Geoscience Reference
In-Depth Information
carried out on the sample. The various petrographic
examination standards listed in
Table 2
give details of
sampling requirements and provide guidance on
appropriate sampling procedures (
Table 3
). For rock and
building stone, the size of sample required depends on the
grain size of the rock, with coarse-grained rock requiring
larger samples than fine-grained rock. Rock/stone
samples may consist of lump samples, drilled cores, or
sawn blocks. For aggregate products it is important to
ensure that a representative number of individual
aggregate particles are examined. For this reason, the
required sample mass increases as the nominal maximum
particle size of the aggregate increases. When sampling
concrete from a structure, broken fragments are not
usually acceptable for petrography, as it is difficult to
differentiate between inherent concrete defects and
sampling damage. Diamond drilled concrete core samples
(
13
) are preferred and the core diameter should be at least
Table 3
Summary of sampling requirements for different geomaterials
Sample type/minimum size for
Material group
petrographic examination
Building stone
100 mm × 100 mm × 50 mm sawn block
or 5 kg lump sample
Roofing slate
1 whole slate
Rock
5 kg of lump or core samples
Coarse aggregate
1
63 mm (75 mm) nominal
50 kg (180 kg)
maximum size
31.5 mm (37.5 mm) nominal
25 kg (90 kg)
maximum size
16 mm (19 mm) nominal
8 kg (45 kg)
maximum size
8 mm nominal maximum size
2 kg
Fine aggregate
1
<4 mm (<4.75 mm) sized
0.5 kg (23 kg)
Concrete
From structure
100 mm diameter core
From production run
150 mm cube specimen
Concrete product
1 unit or 100 mm diameter core sample
Mortar, plaster, and render
From structure
0.5 kg intact lump sample
Screed
From floor
100 mm diameter core sample or
2 kg intact lump sample
Clay brick
From structure or
1 unit
production run
Ceramic tile
1 unit
Architectural glass
100 mm × 100 mm square piece
Bituminous mixtures
From pavement
150 mm diameter core sample
From production run
20 kg
1
EN 932-3 requirements (with ASTM C295 requirements in brackets).
