Fracture examination in concrete through combined digital image correlation and acoustic emission techniques

Syed Yasir Alam,Jacqueline Saliba,Ahmed Loukili

doi:10.1016/j.conbuildmat.2014.07.044

Abstract

In order to build sustainable structures, the study of mechanical behavior must integrate with local phenomena, e.g. fracture propagation and localization zone. Fracture in concrete usually develops in the form of localized zone of microcracks which then coalesce into macrocrack of significant crack openings. In this paper, fracture process in geometrically scaled concrete beams under bending test is analyzed. Acoustic emission (AE) and digital image correlation (DIC) techniques are simultaneously applied to identify fracture parameters such as crack openings and size of fracture zone. The AE technique is useful to identify the location of fracture growth due to microcracks and macrocrack, however, DIC is useful to measure crack openings at various locations of crack. The location of crack tip is also estimated from both techniques. It is observed that the two techniques in coupled position proved effective in identifying the fracture process zone and cracking mechanisms of concrete.

Highlights

Cracking in concrete is a major problem in the design and durability of concrete structures
In the light of the above mentioned facts, the main objective of this paper is to present an experimental approach to study the evolution of fracture process zone size and crack openings in scaled concrete beams by comparing and correlating the results obtained from digital image correlation (DIC) and acoustic emission (AE) technique
In order to analyze the results simultaneously with the AE and DIC techniques, the mechanical behavior can be divided into different stages [25]: pre-peak linear phase, pre-peak non linear phase and the post-peak phase

Summary

Introduction

Cracking in concrete is a major problem in the design and durability of concrete structures. Various experimental methods already employed to detect the fracture process as the holographic interferometry, the dye penetration, the scanning electron microscopy, the acoustic emission, etc Such methods offer either the images of the material surface to observe micro-features of the concrete with qualitative analysis, or the black–white fringe patterns of deformation on the specimen surface, from which it is difficult to observe profiles of the cracked material. The AE technique is a passive method that has been proved to be very effective to locate microcracks and sometimes measure fracture process zone (FPZ) inside the concrete structure [1,2,3,4] It presents a large potential of applications and has been used in the past to study influence of different parameters on FPZ, such as effect of aggregate [5,6,7], porosity [8], the specimen geometry and type of loading [9]. The spatial distribution of damage has not been precisely located

Objectives

Results

Conclusion