, the heavy-load and overload vehicle increase as the volume of traffic in China grows rapidly, which would accelerate the damage of steel bridge deck, shortening its service life. To extend the bridge deck’s service life, break-throughs in steel bridge deck pavement material is needed, through scientific and technological innovations. In this thesis, ECC material is proposed to be used as the steel bridge deck pavement material, due to its typical characteristics of high ductility, crack self-healing capacity and good fatigue property. The use of ECC pavement is expected to prolong the service life of steel bridge deck and reduce the maintenance needs. The material properties of ECC, self-healing mechanism and the applicability in steel bridge deck pavement are investigated in this thesis; the research achievement could provide the experimental and theoretical basis for the application of ECC in steel bridge deck pavement.Firstly, the industrial waste products including fly ash and waste tire crumb rubber were used as inert fillers in the ECC matrix. Based on that, ECC materials with large deformability are successfully produced. The incorporation of fly ash and crumb rubber increase ECC’s bending deformability, and improve the multiple-cracking pattern. Although the addition of crumb rubber increases ECC’s drying shrinkage, the increased deformability of ECC enhances its anti-cracking potential under restraint, which could accommodate the deformation caused the dry shrinkage, and avoids fracture failure. Further, the incorporation of fly ash and crumb rubber eliminates the CO2 emission produced during their disposal process, and improves the environmental friendliness of ECC.Secondly, considering the fast traffic-opening principle after steel bridge deck pavement construction, early strength ECC materials are successfully developed, satisfying the strength demand of traffic-open after 3 days curing. Besides, the links of early strength ECC’s material properties from micro-scale to meso-scale to macro-scale are established based on the micro-fracture mechanics design theory. The effects of curing age and crumb rubber content on early strength ECC material’s mechanical properties are clarified.Thirdly, combining the hydration degree of cementitious materials constituting ECC material and the crack width control capacity of ECC, the increment of ECC matrix’s no-evaporable water content, reaction degree of fly ash and compressive strength at different curing conditions at different ages are investigated. Meanwhile, the crack width of ECC with different mixtures is also studied. Based on the above research results, the evaluation system of ECC’s self-healing capacity is established, providing the design basis for self-healing ECC material. In addition, the effects of self-healing behavior of ECC on its mechanical properties recovery are investigated. It is found that the pre-damaged ECC’s mechanical properties can be recovered to a large degree due to self-healing behavior.Finally, the ECC’s fatigue properties are studied by four-point bending fatigue test; it is found that ECC material has a very high fatigue life when compared with normal cement/asphalt concrete. The finite element method is used to simulate the mechanical response of steel bridge deck ECC pavement under the vehicle load. Considering the ECC’s fatigue properties and the simulation results, it is concluded that optimal thickness of steel bridge deck ECC pavement is 40 mm. |
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