粉煤灰再生混凝土强度的超声检测研究

再生混凝土是环保节能的绿色建筑材料。对再生混凝土试块进行了超声波无损检测单轴轴压试验,对比了试块龄期、粉煤灰替代率以及再生粗骨料替代率等因素对超声波传播速度及抗压强度的影响。试验结果表明:粉煤灰再生混凝土的替代率应适当控制在10%左右;替代率30%的再生混凝土,其抗压强度高于替代率为50%的抗压强度。当应力水平低时,再生混凝土试块应力状态下的超声速度值与初始波速值无太大差别;随应力水平增加,波速值下滑迟缓,最小波速值与初始波速值相比下滑了4%;临近破坏应力,波速出现迅速下降。当超声波波速出现大幅度下降时,则可以断定粉煤灰再生混凝土试块结构趋于破坏,为粉煤灰再生混凝土工作应力状态检测提供依据。

Ultrasonic analysis on strength of recycled concrete with fly ash

Recycled concrete is a green building material of environmental protection and energy saving.The ultrasonic nondestructive testing of the regenerated concrete block was carried out under uniaxial compression test,and the effects of the age of the sample block,the replacement rate of fly ash and the replacement rate of regenerated coarse aggregate on the ultrasonic transmission speed and compressive strength were compared.The results show that the replacement rate of fly ash recycled concrete should be controlled to about 10%.The compressive strength of regenerated coarse aggregate with a replacement rate of 30%is higher than that of regenerated coarse aggregate with a replacement rate of 50%.When the stress level is low,the ultrasonic velocity in the stress state of the regenerated concrete block is not much different from the initial wave velocity.With the increase of stress level,the wave velocity decreases slowly,and the minimum wave velocity decreases by 4%compared with the initial wave velocity.Near the stress of failure,the wave speed drops rapidly.When the ultrasonic wave velocity decreases significantly,it can be concluded that the structure of the regenerated fly ash concrete block tends to be damaged,which provides a basis for testing the working stress state of the regenerated fly ash concrete.