| As an important part of the steel bridge deck structure,the development of steel bridge pavement has gained more and more attention from the academic and engineering circles.In order to solve the two major technical problems: steel bridge fatigue cracking and early disease and poor durability in natural conditions.The author’s research team came up with a new idea of improving the bridge stiffness and lower deck stress amplitude and put forward a new system of ultra high performance concrete bridge deck: The laying of 35 mm thin layer UHPC(ultra high performance concrete)in steel panel turn the steel bridge deck into composite deck.Both the UHPC and steel deck are under load and it also acts as the paving layer.The upper layer is the spreading of 10~15mmTPO(Thin Polymer Overlay)polymer concrete to form ultra high performance light composite deck system.The test results and previous studies show that: the steel deck+UHPC+TPO composite deck structure can reduce the stress and deformation of steel deck,improve the force,is expected to fundamentally solve the problem of steel deck fatigue cracking and rutting damage.This paper focuses on the influence of natural conditions on the pavement durability and study on the performance of the mechanical properties of UHPC-TPO and pavement properties of TPO.It mainly completed the following work:According to the research status of aging resistance of pavement material at home and abroad,we understand the different simulation methods of natural environmental conditions and test methods.Considering the characteristics of ultra-thin UHPC-TPO pavement system,this paper first determines the environmental factors of artificial accelerated weathering test and test cycle:focusing on the UV light and salt,high temperature and high humidity environment.To consider the impact of the natural environment,four simulation conditions are totally completed:“UV irradiation”,“UV irradiation +0%NaCl solution immersion”,“UV irradiation +10%NaCl solution immersion”,“UV irradiation + high temperature”,preliminary selected cycles for 12 times(7).After the environmental simulations,the pull-off tests and the shear tests were carried out to analyze the effects of environmental conditions on the mechanical properties of the interlayer between UHPC-TPO.The test results show that: after the four kinds simulation conditions,the mechanical properties,both the bond strength between layers or shear strength decreased with the increase of cycle number with a big early decline and small post decline.By fitting,the bond strength between UHPCTPO layer and the number of cycles showed exponential relationship.Moreover,the bond strength and shear strength showed a linear correlation.Through four kinds of simulation,the bond strength between layers of UHPC-TPO were 3.56 MPa,3.48 MPa,2.96 MPa,2.80 Mpa and the shear strength were 10.32 MPa,9.95 MPa,9.18 MPa,8.59 MPa.According to the degree of influence on the bond strength,the order of the environmental factors are as follows: “UV irradiation + high temperature”>“UV irradiation +10%NaCl solution immersion”>“UV irradiation”.The most unfavorable environment is “UV irradiation + high temperature”.So we should focus more on the condition of high temperature bonding performance of UHPC-TPO layer under the effect of ultraviolet radiation.Combined with the leakage test,the depth of the surface structure and surface stone expulsion rate TPO test,the study of different environmental factors on TPO pavement permeability,water stability and skid resistance and their influence were carried out to evaluate the durability of pavement system comprehensively.The results show that,compared with the mechanical properties,the change in seepage coefficient,the depth of the surface structure and stone expulsion rate is small.So the influence of environments on pavement performance could be ignored for UHPCTPO. |
