Our Pulse

15 September 2014


Since our acquisition of the SEM/EDS, we’ve used the instrument to explore and understand better the microstructure of cement-based materials in a wide range of applications and settings. Our work was recently recognized by Wiley Interscience and EDAX, the producer of our energy-dispersive-x-ray spectroscopy (EDS) unit, in their Essential Knowledge Briefing (EKB) series. These original science publications are short guides to the latest techniques, applications and equipment used in microscopy and spectroscopy. Reviewed and updated annually, EKBs are an essential resource for scientists working in both academia and industry looking to update their understanding of key developments within each specialty.

The EKBs are free to download at: http://www.essentialknowledgebriefings.com

The fourth EKB in the series is on Energy Dispersive Spectroscopy. It begins with an overview of the history and background of EDS and is followed by a discussion of how it is used in practice. The third section discusses some of the problems and solutions with EDS techniques. The guide concludes with two case studies provided by DRP, and we are delighted that our work was chosen for this.

The first chosen study is from an investigation of a concrete sea wall where both marine water attack and alkali-silica reaction were linked to cracking and damage of the sea wall. The EDS was really essential to recognizing the significance of sea water attack, as the concrete had cracks filled with laminated deposits that appeared to consist of various compositions of ASR to the naked eye and under the stereomicroscope. The EDS analyses revealed layers that were rich in magnesium and in magnesium + silicon, which is consistent with brucite and hydrotalcite, respectively. These are typical products of marine water attack. Other layers in the laminated deposits have compositions typical of ASR gel.

The second study showed elemental and phase maps from a foundation on a multi-family residential unit that was subjected to sulfate attack. The EDS analyses showed how we were able to recognize a major depletion of calcium from the outer layer of the concrete, which is typical of sulfate attack rather than salt weathering.