What is the loss on ignition of fly ash?
In the fields of building materials and environmental protection, fly ash is an important industrial by-product and its performance indicators have attracted much attention. in,Loss on ignitionIt is one of the key parameters to measure the quality of fly ash. This article will analyze in detail the definition, test methods, influencing factors and practical applications of loss on ignition, and combine it with structured data to display relevant standards.
1. Definition of loss on ignition
Loss on Ignition (LOI) refers to the mass percentage lost when fly ash is burned to constant weight at high temperature (usually 950℃±25℃). This indicator reflects the content of unburned carbon, organic matter or volatile components in fly ash, which directly affects its activity and stability in concrete.
| Loss on ignition range | quality level | Applicable scenarios |
|---|---|---|
| ≤5% | Level I | high strength concrete |
| 5%-8% | Level II | Ordinary concrete |
| >8% | Level III or unqualified | Need to be processed before use |
2. Test method for loss on ignition
According to national standardsGB/T 176-2017, the test steps for loss on ignition are as follows:
| step | Operation content | Things to note |
|---|---|---|
| 1 | Weigh 1g of sample (accurate to 0.0001g) | Avoid absorbing moisture |
| 2 | Put it into a constant weight crucible | Use a platinum or porcelain crucible |
| 3 | Burn in muffle furnace at 950℃ for 30 minutes | Temperature fluctuation needs to be ≤25℃ |
| 4 | Weigh after cooling | Cooling in dryer |
3. Analysis of influencing factors
Loss on ignition is mainly affected by the following factors:
1.Combustion process: Insufficient temperature of the power plant boiler or excessively coarse coal particles will lead to an increase in residual carbon content.
2.Collection method: The loss on ignition of fly ash collected by electrostatic precipitator is usually lower than that of mechanical dust removal.
3.Storage conditions: Long-term exposure to humid environment may increase the adsorption of organic matter.
4. Hot topics: technological innovation under dual carbon goals
Recent hot topics show that driven by the "double carbon" policy, the low-carbon application of fly ash has become the focus. A research institute recently proposedMicrowave assisted combustion technology, can control the loss on ignition below 3% and reduce energy consumption by 30%. The table below compares traditional and new technology parameters:
| technology type | average loss on ignition | Energy consumption (kWh/t) | CO₂emission reduction |
|---|---|---|---|
| traditional craft | 6.5% | 120 | base value |
| microwave technology | 2.8% | 85 | twenty two% |
5. Practical application suggestions
1.ready mix concrete: Choosing Grade I ash with a loss on ignition of less than 5% can reduce the amount of water reducing agent.
2.roadbed filling: Fly ash with a loss on ignition of 8%-12% needs to be used with lime solidification.
3.emerging areas: Low ignition loss fly ash (≤3%) is being used in 3D printing building materials.
Through the systematic analysis of this article, it can be seen that loss on ignition is not only the core indicator of fly ash quality control, but also a key parameter linking circular economy and green buildings. With the intelligent development of detection technology (such as the promotion of near-infrared rapid detectors), the management and control of this indicator will be more accurate and efficient in the future.
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