混凝土超声波速与抗压强度之间关系的试验研究

Experimental study on relationship between ultrasonic velocity and compressive strength for different grades of concrete

利用混凝土超声波无损检测技术,对5种不同强度等级(C20、C25、C30、C35、C40)、不同龄期(3、7、14、21、28 d)的混凝土试样进行超声波测试,同时作了抗压强度试验,通过回归分析得出了超声波速与抗压强度之间的函数关系式。结果表明:超声波在混凝土内传播的速度与混凝土的抗压强度两者之间具有较强的相关性,其回归方程可用作非破损条件下推断混凝土强度的计算依据;对于不同强度等级的混凝土,其波速与抗压强度之间的关系存在明显差异。对于同一波速,当混凝土强度等级不同时,其强度也不同,即对于不同强度等级的混凝土,其回归方程不同;强度等级为C20、C30、C40的混凝土,Gauss函数的拟合性较好,而对于强度等级为C25、C35混凝土,指数函数拟合超声波速与抗压强度的关系更加贴近实际。

Based on the technique of nondestructive ultrasonic test, the ultrasonic velocity and compressive strength of five different strength grades （ C20, C25, C30, C35, C40 ） and different age standard （ 3,7,14,21,28 d ） concrete were measured. The function relation between compressive strength and ultrasonic velocity were obtained through the regression analysis. The results indicate that there is a strong correlation between the propagation speed of ultrasonic velocity in concrete and the concrete strength, and it would provide mathermatical dasis for nondestructive ultrasonic testing concrete strength by establishing regression equation. For the different grades concrete, there existed distinctly difference between the propagation speed of ultrasonic velocity in concrete and the concrete strength, for the same ultrasonic velocity, when the concrete grade was different, the concrete strength was also different, that was to say the regres- sion equation was different for the different grades of concrete. For concretes of C20, C30 and C40, the Gauss function fitted better, while for concretes of C25 and C35, the exponential function was much more close to practical application for the correlation between ultrasonic velocity in concrete and the concrete strength.