Use of scanning electron microscopy in concrete studies

Abstract

This paper offers a brief review of the present use of scanning electron microscopy (SEM) in concrete studies, from the perspective of how research in materials science is translated into applications in construction engineering. It describes the scope of present use of the method, and attempts a prospective for the near future in areas where more work could make productive use of the technology. Selected case studies have also been discussed. The electron microscope has been used as a research tool in understanding the root cause of the differing performance of various types of concrete under various conditions, a development tool in making better concrete, and a diagnosis tool on problems like cracking of concrete. The paper also explains how sample preparation affects the type and quality of information which the SEM can produce.

Scanning Electron Micrograph and Surface Hardness of Mineral Trioxide Aggregate in the Presence of Alkaline pH

“…The intensities of electrons backscattered from a point of a specimen depend on the mean atomic number of the material at that point. Therefore, it is possible to distinguish four phases in WMTA specimens: unhydrated cement grains appear bright, calcium hydroxide appears light gray, other hydration products appear darker gray, and pores appear black (25,26). According to this study because of the constant dark gray appearance of the BSE image of WMTA at a pH of 8.4, WMTA had been hydrated completely (Fig.…”

“…SE consists of low-energy electrons, which come from the surface layers of the specimen (26). BSE consists of high-energy electrons, which are back scattered from some depth into the specimen.…”

“…The primary usefulness of SE lies in the evaluation of topographic contrast. The intensity of SE depends on the local inclination of the specimen surface so that a topographic image is produced (26). BSE provides a means of directly examining the relative densities of different phases of the microstructure.…”

Laboratory comparison of roller-compacted concrete and ordinary vibrated concrete for pavement structures

“…Electron microscope can be used as a diagnosis tool for nanoand micro-scale cracking of concrete [35]. The FESEM is an advanced microscope that offers increased magnifications and the ability to observe fine features with a lower voltage compared to the typical scanning electron microscope (SEM) GRAĐEVINAR 72 (2020) 2, 127-137…”

Experimental Investigations of Fracture Process Using DIC in Plain and Reinforced Concrete Beams under Bending

“…A direct observation of fracture is difficult because of a small scale at which micro‐structural events interact with a failure process. Different techniques have been used up to now to experimentally investigate a fracture process in quasi‐brittle materials (concrete, rock and masonry) at the laboratory scale such as scanning electron microscopy (SEM) , high‐speed photography , laser speckle interferometry , acoustic emission technique , X‐rays and digital image correlation technique . Recently, the most popular method (due to its availability, simplicity and low cost) has become the digital image correlation (DIC) technique, which is an optical and a non‐contact measurement method to visualize surface displacements—obtained by tracking the deformation of a random speckle pattern applied to the surface through digital images acquired at different instances of deformation.…”