--. "V ~ \~I UDC 666.972: 691.32: 620.1 DEUTSCHE NORM Testi n9 concrete Testing of hardened concrete (specimens prepared in mould) June 1991 DIN 1048 PrOfverfahren fOr Beton; Festbe!on, gesondert hergestellte Probekorper Part 5 This standard, together with DIN 1048 Part 1, June 1991 edition, supersedes DIN 1048 Part 1, December 1978 edition. In keeping with current practice in standards published by the International Organization for Standardization (ISO), a comma has been used throughout as the decimal marker. This standard has been prepared by Section VII Beton und Stahlbeton I Deutscher AusschuB fUr Stahlbeton of the NormenausschuB Bauwesen (Building and Civil Engineering Standards Committee). ~ q; co :> ,. Dimensions in mm Contents oj '" c '" E- d Z a> ~ > ,'".- :s ~E ~:; ::; '" "" .<:;.<:; o- j!)" :J '" ~~ z"" is ~ c - a 0" c" 0.0 'ij :g .- :J Eo ~.<:; "" 0.- ~ '" a c ~:~ a> 0 -= " - '" '" '" 0'" €'" .- c ~.s '" .: " '" "E :J ~ '" a> eC) ~~ "- .0-.0 >-'" '" a E'" ",'0 :C" '" " c<ll '" 0 Q;E " :s '0 1: '" 0. a Z iQ> Page 1 Scope and field 0' application. ............. 1 2 Sampling 1 2.1 Suitability testing. ..................... 1 2.2 Qualitytesting and testing of hardened concrete 1 2.3 Number of specimens................... 1 3 Shape and size of specimens. ............. 1 3.1 General 1 3.2 Compressive strength. .................. 2 3.3 Flexural strength. ..................... 2 3.4 Tensile splitting strength. ............... 2 3.5 Static modulus of elasticity. .. . . . . . . . . . . . . 2 3.6 Water permeability. .................... 2 4 Apparatus 2 4.1 Moulds 2 4.2 Accessories.. ......................... 2 4.3 Test equipment. ...................... 2 ~ -- ~- Page 5.3 Treatment after compaction. ............. 3 6 Curing 0' specimens.. .. .. .. .. .. . .. .. . .. . 3 6.1 General 3 6.2 Compressive strength and static modulus of elasticity. ........................... 3 6.3 Flexural strength and tensile splitting strength. 3 6.4 Water permeability. .................... 4 7 Testing 4 7.1 Density 4 7.2 Compressive strength. .................. 4 7.3 Flexural strength. ..................... 4 7.4 Tensile splittingstrength. ................ 5 7.4.1 Cylindricalspecimens. ................ 5 7.4.2 Prismatic and cubic specimens. .......... 5 7.5 Static modulus of elasticity. .............. 5 7.6 Water permeability. .................... 6 7.7 Moisture content. ...................... 6 -I 5 Specimen preparation. .................. 2 5.1 General 2 ~2 Compaction 3 1 Scope and field of application This standard specifies methods of testing the com- pressive strength, flexural strength, tensile splitting strength, static modulus of elasticity, water permeabil- ity and moisture content of hardened concrete as de- fined in subclause 2.1 of DIN1045, July 1988 edition, and in DIN 4232. The assessment of test results and the requirements to be met by concrete are covered in DIN 1045. - 8 Testreport............................ 6 Standards referred to ...................... 8 The type of mixer used, mixing time, ambient tempera- ture and concrete temperature shall be recorded. 2.2 Quality testing and testing of hardened concrete*) ~ For quality testing and testing of hardened concrete, sampling and specimen preparation are generally car- ried out on site, the samples being taken from the con- crete intended to be used for a particular structural member. 2.3 Number of specimens Unless otherwise specified in the relevant standards (e.g. DIN 1045) or specifications, three specimens shall be prepared for each test. '. If 2 Sampling 2.1 Suitability testlng*) For suitability testing, the specimens shall be prepared using a mould and taking into account the property of concrete to be determined. The concrete shall be mixed from the materials in- tended for use in the actual structure. Their origin and the concrete composition shall be recorded. Once all the constituent materials have been added, the concrete shall be mixed in a DIN 459 mixer. 3 Shape and size of specimens 3.1 General The minimum specimen dimensions shall be at least equal to fourtimesthe maximumttggregateparticlesize. *) Cf. subclause 7.4 of DIN 1045for definition. Continued on pages 2 to 8 BeuthVerlag GmbH, Berlin, has the exclusive right of sale for German Standards (DIN-Normen). 05.93 DIN 1048 Part 5 Engl. Price group 6 Sales No. 0106 f I II I
Transcript
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UDC 666.972: 691.32: 620.1 DEUTSCHE NORM
Testi n9 concreteTesting of hardened concrete
(specimens prepared in mould)
June 1991
DIN1048
PrOfverfahren fOr Beton; Festbe!on,gesondert hergestellte Probekorper
Part 5
This standard, togetherwith DIN 1048 Part 1, June1991 edition, supersedesDIN 1048 Part 1, December1978 edition.
In keeping with current practice in standards published by the International Organization for Standardization(ISO), a comma has been used throughout as the decimal marker.
This standard has been prepared by Section VII Beton und Stahlbeton I Deutscher AusschuB fUr Stahlbeton of theNormenausschuB Bauwesen (Building and Civil Engineering Standards Committee).
1 Scope and field of applicationThis standard specifies methods of testing the com-pressive strength, flexural strength, tensile splittingstrength, static modulus of elasticity, water permeabil-ity and moisture content of hardened concrete as de-fined in subclause 2.1 of DIN1045, July 1988 edition,and in DIN 4232.
The assessment of test results and the requirements tobe met by concrete are covered in DIN 1045.
The type of mixer used, mixing time, ambient tempera-ture and concrete temperature shall be recorded.
2.2 Quality testing and testing of hardenedconcrete*) ~
For quality testing and testing of hardened concrete,sampling and specimen preparation are generally car-ried out on site, the samples being taken from the con-crete intended to be used for a particular structuralmember.
2.3 Number of specimensUnless otherwise specified in the relevant standards(e.g. DIN 1045) or specifications, three specimens shallbe prepared for each test.
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2 Sampling
2.1 Suitability testlng*)
For suitability testing, the specimens shall be preparedusing a mould and taking into account the property ofconcrete to be determined.The concrete shall be mixed from the materials in-tended for use in the actual structure. Their originand the concrete composition shall be recorded.Once all the constituent materials have been added, theconcrete shall be mixed in a DIN 459 mixer.
3 Shape and size of specimens3.1 General
The minimum specimen dimensions shall be at leastequalto fourtimesthe maximumttggregateparticlesize.
*) Cf. subclause 7.4 of DIN 1045for definition.
Continued on pages 2 to 8
BeuthVerlag GmbH, Berlin, has the exclusive right of sale for German Standards (DIN-Normen).05.93
DIN 1048 Part 5 Engl. Price group 6Sales No. 0106
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3.2 Compressive strengthFor determining the compressive strength, either100mm, 150mm, 200 mm or 300 mm concrete cubesor cylinders 100mm, 150mm, 200 mni or 300 mm indiameter and witha height to diameter ratio of 2, shallbe used.
3.3 Flexural strengthFor determining the flexural strength, moulded con-crete beams, preferably 150mm x 150mm x 7oommin size, shall be used.1) Where the maximum aggre-gate particle size necessitates the use of largerbeams, these shall be 200 mm x 200 mm x 900mm.
3.4 Tensile splitting strengthThe specimens used for determining the tensilesplitting strength should preferably be cylinders150mm in diameter and 300 mm in height. Alter-natively, beams may be used provided that the lengthto width ratio of the cross section is not more than1: 1,5.
3.5 Static modulus of elasticityThe specimens used for determining the static modulusof elasticity should preferably be cylinders 150 mm indiameter and approximately 300 mm in height. For spe-cial applications, specimens 100mm, 150mm or200 mm in diameter may be used, provided that theheight to diameter ratio is not less than 2 nor morethan 4. For prisms with a side length (of the endfaces) of 100mm, 150mm or 200 mm, the height toside length ratio shall be not less than 3 and not morethan 4.Different results may be obtained when testing speci-mens prepared from the 'same concrete but different insize-
3.6 Water permeabilityUp to a maximum aggregate particle size of 32 mm,the specimens used for determining the water per-meability should preferably be slabs 200 mm x200 mm x 120mm in size. Alternatively, 200 mm cubesor circular slabs 150mm in diameter may be used.Where the maximum particle size exceeds 32 mm,300 mm cubes or square slabs, or circular slabs300 mm in diameter, shall be used. The slab thicknessshall be at least 120mm, where the particle size is32 mm or more. (Otherwise, it shall be at least equalto four times the diameter of the maximum particlesize.)For special applications, and subject to compliancewith the requirements specified in subclause 3.1,150mmcubes or square slabs may be used.
4 Apparatus4.1 Moulds
Specimens shall be prepared using a mould complyingwith DIN 51229*).Square slabs for the water permeability test may alsobe made using a cubic mould, which shall be providedwith an internal lining of non-absorbent material beforethe specimens are cast.
4.2 Accessories
The following accessories shall be used for preparingthe specimens.
a) Collar complying with DIN51 229, which can be se-curely and tightlyfastened to the mould. Its heightshall be approximately equal to the edge length ofcubes, or approximately 1,5 times the diameter ofcylinders, or 200 mm in the case of beams.
b) Steel rule.c) Vibratingtable complying with DIN4235 Part 3, or
internal vibrator complying with DtN4235 Part 2,preferablywith a diameter of not less than 35mm.
d) Tamper with a mass of approximately 12kg, havinga rectangular or circular end. .
4.3 Test equipmentStrength properties shall be tested using a DIN 51 223compression testing machine or a DIN51227 bend test-ing machine. For the purposes of internal control (I.e.on-site control) by types E and W concrete testinglaboratories, they shall conform to at least class 3 asspecified in DIN 51 220, and in all other cases, to atleast class 2, the machine class requirements beingverified by a certificate not more than two years old, is-sued by an accredited test house2).Testing machines used for verification purposes (cf.DIN51300) shall meet at least the requirements Jorclass 2 when tested as specified in DIN51302 Part 1.Compliance with the requirements shall be verified bya test certificate not more than one year old or, whereinternal control (e.g. using a pressure transducer) iscarried out at intervals of three months, by a test cer-tificate not more than two years old, issued by anaccredited test house2).The static modulus of elasticity shall be determinedusing a DIN51223 compression testing machine of atleast class 2, capable of maintaining the applied loadconstant for approximately one minute.Length measuring instruments (e.g. mirror or dialgauge extensometers, inductance gauges) and strainmeasuring devices (e.g. strain gauges) shall have agauge length of not less than five times the diameterof the maximum aggregate particle size, with a mini-mum of 80mm. The sensitivity of instruments shall besuch that a maximum change in length of 511m/m willcause a change of 1 mm for analog indication or, in thecase of digital indication, of one increment (cf.DIN1319Part 2).The permeability test may be carried out using anyequipment suitable for the procedure specified in sub-clause 7.6 and which permits specimens complyingwith the specifications of subclause 3.6, to be placedin such a way that the water pressure acts either fromabove or below the specimen, and permits theunexposed faces to be observed for signs of water per-meation (Cf.figure 1). The internal diameter of the seal-ing ring as installed shall be 100mm for specimens upto 200 mm edge length or diameter, and 150mm for spe-cimens with an edge length or diameter of 300 mm.
5 Specimen preparation5.1 GeneralIf the fresh concrete sample has to be transported, itshall be protected against its losing or gaining water,and against the effect of frost, heat, etc. To this effect,the sample shall be transported in a sealed container,
1) In road construction, beams 100mm x 150mm x700 mm in size shall be used for testing.
2) Cf. Explanatory notes, last paragraph.*) At present at stage of draft.
Figure 1. Typical arrangement for determining thewater permeability of 200 mm x 200 mm x120mm slabs
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made of non-absorbent material, which shall be damp-ened before filling with concrete.Specimen preparation shall be started as soon as pos-sible after sampling and, except for concrete with a pro-longed workability time, completed not later than 90minutes after the addition of water. .
Before the specimens are cast, the internal surface ofthe mould shall be thinly coated with oil, grease or re-lease agent. Where the concrete is compacted by vibra-tion, a collar may be fitted on the mould. The mouldshall be filled with concrete to give an excess of about20 to 30 mm above its edge after compaction. For thepreparation of specimens with an hid ratio greaterthan 2, moulds with collar shall be vibrated during filling.Slabs used for the water permeability test shall be pre-pared with the mould. standing upright so that in thetest, the water pressure will act normal to the mould-fill-ing direction.
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5.2 CompactionImmediately after filling the mould, the concrete shallbe compacted so that its degree of compaction is asclose as possible to that in the structural member.Where concrete is compacted by means of an internalvibrator (ct subclause 4.2), this shall be introduced ver-tically at the centre of the mould when preparing cubes,slabs and cylindrical specimens, and, additionally, ateach of the four corners in the case of 300 mm cubes.When preparing 700 mm long beams, the vibrator shallbe placed at an angle into the concrete at not less thanfour points along the long axis of the mould, and atfurther points in the case of longer beams (cf. figure 2).The vibrator shall be immersed to a depth of approxi-mately 20 mm above the base of the mould and left inthis position until the formation of air bubbles of signifi-cant size has markedly decreased. It shall then begradually withdrawn from the concrete so that thehole left by the vibrator closes fully without any airbeing entrapped.Air-entrained concrete may only be compacted bymeans of an internal vibrator if this procedure is alsoadopted for the concrete used in the structure.Concrete of consistence range KS may also be com-pacted by tamping, using a tamper as described in sub-clause 4.2, and concrete of consistence range KF, byrodding. Concrete used for the preparation of perme-ability test specimens is always to be compacted byvibration.For the compaction of lightweight concrete, under animposed load if necessary, use of vibrating tables isrecommended, dense lightweight aggregate' concrete
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DIN.1048 Part 5 Page 3
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Figure 2. Compacting with immersion vibrator whenpreparing 150mm x 150mm x 700mm longbeams
only being compacted by vibrating or rOdding, and po-rous lightweight aggregate concrete, only by rodding,in each case to a degree sufficient to provide a densitynot greater than that in the structure or structural mem-ber.
When compacting concrete containing aggregates ofsignificantly different particle densities (e.g. light-weight concrete with natural sand), care shall be takento ensure that the coarse material does not segregate.
5.3 Treatment after compactionImmediately after compaction, the excess concreteshall be struck off and the concrete surface smoothedlevel with the top of the mould by means of a steel rule.The specimens so produced shall be clearly and du-rably marked. the marking incorporating the date ofspecimen preparation.
6 Curing of specimens6.1 General
During hardening, the concrete shall be protected fromvibration. Once the concrete has hardened sufficiently,usually after 16 hours. the specimens shall be carefullydemoulded. Until testing, they may be left on the base-plate to reduce the risk of damage.Immediately after preparation, specimens for suitabil-ity and quality testing shall be stored in the mould ina closed room at a draught-free location, protectedfrom loss of water, at a temperature of 15 to 22°C (pre-ferably at (20:1::2) °C). After demoulding they shall beplaced on gratings and cured in water or in a moistcabinet at 15 to 22°C (preferably at (20:1::2) °C).During storage in a moist cabinet, lightweight concretespecimens shall be protected against the absorption offurther moisture (e.g. by wrapping them in suitablesheeting).Prior to testing, hardened concrete specimens shall bestored in the mould and further cured under conditionsas similar as possible to those existing in the concreteintended for use in the structure.
6.2 Compressive strength and stallc modulus o'elasticity
Specimens for determining the compressive strength(cf.subclause 7.2) and the static modulus of elasticity(cl. subclause 7.5) shall be moist-cured for sevendays after preparation. then placed on gratings and
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stored at a draught-free location at a temperature of 15to 22°C (preferably at (20 :I: 2) °C).
6.3 Flexural strength and tensile splitting strength
Specimens for determining the flexural strength andtensile splitting strength (ct. subclauses 7.3 and 7.4)shall be cured in water at a temperature of 15 to 22 °C(preferably at (20:I: 2) °C). After removal from thewater, the specimens shall be covered with a dampcloth and stored for a maximum of one hour until testing.
6.4 Water permeability
Immediately after demoulding the specimens, the cir-cular areas (100 mm or 150mm in diameter) to be sub-jected to water pressure (cf. subclause 7.6) shall beroughened by wire brushing and the specimens thenplaced on gratings and cured In water at a temperatureof 15 to 22°C (preferably at (20 :I: 2) °C) until testing.
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7 Testing
7.1 Density
The density of hardened concrete, tlR, in kg/m3, shall bedetermined for the specimens prepared for strengthtesting, using the following equation:
f2R= mlV
where
m is the specimen mass, in kg;V is the specimen volume, in m3.The volume shall be determined by measuring thespecimen dimensions to an accuracy of 1 mm and thespecimen mass determined to an accuracy of 20 g.The density obtained shall be given to the nearest10kg/m3.The density shall be determined before applying anycapping layers necessary for further testing (ct sub-clauses 7.2 to 7.5). From I?R,the dry density, I?Rd'shallbe calculated using the following equation:
l1RI?Rd = 100+h .100
where h is the moisture content to be determined asspecified in subclause 7.7.
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7.2 Compressive strength
Before each test, it shall be checked whether the spec-imen surfaces to be subjected to testing are plane towithin 0,1 mm. Where surfaces are uneven or not paral-lel, they shall be ground by the wet method or capped,to a thickness not exceeding 3 mm.The capping material shall normally consist of a cementmortar composed of one part by mass of Z 45 F or Z 55cement complying with DIN1164 Part 1 and one part bymass of washed natural sand of particle size group 0/1complying with DIN 4226 Part 1.The mixture shall be ap-plied by means of a glass or steel capping plate so as toobtain plane and square end surfaces. The specimensshall then be stored in moist air for 48 hours at a tem-perature of 15 to 22°C (preferably at (20:I: 2) °C) andtested at an age of not less than three days.After grinding or capping, the specimens shall befurther cured as specified before testing. Specimensto be dry-cured shall not be tested within 24 hours aftergrinding or capping.The faces of specimens to be tested at an age of up toseven days shall be wiped dry with a cloth after moistcuring and the specimens stored for approximatelyone hour at ambient temperature before testing.
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Cubes shall be placed in the testing machine so that themould-filling direction is normal to the direction of load-ing, and cylinders so that the load is applied to the endfaces. The specimen shall be placed on the lower plat-en of the testing machine and aligned with the centre ofthe thrust of the machine using a centring device wher-ever possible. Use of packing between the specimenand the platens is not permitted. The surface of theplatens shall be free from oil residues.The load shall not be applied until the upper platen ofthe testing machine is in full contact over its entirearea with the upper surface of the specimen.The load shall be applied steadily so as to increase thestress at a rate of (O,5:I: 0.2) N/mm2 per second. Thecompressive strength. fJo. in N/mm2, shall be calcu-lated from the following equation:
13D= F/A (2)
whereF is the maximum load, in N;A is the area of the platens, in mm2, calculated from the
side lengths of the specimen, measured to an accu-racy of 1 mm at mid-height of the specimens.
The compressive strength shall be given to the nearest1 N/mm2 for values of 10N/mm2 or more, and to thenearest 0,1 N/mm2 for values below 10N/mm2.
(1)
7.3 Flexural strength
For flexure testing, beams shall be placed in the testingmachine so that the mould-filling direction is normal tothe direction of loading (cf. figure 3).The supporting and loading rollers of the testing ma-chine shall have'a circular cross section with a diam-eter of 20 mm to 40 mm and be at least 10 mm longerthan the width of the beam. They shall be arranged sothat the beam is supported over a span that is 100mmless than the beam length and that two equal loads,FI2, act at the third-points of the span, thE! roller axeslying in a plane normal to the longitudinal axis of thebeam (cf. figure 3)3).Loading shall not be started until the loading rollershave been slowly lowered onto the specimen and allrollers are in full contact with the beam.
The load shall be applied so as to increase the stress ata rate of (O,05:I:0,02) N/mm2 per second, until failure,this being equivalent to a rate of loading of approxi-
3) Where the concrete is intended to be used in roadconstruction, beams 100mm in height, 150mm inwidth and 700 mm in length shalt be placed in themachine so that the original finished surface is intension. They shall be supported over a span of600 mm and subjected to a central load (i.e. one-point loading).The points of contact between specimen and rollersshall be capped with mortar strips approximately30 mm wide. A minor unevenness of the surfacemay also be compensated for by rubber strips ofShore A hardness (50:I: 5) as in DIN 53 50S, 5 mmthick and not less than 20 mm wide.The load shall be applied so as to increase thestress at a rate of approximately 0,1 N/mm2 per sec-ond until failure, this being equivalent to a rate ofloading of approximately 170N/s. The flexuralstrength, 13Bz'shall be calculated from the followingequation:
F.1,5.fI3Bz= b.iz2
(3)
, L'cj\J5","" - '~"" ."",os,"o"'f ""(,
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200 200
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Figure 3. Loading arrangement for 150mm x 150mmx 700 mm long beam (two-point loading)
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mately 280 N/s for a 150mm x 150 mm x 700 mm beamand of approximately 500 N/s for a 200 mm x 200 mm x900 mm beam3).The flexural strength, 13BZ,in N/mm2, shall be calcu-lated from the following equation:
F./13az= b.h2
where
F is the breaking load, including the self-weight of theloading rollers (if relevant), in N;
/ is the span between the supporting rollers, in mm;b is the beam width at the point of failure, in mm;h is the beam height at the point of failure, in mm.band h shall be measured to an accuracy of 1mm and13BZbe given to the nearest 0,1 N/mm2 for values of1 N/mm2 or more, and to the nearest 0,01N/mm2 forvalues below 1N/mm2.
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7.4 Tensile splitting strength7.4.1 Cylindrical 8peclmensA concrete cylinder shall be placed centrally betweenthe platens of a testing machine of the type used forcompression testing.Packing strips, 10 mm wide and 5mm thick, preferablymade of plywood, with a density of 850 kg/m3, as speci-fied in DIN68 750, or of F 5 or H 1 compacted felt com-plying with DIN61200 shall be placed between theplatens and the cylinder (cf. figure 4).Loading shall not be started until platens, packingstrips and specimen are in full contact with eachother. The load shall be applied so as to increase thestress at a rate of (0,05 ~ 0,02) N/mm2 per second,this being equivalent to a rate of loading of approxi-mately 3500 N/s for cylindrical specimens 150mm indiameter and 300 mm in length.The tensile splitting strength, 13sz,in N/mm2, shall becalculated from the following equation:
!3sz=~= O,64F7(".d./ d.lwhereF is the maximum load, in N;d is the specimen diameter, in mm;I is the specimen length, in mm.d and I shall be measured to an accuracy of 1 mmand 13szgiven to the nearest 0,1 N/mm2 for values of1N/mm2 or more, and to the nearest 0,01 N/mm2 forvalues below 1N/mm2.
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DIN1048 Part 5 Page 5
Packing strips,5mm thick,10mm wide
Figure 4. Arrangement of loading of cylindrical speci-mens for determining the tensile splittingstrength
(4)
7.4.2 Prlsmade and cubic specimensPrismatic and cubic specimens (e.g. pieces remainingfrom flexure testing, cubes, etc.) shall be placed in thetesting machine, with packing strips (cf. subclause7.4.1) positioned along the top and bottom of the planeof loading of the specimen. The load shall be appliedas a line load on the moulded faces in such a way thatthe fracture plane will cross the trowelled surface(cf.figure 5).The load shall act along the entire width of the spec-imen. The packing strips shall be located on themoulded faces so that the upper strip Is directly overthe lower strip, their distance from the specimen endbeing at least equal to half the specimen height.The load shall be applied steadily so as to increase thestress at a rate of (0,05 ~ 0,02) N/mm2 per second, thisbeing equivalent to a rate of loading of approximately1750N/s for a 150mm square beam. The tensile split-ting strength, !3sz, in N/mm2, shall be calculated fromthe following equation:
/3sz=~ - O,64F7(".b.h-/;:h (6)
where
F is the maximum load, in N;b is the width of the specimen (as shown in figure 5), in
mm;h is the height of the specimen (as shown in figure 5),
in mm.band h shall be measured to an accuracy of 1 mmand !3sz given to the nearest 0,1 N/mm2 for values of1 N/mm2 or more, and to the nearest 0,01 N/mm2 forvalues below 1 N/mm2.
(5)
7.5 Sialic modulu8 of elasticityThe static modulus of elasticity in compression is thesecant modulus calculated as the ratio of a givenstress to the corresponding strain (normally deter-mined for specimens at an age of 28 days).Unless otherwise specified, the upper loading stress,0"0' shall be approximately one-third of the com-pressive strength, 13, of the specimen, determinedas the mean from three companion specimens, fromthe same batch as those to be used for deter-mining the static modulus of elasticity, and made andcured under similar conditions. Where the modulus of
Arrangement of loading of prismatic and cu-bic specimens for determining the tensilesplitting strength
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elasticity is to be determined at a specific stress (e.g. ata stress equal to f3Rt2,1(cf. DIN1045)), this stress shallbe used as upper loading stress.The specimen surfaces subjected to compression shallbe plane and smooth (cf. subclause 7.2). The lengthmeasuring instruments shall be attached on oppositesides of the specimen and parallel to its axis in sucha way that the gauge points are symmetrical aboutthe middle of the specimen and are not nearer to eitherend of the specimen than a distance equal to half itsdiameter for cylindrical and equal to the larger sidelength of the end face for prismatic specimens.The specimen shall be placed centrally in the testingmachine and the upper platen aligned so that it is infull contact with the sp-;cimen.The specimen shall be subjected to a basic stress ofapproximately 0,5 Ntmm2 (O'u)and the actual stresscalculated on the basis of the cross-sectional area atmid-height of the specimen.Loading and unloading shall be carried out at a rate of(0,51: 0,2)Ntmm2 per second, in accordance with theloading diagram shown in figure 6.After all elasticity measurements have been com-pleted, the specimen shall be loaded at the specifiedrate until failure (cf. subclause 7.2). If the compressivestrength of the specimen differs from the mean value bymore than 20%, this shall be stated in the test report.The static modulus of elasticity in compression, Eb' inNtmm2,shall be calculated from the following equation:
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Eb = 6.0'/6.13' = 0'0 - O'uEo - Eu
where
0'0 is the upper stress during third loading cycle, in Ntmm2;
O'uis the basic stress prior to third loading cycle, in Ntmm2;
Eo is the mean strain under the upper loading stress atpoint 8 (cf. figure 6);
Eu is the mean strain under the basic loading stress atpoint A (cf. figure 6).
The modulus of elasticity shall be given to the nearest100 N/mm2.
7.6 Water permeabilityThe permeability test gives a measure of the resistanceof concrete against the penetration of water exerting
0', inN/mm2
B(fo
(fu
*t *t *30 Nt N3O Time, t,in 5
In the above diagram,A is the point of reading the basic stress, O'u (and cor-
responding strain, Eu, and gauge length lu' respec-tively), prior to the third loading cycle;
8 is the point of reading the upper stress, 0'0 (and cor-responding strain, co' and gauge length, 10,respec-tively), during the third loading cycle;
t is the time of loading and unloading resulting fromthe rate of loading and unloading.
Figure 6. Stress-time diagram for determining themodulus of elasticity
pressure. It shall normally be carried out when theage of the concrete is 28 to 35 days.A concrete specimen shall be exposed either fromabove or below to a water pressure of 0,5 N/mm2 act-ing normal to the mould-filling direction, for a periodof three days. This pressure shall be kept constantthroughout the test. If water penetrates through to theunderside of the specimen, the test may be terminatedand the specimen rejected as failed.It shall be checked whether and when the unexposedspecimen faces show signs of water permeation. Im-mediately after the pressure has been released, thespecimen shall be removed and split down the centre,with the face which was exposed to water facingdown. When the split faces show signs of drying (afterabout 5 to 10 minutes), the maximum depth of penetra-tion in the direction of slab thickness, shall be mea-sured, . in mm, and the extent of water permeationestablished.The mean of the maximum depth of penetration ob-tained from three specimens thus tested shall be takenas the test result.
(7)
7.7 Moisture content
For determining the moisture content, broken pieces ofspecimens that have been tested in accordance withsubclauses 7.2 to 7.5 shall be weighed immediatelyafter testing and then dried to constant mass at a tem-perature of 105°C. Constant mass shall be deemedreached when the mass determined by weighing after24 hours does not change by more than 1%0.The mois-ture content shall be calculated as the ratio of the differ-ence in mass to the mass of the dried specimen, as apercentage, using the following equation:
h = mh - md .100md
(8)
where
mh is the specimen mass before drying, in g;md is the specimen mass after drying, in g.
8 Test reportThetest report shall include all informationrelevantforassessment of the test results.
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8.1 Information to be provided by the manufacturer orrepresentative of the test house taking samples:
a) sampling site and structural member from wherethe specimens originate;
b) date of specimen preparation and, if appropriate,place and method of sampling;
c) identification of specimens;d) conditions of storage and curing of specimens until
supplied to the testing laboratory;e) required properties of the concrete.
8.2 Information to be provided by the test house:a) date of receipt of the specimens;b) appearance of specimens wh.en received;c) identification of specimens;d) conditions of storage and curing until testing (includ-
ing binders used in capping or grinding method)e) date of test;
DIN 1048 Part 5 Page 7
f) age of specimens at start of test;g) specimen dimensions;h) density of specimens prior to testing as specified in
subclauses 7.2 to 7.7: individual and mean values;
i) results of testing as specified in subclause 7.2 to7.7: individual and mean values;
j) any occurrences that might have affected the testresults.
8.3 Additional information to be provided where thestatic modulus of elasticity was determined:
a) type of measuring Instruments and gauge length;b) basic loading stress;c) upper loading stress;d) mean strain under upper and basic loading stress;e) calculated static modulus of elasticity in compres-
sion.
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Page 8 DIN 1048 Part 5
Standards referred to
DIN 459 Concrete mixers; concepts, sizes and requirements
DIN 1045 Structural use of concrete; design and construction
DIN 1164 Part 1 Portland, Portland blastfurnace, blastfurnace slag and trass cement; concepts, constituents,requirements and supply
Basic concepts in metrology; terminology relating to the use of measuring instruments
Aggregates for concrete; aggregates of dense structure (heavy aggregates); terminology, desig-nation and requirements
No fines lightweight concrete walls; design and construction
Compaction of concrete by vibration; compacting with internal vibrators
Compaction of concrete by vibration; compacting with external vibrators in the production of pre-cast elements
(at present at stage of draft) Moulds for concrete specimens
Materials testing machines; verification of materials testing machines; general
Materials testing machines; verification of tensile, compression and bend testing machines; prin-ciples
Shore hardness testing A and D of rubber, elastomers and plastics
Hardness of felt
Fibre building board; softboard and hardboard; grading
Concrete; determination of flexural strength of test specimens
Previous editions
DIN 1048: 09.25, 04.32, 10.37, 43x; DIN 1048 Part 3: 01.75; DIN 1048 Part 1: 01.72, 12.78.
Amendments
Incomparisonwiththe December1978editionof DIN1048Part 1,specifications for hardenedconcrete are now givenin this Part of DIN 1048(testing of fresh concrete being covered in Part 1).
Explanatory notesIn the flexure test (which is based on ISO 4013: 1978), the direction of loading has been specified as running normal tothe mould-filling direction. Since the strength of the beam is normally at its greatest in the zone which is at the bottomduring filling of the mould, the values obtained when using this arrangement may be somewhat lower than normal,but are nonetheless on the safe side. On the other hand, the test has been made simpler to perform since mortar orrubber strips are no longer required in connection with the loading arrangement.
The number of loading cycles for determining the modulus of elasticity has been reduced to three, since experiencehas shown that the modulus does not change significantly after the third cycle. The water permeability test has beensimplified by specifying a constant water pressure of 0,5 N/mm2 acting for three days instead of varying water pres-sures (0,1, 0,3 and 0,7 N/mm2) for a total of four days. Interlaboratory tests have shown both methods to be equivalent.The Verband der Materialpriifungsamter (Association of Materials Testing Institutes) keeps a list of testing centresaccredited for verifying materials testing machines in compliance with DIN 51 300 (cf. subclause 4.3).
