GeoTesting Express is a provider of Aggregate Testing Services – ASTM C, Standard Test Method for Total Evaporable Moisture Content of Aggregate by. ASTM C Standard Test Method for Total Evaporable Moisture Content of Aggregate by Drying. This standard is issued under the fixed designation C ; the number 1 This test method is under the jurisdiction of ASTM Committee C-9 on Concrete.
|Published (Last):||22 May 2016|
|PDF File Size:||1.57 Mb|
|ePub File Size:||20.43 Mb|
|Price:||Free* [*Free Regsitration Required]|
To maintain a constant flow of material over the moisture probe, it can be positioned under the aggregate dosing gate.
E xcessive water can destroy a concrete mix design. Discovering the detrimental effects can be easily seen in a small-scale experiment using compressive-strength cylinders and a common mix design.
Controlling Moisture to Ensure Quality
For one cylinder, increase the amount of mix water and keep all other parameters the same. Then, take the pair of cylinders and break them. Approximate relationship between compressive strength and water-cementitious materials ratio for concrete. Excess moisture in fine aggregates can easily account for a gallon of water.
So the real question is: Do you aztm moisture probes or nationally recognized ASTM manual test methods for determining moisture?
ASTM C566 – 13
We could make strong cases for both methods. However, with either choice, accurate accounting of moisture in aggregates is essential to keep your mix on target and within specified limits. These tests are typically performed daily by the quality control technician and may occur more than once per day depending on aggregate consumption, the prevailing weather conditions, whether or not bins are exposed to the elements and project-specific requirements.
ASTM C uses the sampled aggregate mass against the same sample following drying. Once the moisture of the aggregates has been determined, these values are typically given to the batcher for entry into the batching computer or to make the appropriate manual proportioning changes.
The use of moisture probes for determining aggregate moisture has been widely used as an accepted practice in precast plants across the country for more than 25 years. There are several types of probes on the market today. These technologies allow automatic moisture evaluations of materials. Resistance-type probes measure the resistance of an electric potential between two locations.
ASTM C – 13 Standard Test Method for Total Evaporable Moisture Content of Aggregate by Drying
However, this measurement method is not always accurate since it depends on the impurities, or minerals, present in zstm water. Microwave-type probes do not rely on measuring impurities, making it a better option to use, he said.
Lastly, radar-type probes consist of guided radar waves to facilitate measurements. The probe sends radar waves into the sand and measures the reflection returned. By measuring the reflection points, a sine wave, or data pattern, is then created to guarantee an accurate moisture reading.
Moisture probes can be inspected for damage and buildup when positioned in the floor of a countercurrent planetary mixer. Photo asstm Advanced Concrete Technologies.
ASTM C – 13 – Standard Test Method for Total Evaporable Moisture Content of Aggregate by Drying
Probes can be placed in bins just under the discharge gates and above the weigh belt or directly in the path of the aggregates after they have dropped onto the belt. Probes can also be placed in the mixer. Probes do not eliminate the need to perform manual tests for verification of aggregate moisture.
However, they significantly reduce the frequency of manual tests.
One of the biggest advantages over manual methods is they obtain values of aggregate moisture as they are batched in real time or with very minimal delay. This information is then fed directly into the automated mixing water batch controller of the plant. Automated input allows the plant to make fine adjustments to mix proportions and leads to a much narrower set of final batched concrete tolerances.
Aggregate moisture requirements are addressed in Section 5.
The subsection goes on to state that when aggregate bins are fitted with moisture satm or meters, aggregate surface moisture content shall be determined a minimum of once per week in order to validate probe calibration. For SCC processes made without moisture probes or meters and automatic mixing water adjustment systems, the aggregate surface moisture content must be determined at least once per day prior to the batch and once every four hours after the first batch.
In addition, the language states that slump flow testing will take place for every three batches of SCC produced. This is to ensure that the moisture fluctuations of aggregates are accounted for correctly.
For x566 information on moisture probes, please contact the NPCA technical services department at Thank you for your comment Sufian. Your email address will not be published. Comments How is the price for the probe including installation charge?
Leave a Reply Cancel reply Your email address will not be published.