High temperatures impose a negative effect on the mechanical properties of concrete. An experimental setup designed by the theory of nonlinear resonance vibration, the method of mercury intrusion porosimetry (MIP) and split Hopkinson pressure bar (SHPB) were used to test damage, porosity and mechanical properties of the pre-heated Brazilian discs of 10-year-old concrete respectively. According to the nondestructive test, the hysteretic nonlinearity parameters β h became larger as the temperature went up. The damage calculated by β h , which was 0, 0.57, 0.88 and 0.95 at 20 °C, 200 °C, 400 °C and 600 °C respectively, could be fitted by a power function. Based on MIP, the compound lognormal distribution model was used to simulate the pore size distributions. The quantitative relationship between porosity and damage was established by a power function, with the porosities of 13.96% at 20 °C, 15.77% at 200 °C, 19.17% at 400 °C and 20.22% at 600 °C. Finally, by the method of impact splitting tensile tests under gas pressures of 0.3 MPa, 0.4 MPa and 0.5 MPa, which represented impact velocity of 7.11 m/s, 10.26 m/s and 13.02 m/s respectively, the dynamic tensile strengths were obtained and the quantitative relationship between damage and macroscopic splitting tensile strength was established and the average value of exponential parameter b was 0.281.

中文翻译：

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10 年龄混凝土核心暴露于高温后的损伤评估、孔结构和冲击拉伸行为的试验研究

高温会对混凝土的机械性能产生负面影响。利用非线性共振振动理论、压汞孔隙率法（MIP）和分裂霍普金森压力棒（SHPB）设计的实验装置，对预热10年的巴西圆盘进行损伤、孔隙率和力学性能测试。 -分别为旧混凝土。根据无损检测，滞后非线性参数βh随着温度的升高而变大。由 β h 计算的损伤，在 20 °C、200 °C、400 °C 和 600 °C 下分别为 0、0.57、0.88 和 0.95，可以通过幂函数拟合。基于MIP，使用复合对数正态分布模型来模拟孔径分布。孔隙率与损伤之间的定量关系由幂函数建立，孔隙率在 20 °C 时为 13.96%，在 200 °C 时为 15.77%，在 400 °C 时为 19.17%，600 °C 时为 20.22%。最后，在0.3 MPa、0.4 MPa和0.5 MPa的气压下进行冲击劈裂拉伸试验，分别代表冲击速度为7.11 m/s、10.26 m/s和13.02 m/s，得到动态拉伸强度建立了损伤与宏观劈裂抗拉强度的定量关系，指数参数b的平均值为0.281。