Fly Ash Testing
Testing services for your products and materials
What is Fly Ash?
Fly ash is a fine, gray powder that is a byproduct of burning coal in power plants. It is made up of tiny particles of ash that are carried out of the boiler by the flue gas. Fly ash is a pozzolanic material, which means that it reacts with lime to form cementitious compounds. This makes fly ash a valuable material that can be used to improve the properties of concrete.
Fly ash is used in a variety of concrete applications, including:
- Concrete mix design: Fly ash can be used to reduce the amount of cement needed in concrete. This can save money and reduce the environmental impact of concrete production.
- Strength: Fly ash can improve the strength of concrete. This is especially beneficial for high-performance concrete applications, such as bridges and high-rise buildings.
- Durability: Fly ash can improve the durability of concrete. This is important for concrete that will be exposed to harsh environments, such as marine environments or areas with extreme weather conditions.
- Workability: Fly ash can improve the workability of concrete. This makes it easier to place and finish concrete, which can save time and money on construction projects.
Here are some of the benefits of using fly ash in concrete:
- Reduces the amount of cement needed: Fly ash can be used to replace up to 50% of the cement in concrete. This can save money and reduce the environmental impact of concrete production.
- Improves the strength of concrete: Fly ash can improve the compressive strength of concrete by up to 20%. This is especially beneficial for high-performance concrete applications, such as bridges and high-rise buildings.
- Improves the durability of concrete: Fly ash can improve the resistance of concrete to cracking, spalling, and corrosion. This is important for concrete that will be exposed to harsh environments, such as marine environments or areas with extreme weather conditions.
- Improves the workability of concrete: Fly ash can make concrete easier to place and finish. This can save time and money on construction projects.
What is Fly Ash Testing?
Fly ash testing is a process of evaluating the quality of fly ash to ensure that it meets the requirements for use in concrete. The tests are typically performed by a third-party testing agency, and the results are used to verify that the fly ash is safe and effective for use in concrete.
There are a variety of tests that can be performed on fly ash, including:
- Physical properties: These tests measure the physical properties of fly ash, such as its particle size, specific gravity, and chemical composition.
- Chemical properties: These tests measure the chemical properties of fly ash, such as its pozzolanic activity and potential for alkali-silica reaction.
- Performance tests: These tests measure the performance of fly ash in concrete, such as its compressive strength, tensile strength, and durability.
The specific tests that are performed on fly ash will vary depending on the intended use of the fly ash. For example, fly ash that will be used to make high-performance concrete will need to be tested for its physical and chemical properties, as well as its performance in concrete.
Fly ash testing is an important part of ensuring the quality and safety of fly ash. By performing these tests, manufacturers can help to ensure that their fly ash meets the required standards and that it is safe and effective for use in concrete.
Here are some of the benefits of fly ash testing:
- Improved quality: Fly ash testing can help to identify and correct any defects in the fly ash before it is used in concrete. This can help to improve the overall quality and durability of the concrete.
- Increased safety: Fly ash testing can help to ensure that the fly ash is safe to use in concrete. This can help to prevent accidents and injuries.
- Reduced costs: Fly ash testing can help to identify and correct any problems with the fly ash early on. This can help to reduce the cost of repairs and replacements.
Fly Ash Testing Plans
The following is a list of tests that are often included in testing plans for fly ash:
| Test Type | Test Standard | Parameter | Notes |
|---|---|---|---|
| Chemical | ASTM C311 (110°C) | Moisture Content | Percentage of moisture in a typical sample |
| ASTM C311 (750°C) | Loss on Ignition | Percentage of material lost during ignition in muffle oven at 750°C | |
| ASTM C114 | Chemical Analysis | Determination of Silicon Dioxide, Aluminum Oxide, Iron Oxide, Calcium Oxide, Sulfur Trioxide, Sodium Oxide, and Potassium Oxide | |
| ASTM C311 / C114 | Available Alkali | Calculates “Equivalent Na2O %” of a typical sample. Equivalent sodium oxide. | |
| ASTM D1426 | Ammonia | Determination of ammonia content of a typical sample, expressed on a mg/kg basis. Method A – Direct Nesslerization. Method B – Selective Ion Electrode. | |
| Physical | ASTM C109 | Strength-Activity Index | Comparison of strength performance of control/test mixtures, using 2″ x 2″ mortar cube specimens |
| ASTM C151 | Soundness | Standard autoclave soundness test, performed on samples containing 20% by mass of fly ash/natural pozzolan | |
| ASTM C157 | Increase of Drying Shrinkage | Determines the impact on drying shrinkage of a supplementary cementitious material, when compared to a control sample | |
| ASTM C185 | Air-Entrainment | Calculates air content (volume %) of a mortar, utilizing neutralized vinsol resin solution | |
| ASTM C188 | Density | Standard density (specific gravity) test using volumetric displacement of kerosene | |
| ASTM C430 | Fineness | Determines the percentage material retained when washed on a 45-µm (No. 325) sieve | |
| ASTM C604 | Density | Alternate density test for “true specific gravity” of refractory materials by gas-comparison pycnometer | |
| ASTM C1437 | Water Requirement | Compares amount of water required to produce similar consistency material (control vs fly ash/pozzolan) | |
| Reactivity | ASTM C441 / C227 | Alkali-Silica Reaction Control | Compares expansion of control/test mortars. Control mortar contains an equivalent alkali of <0.60%. A test cement of higher equivalent alkali is used. |
| ASTM C1012 | Sulfate Resistance | Measures length change of control/test mortars when exposed to a sulfate solution (6 month test minimum) |
Fly Ash Testing Standards
Standards and acceptance criteria related to fly ash testing:
- ASTM C109 – Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or [50-mm] Cube Specimens)
- ASTM C114 – Chemical Analysis of Hydraulic Cement
- ASTM C151 – Autoclave Expansion of Hydraulic Cement
- ASTM C157 – Length Change of Hardened Hydraulic-Cement Mortar and Concrete
- ASTM C185 – Air Content of Hydraulic Cement Mortar
- ASTM C188 – Density of Hydraulic Cement
- ASTM C227 – Potential Alkali Reactivity of Cement-Aggregate Combinations (Mortar-Bar Method)
- ASTM C311 – Sampling and Testing Fly Ash or Natural Pozzolans for Use in Portland-Cement Concrete
- ASTM C430 – Fineness of Hydraulic Cement by the 45-μm (No. 325) Sieve
- ASTM C441 – Effectiveness of Pozzolans or Ground Blast-Furnace Slag in Preventing Excessive Expansion of Concrete Due to the Alkali-Silica Reaction
- ASTM C604 – True Specific Gravity of Refractory Materials by Gas-Comparison Pycnometer
- ASTM C1012 – Length Change of Hydraulic-Cement Mortars Exposed to a Sulfate Solution
- ASTM C1437 – Flow of Hydraulic Cement Mortar
- ASTM D1426 – Ammonia Nitrogen In Water
More Information on Fly Ash Testing
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