a sieve analysis once for every 500 tons of mix production, 2 per day maximum. For QC/QA projects, the special provisions require the QC laboratory to perform a sieve analysis for every 500 tons of mix production and Caltrans to verify the sieve analysis at least once for every ten tests (sieve analysis) performed by the QC laboratory.
If lime slurry marination is required by the contract some test results may be in error. Production tests for cleanliness and sand equivalent will be in error if the testing occurs
after lime treatment.
Therefore, samples for cleanliness and sand equivalent must be
representative samples when sampling in this manner. on aggregates after lime slurry marination without a results.
Sieve analysis may be performed significant affect on the grading
Completed Mix Sampling and Testing All testing on the AC mixture is performed on samples obtained from the street following the instructions in CT 125. Always take enough of sample to perform all the desired tests. It is always better to have too much material than to not have enough.
Failing Test Results It is the Plant Inspectors responsibility to inform the Resident Engineer of any failing test results as soon as possible. Retain any split portions for all samples taken, until the Resident Engineer instructs you to discard it.
Tricks of the Trade If the aggregate samples are very wet, spread them out on a sheet of metal placed in the direct sunlight. This method along with a little stirring will dry out the sample very quickly. The sample only has to be dry enough so that the fines won’t stick to larger aggregates or the screens used for sieving. This will greatly reduce the overall time required to perform a sieve analysis.
You are inspecting at a continuous mixing AC plant, and the aggregates have been treated with lime slurry. Looking at the mixture being discharged from the drum mixer, you notice some uncoated coarse aggregate. The lime residue when mixed with the liquid asphalt has a tendency to increase the viscosity of the asphalt binder. A couple of changes can be made to correct this situation. Increasing the temperature of the asphalt binder or increasing the temperature of the completed mix will help coat all the aggregate. The asphalt binder’s viscosity is reduced if the temperature is increased allowing for a better distribution of the asphalt cement. Be sure to keep an eye on the maximum allowable temperatures for the asphalt binder and the completed mix.