高温处理后活性粉末混凝土动力学行为及本构模型研究

 利用分离式霍普金森压杆系统，采用铅片作为整形器，分别对常温下及400、600、800 ℃高温处理后的活性粉末混凝土（Reactive Powder Concrete，RPC）试样进行单轴冲击压缩实验，研究高温后RPC材料的动态力学性能，建立高温处理后材料的率型本构模型。结果表明：经不同高温处理后的RPC材料的动态抗压强度和韧性指标均有较明显的应变率敏感性，而峰值应变、初始弹性模量受应变率影响不大；不同应变率下，400 ℃以上高温处理后RPC材料的单轴动态压缩力学性能有所降低。扫描电镜分析表明，高温处理后RPC材料微观结构的劣化是宏观力学性能降低的根本原因。对ZWT粘弹性本构模型进行了修正，修正后的模型适用于混凝土材料经高温处理后的率型本构关系的分析。

Study on Dynamic Mechanical Behavior and Constitutive Model of Reactive Powder Concrete after Exposure in High Temperature

The dynamic mechanical behavior and rate constitutive model of reactive powder concrete(RPC) after exposure in high temperature are studied experimentally by means of split Hopkinson pressure bar system.Both the untreated specimens and those after exposure in high temperature(400,600 and 800 ℃) are tested with lead flakes as pulse shapers.The experimental results show that both dynamic compressive strength and toughness of RPC after different high temperature treatments exhibit remarkable strain rate sensitivity while the peak strain and initial Young modulus do not.Furthermore,the dynamic uniaxial compressive mechanical properties of RPC at different strain rate debased after exposure at high temperature over 400 ℃.The scanning electron microscope(SEM) technology is also used to investigate the microstructure change of the RPC material;it proves that the deterioration of microstructure is the essential reason for the reduction of the RPC’s macroscopic mechanical performance.In addition,ZWT viscoelastic constitutive model is utilized and modified,thus it can be used to analysis the rate constitutive relations of concrete after exposure in high temperature.