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How to Establish Sieve Shaking Time

The optimal duration of a sieve analysis could be casually described as "long enough to get accurate results, but no longer than necessary." According to AASHTO T 27, the industry guideline for sieve analysis, 10 minutes is usually considered sufficient, but defaulting to this one-size-fits-all time frame does not account for the fact that each type of sample will perform differently based on a variety of factors. Luckily, there is a method of fine-tuning the sieve analysis protocol, and it only requires a bit of basic math.

Instructions

- 1
  Run portions of your sample through the full sieve analysis procedure, gradually increasing the duration of the test. Shake several samples each for five, 10, 15 and 20 minute durations. Record the results.
- 2
  Compare the results for each shake time. For each pan and each increase in time, compute the difference in results as a percentage. This value can be found by dividing the change in mass between two samples by the weight of the sample.
- 3
  Find the test times for which the difference in results is less than one percent for all pans in the analysis. Use the shorter of these two times as your optimal test time as you continue testing your sample.

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