In-Situ Examination of Hydration Processes

In-situ studies of hydrated systems, such as cement or gypsum, can now be carried out inside any Scanning Electron Microscope by applying QuantomiX proprietary WETSEMTM Technology. Using WETSEMTM, the sample is placed in a sealed specimen capsule under atmospheric pressure. The "as prepared" water to powder ratio is maintained, and the hydration process is unaffected by the vacuum in the SEM chamber. The wet sample can be placed and observed in a conventional SEM without the need for drying, freezing or employing low pressure or environmental SEM. In addition, qualitative elemental analysis can be performed with Energy Dispersive X-Ray Spectroscopy (EDS).

Cement Hydration with the QX-202C Capsule

Early age hydration reactions of cementitious systems are crucial factors in controlling properties such as workability retention and setting. These reactions have a significant impact on the properties of the hardened material, since at this stage the template of the mature hardened microstructure is being set. WETSEMTM technology enables continuous viewing of the developing microstructures, and following of the morphology formation at this early stage, by making in-situ observations using a scanning electron microscope. To view the hydration process of Portland cement click here.

Gypsum Hydration with the QX-202C Capsule

The following images show the early stages of gypsum hydration; the growth of needle like crystals can be followed in the sequence of micrographs. Images were taken at 8, 16, 24, and 60 minutes. The formation of a network of gypsum crystals is evident within the first hour of observation.

8 min. 16 min. 24 min. 60 min.

FAQ

What are WETSEMTM Technology and QX-202C capsules?

WETSEMTMTechnology is a novel, breakthrough technology enabling the imaging of fully wet samples in a scanning electron microscope (SEM). The technology provides an opportunity to study samples in the SEM, which are isolated from the SEM's vacuum chamber in terms of pressure and humidity.

The QX-202C capsule is a product based on WETSEMTM Technology which is designed specifically for the imaging of dynamic hydration processes such as the curing of cementitious systems.

The QX-202C capsule enables the user to follow, in-situ, the dynamics of a reaction, by creating a sequence of SEM images which reflects the structural development of the sample.

For specific information for which answers do not appear on this page please contact info@quantomix.com.

Who could benefit from the use of the QX-202C capsules?

Any laboratory studying time dependant processes such as the curing process of cementitious or gypsum systems can obtain valuable information by using the capsules.

What type of samples is the QX-202C intended for?

The QX-202C capsules are intended for use with cementitious and other systems involving a dynamic hydration process. For more information please contact tech@quantomix.com.

What are the advantages of WETSEMTM over E-SEM preparation techniques?

WETSEMTM Technology can be applied in any SEM and does not require a special system (e.g. E-SEM, low-vac, variable pressure etc.)

WETSEMTM Technology enables the imaging of dynamic hydration processes in their native environment. The sample is sealed in the ambient environment. The pressure, temperature and humidity conditions it is under, and its water content do not change when it is placed in the SEM vacuum chamber.

Imaging with WETSEMTM Technology does not require a cooling stage, and the temperature of the sample remains close to ambient temperature.

The curing process proceeds in the SEM vacuum chamber with minimal intervention - water/cement ratio does not change and imaging is not limited to the layer which is above water level. In this way samples can be probed frequently, and the true dynamics of the process can be studied in-situ.

In addition, WETSEMTM Technology is very easy to use, and does not require the operator's skill and experience that E-SEM imaging does.

What are the advantages of WETSEMTM over cryo-SEM techniques?

By avoiding the need to freeze samples, it becomes possible to conduct "in-situ" studies. WETSEMTM Technology creates the possibility to image and study a full process rather than intermittent results. It enables the user to prepare a single sample and follow its development rather than deduce what the development process is from a jigsaw of several independent samples.

If samples are also being freeze-fractured, results will normally be obtained from the least cohesive plane - the plane where the fracture occurred. Using WETSEMTM Technology, the plane observed will not be dependant on forces, internal or external, which are applied on the sample.

Preparing WETSEMTM samples is quick and easy and takes only a few minutes, saving time and effort.

I am using calorimetry to study the early stages of cement hydration. Why would I need WETSEMTM as well?

WETSEMTM is a complementary method to calorimetry as well as to other analytical techniques such as XRD. While calorimetry provides information about the heat evolution during hydration, and XRD provides phase composition data, WETSEMTM provides insight on the morphology of the developing phases and their elemental composition.

Do I need a special SEM in order to use WETSEM™ Technology?

QX-202C capsules are the small devices in which wet cementitious samples can be placed and observed. The capsules fit in almost all of the currently available SEM models. Imaging is normally done in a high vacuum environment, but can also be performed in other environments (variable pressure, low-vac or E-SEM).

For best results a back-scattered detector should be used. If a back-scattered detector is not part of your system, please consult your local distributor or tech@quantomix.com.

Will I be able to obtain information about the material constituents of my sample?

For best results, one needs to use WETSEM™ Technology in conjunction with a backscattered electron detector. Thus, the images obtained will correspond mainly to the average atomic number of the constituents of the sample.

Is it possible to apply EDS when using the QX-202C capsules?

Yes. The electron-transparent membrane which is the heart of the WETSEM™ Technology is also transparent to X-rays, making it possible to obtain qualitative EDS spectra of the sample within it.

For how long can I follow a dynamic reaction without removing the QX-202C capsule from the SEM?

The QX-202C capsules are specifically designed to remain vacuum tight for long periods of time, and can remain in the SEM chamber, under high vacuum, for 24 hours or more. Through this whole period the samples can be continuously imaged

Is it possible to remove a QX-202C capsule from the SEM vacuum chamber and then re-insert it?

Yes. You can conduct a dynamic study by intermittently imaging a sample. It is possible to make full use of your SEM by removing the QX-202C capsule from the SEM in the intervals between one image and the next and efficiently using this time to image other samples. This can be done through the whole length of the hydration process and will not interfere with the dynamics of the process which takes place inside the isolated capsule.

Do I need to coat the sample prior to WETSEM™ imaging?

When using WETSEM™ Technology there is no need to coat the sample. The purpose of sputter-coating is to create a conductive layer on the sample's surface and thus to prevent charging artifacts. With WETSEM™ Technology the presence of water in the body of the sample totally eliminates these artifacts.

What is the price of the QX-202C capsules?

The QX-202C capsules are supplied in several package sizes. One of the options is a Starter Kit, designed for first-time users, which includes all of the required tools and accessories. For details please contact your local distributor or sales@quantomix.com.

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