As 1012.13-1992 Methods of Testing Concrete - Prepared i

Title

AS 1012.13-1992 Methods of testing concrete - Determination of the drying shrinkag of concrete for samples prepared in the field or in the laboratory

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AS 1012.13—1992

Australian Standard

Me th ods o f te s t in ing c on c re te Me th od 1 3 : De te rmi min a tio ion of t h e d ry iin ng s h r i n k a g e o f c o n c re t e f o r s a m p l e s pr e p a re d i n the f iie e ld ld o r in t he lla a b o r a t o ry PREFACE This Standard was prepare d by the Stand ards Australia Committee on Methods of Testing Concrete, to supersede AS 1012, Methods of testing concrete , Part 13—1970, Determin ation of dryi ng shri nkage of concr ete .

. d e it ib h o r p k r o tw e n n o e s u r o n o ti u ib rt is d , e g a r to S . y l n o e c n e c li r e s u e l g in S . 2 0 0 2 n u J 4 0 n o H S E R U .S .S E to d e s n e c i L

The format of the Standard has been rearranged to comply with AS 2929, Test methods — Guid e to the format, style and content and with Stand ards Australia Format B, which is the preferred format for a series of test methods as it reduces the amount of common content and precludes the need for separate covers . The technica l content of this editio n i s gener ally unchanged from the 1970 edition, except that — (a) the differe nces betwee n laboratory sampling/ standard initi al curing and fiel d sampling/ non-standard initial curing have been acknowled ged with the inclusion of a requirement that samples prepared in the field be trea ted separately and reported as such; (b) provision for the reject ion of obviously incorrect spec imens has been adde d; and (c) a precisi on statement for labora tory prepare d samples has been add ed. (d) Pro vision has been made for the testi ng of concrete with aggregate up to a nominal 40 mm in size.

CONTENTS

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SCO PE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 REFE RE NCED DOCUMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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3 DEF INITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 4 PRI NCIPLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 5 APP ARATUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 6 SAMPLIN G AND TES T SP ECIMENS . . . . . . . . . . . . . . . . . . . . . . . 5 7 PRO CED URE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 8 CALC ULA TION AND EX PRE SSI ON OF RES ULT S . . . . . . . . . . . . . 9 9 PREC ISI ON FOR LABORAT ORY -PREP ARE D SPECIMENS . . . . . . 9 10 REC ORD S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 11 REPO RT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 APPE NDIX AA SUI TAB LE HORIZO NTAL LENG TH COMPARA TOR . . 11 COPYRIGHT

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AS 1012.13—1992

METHOD 1 SC OPE This Stan dard sets out a method for preparing and curing of concrete shrinkage specimens, and for determin ing the leng th changes of these specimens due to drying in air. It provides for testing of specimens prepared in the laboratory or in the field, in which the nominal size of aggregate in the conc rete, in accordance with AS 2758 .1, does not exceed 40 mm. The precision statement in Clause 9 does not apply to specimens which have had non-stand ard initial curing (norm ally field- prepar ed specimens). In addition this Standa rd requires that field- prepar ed specimens are marked, recorded and reported as such. NOTES: 1 This test m ethod is not always suitable for very low slump conc rete (less than 20 mm), primarily due to t he difficulties in obtaining adequat e compac tion. Provided adeq uate compaction is obtained , the method is applicable. 2 The method is spec ifically designed for measuremen t of drying shr inkage of concrete, but it is capable of adap tation for measu rement of length change s of specimens subjected to a variety of environmental conditions.

2 REFEREN CED DO CUMENTS The following docu ments are referre d to in this Stand ard:


AS 1012 1012.1 1012.2 1012.3

Methods Part 1: Part 2: Part 3:

1012.4 1012.8

Part 4: Part 8:

2758 2758.1

Aggregates and rock for engineering purposes Part 1: Concrete aggregates

of testing concrete Method for sampling fresh concrete Method for preparation of concrete mixe s in the laboratory Methods for the de termination of propertie s related to the co nsist ence of concrete Methods for th e determin ation of air content of fresh ly mixed concrete Method for making an d curing con crete compression, indire ct tens ile and flexure test specimens in the laboratory or in the field

3 DEFINIT IONS For the purpose of this Standard, the definitions below apply. 3.1 Standa rd moi st curing con ditions —as required by AS 1012.8 for lime-saturated water. NOTE: Standa rd t emperate conditions are required for a

minimum of 24 h pri or to initial meas urement(se e Clause 7.3. 3).

3.2 Pre paring labora tory —the laborat ory responsible for sampl ing of concrete, moulding of specimens, init ial curing in moulds, demouldin g, initi al moist curing , tran sport to measuring laboratory (if required). 3.3 Mea suring labor ator y —the labor atory responsible for completi on of initial moist curing, storage in drying room, measurement of specimens. NOTE: In some instance s the preparing and measur ing laboratories will be the sam e.

3.4 Micro meter —a l inear measu ring system. NOTE: Typical exampl es include dial gauge s and digital readout systems.

4 PRIN CIP LE Specimens are cured and air dried for a specified time and the change in length is measured. 5 APPA RAT US 5.1 General The apparatus shall consist of— (a) a dryi ng r oom for dryi ng the specime ns and in which they can be measu red; and (b) equipme nt for making and measu ring the test specim ens. drying room withinsui controlled temperature, humidity and air circulation 5.2 Dry ing room shall be provided for A storing specimens air tably in accordance with the following requirements: (a) Air shall be circulate d throug h the room in a unifo rm mann er so that the spe cified cond itions are attained adjacent to all specimens under test. (b) The temp erature in the dry ing room sha ll be ma inta ined at 23 ± 2 °C. period, at all times remaining within the range 23

±1°C

(c) The relati ve humi dity in the drying room sh all be main tained at 50

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for 90% of each 24 h

± 5%

at all times.

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AS 1012.13—1992

(d) The temper ature s and relat ive humidit ies shal l be reco rded at all times by a which is capable of rapid response to changes in room conditions.

recor ding device

The recordin g detec tors shall be verif ied again st a standardized Assmann hygro meter at least once per week. NOTES: 1 A su ita ble rap id res ponse device for rec ording temp eratur e and humi dity us es a comb ined detector with a thin-film capacitor for humidity and a platinum resistanc e t hermocou ple fo r temper ature measurement. Response time for this type of detecto r is meas ured i n sec onds, and is virtua lly insta ntaneous withi n the narrow range required for this test method. 2

The detector i s used in conjunction with a suitably matche d chart recorder. Most thermoh ygrograph s are un suitable for the purpo se as the resp onse is too slow to de tect the ful l extent of fluctuations, particularly with the hair type of humidity detector.

(e) The rate of air movement in the dryi ng room shall be such that the rate of evapo ration is 12 ±5 mL per 24 h, with a minimum value of 7 mL per 24 h. The evaporation rates shall be determined by measuring the loss in weight of water in 400 mL low-form beakers of internal diameter 78 ±5 mm, init ially con taining approximately 375 g of wate r at a temperatu re of 23 ±2 ° C. The weight of water in the beaker shall not fall below 325 g. Each beaker shall be placed midway between test specimens on the storage racks with the water level at approximately the same height as the top of the specimens. Sys tematic checks on the evaporation rates shal l be carried out by varyi ng the location of t he beake rs within the drying room at least monthl y or where conditi ons have changed and the resul ts r ecorded. NOTE: The rate of evapo ration should be maintaine d as close to 12 mL per 24 h as possible.

(f)


The requirements for temperature, hu midity and evaporation rate apply to each storage position. Positions which do not comply shall not be used for storage of test specimens.

(g) The drying room shall be fitted with suitable racks for stori ng specimens. The rack s shall provide free circulation of air around specimens, except for necessary supports, and shall be so situat ed with resp ect to the near est wall or other obstru ction that air circul ation is not restricted in the interv ening space. The horizon tal supports shall consist of non-a bsorp tive members having a total be aring width suppo rting the spe cimen of not more than 25 mm. All storage positions shall be kept occupied at all times, with dummy specimens if necessary. NOTE: It is recommended

that dummy specimens

be concr ete prisms with the same dim ension s as the t est specimens .

5.3 Mo ulds 5.3.1 General Moulds shall be made of non-ab sorbent material which does not react with ce ment paste and their internal surfaces shall have a smooth finish. The moulds shall be substantial enough to hold their form without distortion and shall be substantially leak-proof. Each mould shall be provided with a base plate to which two end plates are securely fastened by screws, two side plat es which ar e fastene d to t he end plates by screws, and two partially loose end plates which act as gauge stud holders. Each gauge stud holder shall fit inside the end of the mould and shall locate and secure a gauge stud during the setting period of the concrete . Each gaug e stud holder shall be held in position agains t the end plat e by a retaining scre w and sha ll be cap able of release after compaction of the concrete. The opposite side plates shall be parallel and the distance between them shall be 75 ± 1 mm. The inside height shall be 75 ± 1 mm. 5.3.2 Construction of t he mould The cons truction of the moul d shall be aligned co axially along the central axis of the mould ed specimen, wi th the distance betwee n the inner ends of the two studs being 250 ± 0.5 mm, and that between the outer ends 295 ±1 mm. Gauge studs shall protrude from the gauge stud holders to a distance of 15 ±1 mm. A suitable form of construction of the moulds is shown in Figure 1. 5.4 Gauge st uds Gauge studs shall be of stainless steel and shal in Figure 2. The radius of the gauge stud end shall be as follows:

l comply with dimensi ons s hown

(a) Horizonta l comparato r: 147. 5 ±7.5 mm. (b) Vertical com parat or: Approx imately 5 mm. Gauge studs for horizo ntal and vertical compa rators shall not be interc hanged. NOTE: As gauge studs are not interchangeable, it is recommended that the preparing laboratory confirm that the proposed gauge studs are compatible with the measuring laboratory’s equipment.

5.5 Len gth gaug e A lengt h gauge shall be provide d f or check ing the nominal length between gauge studs. The length gauge shall be made of metal and shall have a diameter of at least 6 mm and a length of 250 ± 0.2 mm. The ends of the bar shall be flat and perpendicular to its length. 5.6 Tamping bar (hand c omp action) The bar used for compa cting concret e in the moul ds shall be a straigh t metal recta ngular bar having nomina l dimensions of 25 mm × 10 mm × 300 mm long with a ramming face square with the axis. COPYRIGHT

AS 1012.13—1992


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DIMENSIONS IN MILLIMETRES

FIGURE 1 DETAIL S OF A TYPICA L MOULD

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AS 1012.13—1992

DIMENSIONS IN MILLIMETRES

FIGURE 2 GAUGE STU D DETAILS

5.7 Vib rato r The external vibrator used to compact concrete in the moulds shall be a table type with provision for clamping of the mould. Internal vibrators shall not be used. NOTE: A vibrat ing table with a nominal f requ ency of vibration of 50

Hz is usually suitable.

5.8 Mal let The mallet used in the moulding of specimens shall comply with the relevant requirements of AS 1012.4. . d e it ib h o r p k r o tw e n n o e s u r o n o ti u ib rt is d , e g a r to S . y l n o e c n e c li r e s u e l g in S . 2 0 0 2 n u J 4 0 n o H S E R U .S .S E to d e s n e c i L

5.9 Len gth com parat or 5.9.1 General The compa rator for meas uring length changes shall be capa ble of measuring the length of specimens over a range of 290 mm to 300 mm, with a precision of 0.001 mm. NOTES: 1 It is recomm ended that w here a horizon tal comparato r is used, microme ters be of the digi tal read-ou t type. 2 Details of a suitable ho rizont al comp arator are prov ided in Appe ndix A.

5.9.2 Check of precision The prec isio n of the leng th comparator and the perfor mance of the operator shall be chec ked by record ing the difference in l ength between the refer ence bar and a typical spe cimen 20 times, replacing e ach in the comparator for each read ing. The standard deviati on of t hese 20 length differen ces shall not exceed 0.002 mm. When a check of precision fails to meet this requirement, further checks shall be made with another specimen or with another operator, to ascertain whether the lack of precision is associated with the comparator or with the operator. 5.9.3 Reference bar A specific reference bar shall be used with eac h comparator and shall consist of a material char acteri zed by an extremel y low coefficie nt of thermal expa nsion, not less than 6 mm in diameter with an overall length of 295 ±1.5 mm. Each end shall be reduc ed in diameter and the end 5 mm shall be approximately the same diamet er and have the same end radius as the projecting end of the gauge stud being used in the specimen (see Clause 5.4). Each end of the reference bar shall be polished. The central section of the reference bar shall be covered by a rubber tube, or equivalent, of length approximatel y 100 mm and wall thickn ess of at least 3 mm to minimize the effect of temperature change during han dling . The referen ce bar shal l be provid ed with a positioning mark and shall always be placed in the comparator in the same orientation. 6 SAMPLIN G AND T EST SPECI MENS NOTE: Specim ens may be prepare d either in the labor atory or in the field. P articu lar care should be take n to ensu re sampling and preparation are strictly in accordance with this Clause (6) as these activities are crucial to the accuracy and repeatability of the test. Full r ecords should also be kept for inclu sion in the report (see Claus es 9 and 10).

6.1 Sam pling 6.1.1 Field sampling For conc rete sampled in the fiel d, the test sampl e shall be obta ined in accorda nce with AS 1012.1.

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AS 1012.13—1992

6.1.2 Laboratory sampling For concrete made in the laborato ry, the test sample shall be prepa red in accordance with AS 1012.2. 6.2 Pre para tion of test spec imens 6.2.1 General At least three specimen s shall be p repared f or each s ample of concrete. The nominal size of the aggregate in the concrete, in accordance with AS 2758.1, shall not exceed 40 mm. 6.2.2 Size and shape of standa rd test specimens The test spe cimen shall be a prism 75 mm mm and approximately 280 mm long. A stainless steel gauge stud shall be cast into each end of the specimen. The gauge studs shall be cast so that their principal axes coincide with the principal axis of the test specimen, and shall extend into the specimen approximately 15 mm.

×

75

6.2.3 Identification of specimens Each specimen shall be identified by the mould marking or by other means which will not adversely affect the concrete. Scratch markings shall not be used. NOTE: The use of permanent markings on the external face of the mould is recommended.

7 PRO CED URE 7.1 Mea surem ent of cons isten ce The procedure is as follows: (a) Measure slump and, if required, other consi stenc e, i n accordan ce with AS 1012. 3. (b) Record t he temp erature of the concrete at the time of mould

ing.

7.2 Mou lding s pecime ns 7.2.1 Moulding procedure


The appa ratus and the samp le are prepa red as follow s:

(a) Treat asse mbled drying shrink age mould s t o prev ent adhe sion of the conc rete by the use of a thin coating of mineral oil or other suitable release compound applied to the whole of the inside surfaces of each mould. (b) Prepa re the gaug e stud assem bly as follow s: (i)

Lubrica te the thr eading of the ga uge stud holder.

(ii)

Screw the ga uge stud int o the gau ge stud holde r, taking care tha t no mineral oil or othe r contami nant remain s on the surface of the gaug e stud which comes into contact with the concrete.

(iii) Using t he leng th gauge (see Claus e 5.5), set the effec tive gaug e length, i.e. the length between the innermost ends of the gauge studs, at 250 mm. (c) Take the sam ple of concrete as qu ickly as pos sible to the plac e selected for moulding the specimens. (d) After a minimum of mixing to offset any segr commence moulding without delay.

egatio n that h as occur red during transpo rtation ,

(e) Complete moulding withi n 30 min of the comp letion of obta ining the test sampl e. NOTE: This may not always be poss ible for conc rete sampled in the field. Whe re t his is the case , variations sho uld be noted in the report.

(f)

Using a scoop, place concrete in the mould in two approximately equal layers ens uring symmetrica l distribution of the conc rete within the mould.

(g) Compact the concrete by t amping or vibrating, as appropria te, as describe d in Claus e 7.2.2 or Clause 7.2.3 without causing segregation or excessive laitance. NOTE: The object is to achieve full compacti on. Compaction by tamping is not recom mended for concrete with a slump less than 40 mm, nor is vibration recommended for concrete with a slump greater than 100 mm.

7.2.2 Compaction by tamping follows:

The proced ure for the compa ction of specime ns by tampin g is as

(a) Compact each of t he two laye rs with the tamping bar, the tamping stroke s being distribut ed uniformly over the area of the specimen. Take care to avoid striking the gauge stud. (b) The numb er of tampi ng strokes per layer required to produ ce adequ ate compaction will vary according to the type o f concret e used. T he total numb er of t amping stroke s per laye r shall be not less than 35. (c) As the top layer of conc rete is being place d, ensure t hat the concr ete aroun d the gaug e st uds is adequately compacted. Take care not to loosen the gauge studs. (d) Close any hol es remaining in the surface of each layer by lightly tapping the sides o f the moul d with the mallet. (e) Slightl y overfill the top layer of the mould. After the top layer ha and smooth the surface of the concrete with a wooden float. COPYRIGHT

s been compacted, strike off

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7.2.3 Compaction by vibration follows:

AS 1012.13—1992

The proce dure f or the compa ction of specimen s by vibratio n is as

(a) Fill the moul ds i n two appr oxima tely equal layers. Rigid ly attach the mo uld to t he vibr ating table. (b) Vibrate each layer until the surface be comes relativ ely smo oth in app earance. Do not prolon g vibration beyond the point at which mortar commen ces to collect on the surface . (c) After the top laye r has been com pacted, stri ke off an d smooth the surfa ce of the concre te with a wooden float. 7.3 Curing of spec imens 7.3.1

Initial cur ing in mo ulds

7.3.1.1 General Immediately after the test specimen has be en moulded, place the mould containi ng the specimen in the initial curing environment and loosen the gauge stud holder retaining screws so as to prevent restraint of the gauge stud in case of shrinkage of the concrete during initial curing. 7.3.1.2 Initial curing under stand ard condition s Store the spec imens in a saturated conditio n (minimum 95% relative humidity), undisturbed in their moulds on a rigid horizontal surface in air at the following temperatures until demoulded: (a) Stand ard temp erate zone: 23 (b) Stand ard tropi cal zo ne: 27

±2° C.

±2 °C.

NOTES: 1 The sta ndard tempe rature zo nes refer red to above are as

specified in AS 1012. 8.

2 Saturated condit ions can be maintaine d either by moisture retaini ng covers appl ied to the moulds, or by placi ng specimens in a humidity controlled environment. . d e it ib h o r p k r o tw e n n o e s u r o n o ti u ib rt is d , e g a r to S . y l n o e c n e c li r e s u e l g in S . 2 0 0 2 n u J 4 0 n o H S E R U .S .S E to d e s n e c i L

7.3.1.3 Storage of spec imens in the field 18 h from moulding, as follows:

In the fi eld, store spe cimen s for a period of not less than

(a) In a cove red location adja cent to the mould ing site, preferably indoo rs and protected from wind and extremes of temperature. (b) Undisturb ed in their mou lds on a rigid hori zontal surfac e, with lids fitted so as to preven loss of moisture from the specimen. NOTE: The aim is to prov ide condi tions for test spec imen s which give a maximum of temperatu res and loss of moisture during thei r stor age in the field.

t the

protec tion from extr emes of

As soon as is pract icabl e after a pe riod of 7.3.1.4 Initial curing under non -standard conditions 18 h from moulding, transport specimens stored under non-standard conditions to the laboratory for demouldin g, such that they are placed under standard moist curing cond itio ns withi n 24 h of moulding. 7.3.2 Demoulding of specimen s 7.3.2.1 General Demould specimens w ithin 24 ±2 h from the time of moul ding. Where variations to this time period are necessary, standard moist curing cond itions shall be maintaine d during any additional curing period and full details shall be noted in the report. Minor damage to the gau ge studs may be repair ed, howev er the exte nt of this dam age and detai ls of any repairs carried out shall be noted and reported. Take extreme care to ensure that the gauge stud is not disturbed while the gauge stud holder is being unscrewed from the stud. NOTES: 1 Same grades of concr ete with specified compressive strength less t han 10 MPa at 28 days will need at least 48 h after moulding before demoulding to avoi d damage t o the spe cimens . 2 If the damage to the gauge studs is rest ricted to dislo dgment of one or both gauge studs, the studs may be carefully cemented in place by m eans of a suitable f ast-set ting cemen t, e.g. a catalyze d epoxy or polyeste r. It is, how ever, essential that the cement be allowed at least 24 h t o harden before initi al measurement .

7.3.2.2 Acceptance criteria Specimens may be rejected if there is evide nce of poor compaction or damage, e.g. cracks, loose studs. 7.3.2.3 Identification of specimens As it i s remo ved from its mould, mark eac h specim en with a suitable indelible marke r to show identificatio n. NOTE: Specim ens may also be marked at

this time for orientation (see Clause 7.4.2.2(b)).

7.3.3 Standard m oist cur ing Except where minor repa irs are necessary, place spe cimens in standard moist curing conditions (see Claus e 3.1) within 15 min of demouldi ng. Maintai n these con ditions until 7 days from moulding, subject to the altern ative requirements for tran sport set out in Clause 7.3.4. COPYRIGHT

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AS 1012.13—1992

Demoulded specimens may be transported from the preparing laboratory to the measuring laboratory (see Clau se 7.3. 4) during the standa rd moist curing perio d afte r a mini mum period of 24 h in standard moist curin g condition s in the preparing laborator y (see Claus e 7.3.1). Store all specimens in standard temperate moist curing conditions at the measuring laboratory for a minimum of 24 h prior to initial measurement. 7.3.4 Transport of specimens to the me asuring laboratory When spe cimen s are transp orted to a laboratory, they shall be carried in such a way that physical damage is avoided and loss of moisture and temperature extremes are prevented. The transpo rting ti me, i.e., the total time during which the specime curing conditions, shall not exceed 24 h. Specimens which arrive at rejected.

ns are not in standa rd moist

the meas uring laborato ry other than in a saturated cond ition may be

NOTE: Adequate protection may be obtained by wrapping the specimens with wet hessian or wet newspaper and packing in plastic bags within strong containers.

7.4 Drying and meas ureme nt of specim ens 7.4.1 General All drying and measu rement of speci mens shall be carried out in the dry ing room, with the temperature and relative humidity within the range specified in Clause 5.2. 7.4.2 Setting the l ength comparator Zero the microm eter of the length comparator with the reference bar suitably held in a position which is accurately aligned with the measuring anvil. 7.4.3 Initial measurements 7.4.3.1 Horizontal comparator comparato r is as follows: . d e it ib h o r p k r o tw e n n o e s u r o n o ti u ib rt is d , e g a r to S . y l n o e c n e c li r e s u e l g in S . 2 0 0 2 n u J 4 0 n o H S E R U .S .S E to d e s n e c i L

The procedu re for taking the initial meas urements with a horizont al

(a) At an age of 7 days fro m moulding, remove the specimens one at a time fro m the lime-saturated water and wipe the surface dry with a damp cloth. (b) Ensure that the ends of the gaug e studs are clean and po lishe d. (c) Immediate ly after wiping th e surface dry, plac e the spec imen in the comp arator so that its axis is aligned with the measuring anvil and its top surface, as cast, does not bear on the locating supports of the comparator. Record the micrometer reading (length difference) when the anvils are in contact with the specimen. (d) Remove the specimen and replac e it in the com parator in the same orien tation. Repeat taki ng replicate measureme nts until at least five consecutive determina tions have been made, all of which are within 0.001 mm of the average measurement. These readings shall be completed within 2 min of removing the specimen from the lime-saturated water. Record as the initial measurem ent the mean of these fi ve determinat ions. (e) Place the sp ecimen s on racks in the drying room so that there is a clear ance of at l east 50 mm on all sides, except for the necessary support. (f)

Using the referenc e bar, chec k the ze ro setting of the compa rator at appropriate time i nterva ls during measurement. Where the comparator is found to have varied by more than 0.002 mm, all readings taken since the previous reference bar check shall be repeated.

7.4.3.2 Vertical comparat or The proce dure for taking the initial measureme nts with a vert ical comparato r is as follows: (a) At an age of 7 days fro m moulding, rem ove the specimens one at a time fro m the lime-saturated water and wipe the surface dry with a damp cloth. (b) Mark each specime n to iden tify one end as the top. These marking s shall be made on one cast face of each specimen only, and the marked face shall be the front. (c) Before each spe cimen is measur ed, wipe both stud end s to remove any dust particles. Also wipe clean both the base anvil and the dial gauge anvil.

NOTE: If the specimen is incorrectly l ocated, the bottom concrete surface may bear on the base anvil. I f this occu rs the spec imen should be remov ed from the com parator, so that all dus t can be cleaned fr om the anvil befor e that specimen is measured.

(d) Immediate ly after wipin g the sur face dry, place each specimen in the comparato r by first positioni ng the bottom gaug e stud in the base anvil . Then ra ise the dial gauge anvi l, make the specimen vertical and lower the dial gauge anvil into position on the top gauge stud. (e) While ensu ring that the gauge is correctly seat ed, rotate t he spe cimen axially until the front face is parallel to the face of the dial gauge and facing the operator. Read the dial gauge and record the reading. NOTE: A light downward force applied to the dial gauge anvil or shaft together with rotation of the specimen can assist in correctly seating the dial gauge.

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AS 1012.13—1992

(f)

Remove the specimen and repl ace it in the compa rator in the same orien tation. Continue takin g replicate measurements until at least five consecutive determinations have been made, all of which are within 0.001 mm of the average measurement. These readings shall be completed within 2 min of removing the specimen from the lime-sa turated water. Record as the initial meas urement the mean of these five determinations. (g) Place the spec imens on racks in the drying room so that there is a clearance of at least 50 mm on all sides, except for the necessary support. (h) Using the referen ce bar, check the zero setting of the compara tor at appropria te time interval s during measurement. Where the comparator is found to have varied by more than 0.002 mm, all readings taken since the previous reference bar check shall be repeated. 7.4.4 Subsequent measurements The procedure for taking the subsequent measurements using either form of comparator is as follows: (a) Take the length me asurement for each specime n as set out in Clause 7.4.3.1(c) or Clau se 7.4.3.2(d) as appropriate after total periods of air drying of 7, 14, 21, 28 and 56 days, as required and any other specifically requested drying periods. A single measurement for each specimen (i.e. not an average of five or more) will normally be adequate. NOTE: With non-digital micrometers a second check-reading is recommended.

(b) Check the zero setting of the comparator as set out in Clause 7.4.3.1(f) or Clause 7.4.3.2(h), as appropriate. 8 CALCULATION AND EXPRESSION OF RESULTS The results are calculated and drying shrinkage is expressed as follows: NOTE: Calculations should be performed on the day of each measurement. . d e it ib h o r p k r o tw e n n o e s u r o n o ti u ib rt is d , e g a r to S . y l n o e c n e c li r e s u e l g in S . 2 0 0 2 n u J 4 0 n o H S E R U .S .S E to d e s n e c i L

(a) For each period o f drying time, subtract the length measu rement, in millimetres, at that time from the mean initial length measurement, in millimetres. (b) Divide the differenc e obtained from Item (a) by the srcinal effective gauge length, which shall be taken as 250 mm. (c) Express the result, drying shrinkage, in microstrain. (d) For each drying period for the one sample of concrete, calculate the average drying shrinkage of only the individual results which are within ±40 microstrain of the median value result. 9 PRECISION FOR LABORATORY-PREPARED SPECIMENS For a set of three specimens moulded in the laboratory from the same sample of concrete cured under identical conditions and with a nominal aggregate size (see AS 2758.1) not greater than 20 mm, the repea tability expressed as a percentage of the mean of the set of three specimens is 8% at the 95% probability level. Precision data are not available for field-moulded specimens or specimens prepared in a laboratory other than the measuring laboratory. NOTE: This sta tement on repeatabili ty is based on limited Austra lian data and may be amended when more data are collected.

10 RECORDS The following information concerning the specimens shall be recorded by the preparing laboratory or the measuring laboratory as appropriate: (a) (b) (c) (d) (e) (f) (g)

Identification of specimen. Date and tim e of moulding. Any deviation from the required time for moulding. Slump and, if required, ot her consistence determination of the concrete . Field or lab oratory sampled. Temperature of concrete immediately prior to moulding. Method of compaction.

(h) Initial curing history of specimen s, i.e. standard or non-stan dard including, if non-stand ard— (i) the maximum and minimum temperatures to which the specimens have been subjected; and (ii) the dates and times of despatch and receipt of transport ed specimens. (i) Date and time of demoulding. (j) Where applicable— (i) the moisture condition of the specimen when received at the measuring laboratory, i.e. saturated or not; (ii) damage resulting from transport or handling; (iii) any other damage; and (iv) details of any repairs or other remed ial measures carried out. COPYRIGHT

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AS 1012.13—1992

(k) Date of initial length measurements. (l)

Initial length readings of each specimen.

(m) Subsequent length reading for each specimen— (i)

date;

(ii)

duration of drying period;

(iii)

reading of lengt h comparator for s pecimen; and

(iv)

calculated drying shrinkage.

(n) Drying room temperature, humidity and evaporation rates. measuring laboratoryshall is not the preparing laborareport: tory, each laboratory shall 11 REP ORT Where prepare separate reportsthe which, when combined, constitute the complete (a) Part A — Preparing laboratory report (i)

Identification of specimen.

(ii)

Field or laboratory sampled.

(iii)

Date of moulding.

(iv)

Job site or laboratory where moulded.

(v)

Initial curing period— (A) standard; or (B) non-standard—include details of deviations from standard .


(vi)

Date of demoulding.

(vii)

Where applicable, any damage to the specim en and details of an y repairs carried out.

(viii) Date and time of despa tch. (ix)

Such other information contained in the records as may be requested.

(x)

The number of this Australian Standard, i.e. AS 1012.13.

(b) Part B —Measuring laboratory report (i) Identification of specimen. (ii)

Date and time of receipt.

(iii)

Where applicable, any damage to the specimen and details of any repairs carried out.

(iv)

Date of initial measurement.

(v)

Drying shrinkage for each specimen and th e average for each set , at each requ ired drying period, to the nearest 10 microstrain.

(vi)

Such other information contained in the records as may be requested.

(vii)

The number of this Australian Standard, i.e. AS 1012.13.

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APPENDIX A

A SUITABLE HORIZONTAL LENGTH COMPARATOR (Informative) A1 GENERAL The comparator for measuring length changes should be capable of measuring the length of specimens over a range of 290 mm to 300 mm, with a precision of 0.001 mm. It should consist of a frame for supporting the specimen during measurement, in such a way that no weight is carried by the gauge studs and a measuring device, e.g. a micrometer with an accuracy of 0.001 mm. This Appendix sets out recommendations for a comparator which holds the specimen in a horizontal position and uses a micrometer for measurement (see Figure A1). A2 COMPARATOR FRAME The frame should be capable of supporting the specimen horizontally and of locating it in a reproducible position parallel to the axis of the frame and perpendicular to the measuring anvils, which should contact the gauge studs as near as possible to the centres of the anvils. The frame should be rigid enough to prevent distortion during normal handling of the specimen, so that the micrometer reading is not affected by touching the specimen during measurement. The diameters of the measuring anvils should be between 6 mm and 10 mm. The surfaces of the anvils should be made of tungsten carbide, and shoul d be flat. One anvil should be fixed in relatio n to the frame, and should be attached to a pedestal comply ing with the requirements for rigidity. The other anvil should be attached to, or be part of the shaft of the microm eter which shoul d be firmly attached to a simila r pedestal. The orientation of the pedestals relative to the base of the frame should be adjustable so as to bring the anvils into the correct measuring position.


The anvils at all times during use should be parallel to each other, and perpendicular to the axis of the frame. The distanc es between hori zontally opposite point s on the two anvils should not vary by more than 0.001 mm from the distance measured between the centre points of the anvils. A3 MICROMETER The micrometer s hould be digitally indicating in units of 0.001 mm or less, and accurate to within 0.001 mm in any 0.10 mm range with a total travel of at least 10 mm. It should be equipped with a zeroing device to enable the length of the reference bar to be set at zero. The shaft of the micrometer should be spring loaded, and should be accurately aligned with the axis of the frame, with the anvil face perpendicular to the shaft. The orientation of the anvil should not be affected by movement of the shaft along its axis. In use, the shaft of the micrometer will be retracted during loading of the specimen into the frame, one gauge stud of the specimen then being brought into contact with the fixed anvil before the shaft is gently released, allowing it to contact the other gauge stud.

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. d te i ib h ro p k r o w t e n n o e s u r o n o it u b rit s i d , e g ra o t S . y l n o e c n e ilc r e s u le g in S . 2 0 0 2 n u J 4 0 n o H S E R U S . S . E to d e s n e ic L

NOTE: Adjustment of screw A results in movement in direction A, as is the case with B, C and D. FIGURE A1 HORIZON TAL LENGTH COMPARA TOR

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This Australian Standard was prepared by Committee BD/42, Methods of Testing Concrete. I t was approve d on behalf of the Counc il of Standards Australia on 10 Dece mber 1991 and publish ed on 15 May 199 2.


Review of A ustral ian Sta ndards. To keep abreast of progre ss in industry, Aust ralian St andards are subject to periodic rev iew and are kept up to date by the i ssue of amend ments or new editions as neces sary. It is important t herefore t hat Stan dards users ensure that they are in poss ession of the latest edition, and any amendments thereto. Full details of all Austral ian Standards and related publica tions will be found in the Stand ards Australia Catalogue of Publications ; this informat ion is supp lemented each month by the maga zine ‘The Australian Standard’, which subsc ribing members receive, and which gives detai ls of new publications, new editions and amendments, and of withdrawn Standards. Suggestions for improvemen ts to Australian Standards , addressed to the head office of Standard s Australia, are welcomed . Notification of any inaccuracy or ambigu ity found in an Austr alian Standard should be made without delay in order that the matter may be investigated and appropriate action taken .

First publ ished as AS 1012.13— 1970. Second edition 1992. Incorporating: Amdt 1—1993.

This Standard was issued in draft f orm for commen t as DR 90126 . Copyright STANDARDS AUSTRAL IA Users of Standa rds are reminded that copyr ight subsists in all Standar ds Australia publi cations and software. Excep t where the Copyright Act allows and except where provided for below no publications or software produce d by Standa rds Australia may be repro duced, stor ed in a retrieva l syste m in any form or transm itted by any means without prior permiss ion in writing from Standards Australia. Permission may be conditional on an appropriate royalty payment. Requests for permission and information on commercial software royalties should be directed t o the hea d office of Stand ards A ustralia. Standards Australia will perm it up to 10 percent of the tec hnic al content pages of a Standa rd to be copied for use exclusively in-house by purchaser s of the Standard without payment of a royalty or advice t o Standa rds Australia. Standards Australia will also permit the inclusion of its copyright material in computer software programs for no royalty payment provided such programs are used excl usively in-house by the creators of the programs. Care should be taken to ensur e that mater ial used is from the cur rent edition of the Stan dard and t hat it is updated when ever the Standa rd is amend ed or revised. The numbe r and date of the Standard should t herefore be cl early i dentified. The use of material in print form or in computer software programs to be used commercially, with or without payment, or in commercial contracts is subject to the payment of a royalty. This policy may be varied by Standards Australia at any time.

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