Research On Flexural Fatigue Property Of Reinforced Concrete Beams With Recycled Coarse Aggregate

The fatigue experiment of six recycled coarse aggregate concrete beams and one ordinary concrete beam has been made. Specimens'cracking load under dead-load, fatigue failure characteristic, fatigue life, deflection of span-centre, fatigue flexural rigidity, maximal crack width, development of cracks and strain of concrete and steel bars have been investigated. The influence of fatigue cycle characteristic, ratio of reinforcement, kinds of aggregate and concrete compressive strength on the specimens'fatigue behavior has been also investigated. The main conclusions are as following:1. Specimens have four kinds of fatigue failure characteristics such as normal section crack width and truncated section crack width beyond the limit, the fatigue damage of steel bars. Specimens'fatigue life is from 15 thousand to 1800 thousand.2. Specimens'cracking loads under dead-load have been calculated based on the tension model of ordinary concrete. The calculating value is larger than the testing value by 29% to 37%.3. Deflections of span-centre increase under fatigue-load. The increment of deflection under upper limit load is from 5.0% to 22.1% and the increment of residual deflection is from 12.3% to 66.7%.4. Specimens'fatigue flexural rigidity reduces gradually while cycle time increasing.5. Specimens have normal section crack and truncated section crack. When the stress level is lower and the stress ratio is larger, the maximum crack width is smaller and develops more placidly.