ASTM C39/C39M-16 Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens PDF

Designation: C39/C39M − 16 Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens1 This standard is issued under the fixed designation C39/C39M; the number immediately following the designation indicates the year of...

Designation: C39/C39M − 16 Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens1 This standard is issued under the fixed designation C39/C39M; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the U.S. Department of Defense. 1. Scope* C192/C192M Practice for Making and Curing Concrete Test 1.1 This test method covers determination of compressive Specimens in the Laboratory strength of cylindrical concrete specimens such as molded C617/C617M Practice for Capping Cylindrical Concrete cylinders and drilled cores. It is limited to concrete having a Specimens density in excess of 800 kg/m3 [50 lb/ft3]. C670 Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials 1.2 The values stated in either SI units or inch-pound units C873/C873M Test Method for Compressive Strength of are to be regarded separately as standard. The inch-pound units Concrete Cylinders Cast in Place in Cylindrical Molds are shown in brackets. The values stated in each system may C1077 Practice for Agencies Testing Concrete and Concrete not be exact equivalents; therefore, each system shall be used Aggregates for Use in Construction and Criteria for independently of the other. Combining values from the two Testing Agency Evaluation systems may result in non-conformance with the standard. C1231/C1231M Practice for Use of Unbonded Caps in 1.3 This standard does not purport to address all of the Determination of Compressive Strength of Hardened Cy- safety concerns, if any, associated with its use. It is the lindrical Concrete Specimens responsibility of the user of this standard to establish appro- E4 Practices for Force Verification of Testing Machines priate safety and health practices and determine the applica- E74 Practice of Calibration of Force-Measuring Instruments bility of regulatory limitations prior to use. (Warning—Means for Verifying the Force Indication of Testing Machines should be provided to contain concrete fragments during Manual of Aggregate and Concrete Testing sudden rupture of specimens. Tendency for sudden rupture increases with increasing concrete strength and it is more likely 3. Summary of Test Method when the testing machine is relatively flexible. The safety precautions given in the Manual of Aggregate and Concrete 3.1 This test method consists of applying a compressive Testing are recommended.) axial load to molded cylinders or cores at a rate which is within 1.4 The text of this standard references notes which provide a prescribed range until failure occurs. The compressive explanatory material. These notes shall not be considered as strength of the specimen is calculated by dividing the maxi- requirements of the standard. mum load attained during the test by the cross-sectional area of the specimen. 2. Referenced Documents 2.1 ASTM Standards:2 4. Significance and Use C31/C31M Practice for Making and Curing Concrete Test 4.1 Care must be exercised in the interpretation of the Specimens in the Field significance of compressive strength determinations by this test C42/C42M Test Method for Obtaining and Testing Drilled method since strength is not a fundamental or intrinsic property Cores and Sawed Beams of Concrete of concrete made from given materials. Values obtained will depend on the size and shape of the specimen, batching, mixing 1 procedures, the methods of sampling, molding, and fabrication This test method is under the jurisdiction of ASTM Committee C09 on Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee and the age, temperature, and moisture conditions during C09.61 on Testing for Strength. curing. Current edition approved March 1, 2016. Published April 2016. Originally approved in 1921. Last previous edition approved in 2015 as C39/C39M – 15a. 4.2 This test method is used to determine compressive DOI: 10.1520/C0039_C0039M-16. 2 strength of cylindrical specimens prepared and cured in accor- For referenced ASTM standards, visit the ASTM website, www.astm.org, or dance with Practices C31/C31M, C192/C192M, C617/C617M, contact ASTM Customer Service at [email protected]. For Annual Book of ASTM Standards volume information, refer to the standard’s Document Summary page on and C1231/C1231M and Test Methods C42/C42M and C873/ the ASTM website. C873M. *A Summary of Changes section appears at the end of this standard Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States Copyright by ASTM Int'l (all rights reserved); Wed Jun 8 09:22:40 EDT 2016 1 Downloaded/printed by Universite Laval (Universite Laval) pursuant to License Agreement. No further reproductions authorized.  C39/C39M − 16 4.3 The results of this test method are used as a basis for 5.1.3.3 The test load as indicated by the testing machine and quality control of concrete proportioning, mixing, and placing the applied load computed from the readings of the verification operations; determination of compliance with specifications; device shall be recorded at each test point. Calculate the error, control for evaluating effectiveness of admixtures; and similar E, and the percentage of error, Ep, for each point from these uses. data as follows: 4.4 The individual who tests concrete cylinders for accep- E5A2B (1) tance testing shall meet the concrete laboratory technician requirements of Practice C1077, including an examination E p 5 100~ A 2 B ! /B requiring performance demonstration that is evaluated by an where: independent examiner. A = load, kN [lbf] indicated by the machine being verified, NOTE 1—Certification equivalent to the minimum guidelines for ACI and Concrete Laboratory Technician, Level I or ACI Concrete Strength B = applied load, kN [lbf] as determined by the calibrating Testing Technician will satisfy this requirement. device. 5. Apparatus 5.1.3.4 The report on the verification of a testing machine shall state within what loading range it was found to conform 5.1 Testing Machine—The testing machine shall be of a type to specification requirements rather than reporting a blanket having sufficient capacity and capable of providing the rates of acceptance or rejection. In no case shall the loading range be loading prescribed in 7.5. stated as including loads below the value which is 100 times 5.1.1 Verify the accuracy of the testing machine in accor- the smallest change of load estimable on the load-indicating dance with Practices E4, except that the verified loading range mechanism of the testing machine or loads within that portion shall be as required in 5.3. Verification is required: of the range below 10 % of the maximum range capacity. 5.1.1.1 Within 13 months of the last calibration, 5.1.3.5 In no case shall the loading range be stated as 5.1.1.2 On original installation or immediately after including loads outside the range of loads applied during the relocation, verification test. 5.1.1.3 Immediately after making repairs or adjustments 5.1.3.6 The indicated load of a testing machine shall not be that affect the operation of the force applying system or the corrected either by calculation or by the use of a calibration values displayed on the load indicating system, except for zero diagram to obtain values within the required permissible adjustments that compensate for the mass of bearing blocks or variation. specimen, or both, or 5.1.1.4 Whenever there is reason to suspect the accuracy of 5.2 The testing machine shall be equipped with two steel the indicated loads. bearing blocks with hardened faces (Note 3), one of which is a 5.1.2 Design—The design of the machine must include the spherically seated block that will bear on the upper surface of following features: the specimen, and the other a solid block on which the 5.1.2.1 The machine must be power operated and must specimen shall rest. Bearing faces of the blocks shall have a apply the load continuously rather than intermittently, and minimum dimension at least 3 % greater than the diameter of without shock. If it has only one loading rate (meeting the the specimen to be tested. Except for the concentric circles requirements of 7.5), it must be provided with a supplemental described below, the bearing faces shall not depart from a plane means for loading at a rate suitable for verification. This by more than 0.02 mm [0.001 in.] in any 150 mm [6 in.] of supplemental means of loading may be power or hand oper- blocks 150 mm [6 in.] in diameter or larger, or by more than ated. 0.02 mm [0.001 in.] in the diameter of any smaller block; and 5.1.2.2 The space provided for test specimens shall be large new blocks shall be manufactured within one half of this enough to accommodate, in a readable position, an elastic tolerance. When the diameter of the bearing face of the calibration device which is of sufficient capacity to cover the spherically seated block exceeds the diameter of the specimen potential loading range of the testing machine and which by more than 13 mm [0.5 in.], concentric circles not more than complies with the requirements of Practice E74. 0.8 mm [0.03 in.] deep and not more than 1 mm [0.04 in.] wide shall be inscribed to facilitate proper centering. NOTE 2—The types of elastic calibration devices most generally available and most commonly used for this purpose are the circular NOTE 3—It is desirable that the bearing faces of blocks used for proving ring or load cell. compression testing of concrete have a Rockwell hardness of not less than 5.1.3 Accuracy—The accuracy of the testing machine shall 55 HRC. be in accordance with the following provisions: 5.2.1 Bottom bearing blocks shall conform to the following 5.1.3.1 The percentage of error for the loads within the requirements: proposed range of use of the testing machine shall not exceed 5.2.1.1 The bottom bearing block is specified for the pur- 61.0 % of the indicated load. pose of providing a readily machinable surface for mainte- 5.1.3.2 The accuracy of the testing machine shall be verified nance of the specified surface conditions (Note 4). The top and by applying five test loads in four approximately equal bottom surfaces shall be parallel to each other. If the testing increments in ascending order. The difference between any two machine is so designed that the platen itself is readily main- successive test loads shall not exceed one third of the differ- tained in the specified surface condition, a bottom block is not ence between the maximum and minimum test loads. required. Its least horizontal dimension shall be at least 3 % Copyright by ASTM Int'l (all rights reserved); Wed Jun 8 09:22:40 EDT 2016 2 Downloaded/printed by Universite Laval (Universite Laval) pursuant to License Agreement. No further reproductions authorized.  C39/C39M − 16 greater than the diameter of the specimen to be tested. Concentric circles as described in 5.2 are optional on the bottom block. NOTE 4—The block may be fastened to the platen of the testing machine. 5.2.1.2 Final centering must be made with reference to the upper spherical block. When the lower bearing block is used to assist in centering the specimen, the center of the concentric rings, when provided, or the center of the block itself must be directly below the center of the spherical head. Provision shall be made on the platen of the machine to assure such a position. 5.2.1.3 The bottom bearing block shall be at least 25 mm [1 in.] thick when new, and at least 22.5 mm [0.9 in.] thick after any resurfacing operations. 5.2.2 The spherically seated bearing block shall conform to the following requirements: 5.2.2.1 The maximum diameter of the bearing face of the NOTE 1—Provision shall be made for holding the ball in the socket and for holding the entire unit in the testing machine. suspended spherically seated block shall not exceed the values FIG. 1 Schematic Sketch of a Typical Spherical Bearing Block given below: Diameter of Maximum Diameter Test Specimens, of Bearing Face, mm [in.] mm [in.] radius of the specimen. The least dimension of the bearing face shall be at least as great as the diameter of the sphere (see Fig. 50 105 75 130 1). 100 165 [6.5] 5.2.2.6 The movable portion of the bearing block shall be 150 255 held closely in the spherical seat, but the design shall be such 200 280 that the bearing face can be rotated freely and tilted at least 4° NOTE 5—Square bearing faces are permissible, provided the diameter of in any direction. the largest possible inscribed circle does not exceed the above diameter. 5.2.2.7 If the ball portion of the upper bearing block is a 5.2.2.2 The center of the sphere shall coincide with the two-piece design composed of a spherical portion and a surface of the bearing face within a tolerance of 65 % of the bearing plate, a mechanical means shall be provided to ensure radius of the sphere. The diameter of the sphere shall be at least that the spherical portion is fixed and centered on the bearing 75 % of the diameter of the specimen to be tested. plate. 5.2.2.3 The ball and the socket shall be designed so that the 5.3 Load Indication: steel in the contact area does not permanently deform when 5.3.1 If the load of a compression machine used in concrete loaded to the capacity of the testing machine. testing is registered on a dial, the dial shall be provided with a graduated scale that is readable to at least the nearest 0.1 % of NOTE 6—The preferred contact area is in the form of a ring (described the full scale load (Note 8). The dial shall be readable within as “preferred bearing area”) as shown on Fig. 1. 1 % of the indicated load at any given load level within the 5.2.2.4 At least every six months, or as specified by the loading range. In no case shall the loading range of a dial be manufacturer of the testing machine, clean and lubricate the considered to include loads below the value that is 100 times curved surfaces of the socket and of the spherical portion of the the smallest change of load that can be read on the scale. The machine. The lubricant shall be a petroleum-type oil such as scale shall be provided with a graduation line equal to zero and conventional motor oil or as specified by the manufacturer of so numbered. The dial pointer shall be of sufficient length to the testing machine. reach the graduation marks; the width of the end of the pointer shall not exceed the clear distance between the smallest NOTE 7—To ensure uniform seating, the spherically seated head is designed to tilt freely as it comes into contact with the top of the specimen. graduations. Each dial shall be equipped with a zero adjust- After contact, further rotation is undesirable. Friction between the socket ment located outside the dialcase and easily accessible from the and the spherical portion of the head provides restraint against further front of the machine while observing the zero mark and dial rotation during loading. Petroleum-type oil such as conventional motor oil pointer. Each dial shall be equipped with a suitable device that has been shown to permit the necessary friction to develop. Pressure-type at all times, until reset, will indicate to within 1 % accuracy the greases can reduce the desired friction and permit undesired rotation of the spherical head and should not be used unless recommended by the maximum load applied to the specimen. manufacturer of the testing machine. NOTE 8—Readability is considered to be 0.5 mm [0.02 in.] along the arc 5.2.2.5 If the radius of the sphere is smaller than the radius described by the end of the pointer. Also, one half of a scale interval is readable with reasonable certainty when the spacing on the load indicating of the largest specimen to be tested, the portion of the bearing mechanism is between 1 mm [0.04 in.] and 2 mm [0.06 in.]. When the face extending beyond the sphere shall have a thickness not spacing is between 2 and 3 mm [0.06 and 0.12 in.], one third of a scale less than the difference between the radius of the sphere and interval is readable with reasonable certainty. When the spacing is 3 mm Copyright by ASTM Int'l (all rights reserved); Wed Jun 8 09:22:40 EDT 2016 3 Downloaded/printed by Universite Laval (Universite Laval) pursuant to License Agreement. No further reproductions authorized.  C39/C39M − 16 [0.12 in.] or more, one fourth of a scale interval is readable with specimen to the nearest 1 mm [0.05 in.] at three locations reasonable certainty. spaced evenly around the circumference. Compute the average 5.3.2 If the testing machine load is indicated in digital form, length and record to the nearest 1 mm [0.05 in.]. Alternatively, the numerical display must be large enough to be easily read. determine the cylinder density by weighing the cylinder in air The numerical increment must be equal to or less than 0.10 % and then submerged under water at 23.0 6 2.0 °C [73.5 6 3.5 of the full scale load of a given loading range. In no case shall °F], and computing the volume according to 8.3.1. the verified loading range include loads less than the minimum 6.5 When density determination is not required and the numerical increment multiplied by 100. The accuracy of the length to diameter ratio is less than 1.8 or more than 2.2, indicated load must be within 1.0 % for any value displayed measure the length of the specimen to the nearest 0.05 D. within the verified loading range. Provision must be made for adjusting to indicate true zero at zero load. There shall be 7. Procedure provided a maximum load indicator that at all times until reset 7.1 Compression tests of moist-cured specimens shall be will indicate within 1 % system accuracy the maximum load made as soon as practicable after removal from moist storage. applied to the specimen. 7.2 Test specimens shall be kept moist by any convenient 5.4 Documentation of the calibration and maintenance of method during the period between removal from moist storage the testing machine shall be in accordance with Practice and testing. They shall be tested in the moist condition. C1077. 7.3 All test specimens for a given test age shall be broken 6. Specimens within the permissible time tolerances prescribed as follows: Test Age Permissible Tolerance 6.1 Specimens shall not be tested if any individual diameter of a cylinder differs from any other diameter of the same 24 h ±0.5 h or 2.1 % cylinder by more than 2 %. 3 days ±2 h or 2.8 % 7 days ±6 h or 3.6 % NOTE 9—This may occur when single use molds are damaged or 28 days ±20 h or 3.0 % deformed during shipment, when flexible single use molds are deformed 90 days ±2 days or 2.2 % during molding, or when a core drill deflects or shifts during drilling. 7.4 Placing the Specimen—Place the plain (lower) bearing 6.2 Prior to testing, neither end of test specimens shall block, with its hardened face up, on the table or platen of the depart from perpendicularity to the axis by more than 0.5° testing machine directly under the spherically seated (upper) (approximately equivalent to 1 mm in 100 mm [0.12 in. in 12 bearing block. Wipe clean the bearing faces of the upper and in.]). The ends of compression test specimens that are not plane lower bearing blocks and of the test specimen and place the test within 0.050 mm [0.002 in.] shall be sawed or ground to meet specimen on the lower bearing block. If using unbonded caps, that tolerance, or capped in accordance with either Practice wipe clean the bearing surfaces of the retaining ring or rings C617/C617M or, when permitted, Practice C1231/C1231M. and center the unbonded cap or caps on the cylinder. Carefully The diameter used for calculating the cross-sectional area of align the axis of the specimen with the center of thrust of the the test specimen shall be determined to the nearest 0.25 mm spherically seated block. [0.01 in.] by averaging two diameters measured at right angles 7.4.1 Zero Verification and Block Seating—Prior to testing to each other at about midheight of the specimen. the specimen, verify that the load indicator is set to zero. In 6.3 The number of individual cylinders measured for deter- cases where the indicator is not properly set to zero, adjust the mination of average diameter is not prohibited from being indicator (Note 10). After placing the specimen in the machine reduced to one for each ten specimens or three specimens per but prior to applying the load on the specimen, tilt the movable day, whichever is greater, if all cylinders are known to have portion of the spherically seated block gently by hand so that been made from a single lot of reusable or single-use molds the bearing face appears to be parallel to the top of the test which consistently produce specimens with average diameters specimen. within a range of 0.5 mm [0.02 in.]. When the average NOTE 10—The technique used to verify and adjust load indicator to zero diameters do not fall within the range of 0.5 mm [0.02 in.] or will vary depending on the machine manufacturer. Consult your owner’s when the cylinders are not made from a single lot of molds, manual or compression machine calibrator for the proper technique. each cylinder tested must be measured and the value used in 7.4.2 Verification of Alignment When Using Unbonded calculation of the unit compressive strength of that specimen. Caps—If using unbonded caps, verify the alignment of the When the diameters are measured at the reduced frequency, the specimen after application of load, but before reaching 10 % of cross-sectional areas of all cylinders tested on that day shall be the anticipated specimen strength. Check to see that the axis of computed from the average of the diameters of the three or the cylinder does not depart from vertical by more than 0.5° more cylinders representing the group tested that day. (Note 11) and that the ends of the cylinder are centered within 6.4 If the purchaser of the testing services or the specifier of the retaining rings. If the cylinder alignment does not meet the tests requests measurement of density of test specimens, these requirements, release the load, and carefully recenter the determine the mass of specimens before capping. Remove any specimen. Reapply load and recheck specimen centering and surface moisture with a towel and measure the mass of the alignment. A pause in load application to check cylinder specimen using a balance or scale that is accurate to within alignment is permissible. 0.3 % of the mass being measured. Measure the length of the NOTE 11—An angle of 0.5° is equal to a slope of approximately 1 mm Copyright by ASTM Int'l (all rights reserved); Wed Jun 8 09:22:40 EDT 2016 4 Downloaded/printed by Universite Laval (Universite Laval) pursuant to License Agreement. No further reproductions authorized.  C39/C39M − 16 in 100 mm [1⁄8 inches in 12 inches] automatic shut-off of the testing machine is prohibited until the 7.5 Rate of Loading—Apply the load continuously and load has dropped to a value that is less than 95 % of the peak without shock. load. When testing with unbonded caps, a corner fracture 7.5.1 The load shall be applied at a rate of movement (platen similar to a Type 5 or 6 pattern shown in Fig. 2 may occur to crosshead measurement) corresponding to a stress rate on before the ultimate capacity of the specimen has been attained. the specimen of 0.25 6 0.05 MPa/s [35 6 7 psi/s] (see Note Continue compressing the specimen until the user is certain 12). The designated rate of movement shall be maintained at that the ultimate capacity has been attained. Record the least during the latter half of the anticipated loading phase. maximum load carried by the specimen during the test, and NOTE 12—For a screw-driven or displacement-controlled testing note the type of fracture pattern according to Fig. 2. If the machine, preliminary testing will be necessary to establish the required fracture pattern is not one of the typical patterns shown in Fig. rate of movement to achieve the specified stress rate. The required rate of 2, sketch and describe briefly the fracture pattern. If the movement will depend on the size of the test specimen, the elastic modulus of the concrete, and the stiffness of the testing machine. measured strength is lower than expected, examine the frac- tured concrete and note the presence of large air voids, 7.5.2 During application of the first half of the anticipated evidence of segregation, whether fractures pass predominantly loading phase, a higher rate of loading shall be permitted. The around or through the coarse aggregate particles, and verify higher loading rate shall be applied in a controlled manner so end preparations were in accordance with Practice C617/ that the specimen is not subjected to shock loading. 7.5.3 Make no adjustment in the rate of movement (platen to C617M or Practice C1231/C1231M. crosshead) as the ultimate load is being approached and the stress rate decreases due to cracking in the specimen. 8. Calculation 7.6 Apply the compressive load until the load indicator 8.1 Calculate the compressive strength of the specimen by shows that the load is decreasing steadily and the specimen dividing the maximum load resisted by the specimen during the displays a well-defined fracture pattern (Types 1 to 4 in Fig. 2). test by the average cross-sectional area determined as de- For a testing machine equipped with a specimen break detector, scribed in Section 6. FIG. 2 Schematic of Typical Fracture Patterns Copyright by ASTM Int'l (all rights reserved); Wed Jun 8 09:22:40 EDT 2016 5 Downloaded/printed by Universite Laval (Universite Laval) pursuant to License Agreement. No further reproductions authorized.  C39/C39M − 16 8.2 If the specimen length to diameter ratio is 1.75 or less, 9.1.10 When determined, the density to the nearest 10 correct the result obtained in 8.1 by multiplying by the kg/m3 [1 lb/ft3]. appropriate correction factor shown in the following table Note 13: 10. Precision and Bias L/D: 1.75 1.50 1.25 1.00 10.1 Precision Factor: 0.98 0.96 0.93 0.87 10.1.1 Single-Operator Precision—The following table pro- Use interpolation to determine correction factors for L/D vides the single-operator precision of tests of 150 by 300 mm values between those given in the table. [6 by 12 in.] and 100 by 200 mm [4 by 8 in.] cylinders made NOTE 13—Correction factors depend on various conditions such as from a well-mixed sample of concrete under laboratory con- moisture condition, strength level, and elastic modulus. Average values are ditions and under field conditions (see 10.1.2). given in the table. These correction factors apply to low-density concrete Coefficient of Acceptable Range4 of weighing between 1600 and 1920 kg/m3 [100 and 120 lb/ft3] and to Variation4 Individual Cylinder Strengths normal-density concrete. They are applicable to concrete dry or soaked at 2 cylinders 3 cylinders the time of loading and for nominal concrete strengths from 14 to 42 MPa 150 by 300 mm [2000 to 6000 psi]. For strengths higher than 42 MPa [6000 psi] correction [6 by 12 in.] factors may be larger than the values listed above3. Laboratory conditions 2.4 % 6.6 % 7.8 % Field conditions 2.9 % 8.0 % 9.5 % 8.3 When required, calculate the density of the specimen to 100 by 200 mm the nearest 10 kg/m3 [1 lb/ft3] as follows: [4 by 8 in.] Laboratory conditions 3.2 % 9.0 % 10.6 % W 10.1.2 The single-operator coefficient of variation repre- Density 5 (2) V sents the expected variation of measured strength of compan- where: ion cylinders prepared from the same sample of concrete and W = mass of specimen, kg [lb], and tested by one laboratory at the same age. The values given for V = volume of specimen computed from the average diam- the single-operator coefficient of variation of 150 by 300 mm eter and average length or from weighing the cylinder in [6 by 12 in.] cylinders are applicable for compressive strengths air and submerged, m3 [ft3]. between 2000 and 15 to 55 MPa [8000 psi] and those for 100 by 200 mm [4 by 8 in.] cylinders are applicable for compres- 8.3.1 When the volume is determined from submerged sive strengths between 17 to 32 MPa [2500 and 4700 psi]. The weighing, calculate the volume as follows: single-operator coefficients of variation for 150 by 300 mm [6 W 2 Ws by 12 in.] cylinders are derived from CCRL concrete profi- V5 (3) γw ciency sample data for laboratory conditions and a collection of 1265 test reports from 225 commercial testing laboratories in where: 1978.5 The single-operator coefficient of variation of 100 by Ws = apparent mass of submerged specimen, kg [lb], and 200 mm [4 by 8 in.] cylinders are derived from CCRL concrete γw = density of water at 23 °C [73.5 °F] = 997.5 kg/m3 proficiency sample data for laboratory conditions. [62.27 lbs ⁄ft3]. 10.1.3 Multilaboratory Precision—The multi-laboratory co- efficient of variation for compressive strength test results of 9. Report 150 by 300 mm [6 by 12 in.] cylinders has been found to be 9.1 Report the following information: 5.0 %4; therefore, the results of properly conducted tests by 9.1.1 Identification number, two laboratories on specimens prepared from the same sample 9.1.2 Average measured diameter (and measured length, if of concrete are not expected to differ by more than 14 %4 of the outside the range of 1.8 D to 2.2 D), in millimetres [inches], average (see Note 14). A strength test result is the average of 9.1.3 Cross-sectional area, in square millimetres [square two cylinders tested at the same age. inches], NOTE 14—The multilaboratory precision does not include variations 9.1.4 Maximum load, in kilonewtons [pounds-force], associated with different operators preparing test specimens from split or 9.1.5 Compressive strength rounded to the nearest 0.1 MPa independent samples of concrete. These variations are expected to [10 psi], increase the multilaboratory coefficient of variation. 9.1.6 When the average of two or more companion cylin- 10.1.4 The multilaboratory data were obtained from six ders tested at the same age is reported, calculate the average separate organized strength testing round robin programs compressive strength using the unrounded individual compres- where 150 by 300 mm [6 by 12 in.] cylindrical specimens were sive strength values. Report the average compressive-strength prepared at a single location and tested by different laborato- rounded to the nearest 0.1 MPa [10 psi]. ries. The range of average strength from these programs was 9.1.7 Type of fracture (see Fig. 2), 17.0 to 90 MPa [2500 to 13 000 psi]. 9.1.8 Defects in either specimen or caps, and, NOTE 15—Subcommittee C09.61 will continue to examine recent 9.1.9 Age of specimen. 4 These numbers represent respectively the (1s %) and (d2s %) limits as described in Practice C670. 3 5 Bartlett, F.M. and MacGregor, J.G., “Effect of Core Length-to-Diameter Ratio Supporting data have been filed at ASTM International Headquarters and may on Concrete Core Strength,”ACI Materials Journal, Vol 91, No. 4, July-August, be obtained by requesting Research Report RR:C09-1006. Contact ASTM Customer 1994, pp. 339–348. Service at [email protected]. Copyright by ASTM Int'l (all rights reserved); Wed Jun 8 09:22:40 EDT 2016 6 Downloaded/printed by Universite Laval (Universite Laval) pursuant to License Agreement. No further reproductions authorized.  C39/C39M − 16 concrete proficiency sample data and field test data and make revisions to 11. Keywords precisions statements when data indicate that they can be extended to cover a wider range of strengths and specimen sizes. 11.1 concrete core; concrete cylinder; concrete specimen; 10.2 Bias—Since there is no accepted reference material, no concrete strength; compressive strength; core; cylinder; drilled statement on bias is being made. core; strength SUMMARY OF CHANGES Committee C09 has identified the location of selected changes to this standard since the last issue (C39/C39M – 15a) that may impact the use of this standard. (Approved March 1, 2016.) (1) Revised 6.4. (2) Revised 10.1.1 and 10.1.2. ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, at the address shown below. This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States. 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