Assessing frost resistance of concrete by impact-echo method

This paper presents the results of an analytical and experimental programme to study the validity of measuring P-wave speed reduction by the impact-echo method as an alternative to the conventional resonance method for evaluating the frost resistance of concrete. It was found that, when subjected to freeze-thaw cycles, the relative dynamic moduli of elasticity (E-d) of concrete obtained from the two methods are in good agreement when the relative E-d is above 60%. The experimental results also show that the decrease of P-wave speed of concrete correlates well with the degradation of the relative E-d with increasing freeze-thaw cycles, implying that frequent monitoring of the in-place P-wave speed can be used to track the deterioration of real concrete structures. This potential utilisation may not be limited just to concrete structures in freezing and thawing environments, but could also be applied to those subjected to extreme environmental conditions.