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

1、Designation: C900 12aStandard 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 in par

2、entheses 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 pulloutstrength of hardened concrete by measuring the force requiredto pull an embedded metal insert a

3、nd the attached concretefragment from a concrete test specimen or structure. The insertis either cast into fresh concrete or installed in hardenedconcrete. This test method does not provide statistical proce-dures to estimate other strength properties.1.2 The values stated in SI units are to be rega

4、rded as thestandard.1.3 The text of this test method references notes andfootnotes which provide explanatory material. These notes andfootnotes (excluding those in tables and figures) shall not beconsidered as requirements of this test method.1.4 This standard does not purport to address all of thes

5、afety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. (WARNINGFresh hydraulic cementitious mixtures are caustic and maycause

6、chemical burns to skin and tissue upon prolongedexposure.)22. Referenced Documents2.1 ASTM Standards:3C670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsE4 Practices for Force Verification of Testing MachinesE74 Practice of Calibration of Force-Measur

7、ing Instrumentsfor Verifying the Force Indication of Testing Machines3. Summary of Test Method3.1 A metal insert is either cast into fresh concrete orinstalled into hardened concrete. When an estimate of thein-place strength is desired, the insert is pulled by means of ajack reacting against a beari

8、ng ring. The pullout strength isdetermined by measuring the maximum force required to pullthe insert from the concrete mass. Alternatively, the insert isloaded to a specified load to verify whether a minimum level ofin-place strength has been attained.4. Significance and Use4.1 For a given concrete

9、and a given test apparatus, pulloutstrengths can be related to compressive strength test results.Such strength relationships are affected by the configuration ofthe embedded insert, bearing ring dimensions, depth ofembedment, and the type of aggregate (lightweight or normalweight). Before use, the r

10、elationships must be established foreach test system and each new concrete mixture. Such rela-tionships are more reliable if both pullout test specimens andcompressive strength test specimens are of similar size, con-solidated to similar density, and cured under similar conditions.NOTE 1Published re

11、ports (1-17)4by different researchers present theirexperiences in the use of pullout test equipment. Refer toACI 228.1R (14)for guidance on establishing a strength relationship and interpreting testresults. The Appendix provides a means for comparing pullout strengthsobtained using different configu

12、rations.4.2 Pullout tests are used to determine whether the in-placestrength of concrete has reached a specified level so that, forexample:(1) post-tensioning may proceed;(2) forms and shores may be removed;(3) structure may be placed into service; or(4) winter protection and curing may be terminate

13、d.In addition, post-installed pullout tests may be used toestimate the strength of concrete in existing constructions.4.3 When planning pullout tests and analyzing test results,consideration should be given to the normally expected de-crease of concrete strength with increasing height within agiven

14、concrete placement in a structural element.1This test method is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregatesand is the direct responsibility of SubcommitteeC09.64 on Nondestructive and In-Place Testing.Current edition approved Dec. 15, 2012. Published January 2013.

15、 Originallyapproved in 1978. Last previous edition approved in 2012 as C900 12. DOI:10.1520/C0900-12a.2Section on Safety Precautions, Manual of Aggregate and Concrete Testing,Annual Book of ASTM Standards, Vol. 04.02.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact AST

16、M Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4The boldface numbers refer to the list of references at the end of this testmethod.*A Summary of Changes section appears at the end of this sta

17、ndardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.4 The measured pullout strength is indicative of thestrength of concrete within the region represented by the conicfrustum defined by the insert head and bearing ring. For typical

18、surface installations, pullout strengths are indicative of thequality of the outer zone of concrete members and can be ofbenefit in evaluating the cover zone of reinforced concretemembers.4.5 Cast-in-place inserts require that their locations in thestructure be planned in advance of concrete placeme

19、nt. Post-installed inserts can be placed at any desired location in thestructure provided the requirements of 6.1 are satisfied.4.6 This test method is not applicable to other types ofpost-installed tests that, if tested to failure, do not involve thesame failure mechanism and do not produce the sam

20、e conicfrustum as for the cast-in-place test described in this testmethod (16).5. Apparatus5.1 The apparatus requires three basic sub-systems: a pull-out insert, a loading system, and a load-measuring system(Note 2). For post-installed inserts, additional equipmentincludes a core drill, a planing to

21、ol to prepare a flat bearingsurface, a grinding tool to undercut a groove to engage theinsert, and an expansion tool to expand the insert into thegroove.NOTE 2A center-pull hydraulic jack with a pressure gauge that hasbeen standardized according to AnnexA1 and that reacts against a bearingring has b

22、een used satisfactorily.5.1.1 Cast-in-place inserts shall be made of metal that doesnot react with the constituents of the concrete. The insert shallconsist of a cylindrical head and a shaft to fix embedmentdepth. The shaft shall be attached firmly to the center of thehead (see Fig. 1). The insert s

23、haft shall be threaded to the inserthead so that it can be removed and replaced by a stronger shaftto pullout the insert, or it shall be an integral part of the insertand also function as the pullout shaft. Metal components ofcast-in-place inserts and attachment hardware shall be ofsimilar material

24、to prevent galvanic corrosion. Post-installedinserts shall be designed so that they will fit into the drilledholes, and can be expanded subsequently to fit into the groovesthat are undercut at a predetermined depth (see Fig. 2).NOTE 3A successful post-installed system uses a split ring that iscoiled

25、 to fit into the core hole and then expanded into the groove.5.1.2 The loading system shall consist of a bearing ring tobe placed against the hardened concrete surface (see Figs. 1and 2) and a tensile loading apparatus, with a load-measuringdevice that can be attached to the pullout shaft.5.1.3 The

26、test apparatus shall include centering features toensure that the bearing ring is concentric with the insert, andthat the applied load is axial to the pullout shaft, perpendicularto the bearing ring, and uniform on the bearing ring.5.2 Equipment dimensions shall be determined as follows(see Fig. 1):

27、5.2.1 The diameter of the insert head (d2) is the basis fordefining the test geometry. The thickness of the insert head andthe yield strength of the metal shall be sufficient to preventyielding of the insert during test. The sides of the insert headshall be smooth (see Note 5). The insert head diame

28、ter shall beat least23 of the nominal maximum size of aggregate.NOTE 4Typical insert diameters are 25 and 30 mm, but largerdiameters have been used (1, 3). Tests (15) have shown that nominalmaximum aggregate sizes up to 1.5 times the head diameter do not haveFIG. 1 Schematic Cross Section of Cast-in

29、-Place Pullout TestC900 12a2significant effects on the strength relationships. Larger aggregate sizesmay result in increased scatter of the test results because the large particlescan interfere with normal pullout of the conic frustum.NOTE 5Cast-inplace inserts may be coated with a release agent tom

30、inimize bonding with the concrete, and they may be tapered to minimizeside friction during testing. The insert head should be provided with themeans, such as a notch, to prevent rotation in the concrete if the insertshaft has to be removed prior to performing the test. As a furtherprecaution against

31、 rotation of the insert head, all threaded hardware shouldbe checked prior to installation to ensure that it is free-turning and can beeasily removed. A thread-lock compound is recommended to preventloosening of the insert head from the shaft during installation and duringvibration of the surroundin

32、g concrete.5.2.2 For cast-inplace inserts, the distance from the inserthead to the concrete surface (h) shall equal the diameter of theinsert head (d2).The diameter of the insert shaft at the head (d1)shall not exceed 0.60 d2.5.2.3 For post-installed inserts, the groove to accept theexpandable inser

33、t shall be cut so that the distance between thebearing surface of the groove and concrete surface equals theinsert diameter after expansion (d2). The difference betweenthe diameters of the undercut groove (d2) and the core hole (d1)shall be sufficient to prevent localized failure and ensure that aco

34、nic frustum of concrete is extracted during the test (see Note6). The expanded insert shall bear uniformly on the entirebearing area of the groove.NOTE 6A core hole diameter of 18 mm and an undercut groovediameter of 25 mm have been used successfully.5.2.4 The bearing ring shall have an inside diame

35、ter (d3)of2.0 to 2.4 times the insert head diameter (d2), and shall have anoutside diameter (d4) of at least 1.25 times the inside diameter.The thickness of the ring (t) shall be at least 0.4 times thepullout insert head diameter. For a given test system, the samebearing ring dimensions shall be use

36、d.5.2.5 Tolerances for dimensions of the pullout test inserts,bearing ring and embedment depth shall be 62 % within agiven system.NOTE 7The limits for dimensions and configurations for pullout testinserts and apparatus are intended to accommodate various systems.FIG. 2 Schematic of Procedure for Pos

37、t-Installed Pullout TestC900 12a35.2.6 The loading apparatus shall have sufficient capacity toprovide the loading rate prescribed in 7.4.NOTE 8Hydraulic pumps that permit continuous loading may givemore uniform test results than pumps that apply load intermittently.5.2.7 The gauge to measure pullout

38、 force is permitted to beof the analog or digital type. Analog gauges shall be designedso that the pullout force can be estimated to the nearest 0.5 kN.Digital gauges shall display the pullout force to the nearest 0.1kN.5.2.8 The force gauge shall have a means to preserve themaximum value of the loa

39、d during a test.5.2.9 Pullout apparatus shall be standardized in accordancewith Annex A1 at least once a year and after all repairs.Standardize the pullout apparatus using a testing machineverified in accordance with Practices E4 or using a ClassAloadcell as defined in Practice E74. The indicated pu

40、llout forcebased on the developed relationship shall be within 62%ofthe force measured by the testing machine or load cell.6. Sampling6.1 Pullout test locations shall be separated so that the clearspacing between inserts is at least seven times the pullout inserthead diameter. Clear spacing between

41、the inserts and the edgesof the concrete shall be at least 3.5 times the head diameter.Inserts shall be placed so that reinforcement is outside theexpected conical failure surface by more than one bar diameter,or the maximum size of aggregate, whichever is greater.NOTE 9A reinforcement locator is re

42、commended to assist in avoidingreinforcement when planning the locations of post-installed tests. Followthe manufacturers instructions for proper operation of such devices.6.2 When pullout test results are used to assess the in-placestrength in order to allow the start of critical constructionoperat

43、ions, such as formwork removal or application of posttensioning, at least five individual pullout tests shall beperformed as follows:6.2.1 For a given placement, every 115 m3, or a fractionthereof, or6.2.2 For slabs or walls, every 470 m2, or a fraction thereof,of the surface area of one face.NOTE 1

44、0More than the minimum number of inserts should beprovided in case a test result is not valid or testing begins before adequatestrength has developed.6.2.3 Inserts shall be located in those portions of thestructure that are critical in terms of exposure conditions andstructural requirements.6.3 When

45、 pullout tests are used for other purposes, thenumber 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 orby other acceptable methods that firmly secure the insert in itsproper location prior to concrete plac

46、ement.All inserts shall beembedded to the same depth. The axis of each shaft shall beperpendicular to the formed surface.7.1.2 Alternatively, when instructed by the specifier of tests,manually place inserts into unformed horizontal concretesurfaces. The inserts shall be embedded into the fresh concr

47、eteby means that ensure a uniform embedment depth and a planesurface perpendicular to the axis of the insert shaft. Installationof inserts shall be performed or supervised by personnel trainedby the manufacturer or manufacturers representative.NOTE 11Experience indicates that pullout strengths are o

48、f lower valueand more variable for manually-placed surface inserts than for insertsattached to formwork (12).7.1.3 When pullout strength of the concrete is to bemeasured, remove all hardware used for securing the pulloutinserts in position. Before mounting the loading system,remove any debris or sur

49、face abnormalities to ensure a flatbearing surface that is perpendicular to the axis of the insert.7.2 Post-Installed Inserts:7.2.1 The selected test surface shall be flat to provide asuitable working surface for drilling the core and undercuttingthe groove. Drill a core hole perpendicular to the surface toprovide a reference point for subsequent operations and toaccommodate the expandable insert and associated hardware.The use of an impact drill is not permitted.7.2.2 If necessary, use a grinding wheel to prepare a flatsurface so that the base of the milling tool