ASTM C851-76

Recommended Practice for Estimating Scratch Hardness of Coarse Aggregate Particles (Withdrawn 1984)

General Information

• Status: Withdrawn
• Technical Committee: C09 - Concrete and Concrete Aggregates
• Drafting Committee: C09.69 - Miscellaneous Tests

Standards Content (Sample)

AMERICAN NATIONAl ANSI/ASTM C 851 - 76
STANDARD
Standard Recommended Practice for Estimating
SCRATCH HARDNESS OF COARSE AGGREGATE
1
PARTICLES
This Stan~a.rd is issue~ untie~ the Hxcd !lc.~i~tn~t!un C R~ I: the number immediately fulluwing the dcsi •nntiun indicates the
ycnr or urrgmal ndophon or, m the ca~c uf rev1s1un, lhc ye.tr uf ln~l rcvi~iun . A numhcr in pmcnlhc\c~ mdlcatcs the yc11r uf
"' last rcupproval.
1. Scope
softening of the surface due to weathering. A
particle with a thin, soft, and weathered sur­
l. I This recommended practice dcscrjbcs a
face and a hard core should normally be
method of estimating the quantity of soft par­
classed as "soft."
ticles in coarse aggregates on the basis of
scratch hardness. It is intended to be used to
2. Apparatus
identify materials that are soft, particularly
2.l Brass Rod, tJu, in. (I .6 mm) in diame­
those which arc so poorly bonded that the
ter, with a rounded point, mounted in a device
separate particles in the piece arc easily de­
so that a force of 2 ± 0.1 lbf (8.9 ± 0.4 N) is
tached from the mass. The test is not intended
applied to the specimen tested. A suitable
to identify other types of deleterious materials
design for this apparatus is shown in Fig. I .
in aggregates, separate mention of which
The brass rod shall be of suitable hardness so
should be made in specifications. Neither is it
that when filed to a shurp point, it will scratch
intended to imply that certain types of aggre­
a copper penny (U. S. Lincoln design) but fail
gate such as limestone, whose mineral constit­
to scratch a nickel (U. S. Jefferson design).
uents may be relatively soft but well bonded
For use in the field, a brass rod of the speci­
will not perform quite adequately in
together,
fied size and hardness can be mounted into
concrete or other end products even though it
the wooden shaft of an ordinary lead pencil.
may be possible to produce a groove in the
particles by the scratch hardness apparatus.
3. Somples
1.2 This recommended practice is intended
3.1 Coarse aggregate for the test shall con­
primarily for field use in estimating the quality
sist of material from which the sizes finer than
of a deposit of coarse aggregate. It will be
the l/11-in. (9.5-mm) sieve have been removed.
helpful in the laboratory, and when used with
The sample tested shall be of such size that it
visual inspection will afford a fast, convenient
will yield not less than the amounts of the
means of determining the amount of soft par­
different sizes prescribed in Table 1 , which
ticles in aggregate. The test may be useful for
shall be available in amounts of 1 0 % or
preliminary screening of aggregate sources,
more.
but should not be considered for specification
3 .2 Should the sample contain less than
enforcement .
I 0 % of any of the sizes prescribed in Table 1 ,
1.3 In case of question, the scratch test
that size shall not be tested; but fo r the pur­
should be made on a freshly broken surface of
pose of calculating the test results, it shall be
the aggregate particle. If the particle contains
more than one type of rock and is partly hard
1
and partly soft, it should be classed as "soft'' This recommended practice is under the jurisdiction of
ASTM Committee C-9 on Concrete and Concrete Aggre·
only if the soft portion is one third or more of
gate
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