Improved crack monitoring in structural concrete by combined acoustic emission and digital image correlation techniques

Abstract

Crack monitoring is crucial for safety, cost-effective design and maintenance of concrete structures. Most stand-alone crack monitoring techniques have some limitations in characterizing concrete cracking. Therefore, this article focuses on a combined use of acoustic emission and digital image correlation techniques for more effective monitoring of cracks in concrete structures at laboratory standard tests level. The combined methodology provides complimentary information from ‘the ear’ aided by the acoustic emission and from ‘the eye’ aided by the digital image correlation. This complimentary approach is applied herein to characterize the mechanical and damage behaviour of prestressed concrete sleepers that plays an important role in the structural mechanism of the railway structure. The obtained acoustic emission datasets were post-processed, in combination with digital image correlation and mechanical information, using parametric analyses to investigate progressive failure of the prestressed concrete sleepers under three-point bending at the rail seat and at the centre section. Digital image correlation clearly identified critical damage areas as a function of loading periods, while acoustic emission was capable of monitoring the damage process and revealed changes in the overall behaviour. It is demonstrated that the combined use of digital image correlation and acoustic emission can enhance practical applications and improve the understanding of concrete cracking behaviour.