海水海砂再生混凝土单轴受压应力-应变全曲线

Complete Stress-strain Curves of Seawater Sea Sand Recycled Aggregate Concrete Under Uniaxial Compression

摘要:

为探究海水海砂再生混凝土（SSRAC）力学性能，设计了不同配合比下海水海砂再生混凝土棱柱体试件，并进行了单轴受压应力?应变全曲线测试。在试验加载应变率10^-5 s^-1和10^-2 s^-1下，得到了试件的破坏模式，分析了峰值应力、峰值应变和弹性模量的变化规律以及应变率、再生粗骨料（RCA）取代率和贝壳含量对上述指标的影响规律，讨论了海水海砂再生混凝土的动态增长因子（DIF）。基于电子计算机断层扫描（CT）测试得到了海水海砂再生混凝土内部的孔隙分布，对应力?应变曲线的特征指标变化趋势进行了解释。最后，在现有再生混凝土单轴受压本构模型的基础上，考虑特征指标的动态增长因子，通过修正下降段形状系数得到了预测应力?应变全曲线。

Abstract:

To explore the mechanical properties of seawater sea sand recycled aggregate concrete （SSRAC）， SSRAC prisms were designed with different mix proportions. The complete stress-strain curves were tested under uniaxial compression with the strain rates of 10^-5 s^-1 and 10^-2 s^-1. Failure modes of specimens and the peak stress， strain at peak stress and elastic modulus were analyzed. And the effects of the strain rate， replacement ratio of recycled coarse aggregate （RCA） and shell particle contents on the above indices as well as the dynamic increase factor （DIF） were discussed. Meanwhile， the pore distribution of SSRAC from computed tomography （CT） tests was used to explain the development of characteristic indices of stress-strain curves. Finally， based on the existing uniaxial compression constitutive models of RAC， the predicted complete stress-strain curve was obtained by taking the DIF of characteristic indices and the modified shape factor of descending branch into account.