AS 1141.27 pdf download – Methods for sampling and testing aggregates Method 27: Resistance to wear by attrition

AS 1141.27 pdf download – Methods for sampling and testing aggregates Method 27: Resistance to wear by attrition
4SAMPLING
Samples shall be obtained in accordance with AS 1141.3.1 when testing aggregatc,and inaccordance with AS 1141.3.2 if rock spalls are sampled to be crushed to provide materialfor the test portion.Obtain a bulk field sample of at least 60 kg of the aggregate to be testedif the test portion is to be prepared remote from the sampling site, or sufficient material toprovide a test portion of at least 30 kg mass if the test portion is screened at the samplingsite. The mass of spalls required will depend on the efficiency of the crusher used inpreparing the test portion required.
5 PREPARATION OF TEST PORTIONThe test portion shall be prepared as follows:
(a) Sieve the bulk sample over 53 mm and 37.5 mm sieves，and separate the material
passing the 53 mm and retained on the 37.5 mm sieve.Discard the remainder of thesample.
(b) Discard any particles which are found to be misshapen when tested in accordance
with AS 1141.14, using a proportional calliper ratio of 2:1.
(c) Discard any particlc where the fractured edges have been rounded by mechanical
handling processes.
(d)By quartering or other suitable means, divide the test sample into the required number
of test portions of approximately 5 kg and adjust the mass of each test portion towithin the mass of one stone by the addition or subtraction of stones. Discard excessmaterial.
(e) Thoroughly wash the aggregate comprising each test portion, to remove all dust from
its surfaces.
(Allow the moisture to evaporate from the surface or blot it off with a soft cloth,and
subsequently oven dry the test portion to constant mass in an oven operating between105°C and i1o.C.
6 PROCEDURE
6.1 General
The aggregate shall be tested to at least one of Clause 6.2 (the dry attrition test) orClause 6.3 (the wet attrition test).Each procedure requires two test portions to be used.6.2 Dry attrition test
The procedure is as follows:
(a)Select two test portions, determine the mass of each test portion to the nearest 1 g andrecord (my).
(b)Place each tcst portion in one of the cylinders of the Deval attrition machine, bolt on
the covers and set the machine to run for 10 0o0 rotations.
(c)Keeping each test portion separate, remove all material from each cylinder and screen
each test portion on a 2.36 mm sieve.
(d)Thoroughly wash the material retained on the sieve to remove all dust from thesurface of the stone for each test portion.
(e)Dry the material retained on the 2.36 mm sieve from each test portion to constant
mass in an oven operating between 105C and 110°C. Determine and record theretained mass (mz) for each test portion.