1、Designation: C1604/C1604M 05 (Reapproved 2012)Standard Test Method forObtaining and Testing Drilled Cores of Shotcrete1This standard is issued under the fixed designation C1604/C1604M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision
2、, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers obtaining, preparing, and test-ing cores drilled from shotcrete for length, comp
3、ressivestrength, or splitting tensile strength determinations.1.2 The values stated in either inch-pound units or SI unitsshall be regarded separately as standard. SI units are shown inbrackets. The values stated in each system may not be exactequivalents; therefore, each system must be used indepen
4、-dently of the other. Combining values from the two systemsmay result in nonconformance with the standard.1.3 The text of this standard references notes and footnotesthat provide explanatory material. These notes and footnotes(excluding those in tables and figures) shall not be consideredas requirem
5、ents of the standard.1.4 This standard does not purport to address the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2. Re
6、ferenced Documents2.1 ASTM Standards:2C39/C39M Test Method for Compressive Strength of Cy-lindrical Concrete SpecimensC42/C42M Test Method for Obtaining and Testing DrilledCores and Sawed Beams of ConcreteC125 Terminology Relating to Concrete and Concrete Ag-gregatesC174/C174M Test Method for Measur
7、ing Thickness ofConcrete Elements Using Drilled Concrete CoresC496/C496M Test Method for Splitting Tensile Strength ofCylindrical Concrete SpecimensC617 Practice for Capping Cylindrical Concrete SpecimensC670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction Mater
8、ialsC823 Practice for Examination and Sampling of HardenedConcrete in ConstructionsC1140 Practice for Preparing and Testing Specimens fromShotcrete Test PanelsC1231/C1231M Practice for Use of Unbonded Caps inDetermination of Compressive Strength of Hardened Con-crete Cylinders2.2 ACI Standards:3318
9、Building Code Requirements for Structural Concrete506.2 Specification for Shotcreting506.4R Guide for the Evaluation of Shotcrete3. Terminology3.1 For definitions of terms used in this standard, refer toTerminology C125.4. Significance and Use4.1 This test method provides standardized procedures for
10、obtaining cored specimens to determine the compressivestrength and splitting tensile strength of shotcrete duringpre-construction, during construction, and from older shotcretestructures.4.2 Generally, test specimens are obtained in situ whendoubt exists about the in-place shotcrete quality due eith
11、er tolow strength test results during construction or signs of distressin the structure. Other uses of this method are to providespecimens for acceptance testing, construction control and toassess the condition, quality and uniformity of the shotcrete inaccordance with Practice C823 (see Note 1).4.3
12、 Specimens obtained by this method are used to verifythe thickness of shotcrete and aid in the visual assessment ofthe shotcrete quality, workmanship, defects, shotcrete-to-substrate bond and the condition of any reinforcement used inthe shotcrete4.4.4 Shotcrete strength is affected by the location
13、of theshotcrete in a structure. Vertical, sub-horizontal and overheadelements of the shotcrete structure may show variability. Corestrength is affected by core orientation relative to direction ofshotcrete application. These factors shall be considered in1This test method is under the jurisdiction o
14、fASTM CommitteeC09 on Concreteand Concrete Aggregates and is the direct responsibility of Subcommittee C09.46Shotcrete.Current edition approved April 1, 2012. Published November 2012. Originallyapproved in 2005. Last previous edition approved in 2005 as C1604/C1604M05.DOI: 10.1520/C1604_C1604M-05R12
15、.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American Concrete Institute, P.O. Box 9094,
16、Farmington Hills,MI 483334Bartlett, F.M. and MacGregor, J.G., “Effect of Core Diameter on ConcreteCore Strengths,” ACI Materials Journal, Vol. 91, No. 5, September-October 1994,pp. 460-470.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United Sta
17、tes.planning the locations for obtaining shotcrete samples and ininterpreting strength test results.4.5 Shotcrete is applied in single or multiple layers, as plainshotcrete, reinforced shotcrete, or fiber-reinforced shotcrete.Core samples containing wire-mesh and reinforcing bars shallnot be used fo
18、r compressive strength testing.4.6 The strength of shotcrete is affected by moisture content,the specified moisture conditioning procedure for cores isintended to provide test specimens with reproducible moisturecontents that minimize within-laboratory and between-laboratory variations.4.7 Sample ac
19、quisition may require a combination of core-drilling, sawing, and grinding that may have the potential toadversely affect the sample condition if care is not taken duringsampling and testing.4.8 A sampling plan shall be established that indicates thenumber of samples and their locations (see Note 1)
20、. Theacceptance criteria for shotcrete core strengths shall be estab-lished by the specifier of tests (see Note 2).NOTE 1Practice C823 provides guidance on the development of asampling plan for concrete in constructions. A number of methods thatsupplement the examination of hardened shotcrete by mea
21、ns of represen-tative core samples and testing are discussed in ACI 506.4R.NOTE 2The core strength acceptance criteria cited in ACI 318 arebased on a comparison of molded cylinder specimens and cores. Shotcretestrengths are always based on core specimens, therefore the 85 % factorused in core to cyl
22、inder comparisons is not relevant to the evaluation ofshotcrete core strengths. A typical shotcrete specification reflecting stan-dard industry practice is contained in ACI 506.2.5. Apparatus5.1 Core Drill, for obtaining cylindrical core specimenswith diamond impregnated bits attached to a core barr
23、el. Thecore drill shall have a rigid mounting base and be capable ofbeing operated in any orientation normal to the shotcretestructure that is being sampled. The core drill shall be free fromexcessive vibration when in operation and shall have sufficienttorque and consistent rotational speed to sust
24、ain uniform ratesof penetration of the core drill. The core barrel shall be cooledand core cuttings flushed with water during operation.5.2 Saw, for cutting core specimens to size for compressivestrength. The saw shall have a diamond or silicon carbidecutting edge and shall be capable of cutting pla
25、in and rein-forced specimens in a single pass that conform with theprescribed dimensions, without excessive heating or shock.5.3 Grinding wheel, to trim and clean plain and fiber-reinforced shotcrete specimens that conform to prescribedtolerances without significantly disturbing the aggregates, ma-t
26、rix or fiber-reinforcement.6. Sampling6.1 General:6.1.1 Sampling shall be planned in accordance with theapplicable provisions of Practice C823. The number ofsamples, sample locations and sampling procedures shall beestablished in the plan.6.1.2 Shotcrete samples obtained from test panels shall be in
27、accordance with the applicable provisions of Practice C1140.6.1.3 Samples of hardened shotcrete for use in the prepara-tion of strength test specimens shall not be taken until theshotcrete is strong enough to permit sample removal withoutdisturbing the bond between the mortar, coarse aggregate (seeN
28、ote 3) and fiber-reinforcement. When preparing strength testspecimens from samples of hardened shotcrete, samples thathave been damaged in the process of removal shall not be used.Specimens of defective shotcrete that cannot be tested shall bereported as such if the defects are representative of the
29、 in-placecondition of the shotcrete (see ACI 506.4R).NOTE 3It is not possible to specify a minimum age when shotcrete isstrong enough to withstand damage during removal, because the strengthat any age depends on the strength grade and curing of the shotcrete. Ifaccelerating admixtures are used durin
30、g shotcrete application, core speci-mens may be obtained for testing at approximately 6 h. If this is notpractical, removal of shotcrete can proceed if cored or cut surfaces do notdisplay erosion of the mortar and the exposed coarse aggregate particlesare embedded firmly in the mortar. Nondestructiv
31、e test methods may beused to estimate level of in-place strength development prior to attemptingremoval of shotcrete core samples (see ACI 506.4R).6.1.4 Specimens containing embedded reinforcement shallnot be used for determining compressive or splitting tensilestrength.6.2 Core DrillingDrill core s
32、pecimens perpendicular tothe surface and avoid drilling near formed joints or edgeplacement. Record the approximate angle between the drilledcore axis and the plane of the shotcrete as placed.7. Measuring the Length of Drilled Cores7.1 Cores for determining the thickness of shotcrete layersor other
33、structural elements shall have a diameter of at least 3.0in 75 mm when the lengths of such cores are to be measuredin accordance with Test Method C174/C174M.7.2 For cores that are not intended for determining structuraldimensions, measure the longest and shortest lengths on the cutsurface along line
34、s parallel to the core axis. Record the averagelength to the nearest14 in. 5 mm.8. Cores for Compressive Strength8.1 DiameterThe diameter of core specimens for thedetermination of compressive strength in load bearing struc-tural members shall be at least 3.0 in. 75 mm (see Note 4).Core diameters les
35、s than 3.0 in. 75 mm shall be permitted asdirected by the specifier of the tests.NOTE 4The compressive strengths of 2-in 50-mm diameter coresare known to be somewhat lower and more variable than those of 3-in.75-mm diameter cores. In addition, smaller diameter cores appear to bemore sensitive to the
36、 effect of the length-diameter ratio4.8.2 LengthThe preferred length of the capped or groundspecimen is nominally two times the diameter.8.2.1 If the ratio of the length to the diameter (L/D) of thecore exceeds 2.1, reduce the length of the core so that the ratioof the capped or ground specimen is b
37、etween 1.9 and 2.1. Corespecimens with length-diameter ratios equal to or less than1.75 require corrections to the measured compressive strength(see. 8.8.1). A strength correction factor is not required for L/Dgreater than 1.75. A core having a length of less than 95 % ofits diameter before capping
38、or a length less than its diameterafter capping or end grinding shall not be tested unless sodirected by the specifyer of the tests.C1604/C1604M 05 (2012)28.2.2 For non-load bearing structural members or when it isimpossible to obtain shotcrete cores with length-diameter ratio(L/D) greater than or e
39、qual to 1.0, core specimens shall besubject to the approval of the specifier of the tests.8.3 Moisture ConditioningThe following procedure isintended to preserve the moisture of the drilled core and toprovide a reproducible moisture condition that minimizes theeffects of moisture gradients introduce
40、d by wetting duringdrilling and specimen preparation.8.3.1 The following procedure is used to obtain coreshaving a moisture condition that is representative of thein-place shotcrete. After cores have been drilled, wipe offsurface water on the drilled core with a dry cloth and allowremaining surface
41、moisture to evaporate. When surfaces ap-pear dry, but not later than 1 h after drilling, place cores inseparate plastic bags or nonabsorbent containers and seal toprevent moisture loss. Maintain cores at ambient temperature,and protect cores from exposure to direct sunlight. Transportthe cores to th
42、e testing laboratory as soon as practicable. Keepcores in the sealed plastic bags or nonabsorbent containers atall times except during end preparation and for a maximumtime of2htopermit capping before testing.8.3.2 If water is used during sawing or grinding of coreends, complete these operations as
43、soon as practicable, but nolater than 2 days after drilling of cores. After completing endpreparation, use a dry cloth to remove surface moisture, allowthe surfaces to dry, and place the cores in sealed plastic bags ornonabsorbent containers. Minimize the duration of exposure towater during end prep
44、aration.8.3.3 Allow cores aged 28 days or more to remain in thesealed plastic bags or nonabsorbent containers for at least 5days after last being wetted and before testing (See Note 5).For early strength testing of specimens aged 28 days or less,test specimens as directed by the specifier of the tes
45、ts.NOTE 5The waiting period of at least 5 days is intended to reducemoisture gradients introduced when the core is drilled or wetted duringsawing or grinding.8.3.4 When the specifier of the tests so directs, test cores ina moisture condition other than achieved by conditioningaccording to 8.3.3. Rep
46、ort the alternative moisture condition-ing procedure.8.4 Sawing of EndsThe ends of core specimens to betested in compression shall be flat, and perpendicular to thelongitudinal axis. If necessary, saw the ends of cores that willbe capped so that the following requirements are met:8.4.1 Projections,
47、if any, shall not extend more than 0.2 in.5 mm above the end surfaces.8.4.2 The end surfaces shall not depart from perpendicular-ity to the longitudinal axis by a slope of more than 1:8d or1:0.3d, where d is the average core diameter in inches ormm.NOTE 6This limitation is intended to avoid cap thic
48、knesses thatexceed the requirements of Practice C617.8.5 CappingIf the ends of the cores do not conform to theperpendicularity and planeness requirements of Test MethodC39/C39M, they shall be sawn or ground to meet thoserequirements or capped in accordance with Practice C617.Ifcores are capped in ac
49、cordance with Practice C617, thecapping device shall accommodate actual core diameters andproduce caps that are concentric with the core ends. Measurecore lengths to the nearest 0.1 in. 2 mm before capping.Unbonded caps in accordance with Practice C1231/C1231Mare not permitted.NOTE 7Before capping, the density of a core may be estimated byweighing it and dividing the mass by the volume calculated from theaverage diameter and length.8.6 MeasurementBefore testing, measure the length of thecapped or ground specimen to the nearest 0.1 in. 2 mm anduse
