BRITISH STANDARD

Part 113. Method for determination of.aggregate abrasion value (AAV)

BS 812 :Part 113 : 1990

Testing Aggregates

BS 812 :Part 113:1990

Contents

Committees rcsponsibleForewordMethod

PageInside front cover

2

1 Scope2 Definitions3 Principle4 Sampling5 Apparatus6 Materials7 Preparation of test portions and specimens8 Procedure9 Calculation and expression of results

10 Precision11 Test report

33333444555

AppendixA Details of the evaluation of precision data 6

Table :1 Precision values for the determination of aggregate abrasion value 6

BS 812 : Part 113 : 1990

Committees responsible for thisBritish Standard

The preparation of this British Standard was entrustcd by the Cement,Gypsum, Aggregates and Quarry Products Standards Policy Committee (CAB/-)to Technical Committee CAB/2, upon which thc following bodies werereprcsented:

Aggregate Concrete Block AssociationAssociation of Consulting EngineersAssociation of Consulting ScientistsAssociation of Lightweight Aggrcgatc ManufacturersBrick Developmenl AssociationBritish Aggrcgatc Construction Materials IndustriesBritish Cement AssociationBritish Ceramic Research Ltd.British Civil Engineering Test Equipmenl Manufacturers' AssociationBritish Geological SciencesBritish Precast Concrete Federation LtdBritish Ready Mixed Concrete AssociationBritish Steel IndustryBuilding Employers ConfederationCalcium Silicate Brick Associalion LtdChartered Institute of BuildingConcrctc SocietyCounty Surveyors’ SocietyDepartment of the Environment (Building Research Establishment.)Department of the Environment (Property Services Agency)Department of TransportDepartment of Transport. (Transport and Road Research Laboratory)Electricity Supply Industry in England and WalcsFederation of Civil Engineering ContractorsInstitute of Concrclc TechnologyInstitution of Civil EngineersInstitution of Highways and TransportationInstitution of Structural EngineersInstitution of Water and Environmental ManagementMortar Producers Association LimitedSand and Gravel Associalion LimitedSociety of Chemical Industry

ISBN 0 580 18828 0 I I

BS 8 1 2 : Part 113 :1990

Foreword

This Part of BS 812 has been prepared under the direction of the Ccmcnt,Gypsum, Aggregates and Quarry Products Standards Policy Committee and is arevision of clause 9 of B S 812 : Part 3 : 1975 which is withdrawn It forms part. ofa general revision of the 1975 edition of BS 812. As each of the tests orcollection of tests is revised it is intended to issue it as a separate Part or Sectionof this standard.

The method describcd in this revision has not been changed technically from thatgiven in BS 812 : Part 3 : 1975. Most of the changes arc editorial and Lhc onlymajor change is that the test sand is no longer allowed to bc re-used. Attention isalso drawn to Lhc dust hazard that can arise during the coursc of the test.

It is intended that other British Standards should call up US 812 test methods asthe basis of compliance. Nevertheless, it is not intended that all aggegatesshould be subjected regularly to all the listed tests. Spccifications in otherstandards should call up only relevant test methods. :

Some of the tests in other Parts of BS 812 arc of limited application, and adviceon the USC of simple t e s t is given, for example, when they can be used for apreliminary sorting of aggregates to see whether more cspcnsivc tcsting isjustified.

Rcfcrence should bc made to BS S12 : P a r t 101 : 1984 for general guidance ontesting aggregates, precision of test methods and variance arising from samplingerrors.

Compliance with a British Standard does not of itself confer immunity fromlegal obligations.

BS 812 : Part 113 : 1990

1 ScopeThis Part of BS 812 describes a method for thedetermination of the aggregate abrasion value(AAV) which gives a measure of the resistance ofaggregate to surface wear by abrasion.NOTE. The titles of the publication referred to in this standardare listed on the inside back cover.

2 DefinitionsFor the purposes of this P a r t of BS 812, thedefinitions given in BS 812 : Parts 100, 101 and 102apply.

3 PrincipleTwo specimens made up f rom selected andcorrectly orientated particles from a test portionembedded in resin arc fixed in contact with ahorizontally rotating lap. The specimens are loadedand an abrasive sand fed continuously through thecontacting surfaces of the specimen and lap for aspecified number of revolutions. The aggregateabrasion value is detetmined from thc differencesin mass of the spccimcns before and after abrasion.

The sample used for the test (the laboratorysample) shall have been taken in accordance withclause 5 of BS 812 : Part 102 : 1989.

5 ApparatusNOTE. All apparatus should comply with the generalrequirements of BS 812 : Part 100.

5.1 Abrasion machine, consisting essentially of amachined flat circular cast iron or steel grinding lapnot less than 600 mm in diameter, which can bcrotatcd in a horizontal plane at a speed of 28 r/minto 30 r/min. The abrasion machine shall bc fittedwith a rcvolution counter, and the followingaccessories: .

(a) al least two machined metal moulds forpreparing spccimcns, manufactured withremovable ends and with internal dimensions of92.0 ± 0.1 mm x 54.0 ± 0.1 mm ×16.0 ± 0.1 mm, if crystic resin is used, or thesedimensions reduced by 0.5 mm if a non-shrinkingresin is used (see note 1 to 6.2);(b) at least two machined metal trays or metalbacking plates for holding the preparedspecimens. Trays made from 5 mm mild steelplate and of internal dimension 02.0 ± 0.1 mmx 54.0 ± 0.1 mm x 8.0 ± 0.1 mm arc suitable;(c) at least two machined flat, plates made from6 mm tnild steel plate of dimensions115 ± 0.1 mm × 75 ± 0.1 mm;

(d) means for locating two of the trays (orspecimens with backing plates) with their centrepoints 260 mm from the centre of the lapdiametrically opposite to each other and withtheir long sides lying in the direction of rotationof the lap. The trays shall bc free to move in avertical plane but restrained from moving in thehorizontal plane;(c) two weights, each with a rounded base forpressing the test specimen against the surface ofthe lap and each having a means for adjusting itsmass, including test spccimcn and tray, to2000 ± 10 g (see clause 8);(f) means for feeding sand cotilinitously on thelap in front. of each test specimen al; a rate of700 g/min to 800 g/min, and for removing thesand after it has passed under the test satnplcs.NOTE. Regular testing of very hard aggregates may visiblyscore the machined surface of the lap. The surface should beinspected between test runs and any such damage should berectified by machining.

5.2 A means of reducing the laboratory sample,e.g. a sample divider, of size appropriate to themaximum particle size t o be handled oralternatively a flat shovel and a clean, flat, hardsurface, e.g. a metal tray for use in quartering.NOTE. A suitable divider is the riffle box illustrated in BS 812 :Part 102.

5.3 Test sieves with an aperture size of 14.0 mm insquare-hole perforated-plate and of 850 µm,600 µm, 425 pm, 300 µm and 212 µm in woven wire.The lest sieves shall comply with BS 410.

5.4 Slotted flake-sorting sieve, of size 20.0 mm t o14.0 mm having a slot width of 10.2 ± 0.15 mmcomplying with BS 812 : Section 105.1.

5.5 A well-ventilated oven, thcrmostaticallycontrolled to maintain a temperaturc of105 ± 5 ºC.NOTE. This is only required if the test portion is to beoven-dried rather than air-dried.

5.6 A balance of at least 1 kg capacity, readable to0.1 g.

5.7 Two fine-haired brushes about 3 mmdiameter.

5.8 A brush with stiff bristles.

5.9 A c l a m p , such as a 200 mm G-clamp.

5.10 A thermometer , complying with BS 593, andstamped as such, that covers the range 100 ºC to110 º C

5.11 A balance, of at least 2.5 kg capacity,readable to 1 g.

Method

BS 812 : Part 113 : 1990

6 Materials6.1 Abrasive, consisting of, Leighton Buzzard silicasand at least 75 % of which shall pass the 600 µmtest sieve (5.3) and be retained on the 425 µm sicvcand all of which shall pass the 850 µm sieve and beretained on the 300 µm sieve. The sand shall be dryand shall not have been previously used. About30 kg is required for each test.

6.2 Polyester resin and hardener, (see note 1)together with a rclcasc agent such as liquid carpolish, a cleaning solvent or a mixture of90 % (V/V) acetone 10 % (V/V) kerosene, anddisposable cups suitable for mixing the resin (seenote 2).NOTE 1. Crystic resin is suitable and gives about 0.5 mmshrinkage on the length and width of the specimen; if a1 mm-shrinking resin is used the appropriate mould dimensions

should be decreased by 0.5 mm.

NOTE 2. Paper, polypropylene or resin-making cups are suitablebut some plastic.5 cups may dissolve in the clearing solvent.

6.3 Fine sand, (passing the 212 µm test sicvc), toprevent the polyester resin from squeezing upbetween the individual picccs of aggregate.

7 Preparation of test portions andspecimens

7.1 Test portionsRcduce the laboratory sample using the proceduresdescribed in clause 6 of BS 812 : Part 102 : 1989 andsieve to produce a test portion consisting ofaggregate passing a 14.0 mm sieve (5.3) andretained on the 20.0 mm to 14.0 mm flak-sortingsieve (5.4). The mass of the test portion shall bcsufficient to allow two test spccimcns to bcprepared as described in 7.2. After sieving theaggregate wash to remove surface dust and allowto dry in air or oven dry for a period not cxceeding4 h at a temperature not exceeding 110 ºC. Theaggregate shall bc tested in a surface-dry conditionand shall bc at room temperature before thepreparation of the test portion as dcscribcd in 7.2.

7.2 Specimens

7.2.1 Prepare two specimens for each test.

7.2.2 Lightly coat the internal faces and top edgesof the mould with release agent. with onefine-haired brush.

7.2.3 From the test portion prepared as dcscribcdin 7.1 select as many particles as possible and inany case not less than 24 and place them in themould in a single layer with their flattest surfacelying on the bottom of the mould.NOTE. The particles may be selected from the test portion a srequired but. care should be taken to ensure that they arerepresentative of the test portion.

7.2.4 Fill the intcrstices between the picccs ofaggregate to approximately thrcc-quarters of theirdepth with the fine sand (see 6.3) and lcvcl withthe other fine-haired brush. Mix sufficient resinand hardener in a disposable cup and use to fill themould to overflowing.NOTE. Approximately equal proportions of resin and hardenerhave been found to be suitable when using crystic resin.

7.2.5 Coal. one side of the flat. plate with therclcasc agent and place it firmly on the mould,coated side down, and hold in position by theclamp. When the resin has hardened (usually after30 min), rcmovc the plate and trim off the excessresin with a knife or spatula.

7.2.6 Removc the specimen from the mould,rcmovc the loose sand with the stiff brush andweigh the specimen to the nearest 0.1 g (mass A).NOTE. The solvent should be used to clean moulds tools, etc.,as required.

8 ProccdurcWarning. The abrasion of the aggrcgate during thecourse of the operations dcscribcd in this clausemay generate particles that could bc injurious tohealth. It is essential therefore that, in addition toensuring that the test equipmetn is properlyguarded, appropriate precautions arc taken such asby the use of dust masks or dust containing and/orextracting facilities.

8.1 Fit each specimen into one of thc machinedmetal trays or metal backing plates, taking care toensure a tight fit. Weigh each specimen in its traywith one of t h e weights and adjust the mass untilthe total is between 2000 ± 10 g.

8.2 Place the two specimens in the abrasionmachine diametrically opposite to each other withtheir centre points 260 mm from the centre of thelap and so that the 92 mm × 54 mm face of exposedaggregate particles rests on the lap over the wholeface area and then place the appropriate wcightscentrally on the specimens.

8.3 Turn thc lap through 500 revolutions at aspeed of 28 r/min to 30 r/min, the abrasive sand(see G.1) being fed continuously on to i t across t h efull width of the specimen immcdiatcly in front ofeach test specimen at a rate of 700 g/minto 900 g/min per specimen.NOTE. A slab of about 1 .3 mm is suitable.

To ensurc that the sand is fed beneath eachspecimen l i f t them clear of the lap for onerevolution before the start of abrasion and at everyhundredth revolution thereafter, Remove the sandwith a rubber-edged bladc, mounted so that therubber edge rests lightly on the lap for its fullwidth, and discard the sand.

4

BS 812 : Part 113 : 1990

8.4 If it becomes apparent that, because of thenature of the aggregate, it has abraded away to thelevel of the resin backing discontinue the test andreport the number of revolutions.

8.5 On completion of 500 revolutions, remove thetest specimens from thc machine, remove the traysor backing plates and the weights and weigh thespecimens to thc nearest 0.1 g (mass B ) .

9 Calculation and expression of results

9.1 Calculate the aggregate abrasion value (AAV)of each test specimen, to three significant figures,from the following equation:

3000 (A - B )AAV = d

whcrc

A is the mass of specimen before abrasion(in g);

B is the mass of specimen after abrasion(in g);

d is the particle density of the aggregate(on saturated surface-dried basis) asdetermined in clause 5 of BS 812 : Part 2 :1975.

NOTE. The calculation is based on the percentage loss in mass ofan assumed 33 mL volume of the aggregate.

9.2 Calculate the mean of the two results to twosignificant figures. Report the mean as theaggregate abrasion value, unless the individualresults differ by more than 0.2 times the meanvalue. In this case repeat the test on two furtherspecimens, calculate the median of the four resultsto two significant figures, and report the median asthe aggregate abrasion value.NOTE. The median of four results is calculated by excluding thehighest and the lowest result and calculating the mean of thetwo middle results.

10 Precision10.1 A precision experiment was carried outinvolving 13 laboratories. Details of the experimentand the precision data are given in appendix A.

10.2 Uses of precision data are described in clause5 of BS 812 : Part 101 : 1084.

11 Test reportThe test report shall affirm that the aggregateabrasion value was dctermincd in accordance withthis Part of BS 812 and whether or not a certificateof sampling is available. If available a copy of thecertificate of sampling shall be provided. The testreport shall include the following informalion:

(a) sample identification;(b) mean aggregate abrasion value.

Appendix

Appendix A. . Details of the cvaluationof precision data

A.1 The precision data given in table 1 weredetermined from an experiment conducted in1989/90 involving 13 laboratories. The experimentwas designed, and the data analysed, following theprinciples set out in BS 5497 : Part 1. A 4 tstockpile of material B was used, and a 1 t

stockpile of material G. Laboratory samples ofapproximately 125 kg were taken of material B,and of approximately 25 kg of material G, inaccordance with BS 812 : Part 102, and onelaboratory sample of each material was sent toeach laboratory. Two test portions were prcparcdfrom each laboratory sample for the determinationof the aggregate abrasion value. (Material B wasalso used for the precision experiments recorded inBS 812 : Parts 110, 111 and 112.)

,

A.2 The tests for outliers given in BS 5497 :Part 1 : 1987 were applied to the data. No datawere found to bc outliers.

A.3 Variation due to the preparation of thesamples ( Vs) in the precision trial may be assumedto be small so that R1 will bc similar to R2. Thedefinitions of repeatability r1 and reproducibility.R1 and R2 and of the variances Vr1, Vs and VL aregiven in BS 812 : Part 101. The values given intable 1 apply when a test result is obtained as theaverage of the determinations of the aggregateabrasion value on two specimens made using thesame test portion and run at the same time.

Table 1. Prccision values for the determination of aggregate abrasion value.

Material Mean value of Repeatabilitythe data

Reproducibility √Fd

R2

√(VL = Vs)

r1

16 2.5, Blast-furnace slag (B) 3.5 0.9 0.9

Gritstone (G) 4 0.7 1.5 0.3 0.5

BS 812 : Part 113 : 1990

BS 812 : Part 113 : 1990

Publications referred to

BS 410BS593BS 812

Specification for test sievesSpecification for laboratory thermomctersTesting aggregatesPart 2 Methods for determination of physical propertiesPart 100 General requirements for apparatus and calibrationPart 101 Guide to sampling and tcsting aggregatesPart 102 Mcthods for samplingPart 105 Methods for determination of particle shapeSection 105.1 Flakiness index

BS 5497

Part 110 Methods for determination of aggregate crushing value (ACV)Part 111 Methods for dctermination of thc ten percent fines value (TFV)Part 112 Methods for dctermination of the aggregate impact value (AN)Precision of test mcthodsPart 1 Guide for thc determination of repeatability and reproducibility for a standard testmethod by inter-laboratory tests

BS 812 :Part 113 : 1990

BSILin ford WoodMilton KeynesMK14 6LE

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