早期高强混凝土准动态损伤试验分析

为了研究早龄期高强混凝土在承受多次反复荷载作用下内部损伤情况及超声波特性,在室内实验室制作了一批混凝土立方体试块,脱模后在标准养护室进行养护。分别测定了1、2和3 d龄期的混凝土立方体试块经历多次50%、70%和80%极限荷载前后的抗压强度和超声波波速变化规律;7、14、28 d龄期混凝土立方体试块的抗压强度和超声波波速。试验结果表明:在28天龄期内声速随龄期增长不断增大,与强度基本呈线性关系;前3天龄期的混凝土试块在承受不同比例的极限荷载时,损伤程度和变化规律不同,单轴抗压强度与超声波波速都能衡量这种变化规律。这对于研究超声波测试技术衡量爆破工程中的早龄期高强混凝土在经受多次爆破荷载作用下的损伤累积规律具有一定的指导作用。

EXPERIMENTAL ANALYSIS OF QUASI DYNAMIC DAMAGE OF EARLY-AGE HIGH STRENGTH CONCRETE

In order to research internal damage and supersonic wave characteristic of early-age high strength concrete subjected to repeated load,cubic concrete samples were made in laboratory,demoulded and maintained in standard curing room. Cubic concrete samples were repeatedly compressed with their 50%,70% and 80% ultimate load at1d,2d and 3d age respectively. Uniaxial compressive strength and supersonic wave velocity were recorded to be used to analyze the variation law of the samples before and after loading. The wave velocities of 7 d,14 d and 28 d cubic concrete samples were measured,and then compressed to crush. The results show that supersonic wave velocity increases with concrete age infirst 28 days,and has linear relationship with strength. Damage and variation law are different for the first 3 d age concrete samples subjected to different proportion ultimate load,which can be observed by uniaxial compressive strength and supersonic wave velocity. It is helpful to evaluate the accumulated damage law of early-age high strength concrete subjected to repeated blasting load in a blast project.