SCOPE
This IM describes methods for collecting samples for production quality and blockstone testing.
SAMPLING FOR PRODUCTION QUALITY TESTING
Use all the safety precautions outlined in IM 301 under the section “Location for Sampling”. Many times, production quality samples are taken from stockpiles when the streamflow method and template method are not readily available. It is important to get a sample that is representative of a PCC gradation as the particle size gradation may affect test results. Clay minerals tend to be concentrated in finer particles.
When sampling stockpiles, care must be taken when approaching the stockpile. Do not approach stockpiles with steep or unstable slopes, or with partially frozen slopes. These conditions pose a high risk of stockpile collapse, which may result in either trapping, injuring, or causing the death of the sampler. Park vehicles away from the edge of stockpiles. Bag and label your samples away from the stockpile slopes. An alternative sampling method is to have an end loader build three to five “mini-stockpiles” which can be safely sampled by walking around each of the mini-stockpiles. Only individuals who are certified as an aggregate technician or aggregate sampler through the Iowa DOT’s Technical Training and Certification Program may sample aggregates that are used for Quality Control/ Quality Assurance or Independent Assurance purposes. Please see IM 301 for sampling methods using the Conveyor Belt/Template Method, the Stream Flow Method, or the Stockpile Method. These methods may all be used in the collection production quality samples.
BLOCKSTONE SAMPLING
Blockstone sampling involves removing rock samples from the quarry face. This must only be done accompanied by the DOT District Geologist and taken under their supervision. This should be done in cooperation with the aggregate producer.
It is generally unsafe to approach the high-wall but can be done if the ledge is low and does not contain over-hangs, which should never be approached as it puts the sampler in an unsafe situation. Material may be pried from the face using a long pry bar at the direction of the Geologist. Other ways of securing the sample may involve a company lift with a person trained in harness safety. An end loader or scaler may also be used to dislodge samples from the quarry face. Care must be taken when one is retrieving the samples. Retrieving the samples should only be done after communication with the person doing the sampling from the quarry face. Appropriate blockstone sampling should be done vertically at 3-to-5-foot increments covering the beds of interest or the beds being approved. This sampling should be repeated in at least three (3) locations along the face or faces in the quarry. This procedure can be amended at the time of sampling as the Geologist on site finds necessary.