Evaluation Of Frozen Damage Of Concrete At Early Age By Impact Elastic Wave Method

Concrete is an important civil engineering material.In the actual production and construction process,it often causes major safety accidents because of inaccuracy in its quality assessment.Impact elastic wave technology has little effect on the scattering of concrete aggregate particles,strong field applicability,and easy operation.With many advantages,this method is widely used in the evaluation of concrete quality.The early strength of concrete is low,and the interior is susceptible to freezing ice after negative temperature,which will damage the microstructure of concrete.Therefore,it is of practical significance to evaluate the early freezing of concrete by the impact elastic wave technology.In order to study the use of impact elastic wave technology to evaluate the early frost damage of concrete,this paper carried out experimental research,theoretical analysis and numerical simulation analysis.The specific research content is as follows:The impact echo,penetration and compressive strength test research of positive temperature concrete were carried out,and the change law of impact elastic wave P wave velocity,compressive strength and penetration depth with age and the correlation between them.The similarities and differences of P-wave velocity and penetration depth of concrete with different strength levels are compared,and compared with related studies.It is pointed out that the compressive strength and the elastic wave velocity of the concrete cured at positive temperature are in a linear relationship when the wave velocity in the early age is small.Analyze and discuss the problems of P wave velocity,compressive strength and penetration depth used to evaluate the performance of concrete on site,which lays a foundation for the engineering applications.The impact echo method was used to conduct experimental research and theoretical analysis on the change of wave velocity of ordinary and high-strength concrete after negative temperature freezing.the law of the development of the velocity of shock elastic wave P waves in negative temperature concrete is obtained.The impact elastic wave is used to evaluate the frozen damage and compressive strength of negative temperature concrete.A method to jointly evaluate the freezing damage of negative temperature concrete on site from the two aspects of observing the internal freezing damage signal of the concrete and combining the maturity is proposed.The transient dynamics analysis method in ANSYS is used to simulate and calculate the propagation problem of concrete elastic waves with different elastic moduli,revealing the law of elastic waves increasing with the increase of concrete elastic modulus.