Sampling of aggregates,
Department of Public Works and Highways Laboratory Test Procedures Manual
AASHTO T2 / ASTM D75
1. SIGNIFICANCE AND USE
Sampling is equally as important as the testing, and the sampler shall use every precaution to obtain samples that will show the nature and condition of the materials which they represent.
2. PROCEDURE
Sampling from a Flowing Aggregate Stream (Bins or Belt Discharge)
Sampling from the Conveyor Belt
Sampling from Stockpiles or Transportation Units
Sampling from Roadway (Bases and Subbases)
Sampling from Stockpiles AASHTO T2 Annexes
a. In sampling material from stockpiles it is very difficult to ensure unbiased samples, due to the segregation which often occurs when material is stockpiled, with coarser particles rolling to the outside base of the pile. For coarse or mixed coarse and fine aggregate, every effort should be made to enlist the services of power equipment to develop a separate, small sampling pile composed of materials drawn from various levels and locations in the main pile after which several increments may be combined to compose the field sample. If necessary to indicate the degree of variability existing within the main pile, separate samples should be drawn from separate areas of the pile.
b. Where power equipment is not available, samples from stockpiles should be made up of at least three increments taken from the top third, at the mid-point, and at the bottom third of the volume of the pile. A board shoved vertically into the pile just above the sampling point aids in preventing further segregation. In sampling stockpiles of fine aggregate the outer layer, which may have become segregated, should be removed and the sample taken from the material beneath. Sampling tubes approximately 30-mm min by 2-m min in length may be inserted into the pile at random locations to extract a minimum of five increments of material to form the sample.
4. Number and Masses of Field Samples
5. SHIPPING SAMPLES
5.1 Transport aggregates in bags or other containers so constructed as to preclude loss or contamination of any part of the sample, or damage to the contents from mishandling during shipment.
2.2 Shipping containers for aggregate samples shall have suitable individual identification attached and enclosed so that field reporting, laboratory logging, and test reporting may be facilitated
Minimum Test Frequency
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QUALITY TEST OF COARSE AGGREGATE FOR CONCRETE STRUCTURE
(Sampling and testing series)
SPECIFICATION, SAMPLING AND TESTING
QUALITY TEST OF COARSE AGGREGATE AASHTO M80
- Grading
- Clay Lumps and Friable Particles
- Materials Finer than No. 200 Sieve
- Abrasion
- Unit Mass
- Density and Absorption
- Soundness
- *Coal and Lignite (Only for Materials that is Brown-black or black)
- *Alkali Reactivity (If the project requires)
QUALITY TEST OF COARSE AGGREGATE CONCRETE STRUCTURE
Item 311 - Portland Cement Concrete Pavement
Item 405 - Structural Concrete
COARSE AGGREGATE (ITEM 311 AND ITEM 405)
For every 1,500 m3 or fraction thereof:
a.) For a source not yet tested or failed in previous quality test:
1 - Q, Quality Test
(Grading, Bulk Specific Gravity, Absorption, Abrasion, Soundness and Unit Weight)
b.) For a source previously tested and passed quality test:
1 - Q, Quality Test
(Grading, Bulk Specific Gravity, Absorption and Abrasion)
For every 75 m3 or fraction thereof:
1 - G, Grading Test
SAMPLING
AASHTO T2 / ASTM D75 - Sampling of Aggregates