AS 1141.3.1:2021 – Methods for sampling and testing aggregates Method 3.1: Sampling – Aggregates
AS 1141.3.1:2021 – Methods for sampling and testing aggregates Method 3.1: Sampling – Aggregates.
Section 6 Samples. increment size, laboratory crushing of samples and sample reduction
Ideally, sample increments should be taken while aggregate is in motion either at a discharge or transfer point or from a moving conveyor, but this practice is dangerous if carried out manually. Sample increments from stopped conveyor belts provide the best alternative to sampling from material in motion. Belt samples are a case where a single sample increment forms the entire sample. The ability to treat a single belt sample of this type as representative of the lot is acceptable when the production process Is stable, an entire and full depth sample is taken, and the sample size conforms with the requirements of Table 2.
It is more difficult to obtain fully representative samples from material at rest in stockpiles or trucks. However, adequate samples should be obtained froni aggregate in these situations if the instructions of the relevant clauses of this document are conformed to.
Any material that has fallen back into the sampling area after the initial increment has been removed shall not be included in the sample increment. Where it is required that the moisture content is to be determined, special precautions shall be taken to ensure that no loss of moisture occurs during sampling and storage. Sample increments shall be collected as quickly as possible. Increments shall be stored in a sealed container until preparation of the samples.
When obtaining sample increments from pads constructed by power equipment (see Clauses 8.2. 9.1 and 9.3) or from the top of trimmed stockpiles, the following requirements shall be met:
(a) All sampling locations shall be more than 200 mm from the edge of the pad or the edge of the stockpile.
(b) Sampling locations shall avoid any areas of obvious segregation caused by the operation of the power equipment.
(c) If the material in the pad appears homogeneous, material shall be removed to sufficient depth that a sample increment is obtained and conforms with the requirements of Table 1.
(d) If the material in the pad or stockpile is not homogeneous, then either the material shall be re-blended prior to any sampling, or the number of sample Increments be increased to obtain a representative sample.
(e) Material shall be removed from the pad using a suitable shovel, see Clause 4.2(c). All material removed shall be retained as the sample increment.
(1) All sample Increments that are Intended to be combined to form the sample shall be of approximately equal mass or volume.
NOTE 1 ThIs requirement Is to avoid biasing testing results towards the material characteristics of the largest sample increment.
NOTE 2 Sample Increments can he maintained at approximately equal size by either determining the mass of the increment in the field or by lilting standard sized containers to a marked filling point so that each Increment Is of approximately equal volume. Any practical field method that can be demonstrated to return sample increments of approximately the same mass or volume will satisfy this requirement.
(g) All material recovered from all sample increment locations shall be combined and blended before any reduction or splitting occurs. the sample provided at the end of these processes shall conform with the requirements of Table 2.
Where It is necessary to retain moisture in the sample, sample increment mixing and division of a sample shall be carried out under cover so as to minimize moisture loss. Immediately on completion of sample division, the respective samples shall be placed in sealed containers. The container shall be of asize which ensures that when filled, the free air space is at a minimum.
NOTE The moisture content of the sample can be maintained for several days using sealed containers withminimum free air space.
6.2 Sample increment size.