| The carbonation of concrete is an important factor affecting the durability of concrete structure,which causing concrete p H lowered,steel corrosion and structural performance degradation.Under normal atmospheric conditions,road pavement,airport pavement,railway pillow,bridge,crane beam,light rail and other concrete structures undergoing erosion CO2,but also bear the frequent fatigue loading.Carbonation and fatigue load will lead to the decline of durability and service life.This paper has studied the influence of fatigue damage on concrete carbonation.(1)As the experiment of concrete loaded to different stress levels,the relationship of the stress level and the fatigue life,and the developing of strain in flexural fatigue process are studied.The ratio of residual strain and ultimate strain is defined as the degree of fatigue damage.And the fatigue damage evolution equation of concrete is established.(2)The developing rule of concrete carbonation at different degrees of fatigue damage(0、0.2、0.4、0.6、0.8)is analysed from the experiment and draws conclusions including: the carbonation depth of fatigue damaged concrete subject to Fick scattering law;the carbonation depth increase with the fatigue damage aggravating.In addition,the rupture strength of fatigue damaged concrete after carbonization is studied and the result shows: the rupture strength will decline with the fatigue damage aggravating and the age of carbonation increasing.(3)The effects of fatigue damage of concrete permeability is studied and the result shows: the concrete air permeability coefficient will increase with the fatigue damage aggravating.The relationship of carbonation rate coefficient and the air permeability coefficient is established.(4)The carbonation depth of fatigue damaged concrete variation with carbonation age has been fitting analysis by Origin.Finally,the effect of fatigue damage is given as exponential function.A new carbonation depth prediction model considering fatigue damage is established. |
