Loss on Ignition (LOI) is essential for measuring cement’s composition and quality. It calculates the proportion of volatile substances, such as carbon dioxide, moisture, and organic compounds, emitted when the cement endures high temperatures.
This article reviews the step-by-step process of measuring LOI utilizing a thermogravimetric analyzer (TGA), ensuring precise and consistent results adhering to ASTM C150 specifications.
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Acquiring an LOI Measurement from a TGA
1. Weigh the Empty Crucible
The first step in determining an LOI measurement with a TGA is to weigh an empty crucible and document its mass. This preliminary mass is crucial for correctly verifying a cement sample’s mass and its following calculations. Accuracy is paramount, so ensure the balance utilized is properly adjusted.
2. Add the Cement Sample
Add 1 to 10 g of the cement sample to the crucible, then weigh the crucible with the cement sample and document the shared mass. The difference between this mass and the empty crucible’s mass provides the cement sample’s first mass.
3. Heat the Sample
Put the crucible holding the cement sample in a muffle furnace. Adjust the temperature between 900–1000 °C (1650–1830 °F). This range is satisfactory for volatilizing the organic and inorganic components in the cement.
4. Maintain the Temperature
Extend the set temperature for 15 minutes to fully volatilize the LOI components. Stable temperature control throughout this stage is crucial for the test’s precision.
5. Cool the Sample
Cautiously remove the crucible from the furnace with suitable heat-resistant tools. Let the crucible and sample cool to room temperature in a desiccator to avoid environmental moisture uptake.
6. Weigh the Cooled Sample
After cooling, reweigh the crucible containing the cement sample. The change in mass before and after heating shows the volatile components released during the heating process.
7. Calculate the LOI
Determine the LOI using the following formula:
LOI (%) = (Initial Sample mass – Final sample mass/Initial sample mass) x 100
This sum gives the percentage of the initial sample mass lost during heating, demonstrating the LOI.
8. Ensure Precision
Executing the LOI test on several samples and calculating the average value is advised for precision to alleviate the impact of any anomalies or irregularities in individual measurements.
Significance of LOI in Cement Quality
The LOI test determines the number of volatile components in cement, including carbon dioxide, moisture, and organic compounds. Per ASTM C150 guidelines, the maximum acceptable LOI for general-use Portland cement is 3 %.
A lower LOI value typically implies finer cement quality and good storage conditions.
Safety Considerations
Performing the LOI test requires managing high temperatures and possibly dangerous materials. Proper safety equipment, such as heat-resistant gloves and face masks, is essential.
Always run the muffle furnace in a well-ventilated area to avoid inhaling fumes distributed during heating.
Analyze LOI with XRF Scientific’s TGA Machine
Follow these steps to consistently measure LOI via a TGA and overall cement quality. Following safety practices and testing several samples further improves result reliability.
XRF Scientific supplies educational resources and groundbreaking TGAs, including the xrTGA 1100, well-suited for measuring LOI in cement. It delivers exceptionally high throughput with its 30-sample carousel, user-friendly interface, and quick heating and cooling cycles.
Implementing XRF Scientific’s TGAs can drastically improve the precision and effectiveness of experimental procedures.
This information has been sourced, reviewed and adapted from materials provided by XRF Scientific.
For more information on this source, please visit XRF Scientific.