Evolution characteristics of flexural fatigue performance of dense concrete consolidated with high frequency vibration applied in airport pavement

To verify the reliability of slip-form paving technology with high frequency vibration and its influence on the evolution characteristic of flexural fatigue of dry concrete containing large diameter aggregates(maximum to 40 mm), two 40 cm-thick concrete pavement slabs were constructed adopting the small machine construction process(low frequency vibration) and slip-form construction technology(high frequency vibration), respectively, at Xinzheng Airport, Zhengzhou. The flexural tensile strength and fatigue tests were conducted on the specimens(both dimensions are 150 mm×150 mm×550 mm) cut on the field and prepared in the laboratory with the same mixture proportion. The strains and vertical deflections at the mid span bottom of beam were measured. The flexural fatigue life probability distribution characteristics of concrete beams consolidated with different methods were analyzed according to the reliability theory, and the flexural fatigue equations were established. The deteriorations of flexural moduli of specimens and the evolutions of residual strains at the mid span bottom of beam were analyzed as well. Research result shows that the high frequency vibration technology consolidates the concrete denser, and the average fatigue life of specimens is about 27% longer than that consolidated with low frequency vibration. The double logarithmic fatigue equation can well characterize the fatigue behavior of pavement concrete containing large-diameter aggregates. The fatigue life of concrete consolidated with high frequency vibration is 4% longer than that consolidated with low frequency vibration at high stress level, while the fatigue life of concrete consolidated with high frequency vibration is 18% longer than that consolidated with low frequency vibration at low stress level. The flexural tensile modulus of concrete deteriorates linearly with the increase of loading cycle ratio. The flexural tensile moduli of specimens at the failure point are 50%-80% of the initial moduli. The axial residual strain at the bottom of beam increases with the accumulation of loading cycles. The four proposed typical evolutionary morphologies can characterize the complex growth trends of concrete residual strains at different stress levels. The increase of aggregate size mainly leads to the dispersion of the evolution rule of specimen's fatigue performance. The cumulative damage and gradually failure of aggregates under the fatigue load are responsible for the typical step characteristics in the concrete residual strain evolution curves. The research results provide a foundation for the establishment of relation function between the laboratory test and the full scale concrete pavement slab on the field, through the full scale ring track acceleration loading test.