Effect of different clay additions to concrete on its ultrasonic acoustic parameters and compressive strength

Abstract Concrete may have different levels of mud content due to various factors, which can lead to reduction in strength and changes in ultrasonic acoustic parameters. In order to investigate the effect of concrete mud content level on its ultrasonic acoustic parameters and compressive strength. Firstly, the relationship equation for the effect of concrete mud content on acoustic parameters was derived. Then, the acoustic parameters and compressive strength at different mud content levels were tested based on concrete specimens cast in the field. Finally, based on the measured acoustic parameters, the effects of concrete mud on wave velocity, sound time, amplitude, frequency and strength were analyzed and the relationship equation of mud on acoustic parameters was verified, which provides a reference basis for determining the degree of concrete mud defects. The main conclusions are: based on the acoustic field theory, it is concluded that the higher the mud content of concrete, the lower its strength, the lower the sound time value, the higher the sound velocity value, the smaller the amplitude value; the higher the mud content of concrete, the lower its compressive strength, the compressive strength and mud content is a non-linear relationship, R2 = 0.97; except for pure mud specimens, the increase in the age of the concrete will lead to the increase in the value of the speed of sound, the decline of the value of the sound time value, but in the mud content of 0~10%, the magnitude of change is small; the mud content of concrete on the relationship formula for determining the degree of defects in mud, and to determine the degree of defects in the concrete. 10%; the increase of mud content causes the decrease of sound velocity value and the increase of sound time value, the change is small when the mud content is 0~10%, and the change is larger when it exceeds 10%; the sound velocity value has a linear and nonlinear relationship with mud content, R2=0.88, 0.98, respectively, and the sound time value has a linear and nonlinear relationship with mud content, R2=0.97, 0.96, respectively, and the concrete with a high mud content has a long first wave. The concrete with higher mud content rate has longer first wave period, larger waveform spacing and faster signal attenuation; ultrasonic amplitude change law is more dispersed, but in the age of 7 days and 28 days when the magnitude is close to the higher the mud content rate of the concrete, the amplitude decreases the more significant, the amplitude and the mud content rate is a nonlinear relationship, R2=0.91; frequency value with the increase in the age of the concrete and increase when the mud content rate of more than 20%, the change is significant; the mud content rate of the concrete is more than 20%, the amplitude is significant; the mud content rate of the concrete is more than 20%, the change is significant; the mud content rate of the concrete is more than 20%, the change is significant. The frequency value increases with the increase of concrete age, when the mud content is more than 20%, the change is significant, and the frequency value is linearly related to the mud content, R²=0.95.