My Research – Part 3

The third analytical test I performed on the raw fly ash and the geopolymers was dilatometry a.k.a. thermo mechanical analysis (TMA). This is a measure of the deformation of a material under a constant stress over a temperature range.  The result of this method is a plot of the length change of the material as it is heated to a high temperature. This technique is useful for detecting the kinetics of solid state phase transformations. Specifically, dilatometry can be a powerful tool for quickly analyzing the reactivity of different fly ash sources. The high-temperature expansion peak can be linked to the release of chemically bound water and geopolymer samples that exhibit this expansion at higher temperatures tend to have a higher strength. Other phenomena that can be observed from the dilatometry plot include dehydroxylation and viscous sintering.

The dilatometer is ready to sinter some geopolymers!

Here are pictorial instructions on how to perform dilatometry measurements on geopolymers:

First, form a paste in a small plastic syringe.


Second, carefully remove the plastic casing after curing the sample, and cut to approximately 10mm in length.

Third, place the sample into the dilatometer and apply a small force.

Fourth, heat the sample up to a very high temperature and measure its length change. The resulting specimen will appear sintered.

The final data will reveal whether the fly ash source and the activating solution have formed a strong, durable geopolymer matrix.



About Chris Shearer

Chris Shearer grew up in the great state of Ohio in America, and is currently pursuing his PhD in Civil Engineering at Georgia Institute of Technology. With support from the National Science Foundation East Asia and Pacific Summer Institutes (NSF EAPSI) program, he is currently researching fly ash geopolymers at The University of Melbourne under Dr. John Provis during the "summer" of 2011. In his spare time he is an avid movie-watcher, reader, traveler, musician, and supporter of Yellow Jackets sports.
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