Research On Application Of Aramid Fiber Reinforced Concrete In Airport Pavement

The rapid developing civil aviation industry brings up new requirements for the bearing capacity and durability of the pavement structure.In this study,aramid fiber reinforced concrete was used as the research object to explore its application value in airport pavement.The mechanical properties and durability of the aramid fiber reinforced concrete were evaluated in this study by using pvoven test methods and quantitative standards for the mechanical properties and durability of concrete.Besides,several finite element models were established to calculate the mechanical response of the aramid fiber reinforced concrete pavement in airport pavement structure,and to analyze the influence of the incorporation of aramid fiber on the fatigue life of airport pavement.In this study,specimens were casted using concrete with compressive strength of 40 MPa,and the volume fraction of aramid fiber was 0.0%~1.2%.As for the mechanical property tests,domestic test methods were used to evaluate the compressive strength,elastic modulus,Poisson's ratio,splitting tensile strength,flexural strength and flexural toughness of aramid fiber reinforced concrete,which was mixed with fiber of different content.The influence of volume fraction on the mechanical properties of aramid fiber reinforced concrete is obtained.The compressive strength of concrete is i mproved by the addition of aramid fiber,and the elastic modulus,splitting tensile strength,flexural strength and flexural toughness of concrete are significantly improved.To improve the mechanical properties of concrete,the optimum volume fraction of aramid fiber is 0.8%~1.0%.As for the durability tests,appropriate test methods and evaluation criteria were developed and selected to evaluate the shrinkage performance,early-age cracking resistance,resistance to chloride ion penetration and salt scali ng resistance of aramid fiber reinforced concrete.The influence of volume fraction on the durability of aramid fiber reinforced concrete was obtained.The addition of aramid fiber with the volume fraction of 0.8%~1.2% can significantly reduce the drying shrinkage of concrete,and the drying shrinkage prediction model for aramid fiber reinforced concrete is proposed.The aramid fiber with the volume fraction of 0.2% ~ 1.2% can significantly improve the early-age crack resistance of concrete.However,it has little effect on the chloride ion permeability of concrete.The test results also show that the frost resistance of aramid fiber reinforced concrete is inferior to that of concrete without fiber,and the higher the volume content is,the heavier the damage under the freeze-thaw cycles is.Basic conditions such as the pavement structure parameters,aircraft load parameters and interlayer contact were selected to establish the finite element models,and the difference between the force-bar models and the non-force-bar models was clarified.The verification results show that the model has high computational accuracy and the setting of the force bars can effectively simulate the contraction joint.The aramid fiber reinforced concrete with different volume fraction has little effect on the mechanical response of the airport pavement structure,and the magnitude of the change in bending stress and deflection is less than 5%.The aramid fiber reinforced concrete with a volume fraction of 1.0% can effectively reduce the fatigue damage of the airport pavement to enhance its service life.