EN 932-2-1999 pdf download.Tests for general properties of aggregates — Part 2: Methods for reducing laboratoty samples.
6 Consideration before sample reduction
6.) Moisture content and homogeneity of the sample
When the moisture content of an aggregate is to be deteniuned. one or mow test portions .shall be taken prior to drying. A riffle box or a mechanical diider shall not be used.
When test portions are required for other ininx than moisture content and a riffle box or mechanical dMder is to be used, the bbonitomy sample shall be 1)1-ought to a condition in which it is free-flowing.
NO’Tt I For ag 1’gates ennuumng ru that sgrrgate when thy, or rr aggregates containing lumps or day visible to tin’ naked eye, it Is reconiniended that they are subjected to sample rt”diwtlun In the comtit)on in which they are received at the bboratory. not dñed.
NOTE 2 11 on the basis or visual nspettion, the laboratory suuplc needs mixing, tfrn this idiould be perfanned on a sampling tray. For aggrt’gatc that jntains a wide range of particle siaea It can be drsandi1e to separate the laboratory sample Into two (or more) fractions by sieving and to treat each Iraction to sample reduction wpnrately.
6.2 Test methods that specify only a lower limit to the test portion itiass
For test nwiixLs that specify only a minimum mass (rnT) for the test portion or each of several test specimens one of the following pwcedures to yield 100% to 150% of the sixdtled mass shall be used
a) sample reduction IL%ing a mEaty sample (livicler (see clause 7);
b) saniple ivduetio using a nffle l)OX (sec clause 8); c) sample reduction using fractional shovelling (see clause 9);
d) sample reduction by quartering (see clause 10).
N(YK a) above is the preferred prrwmhin’ said d) is nut recuninwtufrd for wide jjjg
6.3 Test methods that allow a sizeable tolerance round a target mass
For test methoth, which require a test portion mass suited to 11w capacity of the equinuenI that is use(t. but can allow a sizeable tolerance around the test portion mass (for example, deteniunation of water-soluble sulfates), one of 11w following pmeedures that gives a test portion mass within ± 15% of the snecified mass shall be used:
6.4 Test methods that specify a test portion mass within a small tolerance
For the following types of test methods, which require a test portion niass to Lw within a small tolemnre of a specified mass, the proce(hire specified in clause I I shall be used:
a) test methods for which the test portion mass is determined by the capacity of a container used in (1w lest (for exaniple, bulk density);
b) test methods that involve the manufacture of specimens (for example mortar or bituminous bound or hydraulically bound test specimens) from aggregate fnwtion.s that have to be weighed to the nearest 5 g or less;
c) test methods where the test 1xwtion mass is specified with a vezy narrow tolemnce.
7 Sample reduction technique using a rotary sample divider
Select a configuration of the sample divider that will yield the test poilions within 100% to 150% of the specified mass, or within 85% to 115% of the specified mass, i appn)pnat4 to the test method requirements.
N(YrF: mc eakulahotis and !(hcmC”i of sainpir odueltan diviuons using a nme hox grvrn w claww 14 can aL%o 1w appIwI to a rotary iunple divider pnwkk’d ii can divide Into a ina11 and evun iiumtwr of ,iadasamples.
Place ttw sample into the hopper and start the rotor When the rotor is rotating at its operating SptC(l stall the vibrating feeder.
(lwclc that at least :15 revolutions are completed before the laboratory sample is exhausted. If this is not achieved, recombine the subsamples and repeat the samI)le reduction with a lower feed nile.
If the mechanical sample divider is not equipped with a feeder and/or 35 revolutions cannot be achieved, the mass of each portion shall be checked and shall be withut 100% to 150% of the specified mass, or within 85% to 115% of 11w specified mass as appropriate.
8 Sample reduction using a rifle box Put the sample into one of the nme box receptacles. Spread the material out evenly over the full length of the receptacle. Place the other two receptacles in position. EN 932-2-1999 pdf download.