ASTM C900-2012 Standard Test Method for Pullout Strength of Hardened Concrete《硬化混凝土拔拉强度的标准测试方法》.pdf

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1、Designation: C900 06 C900 12Standard Test Method forPullout Strength of Hardened Concrete1This standard is issued under the fixed designation C900; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number

2、 in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers determination of the pullout strength of hardened concrete by measuring the force required to pullan embedded metal

3、insert and the attached concrete fragment from a concrete test specimen or structure. The insert is either castinto fresh concrete or installed in hardened concrete. This test method does not provide statistical procedures to estimate otherstrength properties.1.2 The values stated in SI units are to

4、 be regarded as the standard.1.3 The text of this test method references notes and footnotes which provide explanatory material. These notes and footnotes(excluding those in tables and figures) shall not be considered as requirements of this test method.1.4 This standard does not purport to address

5、all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. (WARNINGFresh hydraulic cementitious mixtures are caustic and

6、may cause chemical burns to skinand tissue upon prolonged exposure.)22. Referenced Documents2.1 ASTM Standards:3C670 Practice for Preparing Precision and Bias Statements for Test Methods for Construction MaterialsE4 Practices for Force Verification of Testing MachinesE74 Practice of Calibration of F

7、orce-Measuring Instruments for Verifying the Force Indication of Testing Machines3. Summary of Test Method3.1 A metal insert is either cast into fresh concrete or installed into hardened concrete. When an estimate of the in-place strengthis desired, the insert is pulled by means of a jack reacting a

8、gainst a bearing ring. The pullout strength is determined by measuringthe maximum force required to pull the insert from the concrete mass. Alternatively, the insert is loaded to a specified load to verifywhether a minimum level of in-place strength has been attained.4. Significance and Use4.1 For a

9、 given concrete and a given test apparatus, pullout strengths can be related to compressive strength test results. Suchstrength relationships depend on are affected by the configuration of the embedded insert, bearing ring dimensions, depth ofembedment, and level of strength development in that conc

10、rete. Prior to use, thesethe type of aggregate (lightweight or normalweight). Before use, the relationships must be established for each test system and each new combination of concreting materials.Such relationships tend to be less variable where concrete mixture. Such relationships are more reliab

11、le if both pullout testspecimens and compressive strength test specimens are of similar size, compactedconsolidated to similar density, and cured undersimilar conditions.NOTE 1Published reports (1-17)4 by different researchers present their experiences in the use of pullout test equipment. Refer to

12、ACI 228.1R (14)for guidance on establishing a strength relationship and interpreting test results. The Appendix provides a means for comparing pullout strengths obtainedusing different configurations.1 This test method is under the jurisdiction of ASTM Committee C09 on Concrete and Concrete Aggregat

13、esand is the direct responsibility of Subcommittee C09.64 onNondestructive and In-Place Testing.Current edition approved Dec. 15, 2006Nov. 1, 2012. Published January 2007December 2012. Originally approved in 1978. Last previous edition approved in 20012006as C900 01.C900 06. DOI: 10.1520/C0900-06.10

14、.1520/C0900-12.2 Section on Safety Precautions, Manual of Aggregate and Concrete Testing, Annual Book of ASTM Standards, Vol. 04.02.3 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume info

15、rmation, refer to the standards Document Summary page on the ASTM website.4 The boldface numbers refer to the list of references at the end of this test method.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been m

16、ade to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A

17、 Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.2 Pullout tests are used to determine whether the in-place strength of concrete has reached a specified level so that, fo

18、rexample:(1) post-tensioning may proceed;(2) forms and shores may be removed; or(3) structure may be placed into service; or(4) winter protection and curing may be terminated.In addition, post-installed pullout tests may be used to estimate the strength of concrete in existing constructions.4.3 When

19、 planning pullout tests and analyzing test results, consideration should be given to the normally expected decrease ofconcrete strength with increasing height within a given concrete placement in a structural element.4.4 When planning pullout tests and analyzing test results, consideration should be

20、 given to the normally expected decrease ofconcrete strength with increasing height within a given concrete placement in a structural element. The measured pullout strengthis indicative of the strength of concrete within the region represented by the conic frustum defined by the insert head and bear

21、ingring. For typical surface installations, pullout strengths are indicative of the quality of the outer zone of concrete members and canbe of benefit in evaluating the cover zone of reinforced concrete members.4.5 Cast-in-place inserts require that their locations in the structure be planned in adv

22、ance of concrete placement. Post-installedinserts can be placed at any desired location in the structure provided the requirements of 6.1 are satisfied.4.6 This test method is not applicable to other types of post-installed tests that, if tested to failure, do not involve the same failuremechanism a

23、nd do not produce the same conic frustum as for the cast-in-place test described in this test method (16).5. Apparatus5.1 The apparatus requires three basic sub-systems: a pullout insert, a loading system, and a load-measuring system (Note 2).For post-installed inserts, additional equipment includes

24、 a core drill, a grinding wheel to prepare a flat bearing surface, a millingtool to undercut a groove to engage the insert, and an expansion tool to expand the insert into the groove.NOTE 2A center-pull hydraulic jack with a pressure gauge calibrated that has been standardized according to Annex A1

25、and a bearing ring have beenused satisfactorily.5.1.1 Cast-in-place inserts shall be made of metal that does not react with cement. The insert shall consist of a cylindrical headand a shaft to fix embedment depth. The shaft shall be attached firmly to the center of the head (see Fig. 1). The insert

26、shaft shallbe threaded to the insert head so that it can be removed and replaced by a stronger shaft to pullout the insert, or it shall be anintegral part of the insert and also function as the pullout shaft. Metal components of cast-in-place inserts and attachment hardwareFIG. 1 Schematic Cross Sec

27、tion of Cast-in-Place Pullout TestC900 122shall be of similar material to prevent galvanic corrosion. Post-installed inserts shall be designed so that they will fit into the drilledholes, and can be expanded subsequently to fit into the grooves that are undercut at a predetermined depth (see Fig. 2)

28、.NOTE 3A successful post-installed system uses a split ring that is coiled to fit into the core hole and then expanded into the groove.5.1.2 The loading system shall consist of a bearing ring to be placed against the hardened concrete surface (see Figs. 1 and 2)and a loading apparatus with the neces

29、sary load-measuring devices that can be readily attached to the pullout shaft.5.1.3 The test apparatus shall include centering features to ensure that the bearing ring is concentric with the insert, and thatthe applied load is axial to the pullout shaft, perpendicular to the bearing ring, and unifor

30、m on the bearing ring.5.2 Equipment dimensions shall be determined as follows (see Fig. 1):5.2.1 The diameter of the insert head (d2) is the basis for defining the test geometry. The thickness of the insert head and theyield strength of the metal shall be sufficient to prevent yielding of the insert

31、 during test. The sides of the insert head shall besmooth (see Note 5). The insert head diameter shall be greater than or equal to 23 of the nominal maximum size of aggregate.NOTE 4Typical insert diameters are 25 and 30 mm, but larger diameters have been used (1, 3). Tests (15) have shown that nomin

32、al maximumaggregate sizes up to 1.5 times the head diameter do not have significant effects on the strength relationships. Larger aggregate sizes may result inincreased scatter of the test results because the large particles can interfere with normal pullout of the conic frustum.NOTE 5Cast-inplace i

33、nserts may be coated with a release agent to minimize bonding with the concrete, and they may be tapered to minimize sidefriction during testing. The insert head should be provided with the means, such as a notch, to prevent rotation in the concrete if the insert shaft has tobe removed prior to perf

34、orming the test. As a further precaution against rotation of the insert head, all threaded hardware should be checked prior toFIG. 2 Schematic of Procedure for Post-Installed Pullout TestC900 123installation to ensure that it is free-turning and can be easily removed. A thread-lock compound is recom

35、mended to prevent loosening of the insert headfrom the shaft during installation and during vibration of the surrounding concrete.5.2.2 For cast-inplace inserts, the length of the pullout insert shaft shall be such that the distance from the insert head to theconcrete surface (h) equals the diameter

36、 of the insert head (d2). The diameter of the insert shaft at the head (d1) shall not exceed0.60 d2.5.2.3 For post-installed inserts, the groove to accept the expandable insert shall be cut so that the distance between the bearingsurface of the groove and concrete surface equals the insert diameter

37、after expansion (d2). The difference between the diametersof the undercut groove (d2) and the core hole (d1) shall be sufficient to prevent localized failure and ensure that a conic frustumof concrete is extracted during the test (see Note 6). The expanded insert shall bear uniformly on the entire b

38、earing area of thegroove.NOTE 6A core hole diameter of 18 mm and an undercut groove diameter of 25 mm have been used successfully.5.2.4 The bearing ring shall have an inside diameter (d3) of 2.0 to 2.4 times the insert head diameter (d2), and shall have anoutside diameter (d4) of at least 1.25 times

39、 the inside diameter. The thickness of the ring (t) shall be at least 0.4 times the pulloutinsert head diameter.5.2.5 Tolerances for dimensions of the pullout test inserts, bearing ring and embedment depth shall be 62 % within a givensystem.NOTE 7The limits for dimensions and configurations for pull

40、out test inserts and apparatus are intended to accommodate various systems.5.2.6 The loading apparatus shall have sufficient capacity to provide the loading rate prescribed in 7.4 and exceed the maximumload expected.NOTE 8Hydraulic pumps that permit continuous loading may give more uniform test resu

41、lts than pumps that apply load intermittently.5.2.7 The gauge to measure the pullout force shall have a least division not larger than 5 % of the minimum value in the intendedrange of use.5.2.8 The force gauge shall have a maximum value indicator that preserves the value of the maximum load during t

42、esting.5.2.9 Pullout apparatus shall be calibratedstandardized in accordance with Annex A1 at least once a year and after all repairs.CalibrateStandardize the pullout apparatus using a testing machine verified in accordance with Practices E4 or using a Class A loadcell as defined in Practice E74. Th

43、e indicated pullout force based on the calibrationdeveloped relationship shall be within 62 %of the force measured by the testing machine or load cell.6. Sampling6.1 Pullout test locations shall be separated so that the clear spacing between inserts is at least seven times the pullout inserthead dia

44、meter. Clear spacing between the inserts and the edges of the concrete shall be at least 3.5 times the head diameter. Insertsshall be placed so that reinforcement is outside the expected conical failure surface by more than one bar diameter, or the maximumsize of aggregate, whichever is greater.NOTE

45、 9A reinforcement locator is recommended to assist in avoiding reinforcement when planning the locations of post-installed tests. Follow themanufacturers instructions for proper operation of such devices.6.2 When pullout test results are used to assess the in-place strength in order to allow the sta

46、rt of critical construction operations,such as formwork removal or application of post tensioning, at least five individual pullout tests shall be performed as follows:6.2.1 For a given placement, every 115 m3, or a fraction thereof, or6.2.2 For slabs or walls, every 470 m2 , or a fraction thereof,

47、of the surface area of one face.NOTE 10More than the minimum number of inserts should be provided in case a test result is not valid or testing begins before adequate strengthhas developed.6.2.3 Inserts shall be located in those portions of the structure that are critical in terms of exposure condit

48、ions and structuralrequirements.6.3 When pullout tests are used for other purposes, the number of tests shall be determined by the specifier.7. Procedure7.1 Cast-in-Place Inserts:7.1.1 Attach the pullout inserts to the forms using bolts or by other acceptable methods that firmly secure the insert in

49、 its properlocation prior to concrete placement. All inserts shall be embedded to the same depth. The axis of each shaft shall be perpendicularto the formed surface.7.1.2 Alternatively, when instructed by the specifier of tests, manually place inserts into unformed horizontal concrete surfaces.The inserts shall be embedded into the fresh concrete by means that ensure a uniform embedment depth and a plane surfaceperpendicular to the axis of the insert shaft. Installation of inserts shall be performed or supervised by personnel trained by themanufacturer or manufa