>For Production ofwell Shaped andwellGraded Aggregates. Barmac Rock on Rock VSI Crusher General 0 Classification 0 Source Aggregates from Igneous Rocks Aggregates from Sedimentary Rocks 0 Aggregates from Metamorphic Rocks Size 0 Shape 0 Texture A9gregates Strength 0 Aggregatte Crushing Value 0 Aggregate Impact Value Aggregate Abrasion Value Deval Attrition Test Dorry Abrasion Test 0 LosAngeles Test Modulus of Elasticity Bulk Density 0 Specific Gravity Absorption and Moisture Content General ggregates are the important constituents in concrete. They give body to the concrete, reduce shrinkage and effect economy. Earlier; aggregates were considerd as chemically inert materials but now Bulking of Aggregates Measurement of Moisture Content of Aggregates O Cleanliness are chemicay soundness of Aggregate exhibit chemical Alkali Aggregate Reaction Thermal Properties and paste. The mere fact that the aggregates occupy 70-80 per cent of the volume of concrete, their Grading of Aggregates Specic Surface and Surface Index impact on various characteristics and properties of concrete is undoubtedly considerable. Tb know more it has been recognised that some of the aggregates active and also that certain aggregates bond at the interface of aggregate Standard Grading Curve about the concrete it is very essential that one should Crushed Sand 0 Gap grading Test for Determination of Flakiness Index 0 Test for Determination of know Elongation Index 0 Test for Determination of clay, fine silt and fine dust 0 Test for Determination of Organic Impurities Test for Determination of Specific Gravity 0 Test for Determination of Bulk Density and Voids more about the aggregates major volume in concrete. Without which constitute the study of the aggregate in depth and range, the study of the concrete is incomplete. Cement is the only factory made standard component in concrete. Other ingredients, namely, waterand aggregates are natural materials and can vary to any extent in many oftheir properties. The depth and range ofstudws that are required to be made in respect of aggregates to Aggregates and Testingof Aggregates I understand underrated. their widely Concrete varying effects and inuence can be considered aggregate phase. Having now the aggregates study aggregates as two phase studied materials under phase in this chapter: Classication (6) Source (c) Size ((2') Shape (e) xture (/) gravity (1') Bulking factor (k) be phase and we shall The study of sub-headings: (a) (g) Specic cannot in the earlier chapters, in concrete the following ofconcrete for convenience;paste the paste phase ofconcrete and aggregate can best be done on the properties 67 and bulk density Strength (/1) Moisture (J) Soundness content Cleanliness (Z) Chemicalproperties (m) Thermalproperties (n) Durability (0) Sieve analysis (p) Grading Classification Aggregates can be classifwd as (1) Normal weight aggregates, (Ii) Light weight aggregates and (iii) Heary weght aggregates. Ilght weght aggregate and heavy weght aggregate willbe discussed elsewhere underappropriate topics. In this chapterthe properties ofnormal weght Normal aggregates weght will only be discussed. aggregates can be further classified as natural aggregates and artificial aggregates. Natural Sand, Gravel, Achl Crushed Broken Brick, Rock such as Granite, Quartzite, Air-cooled Basalt, Sintered fly ash Sandstone Aggregates aggregate Bbated can also be classified and ne Slag. clay on the basis of the ske of the aggregates as coarse aggregate. Source Almost a natural rocks, namely, mode aggregate gneous, offormation materials sedimentary ofrocks. originate It may be recalled ofmolten magma orlava at the surface ofthe (granite). The sedimentary rocks are formed lifted up. Metamorphic subsequently properties ofaggregate of the parent Within rocks are originally metamorphosed the main rock group, great extent owing to place. due to changes with that gneous onginally either to some extent group, in the structure bebw gneous heat the subsequent say granite bed rocks. There are three kinds of These classifkations are based on the rocks are formed by the cooling crest (trap and basalt) or deep beneath to extreme are influenced rocks together from and metamorphic. the crest the sea bed and subsequently or sedimentary and pressure. rocks which The concrete are making on the basis ofgeobgwalformation processes the quality of weathering ofaggregate and texture ofthe and alteration. may vary to a very main parent rockfrom place 68 II Concrete Technology Aggregates from Igneous Rocks Most igneous rocks make hghly satisfactory concrete aggregates because normally hard, to ugh and dense. The gneous rocks have massive structure, orwholly glassy orin depending combination in between, upon they are entirely crystalline the rate at which they were cooled during formation. They may be acidic or basic depending upon the percentage ofsllica content. They may occur light cobured ordark cobured. The gneous rocks as a class are the most chemically cement. active concrete This aspect wi type ofrocks of gneous aggregate and show a tendency be discussed later: As the gneous on the face ofthe earth, bulk ofthe to react with the aealies in rock is one ofthe concrete aggregates, widely occur'r'ing that are derived, are origin Aggregates from Sedimentary Rocks Igneous rocks or metamorphic rain and wind. the particles ofrock, of the cementing argillaceous agencies deep beneath materials. ofwater The deposition, bed. and becomes cementation are derived from it. The quality rocks are originally rocks with upon to many centimetres. to show up even in an individual to dense cementation, determining Kthe the and light thickness the suitability Both gneous which rocks show foliated may exhibit foliation rocks wi underwhich to be good these concrete aggregate. thickness ofthe parent Sedimentary a fraction ofa rock is less, it is likely it may impair the strength of the rocks vary from of consolidation, the are all important soft to type of factors in aggregates. rocks may be subjected which structure. changes quartizite to hgh the structure characteristic temperature and texture The thickness ofthisfoliation thickness of this foliation is not a desirable rocks partwularly and concrete from sedimentary rocks may vary from contamination, the becomes Rocks causes metamorphism to many metres. Ethe up and are quarried concrete rock for concrete rocks and sedimentary centimetres metamorphic and ofsedirnentary which lifted and the pressure The degree or subjected layer by layer beneath derived and thereby to heavy. of layers Metamorphic concrete stratication aggregate Aggregates from Metamorphic pressure of sedimentary Such rocks may also ywkl flaky aggregates. porous materialgets get structure also can ywld good of the stratifkation centimetre aggregate. takes place material by some siliceous rock layer: subsequently ofaggregates together be carbonaceous, Some siliceous sand stones have proved Simihzrly, the limestone The thwkness hard, coukl the stratifkd the cementing compacted. and deposit and cemented and consolidation The sedimentary depending such as sun, transport sedimentary rock formations continent. aggregate. materials compact aggregates vary in quality agencies fragmantise, the ocean bed where they are cemented The cementing These sedimentary to weathering decompose, in nature. At the same time the deposited to static pressure ocean rocks are subjected These weathering and ofrocks. may vary from a few is less, then individual in aggregate. aggregate However; and gneiss have been used forproduction many ofgood aggregates. It may be mentioned that many properties ofaggregates namely, chemical and mineral composition, petro-graphic description, specific gravity, hardness, strength, physical and chemical stability, pore structure etc. depend mostly on the quality ofparent rock. But there are some properties possessed making which is concerned size. Whik it is to be admitted by the aggregates have no relation thatgood which with the parent aggregates are important so far as concrete rock, particularly, from good parent the shape and rocks can make good Aggregates and Testingof Aggregates E 69 concrete, inferior it may be wrong aggregates to conclude obtained from good can be used formaking satisfactory paste on aggregates about characteristics. bring Therefore, economic factor selection ofaggregates made concrete is the most important from ifsuch The study will include appraisal not be the most economicalone. In general consideration ofbcation ofcement and strength taking the in making that shouhl source, and the amount processing, the nal that aggregate which shoukl content about a of concrete ofprocessing plant which each directly may more than that ofanother the reduction willbring in making information. to the mixing such as correction accomplishes weigh and examination valuable can be delivered It may require a cement the processing with least overall expense, of durability slightly are not so to be done judiciously may be considered a particular which source. Also very often the cost ofsome concrete. in respect cases are there, provide The aggregate when which to the fact that a coating is required Several factors be made from more than one source is avaihzble. The relative cost ofmaterial with such aggregates, fully recovered, cannot rocks. Aggregates owing improvement Records of use of aggregate source may require. concrete parent ofaggregates into consideration. in the several sources choice. selection where thatgood not so good ofaggregate, in cement may be content of the the desired quality in the concrete be selected. Size The largest maximum ske of aggregate practicable to handle under a given set of conditions should be used. Perhaps, 80 mm size is the maximum size that could be conveniently used for concrete (1) reduction ofthe shrinkage. However; may be limited cement making. content the maximum by the following Using the largestpossible (a) reduction size ofaggregate that can be used in any given condition conditions: ofreinforcement; (lb) Clear cover; (iv) Mixing, handling size ofaggregate and placing should but in any case not greater than member: Ihibbles 160 mm size or upto any reasonable caed the quantity plum concrete, techniques. be as large asposszble specified, In such concrete, in ofdrying (ii) Spacing the maximum ske wlllresult (ii) reduction (1') Thwkness ofsection; Generay, maximum in waterrequirement one-fourth within of the minimum the limits thickness ske may be used in plain ofrubble up to a maximum of the concrete. limit of20 percent by volume ofthe concrete, is used when specially permitted. The rubbles are placed on about 60 cm thwk plastic concrete at certain distance apart and then the plastic concrete is vibrated by powerful internal incorporating large bouklers is adopted in the construction member the nominal than the minimum cover considerations, for reinforced considered Aggregates aggregate. between concrete sink into the concrete. is also caed displacement dam in Maharashtra. whichever work, shoukl the main aggregates of This method For heavily reinforced usually be restricted bars or5 is smaller: This method concrete. concrete to 5 mm less mm less than the minimum But from various having a maximum other practical size of20 mm satisfactory. are divided into two and (ii) Fine aggregate. as coarse aggregate The rubbles size ofaggregate clear distance reinforcement, aggregate ofI§)yna maximum to the are generally vibrators. in the concrete and aggregate categories from The size ofaggregate whose ske is 4.75 the consideration bggerthan ofske (1) Coarse 4.75 mm isconsidered mm and less is considered as ne 70 I Concrete Technology Shape The shape ofaggregates concrete. which It is difficult are derived is an important to really measure characteristic since it affects the workability the shape of irregular body like concrete from various rocks. Not only the characteristic ofthe parent the type ofcrusher used willinuence the shape ofaggregates, about are found to yiekl slightly aky aggregates, willyield cubical aggregate. The shape of the aggregate Pune region as found in Bangbre inuenced by the type ofcrusher into crusher jointing which structure. As a consequence is characteristic flaky for'rns, whereas, particles. and the reduction to the she of the nished Similarly, quartizite good the ratio ofske rocks contain granite rock is very much ofmaterialfed planes the internal ofparting or petrographic schists, slates and shales commonly basalt and quartzite which whereas, It also reflects tendencies, rock, but also e.g., the rocks available round ratio ie., Many of its formation. ofthese granite, product. of aggregate produce usually ywld more or less equidimensional does notposses cleavage planesproduces cubical shape water/cement ratio, aggregates. From the standpoint rounded aggregates cement required ofeconomy are preferable for angular in cement to angular aggregate by greaterdurability as a result ofthe and hgher bond characteristic between in concrete aggregates Flatparticles aggregate cement makes very poor Classication One requirement, ofparticles of the methods given On the other hand, is offset to some extent sometimes workability, requirementfora aggregates. interbcking aggregate wihave strength and by the hgher texture ofthe the additional strengths hardened and concrete and cementpaste. particularly objectwnable influence on the durability. In general, excessively flaky concrete. on the basis ofshape of expressing ofthe the angularity aggregate qualitatively is shown in Table 3.1. is by a figure called Angularity Number; as suggested by Shergold 3-1.This is based on the percentage voids in the aggregate number: aercompaction The method in a specied ofdetermination Table manner: The testgives a value termed is described in IS: 2386 (Part D 1963. 3.1 Shape the angularity of Particle f RTounTde_d . .F2iywaterhworn ToTrTcornpTletely, TTTIiiverorTsTeashoTre V shaped by attrition K. . desert,seashoreand bkrsands ,,Tb~re,TgularlTorT T Naturally ular oTrTpTartly x. T TPartlyrounded ~k shapedby attrition,having 7 i TT7D'und,ededge$:TTT T T sands gravelgpland T.orTdug_ints; cuboid rock, '» . » Possessing Twe-deTnTeTd edges TCrushed r1T9cksToTfalliTfyTpes;T formedTatTth,e~ iiiterseqctibnyof T,, _ talus;screes T ~k roughbl planar faces T T TgFlaky 'T T 'MateTTr'iaTl, usuay angular, TqLaminated rocks» T ofwhich, the thickness.is*T'pT g7 smallrelati've»Tto the width T . 'TT r and/orlength Aggregates and Testingof Aggregates I W/hound (spherica|i)i concrete aggregare. Aquantity ofsingle aggregates by pouring water angularity number sked aggregate number out by knowing ofsuch is zero, the solid volume ofthe gravity ofaggregate the levelofwaterupto is considered is considered aggregate ofthree and the percentage the specic aggregate of such aggregate Crushed concrere aggregare. into metal cylinder manner to bring L aggregare. islkd in a standard to the cylinder per cent the angularity Flaky L concrete are compacted The void can be found V 71 litre capacity. The of void is found out. and bulk density the brim. Ethe zero. Ifthe 11. In other or void is 33 void is 44 per cent the words, ifthe is 67 per cent and ifangularity angularity number is orly shped crushed ggreare.|wi| me 9 Barao crushed 0 mmucal gregre. I poor concrete. will make good concrete. Goodaggregae resu|re lfrom Barmac crusher.20mmcrushed angular aggregares notsogood for Concrete. Courtesy: Durocrefe Pune 72 I Concrete Technology 11, the solid volume suitable Angularity angularity making of the aggregate for making the concrete number zero number 11 indicates concrete Murdock represents The normal number the most practicable the most angular not so unduly suggested is 56 per cent. may have angularity aggregates anything rounded aggregates which from aggregates that could are zero to 11. and the be tolerated for harsh and uneconomical a different method for expressing the shape of aggregate by a parameter called Ang ularity Index fA.3'2 Angularity There Ihdex has been btofcontroversy subject /34 = 3fH + 1.0 20 where /7{is the Angularity number: a on the whether the angular aggregate or rounded aggregate will make better concrete. discussing the shape ofaggregate, While the texture of the aggregate also enters the discussion its close association because of with the shape. rounded smooth Generally, aggregates are textured and angular aggregates are rough textured. Some engineers, use prohibit Of the "0unded V Shape andsize ofaggregates agg reg ate o n the ple a Courtesy :Ambuja Cement that ityieldspoorconcrete, and cementpaste. due to lack ofbond They suggest for economicalreason, it shoukl that ifat enough fordevebping cement gel. following But the angular two points (a) Angular (b) a reasonably aggregate is required to be used aggregate surface ofrounded aggregates are superior is notfullyjustied aggregates is rough the surface and the submwroscopic to rounded aggregates from the ofview: aggregates exhibit a better The total surface area ofrough The hgher the smooth bond between in concrete aggregate surface ofthe and then used. This concept good makes it superior rounded the smooth all the rounded be broken for the reason that even the so called, between aggregate forthe interbcking textured given volume. may show hgher surface area ofangular effect in concrete, which property used for roads and pavements. bond angular strength aggregate aggregate By having greater than rounded with rough is more than smooth surface area, the angular aggregates. texture requires more water fora given workability than rounded aggregates. This means thatfora given set ofconditions from the point of view of water/cement ratio and the consequent strength, rounded aggregate gives hgherstrength. these two kinds ofaggregates Superimposing plus and minus points it can be summed up as follows: in favour and against Aggregates and Testingof Aggregates I Forwater/cement up to 38 percent ratio bebw hgherthan 0.4 the use ofcrushed the rounded aggregate. aggregate has resulted 73 in strength With an increase in water/cement ratio the influence ofroughness ofsurface ofthe aggregate gets reduced, presumably because the strength of the paste itself becomes paramount, and at a water/cement ratio of 0.65, no difference in strength of concrete made with angular aggregate or rounded aggregate has been observed. The shape ofthe aggregates becomes all the more important in case ofhrgh strength and hgh perfor'rnance concrete where very bw water/cement ratio is required to be used. In such cases cubwalshaped aggregates are required for betterworlwbllity. Tb produce mostly cubical shaped aggregate and reduce flaky aggregate, improved versions of crushers are employed, such as Hydrocone crushers, Barmac rock on rock VSIcrusher etc. Sometimes ordinarily crushed aggregates are furtherprocessed to convert them to wellgraded cubical aggregates. In the years to come infnastructuralprojects. normal natural sand will not be available One has to go for manufactured way it is likely to ywkl flaky ne produce cubicalshaped wegradedfine aggregate is being practised for hgh aggregate. in large sand. When Dnproved quantity for rock is crushed version ofcrushers big in the are used to aggregate. This method ofproduction ofgood ne rise building projects at Mumbai and for construction ofMumbai-Pune express hghway. On realising the importance producing hgh strength concrete the improved empbyed in India. Surface texture is the property, the measure version ofshape of crushers ofaggregates are being for extinsively Texture ofwhich to which particle surfaces are polished or dull, smooth hardness, ske, pore structure acting grain on the particle structure, surface depends orrough. upon the relative degree Surface texture depends of the rock, and the degree have smoothed or roughend it. Hard, to which dense, on forces ne-grained materials wigeneray have smooth fracture surfaces. Experience and laboratory exper'iments have shown that the adhesion between cementpaste and aggregate is inuenced by several complex factors in addition to the physical and mechanicalproperties. As surface smoothness increases, contact area decreases, hence a hghly polishedparticle will have less bonding area with the matrix than a rough particle of the same volume. A smooth particle, however; willrequire a thinnerlayerofpaste respect to other aggregate particles. It will, workability and hence, willrequire bwerpaste shown tension to lubricate its movements with therefore, permit denserpacking for equal content than rough particles. It has been also by experiments that rough textured aggregate develops hgher bond strength in than smooth textured aggregate. The beneciale)fects ofsurface texture ofaggregate on flexural strength can be seen from Table 3.2. Table 3.2. Influence of Texture on Strength 74 I Concrete Technology Surface texture characteristics of the aggregate as classified in LS 383: 1970 is shown bebw. Table 3.3. Surface Characteristics of Aggregate Glassy Blackflint I Smooth Cheri;slate;marble; some rhyolite ..~k.°°.l\°i.~ tS'zzn*dstone'; oolitesy l l Granular , Crystaine Fine .' Basalt;trachyte;medium: Dolerite; by granophyre; granulite;microgrunite; some ~ limestones; many dolomites. Coarse : Gabbm; gneiss;'granite;'granodiorite,; fsyenite Honeycombed andpono us Measurement of Surface A large number available direct include indirect ofpossible methods. (1) making of this, irregularities by drawing a ne drawing a trace optical, or electrical and getting are broadly into a section methods a cast of the surface a section mechanical, through examining a magnied include: (1) measurement dispersion of lightfalling l ' Scoria; Pumice, truss. methods Direct magnifying surface i Texture and this may be divided and I and (it) Tracing point the over the magnified by means, (iii) the aggregates image. Indirect of the and methods degree of on the surface, (it) determining the weight ofa fine powder required to up the interstices ofthe surface to a truly smooth surface, held rubber against (122)the rock surface surface is at a standard pressure and the resistance between the two surfaces is measured. to the flow of air Aggregate Crushing Value Apparatus. Strength When we tae ofstrength the aggregates strength are produced, of the aggregate ofaggregate bound quality ofthe cementpaste. and aggregate ofthe is bw, in concrete. together paste and the aggregate. we do not imply the strength because the strength by cementing a concrete rock or aggregate. Since concrete This strength Eeitherthe material is dependant strength ofpoor But when ofthe quality cement ofthe parent rock from which rock does not exactly represent is an assemblage its properties are based primarily also on the bond between ofthe paste orthe bond wibe obtained irrespective paste ofgood quality the of individualpieces between isprovizled on the the cement ofthe the paste strength and its bond Aggregates and Testingof Aggregates I with the aggregate inuence is satisfactory, the strength then the mechanwalproperties of concrete. From the above ofthe 75 rock or aggregate it can be concluded that while wi strong aggregates cannot make strong concrete, for making strong concrete, strong aggregates are an essential requirement. In other words, from a weak rock or aggregate strong concrete cannot be made. By and large naturally making normal concrete. strength in the following When ofhgh strength contemplating (z'u") Aggregate Aggregatte Strength manufactured are strong enough is required to be made for strength concrete. manufactured from weathered rocks. by industrialprocess. Crushing Value ofrock is found out by making 25 mm heght. samples are found to give different 45 MPa to a maximum does not exactly indicate of the aggregate a relative measure applied compressive strength varying from in concrete. crushing Generally, this test is made on 10 mm sieve. The aggregate of40 ton is applied through a plunger: is separated and expressed as a percentage taken in the moukl. is referred as aggregate crushing value ofaggregate used for roads may ofabout ofparent aggregate rock in a standardised crushing to crushing value gives under gradually on single sized aggregate isplaced in a cylindrical The material crushed to ner passing moukl and than 2.36 mm ofthe value. is restricted and 45 per structures. a minimum Thispercentage crushing cent for concrete sample 25 rock strength value test. Aggregate of an aggregate shape ofsize stress. Different For this reason assessment is made by using a sample ofbulk as aggregate bad. 12.5 mm and retained The crushing to compressive of aggregate of the resistance cent ofcylindrical subjected compressive the strength This test is known onginalwerght a test specimen This cylinderis of 545 MPa. As said earlier; the compressive manner: a bad aggregates ofaggregate and ultra hgh to use aggregates mm diameterand ofstrength strength situations: (1') Forproduction (it) avaihzble mineral The testfor The to 30 per and pavements be permitted for other value of aggregate is rather insensitive to the variation in strength of weaker aggregate. This is so because having been crushed before the application ofthe full bad of40 tons, the weaker materials become compacted, so that the amount of crushing during later stages of the test is reduced. For this reason a simple test known as 10 percent aggregate nes crushing value is introduced. value become result is likely to be inaccurate, aggregate value shoukl test which strength ofsuch This test be subjected the case the to 10percentnes about the aggregates. is also as mentioned produce 10 per mm) in which gives a betterpicture aggregate 2.36 When the 30 or hgher; done on above. cent fines is found out a single Ioad (particles by sized required to finer than observing the Aggregate Impact Value Apparatus. 76 I Concrete Technology penetration standard ofplunger: crushing The 10 per cent nes value test for strong more sensitive and gives a truerpicture It shoukl be noted numerical is given at the end ofthis result denotes impact falling to concrete kept in a moukl a heght testing the more or less weak samples. of the aggregate. value test, The detail of this test ofaggregate. from pounding the weght of the nes taken is expressed is usually considered to devebp The most successfulis to fteen willindicate as a percentage. impact ofner ofthe mm size) formed, This is known other wearing such as run ways, roads and pavements. surfaces, through I@s. 2.36 mm) sample ofaggregate. The ratio of to the weght total sample ofthe impact value E283-1970 45 per cent by weghtfor used for concrete of a sample ofstandard (passing as aggregate value shall not exceed than wearing the resistance oftestforaggregates ofa metalhammerofwe@ht14 material the toughness than 2.36 a method the one in which bbws cms. The quantity (ner that aggregate toughness Severalattempts is subjected of38 resulting species under between with this test is value test unlike the crushing strength aggregates, to failure by impact. from a hgher chapter value have been made. aggregate dierences correlation aggregates Impact Value With respect the material ofthe a good while for weaker that in the 10 per cent nes a hgher Aggregate value test shows aggregates surface and 30 percent by weght, aggregate for concrete for Aggregate Abrasion Value Apartfrom the aggregate testing aggregate with respect to its crushing value, impact resistance, testing with respect to its resistance to wear is an important test for aggregate to be used forroad constructions, ware house fbors common use to test aggregate abrasion test (it) Ios Angels Deval Attrition Test In the Deval attrition weight are subjected rotated 10000 ofmaterial as the Dorry Abrasion This test Specification. test (it) Dorry cylinder speed. The proportion material attrition This test has been covered test should Three tests are in attrition 1.7 mm size is expressed 1963. But it ispointed IosAngeles construction. (1) Deval of known in an iron of the original is taken aggregate. IV) test, particles to wear crushed nerthan percentage resistance. test. times at certain as a percentage and pavement for its abrasion taken. value This of the by 132386 (Part out that whereverpossible be used. Test is not covered The test cylindrical specimen diameter to the abrasion sprinkled with quartz cylinder after 1000 by Indian involves of25 cm height against Standard in subjecting and rotating metal sand. The bss in weght revolutions determined. The hardeness expressed in an empirbalformula of the of the rock a 25 cm disk of the table is sample is Los Angeles Abrasion Testing Machine. Aggregates and Testingof Aggregates I Hardness Loss in Grams = 20 Good rock shoukl show an abrasion less than 14 wouhl be considered 77 3 value ofnot less than 17. Arock sample with a value of poor: Los Angeles Test Ios Angeles test was devebped to overcome some of the defects found in Deval test. IosAngeles test is characterised by the quwkness with which a sample ofaggregate may be tested. The applicability of the method to a types ofcommonly used aggregate makes this method popular: The test involves taking specied quantity ofstandard size material abng with specied number ofabrasive charge in a standard cylinderand revolving iffor certain specied revolutions. The particles smaller than 1.7 mm size is separated out. The loss in weight expressed aggregate. as percentage of the original weight taken gives the abrasion value of the The abrasion value shouhl not be more than 30 per centfor wearing surfaces and not more than 50 per centfor values ofcrushing and attrition strength concrete ofrocks, value for different otherthan aggregate wearing crushing surface. Table 3.4 gives average value, abrasion value, impact value rock groups. Modulus of Elasticity Modulus ofelasticity ofaggregate modulus ofelasticity shrinkage and elastic behaviour been conducted properties ofaggregate to investigate ofconcrete. on its composition, the properties and to very sma the inuence ofconcrete is not a linear function, texture and structure. ofconcrete extent creep ofconcrete. of modulus One of the studies indwated effect on the elastic property the concrete depends will inuence ofelasticity with and that the relation The to Many studies have of aggregate that the E ofaggregate but may be expressed respect of E ofaggregate as an equation on the has a decided to that of ofexponential type_3.4 Table 3.4. Average Test Values For Rocks ofDifferent Groups .BaSalt_g . {L207 g12. L, V Gabinof ; T 204: L7;" _g1g7.;6_g.: 1g6gg_,. ._3g'3 if V.55,, 2,8,5 y19.2 *.1827s f 319* ; 3.23: ;2,9,5, V Gritéiwifigets 229, s21.2,} Hqmfezs354T ,i ~11:T 118.13T, T 18.8 Timestone. TI T1;-oijohyry_': *239ffI"i. s,'Qu.mz:i¢ ;339,l ° . ]1i6jiis j.g2.5.4.T7 gore * .2;6g7j g:f2.i7i3.8fC i\2.i88_ » f 19.0. [i2oQ}? 2.,6f %2.67ii2.66il il1t8.9j7Cf«g16t 5 \i_2.i6'2i §/ . ,H1'8i.7= TI i13i'iI_i ; : 3;?! j;4.3f _ g2.76gi 78 I Concrete Technology Bulk Density The bulk density or unit weght ofan aggregate gives valuable informations regarding the shape and grading of the aggregate. Fora given specific gravity the angular aggregates show a bwer bulk density. The bulk density ofaggregate is measured by lling a container ofknown volume in a standard manner and weghing it. Bulk density shows how densely the aggregate ispacked when lled in a standard manner: The bulk density depends on the particle size distrrution and shape of the particles. One of the early methods ofmix desgn make use ofthisparameterbue density inproportioning ofconcrete mix. The hgherthe bue density, the bweris the void content to be ed by sand and cement. The sample which gives the minimum voids or the one which gives maximum bue density is taken as the right sample ofaggregate the method for making economicalmix. fornding out void content Fordetermination are compacted ofbue density the aggregates in a standard manner: The weght cakulated in kg /litre orkg/m3. Iiowing surface-dry condition, The method ofdetermining in the sample ofaggregate. and then they gives the bulk density the specic gravity ofthe aggregate in saturated and Gs voids = ofaggregate aggregate. is ofinterest The parameter Y Gs where Gs = specic gravity ofthe aggregate Bulk density in the container of the aggregate also gives the void ratio can also be cakulated. Percentage heavy weght are ed bulk density and when Y: bulk density in kg/litre. we deal with light weght ofbue for converting the proportions by weght equwments is not avaihzble at the site. x 100 density aggregate is also used in concrete into proportions by volume when and mix desgn weigh batching Specific Gravity In concrete cakulations technology, ofconcrete specific can be converted into solid volume can be cakulated. Specic factorin connection is required Average gravity mixes. With the specic gravity specific gravity when ofthe is made ofeach is also required measurements. we dealwith known, design its weght ofconcrete per unit volume in cakulating the compacting Simihzrly, specic light use ofin constituent and hence a theoreticalyiekl ofaggregate with the wonkabllity to be considered of aggregates gravity weght gravity and heavy ofaggregate weght concrete. rocks vary from 2.6 to 2.8. Absorption and Moisture Content Some ofthe aggregates will affect the water/cement aggregate wlllalso and thawing are porous affect the durability and also when The water absorption ofan oven dry sample weght to the weght aggregate. But when be ofmuch sgnifkance, ofaggregate when ofthe immersed concrete amount ofabsorption is subjected is determined in waterfor aggregates on the other hand, ofaggregate The porosity is subjected to chemically aggressive by measuring the increase 24 hours. may be ofmore and nal is known liquids. in weght increase in as absorption of the 24 hours absorption ofwater sgnifkance. volume to the nal absorption may not during The aggregate ofconcrete. set ofthe of to freezing The ratio ofthe as percentage in concrete a time intervalequal ofconcrete. the concrete the percentage and thus affects the workability within when dry sample expressed we dealwith Porosity and absorption the workability ofconcrete the concrete time intervalequalofnalsetofcement waterin and absorptive. ratio and hence cement the absorbs The rate and wionly be Aggregates and Testingof Aggregates I 79 V» Absorbédmoisturepi-V T '*"r".','+ ',*si:7»*'*"i ; ,.(AbS0rpfi0n)io -. V W: Tm-'-->i<-«-is ~~ :Fféeimoislt1i1:ire7i V T --v-' --'-aT ,i(Mois,turpe c.onter1t)i l i-by-i'iS3.tm3ted3ndi V _ Mmst i g Surgtg"ace_(,iry'g ,, 5T 5:; IlVig.,3*,.1:. Diagramfriatic representation of1\./IOiS,til11Vel._in Aggregate.» 3 TT a sgnicant factor rather realistic to consider owing that absorption to the sealing allowing ofpores for extra water due to absorption, made rather than the 24 hours to be added proper ofthe ofthe the materials aggregates are based on the condition in practice, aggregates it is always that the aggregates in such ideal condition in which moisture aggregates to the sun fora When stacked in heap the top portion portion ofthe heap usuay ifthe aggregates contains ofthe certain are dry they absorb that the ofthe and surface dry. But Aggregates to rain or may have been washed may have been exposed for granted are saturated is rarely met with. or they have surface moisture. dredged be the relative weght been exposed Fine aggregates less time intervalmust taken cakulation to varwus orthe to be sti in rwh mixes. In for the bss ofwater in particular and absorptive they are absorptive. isgoing partwularly mix to compensate and surface dry. In mix desgn degrees It may be more hours absorption. for concrete, are saturated which particle absorption on the basis of24 aggregates of the aggregate. aggregates ofcement to a concrete appreciation than estimating In proportioning capacity by coating absorption are either The aggregates case they may contain bng dry may have surface time in which case from river bed usually contains surface moisture. heap may be comparatively dry, but the bwer amount waterfrom offree moisture. the mixing It shoukl water be noted and thereby that affect the workability and, on the other hand, ifthe aggregates contain surface moisture they contribute extra water to the mix and there by increase the water/cement ratio. Both these conditions are harmful corrective for the quality measures water/cement shouhl of concrete. In making quality be taken both for absorption concrete, it is very essential and for free moisture that so that the ratio is kept exactly as per the desgn. Very often at the site ofconcrete aggregate. The absorption 1 percent by weght capacity ofaggregate. derived from sand stone orotherso excavated in the cuttings unusualy high presented plenty work we may meetdry coarse aggregate of the coarse aggregate is ofthe Ahgher ofPune-Mumbaiexpress for rock of the type Deccan ofproblems absorption and porous and moistne order ofabout 0.5 to value may be met with aggregates rocks. Recently it was observed that the rocks hghway, ofaround 4% characteristic has trap. showed The high for using such stone aggregate absorption absorption for 40 MPa Pavement Quality 80 I Concrete Technology Concrete (PQC). The naturalne to ten percent or more. Fig. aggregates often contain 3.1 shows a diagrammatic free moisture anything representation from one ofmoisture in aggregates. Free moisture in both coarse aggregate in more than one way. Di case ofweigh the aggregate regard. is necessary But when aggregate volume and then correction volume batching does not become ofsand and ne batching, is adopted, aggregate for bueing offree moisture content of ofwater/cement ratio to be e/cted in this the determination ofmoisture content ofne ofsand and correction necessary but the consequent to give allowance affects the quality ofconcrete determination becomes bueing of necessary. Bulking of Aggregates The free moisture phenomenon content in fine can be explained as foows: Free moisture known aggregate results forms a lm around as surface tension which keeps the neghbouring each particle. force exerted by surface tension keeps everyparticle contact ispossible surface tension upon between and consequently the percentage interesting certain to note limit decrease aggregate the particles. and ofmoisture beyond in the volume shows content that the lrther and at a moisture no bulking. is so little that it is always ne aggregate negkcted. bulks as much away from it. Simihzrly, the with ofthe particles exerts what is ske of the ne the increase in moisture in the moisture content representing The extent of aggregate. It is content a content saturation Fig. 3.2 that ne that the coarse aggregate ne volume. are kept away willdepend increase Extremely as about of moisture away from each other: Therefore, no point It can be seen from coarse sand bulks kss. From this itfollows Bulking particles and the particle increases of volume. This lm This causes bulking how far the adjacent that the bulking in bulking results point, upto in the the ne sand bulks more and also bues but the bueing sand and partwularly the manufactured 40 per cent. iigijFirli1éygradingii V, y; iaggregateff "mgddgved ne ingvolumeiév dry, o Per.cent: increase 107i .4 i fl;Perlicieritrofvmoismreiaddéd b'y.Weiighttobdi'y,Agt_ :. F . .fOddZedine.«aggr¢gate ;* Aggregates and Testingof Aggregates I Due to the bulking, absolutely the concrete batching, by volume. the resulting yiekl ofconcrete The extent aggregate aggregate completely Ecognisance concrete is notgiven is lwly of bulking can be estimated into a measuring into the measuring ofthe saturated offsets the bulking the bulking pwture ofthe The ekl the normal and completely ofsand factor affect the ofmoist ne the level, say the sand and shake it. the levelofthe under test. = h1h2 he can be found sand sand say, /'12. Then /21 /'12 x 100 out by lling the wet sand in a water waterto inundate the sand. Then This gives a more realistic factor: out the percentage empbyed for correcting one of the important the volume methods batching is not adopted moisture content ofne aggregate control for controlled is so simple that this could be so found out coukl be to be used. This can be considered as mix and by experience. ofbulking to produce concrete, required. and correction of bulking and the percentage ofekl is notnormally to be determined Note down inundate of sand and express it as a percentage. test to nd ofthe test. A sample manner: down ofbulking in a very short time interval ofquality by a simple fkkl cylinderin conducted examination and harsh. It willalso box (farma) up to the top and then pour bulking it is in case ofvolume sand is the same as that of the dry sand, the inundated of the sample the subsidence Therefore, in proportioning to the effect ofbueing, cylinder effect. Note In a simihzr way the bulking measure volume. content. Percentage measuring unrealistic to be undersanded cement Since the volume tght shows completely must be given to the effect ofbueing for a given islled /'11. Pour water shows ne necessary that consideration 81 quality the determination The quantity ofwater The percentage made only when concrete. of the percentage could be controed offree weigh Since volume moisture batching content is adopted of by visual is required forproduction concrete. Measurement of Moisture Content of Aggregates Determination ofmoisture content the quality ofconcrete partwularly ofthe ofaggregates moisture content by severalfactors. The aggregate porosity. content The water absolutely plus the free water; orthe The measurement reasonably accurate used in the fkkl. content can be expressed aggregate (In) Cakium content which and must require only simple appartus Method Carbide Method (v) Auto matic me asurement ofthe depending on its aggregate when includes the absorbed ofaggregate particles. of aggregate that are being of But it is complicated ofwater weght in the control The measurement means the free water; or that held on content held in the interwrportion of the moisture are given and strength. quantity in terms ofthe wet. Water content Some of the methods ofaggregate (i) Drying a certain or the totalwater water is of vital importance is basically a very simple operation. will absorb dry, surface dry orwhen the surface ofthe in aggregate with respect to workability which in the eld must be quick, can be easily handled used for determination bebw: (a") Displacement Method (iv) Measurement by electrical meter: water and of moisture 82 I Concrete Technology Drying Method The application bss in weght drying method isfairly simple. Drying is carried out in a oven and the before and after drying ofdrying wigive the moisture content is done completely not only the surface at a hgh water made for the saturated temperature and surface dry condition. use. Afairly quick result can be obtained pan. The process can also be speeded spirit or acetone over the aggregate Displacement Method 1h the laboratory gravity the moisture aggregate aggregate wllloccupy The oven drying volume method inflammable lfthe wlinclude may be is too sbw quickly for in an open liquid such as methylated it. can be determined The princurle than aggregate. corrections the aggregate ofaggregate Method. is hgher a greater water: Appropriate up by pouring content ofthe time, the bss in weght by heating and gniting or by using Siphon-Can of normal bng but also some absorbed fkld pycnometer fora made that ofwater use ofis by means that the specic and that a given than the same weght of weght of the aggregate ofwet when dry. By knowing the specic gravity ofthe dry aggregate, the specic gravity ofthe wet aggregate can be cakulated. From the difference between the specific gravities of the dry and wet aggregates, Calcium the moisture Carbide content accurate method gauge. acetylene Cakium gas. The pressure of the aggregates. aggregate ofknown carbide reacts with ofacetylene carbide surface the moisture in a strong moisture gas generated air-tight content a standard content ofne ofaggregate aggregate depends upon scoop and a containerxed Wegh 6 grams ofrepresentative scoop full of calcium sample ofwet carbide powder container and shake it rigorously. acetylene gas, the pressure Cakium ofwhich the moisture consists ofa The procedure into the container: carbide the container: needle out small is as follows: Tlzke one Close the lid of the reacts with surface moisture drives the indwator content is ofen used to nd The equwment with dialgauge. it into with to produce sand and pourit and put ofne a measured quantity of pressure gauge co ukl be directly. This method at the site ofwork content vesseltted in the aggregate The pressure gauge is calibrated by taking moisture content and then such a calibrated used to read the moisture the moisture can be cakulated. of determining is to mix it with an excess ofcakium pressure balance, aggregate Method A quick and reasonably aggregate ofthe and produces on the pressure gauge. The pressure gauge is so calibrated, that itgives directly percentage ofmoisture. The whole job takes only less than 5 minutes and as such, this test can be done at very cbse intervals oftime at the site ofwork. Electrical Metet Method Recently electrical reading of the moisture changed with content the change some sophisticated and also to regulate Automatic meters have been devebped in moisture batching plant, the quantity to measure of the aggregate. content electrical ofwaterto instantaneous The principle of the aggregate that has been made meters are used to nd be added or continuous the resistance out the moisture to the continuous gets use of 1h content mixer: Measurement 1h modern batching plants means ofsome kind ofsensor quantity watergoing offree surface moisture arrangement. with aggregate in aggregates The arrangement is automaticay is automatically recorded by is made in such a way that the recorded and simultaneously that Aggregates and Testingof Aggregates H 83 much quantity to 0.6%. ofwater is reduced. This sophisticated method results in an accuracy of: 0.2 Cleaniiness The concrete aggregates are likely to interfere aggregates and matrix. Generally, should be free from impurities with the process ofhydration, The impurities the ne aggregate sometimes obtained and dehatrious substances prevention reduce ofe/fective the durability from natural stacked in the open and unused bwer ofthe kvel Sand is normay dredged But ifsand organic matters with time may contain moss and mud in the matter; humus, is dredged when in the river: Under such situation organic the aggregates. The presence which reduces matter and other impurities there is a good are likely to get washed fbw ofwaterfrom and also interfere ofmoss abng the river with the are likely to settle very deep bed, the away at the time ofdredging. with the setting action ofcement the concrete organic aggregate does not normally crushed stone dust. Coarse from river beds and streams in the dry season when there is not much flow vegetable down. willinterfere the of the aggregate. stack. bed is dry or when sand, decayed for bng which between sources is likely to contain impurities in the for'rn of silt and clay. The manufactured ne contain organic materials. But it may contain excess ofne aggregate bond The organic matters with the bond characteristics or algae will also result in entrainment ofair in its strength. Tb ascertain whethera sample ofne aggregate containspermissibk quantity oforganic impurities or not, a simple test known as cobrimetric test is made. The sample ofsand is mixed with a liquid containing hours and the cobur sample is darker impurities 3 per cent solution devebped ofsodium is compared than the standard cobur hydroxide with a standard card, it is inferred in the sand is more than the permissible in water: It is kept for 24 cobur card. Ethe cobur that the content ofthe of the organic In that case either the sand is rejected or is used after washing. Sometimes in increased excessive silt and clay contained shrinkage or increased permeability excessive silt and clay may also necessitate The quantity this method, aggregate particles. ofclay, a sample ne silt and ne of aggregate is nwely rodded to disbdge The jar with the liquid greater time interval, the thwkness water or coarse aggregate to poor dust are determined particles ofclay is completely forgiven measuring and silt adhering shaken so that a The workability. by sedimentation into a graduated may result bond characteristics. requirements ispoured mixed with water and then the whole jaris particles willgive aggregate under in the ne in addition method. In jar and the to the aggregate the clay and siltparticles kept in an undisturbed condition. of the layer of clay and silt standing Aera over the ne get certain aggregate a fair idea of the percentage of clay and silt content in the sample of test. The limits ofdeleterious materials as given in lS'383-1970 are shown in Table 3.5. Fine aggregate percentage from ofsalt. and ultimate tidal river orfrom The contamination strength ofconcrete. Salt being Opinions are divided unsghtly appearance. aggregates woukl cause corrosion percentage ofsalt generally appreciable manner: 3 per cent. pits near sea shore willgeneray ofaggregates hygroscopic, in the ne it is a good practice some cause e/fbrescence whether willnot and the salt contained But studies have indwated aggregate contain affect the setting properties willalso on the question ofreinforcement. contained However, by salt wi cause corrosion to wash sand containing in that the usual in any salt more than 84 I Concrete Technology Table 3.5. Limits of Deleterious Materials (IS: 383-1970) (0 Coal'and,lI'gniteL 3 L iIS:L2386L 1.00 L. 1.00 0 1.003. 1.00 L L L. L . (Pom L . . L. L L a. L 13.2386 6V 1.00 3 1.00 L . (PaLrD_ 1963 L 0 6 than 75-Lmicront_L . L .1SSieve i L, L V i(ILLar"t1)- 6 .1963 0 0 1.00: LL1.00 _ L. LL mmlzv-. L L 15.00 23.00 3.00 0 V KK V L L 02;) LSoifragmeints 0V. 3 g 1923867 . if 0 . L 1022) Materfials-'ner 6 L [ 4 .13.-20386 . 3.00 V L L . 31963 0 (,3)iclaylumpsb VLi . . . L 3 La 3.00 V9 3 0 0 0 I if - LL." 1963s (a):shat- . t if rs.-2386L 1.00 i L_ (Par1lD- . . 3 6 . 6 66 L 1963 (U1) 1btalofperce,ntages0fallL I idekzteriousmaterials(except Lmica)including» Sr:iNo.(1)to (12) for col 4,6 and 7 and Sr: No.7(0and (:2)forlcoli5 only i _ 3 . i 0 5.00 L , 3 2.00 05.00. 35.00 Notes: (i) The presenceof micain the ne aggregatehasbeenfound to reduceconsiderablythe durability and compressivestrengthof concreteand further invwtigations areunderwayto determinethe extentof the deleterious effect of mica. It is advisable, therefore, to investigate the mica content of ne aggregateand make suitable allowancesfor the possible reduction in the strength of concreteor mortar. (ii) The aggregateshall not containharmil organicimpurities (testedin accordancewith IS:2386(Part II-1963) in sufcient quantities to effect adverselythe strength or durability of concrete.A ne aggregatewhich fails in the test for organicimpurities may be used,provided that, when testedfor the effect of organic impurities on the strength of mortar, the relative strength at 7 and 28 days, reported in accordance with clause 7 of IS:2386 (Part VI)-1963 is not lws than 95 per cent. Aggregatesfrom and other impurities when concrete particles some source may contain iron pyrites, clay nodules, which are likely to swe when wetted. These particles is subjected cause damage thawing orwetting in Tlzble 3.5. to abrasion to the concrete and drying. and thereby cause pitting particularly, when Alirnitation to the quantity in concrete. subjected ofsuch so shale particles also get worn out Such unsound to alternate impurities freezing and is already shown Aggregates and Testingof Aggregates I 85 soundness of Aggregate Soundness refers to the ability ofaggregate result of changes in physical conditions. of aggregate are the freezing drying under normal porous, weak and containing change when specified amo unt of volume be exposed should subjected matters undergo to the above conditions. change disruptive internalforces Ioss in weght, is measured and growth and magnesium sulphate bad. show bss ofweght bss ofweght that the sulphate them, test butproduce usuay. Alkali Aggregate Reaction time aggregates contain reactive oxide and potassium In the America United States it was found to be used graded and we ghed test specified crystals in the pores ofthe particles is thought ofwaterorcrystallisation ofcycles. soundness Soundness test is specified bss ofweght tested with sodium that be used aggregates breakdown after sulphate Certain aggregates with certain aggregates ofhgh an evidence been extremely will ne pore that disintegrate resistance to freezing ofgood durability, and thawing. whereas a hgh category. considered as inert out that the aggregates silica, which to accept which may or may not be Conversely, in questwnable have test might being those which concrete after 1940s it was clearly brought of the aggregates sodium while but not always, the aggregate For a bng is liable to are going it under the assumption no bss of weght. places partwularly, more than the Ifconcrete and oven drying and 18 per cent when the test is not reliable. almost ofcarefuy sulphate specified number the test are good readily in the sulphate A bw out to reject Unfortunately, structure are respectively. be pointed withstand which and which excessive volume undergo it can be taken that the average not exceed 12 percent satisfactorily which aggregates. simihzr to the action offreezing fora 10 cycles shoukl not immersion ofsalt (Part V). As a generalguide, but as a test. or magnesium to produce It may Aggregates is said to be unsound the coarse and fine aggregate of sodium aggregates wetting extraneous The accumulation in 132386 alternate any undesirable conditions. ofsalt. in temperature, in salt water: Aggregates test consists ofaltemative in a solution in volume that affect the soundness and drying to soundness The soundness variation conditions and wetting to the action offrost, be subjected sample the thawing, conditions to resist excessive changes These physical reacts with materials but later are notfuy alkalies present on, inert. Some in cement zIe., oxide. of for the rst time that many failures of concrete structures like pavement, piers and sea walls could be attributed to the alkali-aggregate reaction. Since then a systematic has been made and now doubt reactive it isproved that study in this regard certain beyond types aggregates of are 7'9 SP0nsib l9 f0 7 PTO"L0 ting TypicalAlkali- Aggregale reacllon.Alkalislllcalegelsof unllmlled alkali-aggregate reaction. swelling iype are formed under favourable condilions. 86 I Concrete Technology The types ofrocks siliceous limestones form ofopals, which contain and certain cherts, chalcedony, volcanic on the reactive siliceous minerals aealies in cement. reactive constituents types ofsandstones. in the aggregate starts with attack by the aealine hydroxide derived from the swelling type are formed. are congenial, ofconcrete concrete The rate of deterioration structures. progressive with rocks occurring Punchal Hill (Jimmu manifestation the spreading There were cases where concrete the basalt Hyderabad, rhyolites, may be in the As a result, the alkali silicate gels of unlimited When the conditions conditions. traps, andesites, glass, zeolites etc. The reaction results in disruption In India, include The reactive constituents by swelling ofpattern may be slow has become in the Deccan and Kishmir), Bengal which of or fast depending the unserviceabla plateau, takes place, cracks and eventualfailure upon in aboutayears Madhya Pradesh, and Bihar shoukl time. Kithiawar; be vkwed with cautwn.3-6 Simihzrly, limestones Indian limestones include and dobmites Madhya Pradesh, Sandstones containing opal are found and Delhi. Rajasthan, Some of the samples obtained quantities of chalcedony be hghly Regions reactive. of occurrence from crypto include Madhya to microcrystalline Madhya Pradesh, which Pradesh, West Bengal could quartz or Bengal Bihar and Kishmir be identified by visual opals, amorphous silica. samples of rock obtained from were also found to be highly Geographically India extensive deposit Deccan traps covering Maharashtra dobmites Kishmir and aggregate aggregates Madhya by altering of Jammu the and source of construction. The rocks be these to see how which to exhibit Pradesh, extensive for concrete cautwusly aggregates The Pnadesh, Punjab and form from a very rocks. the western part of limestones woukl has of volcanic ofMadhya Rajasthan, found like woukl cherty. and Assam. like chakedony, reactive constituents substantial minerals and chert nodules to be hghly to be reactive. Regions ofoccurrence to be containing These contain studied Punjab silica minerals were found examination. Quartzite Kashmir reactive. containing ofBi]'awar series are known contain should far reactive the proportion ofreactive type ofaggregate; (to) Availability may be ofvalue The petrographic asses the potentialreactivity other tests. reaction. ofthe to reduce are its tendency ofthin in cement; temperature ofthe whetheraparticular aggregate. It ispossible alkali content (iv) Optimum examination that only such Reaction the potentialreactivity injudging to note and in partkularneness silica or its neness. (ii) Hgh ofmoisture; It is not easy to determine or harmless. are they. It is interesting reactive silica in partwularproportion Factors Promoting the Alkali-Aggreate aggregates product (swelloble gel). tendencksforalkali-aggregates either (1) Reactive Typicol exomoie oftheo||o_m use no UEENXM ~=mco LL L L L L ¢c LL eo_L L LLLL gmm L L L- . LL.L L H L mmL mmL L mmL LL LL L LLmuL LLL L L_L -L L uwwL LL: m ML Nw _LLLm LL L wwLN L L LLL L ,3 NN y L_ Emma LLom __ om x+L LL L m_m>_w:< cm.L L -L LL Qm L L awn Sn LLL x LL II L W mmL L qLLL mu~ L cm L_ as qoL coLL L8 SLLLL L L LL LLLLL Leem LLeo. L LLL L L LL L L M L.L LU _mu_n>u 0:... L L nc~ L cw LL L cg~ eo~ L .m.n 035... L.L -LLLL _}y LLL mmm H L _L L LL L UL L um L m L_ Sm LL e. m«m~_ LL .=9:g:.e¢m _s:.om L oo~ LS. A . L-L V LLL _ L L LL L Q Q w L» L L- ma~n L- - L mm: L LL .L -L ~=:~m~.~ L L~m:_mu.wL L=2u.§L L:9:a:_es ~==.mmw ESQN §L:.§oS ::=¢w Eu£.$3oL LLsscw_ .Nsgu. 96 I Concrete Technology grading. Often, appropriate fractions with mixing ofcoarse ne ofavailable percentages aggregate aggregate aggregates, aggregate desirable is mixed rst to obtain proportions arithmeticay. fine may produce available gradings. different iustrated. aggregate or more coarse aggregate is mixed Knowing the grading either the chapter of available graphically Mix Desgn. method ofcombining Table 3.10 shows the grading pattern of the avaihzble coarse and ne at site. This table also shows the specified combined Table 3.11 shows the grading first trial and second the specied combined or nearly equal ofdi/ferent trial. The combined grading. ofrst grading ofne aggregate is aggregate and coarse aggregate trial and second Whichevertrialgives to the specied coarse and ne or At this grading. combination grading in two skes can be cakulated, This aspect will be dealt in more detail under stage a simple trial and error arithmetical coarse But sometimes and then the combined the desired of mixing with gradings. the combined for trial is compared aggregate with grading equal has already been is adopted. Specific Surface and Surface Index The importance discussed. extent ofa The quantity good grading ofthe ofwater required to produce coarse and ne aggregate a given workability depends to a large on the surface area of the aggregate. Table 3.10. Shows the grading pattern aggregate and specied 40, L g. 1_2o2 if1 10 in L 1,4175 j 1 V 100, V id, 1,236 ske ofaggregate aggregate particle ofthe grading. so that ne the mix to give workability. The foregoing paragraph surface ofa gives area and This is an very much in the more to the surface area requires more waterforlubricating the impression and for a given quantity ofwater; workability. This impression is correct upto a certain being so ne, as specific surface. mix is, therefore, aggregates; micron particles, ~q,1 0 inuenced more by ner in a sample ofaggregates. more particles is termed contributes contribute hold good for very ne T" surface increases with the reduction Greatersurface The workability than the coarserparticles ; f11q35i " material Qzecic aggregate area than does the coarse aggregate. 100 1 V ,f98i 11,75. 1 f1ii T 1 1 28h i»60 till if j 1 221 T 1 10 1 p111, ,1. 5 1Lg 0111 of o The surface area per unit weght and fine , 1 ,1 111 61 by42 T851,;.ii 01 io_i y la i1I:ji indirect measure ofthe 1 3. if1 ;1oo.i: .92 soil 1 1.18 g600*1 .,30o.1 V g r. fraction 3100 1 95 1 11ioo.ig 3 111 1135 . 1 1 1 £5; .150 of the available coarse combined grading hence require smaller water the presence in FA. The every ne contribute that more extent more towards of aggregate the surface of ofsmaerparticles reduces the This wi not ofthe particles particles for wetting nerfnaction. in FA. zIe., 300 mwron workability. Theirover-ring and 150 influence @ m % .< .5 w D $ 3 c 2 5 : .3 m:_ ....n u:o :o_ a:= no 05 035 Aggregafesand Tesfingof Aggregafes I 97 0uwm 09.50 u:o.. new 05". 5:5 L¢.w .oam Lmxm .g$m .qdw Lmdw e$m com Q: qsm3» LL¢wm mzmm L 3. 3 LEV L L LL 3 L gem L ma mxmL emL sea LLL eew~ mam LLLLmwm Lmwm L.LmxmL .Lm$mL QQNL L m_N_..._. mam Lmmm cewL L_mNmL 2,?LLow LLoow~L cm -L L-L L w$m L LL LL05 L LL-LLLL wuwLL L. LLL mm L a LLL WW L «L L LL~w L mmL L .mm L LL Nw 4L L gem L euwLL_ o¢~ L LL; LLLem Le mm Lu Lo o L _L eg~ Le~L LcL mu ¢L mw L LLLLL LL mm LL L com LLmmw £92360 LmN.w_ Loo~ L mm LL mm Le LLewL LcmL o~L .V m~4 N MN _em~ .Lcom 98 I Concrete Technology in contributing friction to the better between consumption workability coarse particles, ofmixing waterfor Consideration ofspecic to be expected. Tb overcome which is an empirical weghtage given ofaggregate by acting the reduction wetting surface area. greater number related to the nerfnactions. to the specific the set ofsieve The total surface index (r) ofa ofmaterialretained a constant mixture on its skve of330 the internal owing the total surface for any given grading of aggregate is cakulated by the corresponding to the 4020mm. 3. g by 1000. . T T V2.36?-1.I8.mim 7 1.1i8i-6'00irnicmn g 7600300micron 5 5T I by multwlying g , 1 ;_ 7 +1 T by 40 3 3 V 5 5 7 I 9 * 9 5Smallerthan 150mzcmnt 2 y20-g10 mm) . 4;752.30mm 2.36+1.18 mm Index of combined 55 1L 3 L 91 , Grading 715 T T T T1. TT b ofcomputing 92 7 104.75mm the Particles?-2 0 300~15i0msictnmI L T 5 Table 3.13. Surface the surface index The method is 75 i.V4.75~2.36 mm 5 more in Table 3.13 is it with surface index and to their Index of Aggregate 980-40 mm 320-10mm representing in Table 3.12. is shown Table 3.12. Surface of the particle size are given and the result is divided 010-475 mm surface The empirwalnumbers within sum is added to reduce in workability surface gives a somewhat misleading pwture ofthe workability this difficulty Murdock has suggested the use of Surface Index particles percentage like ball bearings far out-weigh 7 -55. 15 7 7 5 4 at 7- 28 Q49 33 7i1~.18600 rnicron 50 7 9; 63 600-300micron 7 39 V 63 5 3004i'-1i50m'icron~ 2 07 7 14 5 Ttzamz7 7 5 7. 177 I Addconstant0 I T 330 507 7 Aggregates and Testingof Aggregates I 99 507 Surface Index(r) = 10m = 0.507 Simihzrly, surface index can be cakulated surface index can be taken as the desirable Thisparameterofsurface aggregate grading curve, and this value of combined index can be made use offornding to coarse aggregate index in the following for standard surface index ofthe avaihzble in the fkld to obtain aggregate. out the proportion specied ofne or desirable surface way. Iet x = surface index ofne aggregate y = surface index ofcoarse aggregate z = surface index ofcombined a = proportion ofne aggregate to coarse aggregate (Z-y) (x-2) 7hena= The following available example coarse aggregate index of the combined could be calculated will show whose aggregate. from how grading to combine patterns The desirable the grading pattern the avaihzble ne are known surface ofthe index of the combined standard grading 20gmm~1o.mm 65 L. is 1 : w 91 s H10mm,*4.75 gar M 35 .LV 7 . V with surface aggregate curve. Coarse Aggregate . aggregate to get the desirable 1":r V 65 rp35p 7bta,l=30. constant =.i330, Vp=i300s~ s 9 3 c300 o V aSurface zdexof Coragseg Aggreggatep l; = 0.30a FineA§§"3gVdfe. g . Vs - 4.75 mrn~2.36'. ' _ , V V 10 74, 40 f V2.V36mm} 1.18 V. 1.18 mm -- 600 micmn v V 20 , 600:micmn4 300 micron.. VV g . 300. micron ~ 150 micron V V 7 V.140 ['9 I80 30, 9 j 270 15: -V7» x V 20 V r V V V V _ 105 V :Iamz=V735h V 1 AddicoVnsitant= 330! ~ f=11o65V Surface Index ofne Aggregate 1065 = Z = 1.065 1000 100 I Concrete Technology Iet the surface index ofcombined aggregate required: 0.6. x = surface index ofEA. = 1.065 y = surface index of CA. = 0.30 z = surface index ofcombined aggregate = 0.60 (z y) a=proportion ofne tocoarse aggregate, a: g Therefore, = (0.60 0.30) 1 =E EA. : C.A. = 1 : 1.55 Standard Grading Curve The grading patterns ofaggregate can be shown limits by means ofa chart gives a good pwtorial a number ofsamples can be made atone glance. is shown by means ofgrading curves. curves are those produced number ofexperiments in tables or charts. Expressing vww. The comparison Forthis One ofthe reason, often grading most commonly by Road Research Iaboratory in connection with bringing ofgrading grading pattern of ofaggregates referred practicalgrading (U.K).3'1 On the basis oflarge out mix design procedure, Road Research 7 5 Pev1fceritia T T if 5 L Lor Iaboratory hasprepared a set oftype 20 mm and 40 mm. They are shown grading in figure aggregate mm and downward with and Erntory.1t . pg by V} J 755,5 1505,, 63001650054; l.1l8fA2§36f 4.5755 10" 20,» F T: 544 5* 5 T ; .ISSi6.V§}NumberorSize. 5} 5 WT 5 5 T maximum is shown size of10 curve for all-in aggregates graded down from 3.4 and Fig 3.5 respectively. Simihzr curves for in Fig. 3.6. Fig. 3.7 shows have been prepared the desirable by Mclhtosh grading limit for 80 mm except 80 mm ske. From aggregate. Four curves are shown values ofpercentage coarsestgrading No. passing for each maximum ske ofaggregate it can be seen that the bwest and curve No. 4 at the top represents 1 to 4 there are three zones: separately. Iiowing theirgradation grading conforming to any one ofthe the coarse it will be possible fourgrading zIe., curve No. the nestgrading. A, B, C. Di practice supplied curve curves. Between and ne to mix them 1 is the the curves aggregates are up to get type %__iPe 1 g Aggregates and Testingof Aggregates I . 101 75,3150 300 460103, 11",1,g;*2;35[C-41.75,fxoj 7203740- _g "ISpSieve.N11mber.priSize 1 5fifi 333 3 Passing 1 iftPe1hccntage $ 33 - :, ; 75g,15o 3010. 76007; 1,118 2.361 4.75,1 ;{ : 71S'Si¢V6Nurnb¢W:SiiZ¢S] In practice, it is difficult curve exactly. Ethe hgh to get the aggregate to conform user insists on aparticularpattem rates. At the same time the user also cannot aggregates. As a via media, grading to conform exactly to aparticulargrading ofgrading, to any one partwular the supplier accept absolutely limits are laid down poorgrading very pattern in various specifications curve. Table 3.14 shows the grading standard may quote of rather than limits ofcoarse aggregates. 7?zble 3.15 shows the grading limits ofne aggregates. 7?zble 3.16 shows the grading limits of all-in-aggregate. It shoukl be noted Sieve is increased thatforcrushed to 20 percent. Fine aggregate complying stone sands, the permissible Figs. 3.8 a, b, c and dshow with the requirements ofany limit on 150 micron the grading grading IS limits ofEA. zone in 7?zble 3.15 is 102 I Concrefe Technology ~V ~ .V Ijasgng P¢'1, 3 u ...cs@\. . ;<3, ",0 _ V: :? 150fi 5£6011 j1;;If8 52§_j: {lzof 46f:_5;]8O7 3Si ;[pmenmge if L T» Aggregates and Testingof Aggregates I 103 T, ,« V.P<;1lcs:g M « g;75p'1t1.5o;.»>3o(m...g .600, 71.158 r;g_2.36_ y;;.4;75tg_10mm;r,, ». 0.0; V V/g/::1Z°,11e,f-yiiiiiil if V V A by iPa \ Pércéntage .80 //: _ slug 5 ON C 2° %t g - ;W . 4> G M... ...4.. .L....._.# 104 I Concrefe Technology V VVV VVSHV Vj: V 5 VV V-VV IVV Sac; M 3.? VV S:V:SV.. VV VV : V VV VoVToV VV V 872.» VVV :V Swan VaV.w _K_ V V.VfVV V2: M Yaw m:= m._ .3.» Em om o.u um .8 oz» VMV (F Vcis VV :V 93 -V VV VV VM VV 31? V1 VVSTV 3.2.. V mxe VV VV VV STS VVu VV© VV V§VTwm. V:3 .V LV H: VV V mmr V -1V VS VV V53 V; emxcV V VVVV V V VV31? eQ~:m 1VLV mwwc -V VSVHVV V mi. VV V VV VM III M V. VV V V gV V:Vearn VV VV yp VV amxo V .V-V -VjV -VQVSV V :V VV ewnw VV R»...«V IV V93 V ST? We VVVV V ; V1.m.rVeVV VVV ms VV 87%V m-oW SN VV VV VV VV VV[V§V=V ::V._ 2..V V.VV Vssm VV- V: WVV VV VV VVV VVSE V SS3 :5. E..VvV mm: SVV ssomx SVSSV QVVNVV Aggregates and Testingof Aggregates I Table 3.15. Grading limits of ne fii_80immf.if @_ (4.75 ~ .600 micrioin ~ is 25~45 bypi r8~,3o.;i, aggregates 100 105 IS: 383-1970 \ ; " '..40im'm,:,. 7 VT if 95g1goiot yr . i f f_ _ " 1oofT V 2io:mm f T 4,5{~;75'795.100 {T f 150micmn_ It must be remembered workability ofconcrete .:06,ig. that the grading than does the grading g Q it ofne aggregates ofcoarse aggregate. usually very coarse sand or very fine sand is unsatisfactory sand results in harshness bleeding greater amount of water departure of5 per centfrom beyond Crushed and segregation, to produce Ior oe6,it has much greater Experience for concrete efct on has shown that making. The coarse and the fine sand requires a comparatively the necessary uidity. zone limits may be allowed. the coarser limit ofzone 30-50 f1o;35 L the finer limit ofzone For fine aggregates, But this relaxation a total is notpermitted IV Sound All along in India, we have been manufactured in India has not been much, using natural sand. The volume when compared to some advanced of concrete countries. The infrastructure devebpment such as express hghway projects, powerprojects and Industrial devebpments have started now. Avaihzbility ofnatural sand isgetting depleted and also it is becoming costly. Concrete industry now wi have to go for crushed sand or what is called manufactured sand. Advantages of natural sand is that the particles are cubical or rounded with smooth surface texture. The grading ofnatural EA. is not always ideal It depends on place to place. Being cubical, rounded and smooth textured itgives good workability. So far, crushed sand has not been used much in India for the reason that ordinarily crushed sand is flaky, badly graded rough textured and hence they result in production of harsh concrete forthe given desgn parameters. We have been also not using superplasticizer 106 I Concrete Technology widely in our concreting operations to improve the workability ofharsh mix. Forthe last about 4-5 years the old methods ofmanufacturing ordinary crushed sand have been replaced by modern crushers specially desgned forproducing, cubical, comparatively smooth textured, wegraded sand, good enough to replace natural sand. Many patented equwments are set up in India to produce crushed sand ofacceptable quality at project site. Pune-Mumbai express hghway is one ofthe bggestprojects undertaken in India recently. Enough quantities of natural sand is not avaihzble in this region. The total quantity of concrete involved is more than 20,000,00 m3 of concrete. The authorities have decided to use crushed sand. A company by name Sbedala is one of the concrete aggregate manufacturers who have been in the forefront for supplying crusher equwments by trade name Jzw master crusher; or Barmac Rock on Rock VH crushers incorporating rock-on-rock crushing technology that has revolutionised the art ofmaking concrete aggregates. This imported technobgy has been used forproducing coarse and ne aggregates of desired quality in terms of shape, texture and grading. Dust is a nuisance and technically undesirable in both coarse aggregate and more so in fine aggregate. Maximum permissible particles ofsize nerthan 75|.Lis 15% in ne aggregate and 3% in coarse aggregate. There are provision avaihzble in these equwments to control and seal the dust Bormoc RockOnRock VSICrusher. In one ofthe hgh rise building sites in western suburb ofMumbai, M 60 concrete was specified. The required slump coukl not be achieved by natural sand with the given parameter of mix desgn. But with the use of manufactured sand with proper shape, surface texture, desirable grading to minimise void content, a hghly workable mix with the given parameter ofmix desgn, was achwved. The foowing is the grading pattern ofa sample coected from a sand crushing plant on a partwular date and time at Pune-MumbaiRoad Project: Table 3.17. Grading Pattern of crushed Sand (Typical) Aggregates and Testingof Aggregates I The introduction scientically of modern operated are operating go a long aggregates 107 crushers which alloverthe worhl, will way for making quality in all cities in India. Ordinary crushers desired shape, grading of both cannot give surface the texture or and fine coarse aggregate. Gap grading So far we discussed the grading Cone Crushers. pattern of aggregates in which particle size are present in certain proportion ske distr)ution is also referred Originally the hgher in the theory size ofthe voids created It was accommodate ofthe that us grading, up by the nextbwer up by one she bwerthan voids created as particle density. It has been seen that the see ofvoids existing between of2 ske bwer 40 mm aggregate voids occurring Therefore, sample or3 when abng is ofthe graded Specic wlllbe surface ofthe the drying graded 4.75 mm orthe is she of 1.18 mm aggregate kast matrix. The following advantages per cent as against about 40 percent will be bw, because ofhlgh C.A. to CA. and also on account ofbwer cement shrinkage to skes smaller than 6.3 mm. needs cbse in the antwqrated graded concrete, continuous supervision, workability. this method as it shows In spite ofmany ofgrading has not grading. OF AGGREGATES of Flakiness Index is the percentage (thickness) is less than three-fths ratio. is reduced. concrete and change ofgap index ofaggregate aggregate ofEA. water/cement than conventional Test for Determination The akiness requires percentage TESTING dimension the void size existing ske is used, the that gap graded to segregation more popular size ofaggregate words, only when between claims of the superwrproperties become the large aparticular In other to 10 mm orpossibly order ofabout26 and bwer contact and matrix content, greaterproneness which prevents grading. and bw (lb) Requires less cement It was also observed to the ske 1.18 mm or so. area of the gap ofC.A. (iv) Because ofpoint small itselfbggerthan concrete: in the case ofcontinuous percentage and so on. are too is used will be in the order ofsay least voids and concrete forgap (1) Sand required (Ii) size equal 20 mm aggregate size being between that fraction. with 20 mm aggregate, willcontain are claimed than fraction in and similarly, those particle size interference, to their maximum of the order ofparticle that the voids present size ofaggregate, by a particular ske. The next bwer what isknown compacting it was assumed are ed the Such pattern grading. are lled the very next bwer voids, it wicreate aggregates ofcontinuo aggregate later in a sample ofaggregate. to as continuous by the bwerske realised all oftheirmean by weght ofparticles dimension. in it whose least The test is not applicable 108 I Concrete Technology This test is conducted 3.9. A su/fkient ofany fraction quantity by using a metal thkkness ofaggregate can be tested. Each fraction The total amountpassing samples in the guage weght ofthe passing the varbus sample taken. Table 3.18 shows Table 3.18. Shows gauges ofthe description shown in Fig. number of200 pkces isgauged in turn forthickness on the metalgauge. is weghed to an accuracy of 0.1 per cent of the taken. The akiness thkkness gauge, is taken such that a minimum index is taken as the total weght expressed the standard Dimensions as a percentage dimensions of thkkness of Thickness (IS: 2386 (Part I) ofthe material of the total weght and length and Length Gauges 1963) * This dimension is equal to 0.6 times the mean Sieve size. 7' This dimension is equal to 1.8 times the mean Sieve size. T I ,: _' All4iirnensions,in'mi11imetres _ of the gauges. e M ?fR0116dOpVergi8mm(PBay s T Aggregatesand Testingof Aggregates I 109 Testfor Determination of Elongation Index The ebngation greatest dimension index on an aggregate (length) isgreater index is not applicable is the percentage by weght ofparticles than 1.8 times their mean dimension. to skes smaller than 6.3 mm. This test is conducted by using metalkngth A su/fkient quantity ofaggregate guage ofthe description shown in Fig. 3.10. is taken to provide a minimum fraction to be tested. Each fraction sha be gauged individuay numberof200 pieces ofany for length on the metalguage. The guage kngth used shall be that specied in column of4 ofT?zble 3.18 forthe ske ofmaterial. The total amount by the guage accuracy ofat least 0.1 percent is the total weight whose The ebngation retained ofthe of the material weght retained ofthe length appropriate shall be weighed to an test samples taken. The ebngation index on the varwus length gauges expressed as a percentage ofthe total weght ofthe sample gauged. The presence ofebngatedparticles in excess of10 to 15 percent isgeneray considered undesirable, but no recoganised limits are laid down. ~ Va .i..i"_ i_t}_assing.ISsi_eve 7L11011121.5}! 16x11 20. 1 "1g{e;tainedlIiS sieve? 6.38 1012.5. L16? tea I I : 33 l-El}$@:'B9$$-®- I or @-§ V1'8.,1t4.7720.1V25.6ii 8T ~- 8i.jo_fi--f . 1,,.%'i Indian method standard explain only the of cakulating Index and Ebngation specifkations both Flakiness Index. But the do not specify the limits. British Standard BS 882 of 1992 the flakiness aggregate index limits coarse to 50 for naturalgraveland to 40 for crushed However; forwearing I-erlglhGouge of the corase aggregate. surfaces a bwer valuesofakiness indexare required. 110 I Concrete Technology Test for Determination of clay, fine silt and fine dust This is agravimetric particles method for determining the clay, ne The sample for test isprepared from the main sample, sample contains a correct proportion of the ner the test is in accordance with Table 3.19. Table 3.19. Weight of Sample dust which includes V _1g0_t.0g6g_,3_ gr *4i.,75T¢risma1le,r, pg Sedimentation pipette air-dry condition, ofthe description In the case ofne passing shown aggregate, togetherwith 300 ml ofdiluted sodium are xed. Care is taken to ensure water tghtness. this axis horkontal, at a speed of80 taken for Fine Silt and y0.5.V. 0.3j in Fig. 3.11 is used fordeterrnination approximately the suspension and the residue washed by gentle swirling sodium the washings ispoured added about per minute and cap its bng axis, for a period into 1000 ml measuring ofsuccessive to the cylinder of in the in the screw topped The rubberwasher The jar is then rotated and decantation being 300 gm. ofsamples and placed 1 20 revolutions minutes solution, of clay, oxalate solution. At the end of15 oxalate care that the test ofsample my the 4.75 mm lS'Sieve, is weghed glassjar; minutes. The amount Dust g to clay and silt content. taking particular material. for Determination Fine with silt and ne upto 20 microns. of15 cylinder 150 mlportions until the volume of is made upto 1000 ml. In the case ofcoarse covered with vgorously to remove 1000 ml measuring to the cylinder: bwered volume all ne cylinder: The volume The suspension gently aggregate a measured material is made bore oftap by opening up into the bur is washed measuring cylinder container between and The percentage aerplacing tap Band to 110°C of the ne W, = weght agitated suspension sodium is thoroughly mixed. suction slit and clay orne weght, the purette airther Aand the to run away and any from The contents and weghed. dust is cakulated in gm ofthe orrginal sample. A is then is then removed container: cooled The purette at C. A small surplus may be E. The pipette into a weghed to constant to the solution. and then bwered the tube inposition, gentle transferred has been transferred oxalate liquid, 1001000W2 J V 0.8 where container; tube C, but this is aowed waterfrom run in a suitable (0.8 gm perlitre), till all clay material the surface ofthe B and applying its contents is dried at 100°C and the liquid cylinder out with distilkd isplaced solution upto 1000 mlwith touches Three minutes drawn adhered in the measuring 10 cm into the solizl matter sample oxalate This process is repeated until the purette B islled the weghed ofsodium from the formula. the of the Aggregates and Testingof Aggregates I W2: weght in gm ofthe drkd V: volume in ml ofthe pipette 0.8 = weght in gm ofsodium 111 residue and oxalate in one litre ofdiluted solution. escatetgiaduate ggttincxri i t_'sgetd;i:nentaitintub,e Test for Determination of Organic Impurities This test is an approximate present in the natural sand from the natural clearglass bottle for estimating quantity source is tested as delivered ised whether organic or within the permissible and without drying. to the 75 ml mark with 3 per cent solution water: The sand is added The volume method sand in an objectwnable gradually until the volume is then made up to 200 ml by adding compounds are The A 350 mlgraduated ofsodium hydroxide in measured by the sand layer is 125 ml more solution. The bottle is then stoppered and shaken vgorously. Roding also may be permitted to disbdge any organic matter adhering to the natural sand by using glass rod. The liquid is then aowed to stand for24 hours. The cobur ofthis liquid aer24 hours is compared with a standard solution freshly prepared, as foows: Add 2.5 mlof2 3 percent allow sodium percent solution hydroxide solution. to stand for24 preceding paragraph. oftannic hours before comparison Alternatively, with the solution an instrument comparison can be obtained, but it is desirable comparison with solution. the standard acid in 10 percent alcohol, to 97.5 ml ofa Place in a 350 ml bottle, stopper; shake vgorously or cobured above and described and in the acetate sheets for making that these shoukl be veried on recewt the by 112 I Concrete Technology Test for Determination of Specific Gravity Eidian Standard Specication LS: 2386 (Part1lD of1963 out the specific gravity ofdifferent skes ofaggregates. to aggregate size larger than 10 mm. A sample ofaggregate nerparticles in distilled immersion, the entrapped water to the aggregate. at a temperature airis 25 mm above the base ofthe removed from the operation, completely in water: washed E is then placed between the sample tank and allowing drop per sec. During immersed procedure not less than 2 kg is taken. E is thoroughly and dust adhering immersed gives various procedures The foowing 22° allowed placed care is taken that the basket in water 22° to 32° C. The basket and the aggregate to drain forafew minutes and furtherdried. 25 times and weghed in water(we@htA2). in air (weight cooled is weghed of100 3. container; from water and is taken outfrom the basket and C (weight is transferred in water,'jolted to atmosphere completely at this temperature and weghed Specific Gravity = E; is exposed appears Then the aggregate to 110°C and maintained in the air-tght untilit hours (weight A1) in water at are then removed The aggregate the aggregate it remain 1 1/2 The empty basket is again immersed less than 10 minutes temperature of24 dried with the ck) th. The aggregate from direct sunlightfornot after and aggregate for a period and then the aggregate to the second dry cbth Immediately it to drop 25 times at the rate ofaboutone They are kept on dry ck) th and the surface isgently the the basket containing afterwards. The basket and aggregate are then jolted and weghed a temperature to remove in a wire basket and to 32°C. by lifting to nd is applicable away surface dry. Then is kept in the oven for24 at a 1 1/2 hours. E is then 6). Apparent Sp.Gravity =E C 100(BC') Water absorption Where, = C A: the weght in gm ofthe saturated aggregate in water (A1 B: the weght in gm of the saturated C: the weght in gm ofoven-dried surface-dry aggregate aggregate A2), in air; and in air: Test for Determination of Bulk Density and Voids Bulk density is the weght per litre. A cylindrical measuring 3.20. ofmaterial measure preferably bue density. The size ofthe in a given 30;: expressed intemal containerfor measuring bulk density is shown for Bulk Density f 5,315,I V0UeVr4VV7V5 mm V. V (VV to 40mm 1 or 3» 5155 T ? ooert4o,mm 2 E is normally to accurate Table 3.20. Size of container ~ 4.75'm'm and under, 53 I volume. machined dimensions in Table, Test ii 17 - V(V [V V g, V 25 if is r 30 5 * _ 3:5.is in kg is used for 31],. T1 3.15 g: (4.002 5.ooa Aggregates and Testingof Aggregates I The cylindrical measure ised about 1/3 each time with thoroughly 113 mixed aggregate and tamped with 25 strokes by a buetended tamping rod, 16 mm diameter and 60 cm bng. The measure is carefuy tamping rod as a straght The net weght of the aggregate struck o/flevelusing in the measure is determined and the bue density = where, 03 = specific gravity ofaggregate Mechanical is cakulated in kg/litre. .capacltyof thecontamer1n11tre Percentage= Gs 7x100 Gs Bulk dinsity IS: 2386 edge. and Y = bue dinsity in kg /litre. Properties of Aggregates Part IV - 1963 Test for determination The aggregate of aggregate crushing crushing value valuegives a relative measure ofthe resistance ofan aggregate to crushing under a gradually applied compressive load. With aggregates of aggregate crushing value30 orhgher; the result may be anomabus and in such cases the ten percent nes value shoukl be determined The standard and retained aggregate and used instead. crushing test is made on aggregate on 10 mm IS Sieve. Erequired, upto 25 mm may be tested. But owing or ifthe standard passing a 12.5 mm IS ske is notavallabk, Sieve othersizes to the nonhomogeneity of aggregates the results will not be comparable with those obtained in the standard About aggregates test. 6.5 kg material passing on 10 mm skve consisting of 12.5 mm and retained is taken. The aggregate a surface dry condition standard cylindrical is filled measure into in the in three layers approximately ofequal depth. Each layeris tamped 25 times with the tamping ord and nally leveed offusing the tamping rod as straight edge. The weght of the sample contained in the cylinder measure is taken (A). The same weght ofthe for the subsequent The cylinder aggregate ed repeat sample is taken test. of the test appartus in a standard in position on aggregate is carefully the with manner isput base-plate and the levelled and the plunge in 7' serte d ho 7'iZO TL 0 TL is surface. The plunger shoukl notjam Aggregofe CrushingVO|UeApporofusl in the cylinder: The appartus, testing machine bad with the test sample and plungerinposition, and is baded uniformly is then released and the whole a 2.36 mm IS Sieve. The fraction ofthe passing upto a totalbad materialremoved isplaced of40 on the compression tons in 10 minutes from the cylinderand the skve is weghed (E, time. The sieved on 114 I Concrete Technology B Theaggregate crushing value = EXIOO where, B = weght offnaction A = weght ofsurface-dry The aggregate for concrete crushing passing value shoukl other than for wearing 2.36 mm sieve, sample taken in mould. not be more than 45 per cent for aggregate surfaces, and 30 per centfor surfaces such a runways, roads and airfiehl Test for determination of ten per cent fines value The sample ofaggregate crushing cylinder forthis test appartus in thirds, each aggregate is carefully third isprepared isplaced being sample used for aggregate in the same way as described in position subjected levelled used used for wearing pavements. test is the same as that ofthe value test. The test sample ofthe concrete earlier: The on the base plate and the test sample added to 25 strokes and the plunger by tamping inserted rod. The surface so that it rests horkontally of the on this surface. The appartus, testing machine. plunger with the test sample and plungerin The bad in 10 minutes is applied at a uniform 15.00 mm forrounded orpartiay rounded aggregates, 24.0 mm for honeycombed aggregates These figure range from bring the percentage percent. ofthe the bad the cylinder and sieved on a 2.36 and the weght adjusted would is expressed fa within ofthe Repeat test is made and the bad ofnes within uncrushed gravels) shales and slags). rounding or honeycombing. is released and the whole mm IS. Swve. The nes as apercentage ofthe weght of the test shall as seems appropriate fines with the range of7.5 which gives a percentage 7.5 to 12.5 expanded penetration, but ifit does not, a irther at a load (forexample to the extent This percentage 7.5 to 12.6, be made aggregates maximum the required the sieve is weghed the test sample. in the compression and (for example, may be varied according of the materialremoved passing isplaced ofabout: 20.0 mm for nor'rnal crushed After reaching position rate so as to cause a totalpenetration to to 12.5 isfound out the range of 14xX Ioad required where, for 10 percent X: nes bad in tons, causing Y: mean bad. percentage = Y+4 7.5 to 12.5 per ce nt fine s. tests at Xtons Test for determination fines of aggregate from two impact value The aggregate of the resistance impact value gives relative measure of an aggregate to sudden impact. Which in some aggregates resistance to a sbw compressive bad. differs shock or from its Aggregate Impact Value Apparatus. Aggregates and Testingof Aggregates I The test sample consists ofaggregate IS Sieve. The aggregate of100°C sha to 110°C and cooled. 25 strokes by the tamping in the standard weight manner: The whole surface rod. Afurther sample discarded duplicate islled ofaggregate is added into a cylindrical steelcup firmly in the cup and allowed to fall freely to a total15 each being The crushed such bbws aggregate Sieve. The fraction 3. The fraction retained the initial of the weight A) and with and tamped The net this weight of test on the same material. about 14 legs. is raised to a heght and a fresh test made. expressed full and tamped (weight C9 is less than The ratio similar quantity one-third is determined is sieved on 2.36 mm IS (B+ about on 10 mm hours at a temperature in the measure be subjected 0.1 gm. (weight islled offour and then struck o/flevel of the aggregate less than one second. 12.5 mm and retained to over-fbwing A hammerweghing sample sha weight The aggregate shall be used forthe machine. through The measure isled of the aggregate aggregate passing be dried in an oven foraperiod 115 is removed passing fixed of380 on the aggregate. delivered from the sieve is weghed A by more The test at an interval ofnot the cup and the whole on the skve is also weghed weght on the base of the mm above the upper than ofit to an accuracy (weight one gm 6). Ethe the result of total shall be Two tests are made. offines formed to the total sample weight in each test is as percentage. B Therefore, Aggregate bnpactValue= 1x100 where, B = weght offnaction A = weght ofoven-dried The aggregate impact should not other than wearing used for concrete concrete to be used as wearing Indian Standard value ofcoarse use ofIosAngeles machine 2386 abrasion namely, be more cent by weight for and 30 percent 45 per by weght for roads and pavements. abrasion value covers two me thodsfornding by the use ofDe val abrasion testing machine. picture ofthe Table 3.21 gives the detail ofabrasive However, out the abrasion testing machine the use ofIosAngeles abrasion resistance ofthe 48 mm in diameter charge which and by the abrasion aggregate. Abrasive 5 1112* 1 Br 11 . Q5 5104 8-, D _6i in 101 consists ofcast and each weghing Table 3.21. Specified E than surfaces testing This method herein. spheres approximately AA Sieve. such as runways, (Part IV) of1963 gives a betterrealistic is only described surfaces, of aggregate aggregates: 2.36 mm IS sample. value aggregates Test for determination passing 312. 1 V 390 to 445 gm. charge V V 500o»_«2i5. v i 5. iron spheres or steel between , 45841; 255 5 g333oi2o .25oo3_«15, j A it 3 50002251 125p A 51 5000:1125 5125,15. 5 15010012554 116 I Concrete Technology The test sample consist ofclean 110°C and it should conform aggregate to one ofthe which gradings Table 3.22. Gradings Est sample and abrasive charge in the IosAngehasAbrasion the machine at a speed rev/min. For machine is rotated for gradings E: Fand 0, revolutions. number gradings of Test Samples and to 33 D, revolutions. it is rotated At the completion ofrevolution, of20 A, B, C and 500 in Table 3.22. are placed testing machine is rotated has ben dried in an oven at 105°C shown the For 1000 of the above the material is discharged from the machine and apreliminary separation of the sample made on a sieve coarserthan 1.7 mm lS'Sieve. Finerportion is then sieved on a 1.7 mm LS'Sieve. The material Swved is washed, 110°C to a substantially accurately weghed The difference and the final drkd coarser than 1.7 mm 15' in an oven constant at 105° weight to and to the nearestgram. between weight the orrginalwerght of the test sample is expressed as apercentage ofthe orrginal weght of the test sample. This value is reported as the percentage of wear: The percentage should not be more than 16 per concrete aggregates. Tjrpicalproperties aggregate of wear cent for of some sample are shown of the Indian in table 3.23. Los Angeles Abrasion Tesiing Machine. to m e L w 9m e: L S L L S 2 3 oacem mo_u. no 9: _.wo_n cm L om L L o §§ 93 c.L L Aggregafes and Tesfingof Aggregafes I 117 SSLG LLLS =.nmou.wm :w_u:_ HES em am Sumemma muuwmxmma 25 SS Sumaw L§.mSmwa SS mL§mSmma SS Lm.LsmS SS $3? SS LmLL L. Bnwmma SS L%.mSmmc ES smmxmmd ELLE Samammn E §mSmm SS Ssmsmma SS §mSm SS Samemm SS Lm.§%EMM _SLL ~Sm cm L Lm.§m ow L em; SE LL LL 25 SS gw L awLL cw L m§,§Lw§b L Sm L 3» L QNLL L cm. QNL LESLQNL L SS 23.» 3 L L vmL.N Ev LL L L ~.m mam SS cm cw LL cm;L ¢N L L L gm L {mam odm Lone Lo.NL 3.. LLL arm Q.m.~ LL L om.Lmm L LL EmLL L oewm LL L L3.3 L omam L Laws L L mm.m L L SEE.§.£ L L~::~u§Ew S£uoO L:E§:L~u LL.323 Eu:L$~L L LL _ Ssfmuwm LL L .:L~R LL .m.~L L .m. SSMSS NSSLRD .N .L:Lu%c «.§z.L.L:L .m L§§m.L LLQ.Lw~ Exmm LLL LL SSEL . 3.9 L .om.mL .nN.n 035... m L L L LL .m .W L LL 6 .5 L LL LL L.m. LL L L LL .3.L L EL 118 I Concrete Technology 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8