循环荷载下再生混凝土疲劳试验*

为了研究再生混凝土循环荷载下的疲劳寿命，采用实验室废弃[C30]混凝土试块，加工处理制成连续粒径级配的再生骨料（5～31.5 mm），用这种再生骨料部分取代天然骨料配制的混凝土试样（100 mm×100 mm×300 mm）进行循环荷载试验。结果表明：随着荷载上限幅值的增大，再生混凝土疲劳寿命逐渐减小。并对再生混凝土疲劳寿命随荷载上限幅值进行线性拟合，且相关系数R的绝对值均大于0.9，表明疲劳寿命与荷载上限线性相关。另外，通过对再生粗骨料取代率与疲劳寿命之间的变化关系研究，得到了当再生粗骨料取代率小于等于50%时，疲劳寿命减小趋势不明显；当再生粗骨料取代率大于50%时，疲劳寿命曲线斜率明显增大，表明疲劳寿命减小趋势迅猛。因此，当采用再生粗骨料进行路基路面施工时，建议再生粗骨料取代率小于等于50%。

Fatigue test of recycled concrete under cyclic loading

In order to study the fatigue life of recycled concrete under cyclic loading, laboratory waste concrete test blocks, C30, were used to produce recycled aggregate (5~31.5 mm) with a continuous particle size grading. Nature aggregate was partially replaced by the recycled aggregate. Concrete test specimens (100 mm×100 mm×300 mm) processed by the partial recycled aggregate were subjected to cyclic loading tests. The results show that with the increase of the upper limit of load, the fatigue life of recycled concrete decreases gradually. In addition, the fatigue life of recycled is linearly fitted with the upper limit of the load, and the absolute value of the correlation coefficient R is greater than 0.9. This indicates that the fatigue life is linearly related to the upper limit of the load. Through the study of the relationship between the replacement rate of the recycled coarse aggregate and the fatigue life, it was found that when the replacement ratio of the recycled coarse aggregate is less than or equal to 50%, the fatigue life is not significantly reduced; when the recycled coarse aggregate is replaced above 50%, the slope of the fatigue life curve increases significantly, indicating that the fatigue life decreases rapidly. Therefore, when using recycled coarse aggregate for subgrade pavement construction, it is recommended that the replacement ratio of recycled coarse aggregate is less than or equal to 50%.