1、Designation: C 1604/C 1604M 05Standard Test Method forObtaining and Testing Drilled Cores of Shotcrete1This standard is issued under the fixed designation C 1604/C 1604M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision, the year of
2、last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon (e) 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, compressivestreng
3、th, 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-dently of th
4、e 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 requirements of the s
5、tandard.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. Referenced Docu
6、ments2.1 ASTM Standards:2C 39/C 39M Test Method for Compressive Strength of Cy-lindrical Concrete SpecimensC 42/C 42M Test Method for Obtaining and Testing DrilledCores and Sawed Beams of ConcreteC 125 Terminology Relating to Concrete and ConcreteAggregatesC 174/C 174M Test Method for Measuring Thic
7、kness ofConcrete Elements Using Drilled Concrete CoresC 496/C 496M Test Method for Splitting Tensile Strengthof Cylindrical Concrete SpecimensC 617 Practice for Capping Cylindrical Concrete Speci-mensC 670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction Material
8、sC 823 Practice for Examination and Sampling of HardenedConcrete in ConstructionsC 1140 Practice for Preparing and Testing Specimens fromShotcrete Test PanelsC 1231/C 1231M 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 C 125.4. Significance and Use4.1 This test method provides standardized procedures f
10、orobtaining 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 ei
11、ther 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 C 823 (see Note 1).
12、4.3 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 locati
13、on 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 jurisdictio
14、n of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC09.46 Shotcrete.Current edition approved Jan. 1, 2005. Published January 2005.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceas
15、tm.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, Farmington Hills,MI 483334Bartlett, F.M. and MacGregor, J.G., “Effect of Core Diameter on ConcreteCore Strengths,”
16、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 States.planning the locations for obtaining shotcrete samples and ininterpreting strength test results.4.5 Shotcrete i
17、s 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 for compressive strength testing.4.6 The strength of shotcrete is affected by moisture content,the specified moisture
18、 conditioning procedure for cores isintended to provide test specimens with reproducible moisturecontents that minimize within-laboratory and between-laboratory variations.4.7 Sample acquisition may require a combination of core-drilling, sawing, and grinding that may have the potential toadversely
19、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). Theacceptance criteria for shotcrete core strengths shall be estab-lished by the specifier of tests (see Note 2).
20、NOTE 1Practice C 823 provides guidance on the development of asampling plan for concrete in constructions. A number of methods thatsupplement the examination of hardened shotcrete by means of represen-tative core samples and testing are discussed in ACI 506.4R.NOTE 2The core strength acceptance crit
21、eria 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 cylinder comparisons is not relevant to the evaluation ofshotcrete core strengths. A typical shotcrete specification
22、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 barrel. Thecore drill shall have a rigid mounting base and be capable ofbeing operated in any orientation normal to th
23、e 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 sustain uniform ratesof penetration of the core drill. The core barrel shall be cooledand core cuttings flushed with w
24、ater 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 plain and rein-forced specimens in a single pass that conform with theprescribed dimensions, without excessive heatin
25、g 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-trix or fiber-reinforcement.6. Sampling6.1 General:6.1.1 Sampling shall be planned in accordance with theapplicable
26、 provisions of Practice C 823. The number ofsamples, sample locations and sampling procedures shall beestablished in the plan.6.1.2 Shotcrete samples obtained from test panels shall be inaccordance with the applicable provisions of Practice C 1140.6.1.3 Samples of hardened shotcrete for use in the p
27、repara-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 (seeNote 3) and fiber-reinforcement. When preparing strength testspecimens from samples of hardened shotcrete, sample
28、s 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 in-placecondition of the shotcrete (see ACI 506.4R).NOTE 3It is not possible to specify a minimum age when shot
29、crete 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 during shotcrete application, core speci-mens may be obtained for testing at approximately 6 h. If this is notpractic
30、al, 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. Nondestructive test methods may beused to estimate level of in-place strength development prior to attemptingremoval of shotc
31、rete 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 specimens perpendicular tothe surface and avoid drilling near formed joints or edgeplacement. Record the approxim
32、ate 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 structural elements shall have a diameter of at least 3.0in 75 mm when the lengths of such cores are to be measu
33、redin accordance with Test Method C 174/C 174M.7.2 For cores that are not intended for determining structuraldimensions, measure the longest and shortest lengths on the cutsurface along lines parallel to the core axis. Record the averagelength to the nearest14 in. 5 mm.8. Cores for Compressive Stren
34、gth8.1 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 less than 3.0 in. 75 mm shall be permitted asdirected by the specifier of the tests.NOTE 4The compressive strengt
35、hs 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 effect of the length-diameter ratio4.8.2 LengthThe preferred length of the capped or groundspecimen is nomina
36、lly 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 between 1.9 and 2.1. Corespecimens with length-diameter ratios equal to or less than1.75 require corrections to
37、 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 or a length less than its diameterafter capping or end grinding shall not be tested unless sodirected by the s
38、pecifyer of the tests.C 1604/C 1604M 0528.2.2 For non-load bearing structural members or when it isimpossible to obtain shotcrete cores with length-diameter ratio(L/D) greater than or equal to 1.0, core specimens shall besubject to the approval of the specifier of the tests.8.3 Moisture Conditioning
39、The following procedure isintended to preserve the moisture of the drilled core and toprovide a reproducible moisture condition that minimizes theeffects of moisture gradients introduced by wetting duringdrilling and specimen preparation.8.3.1 The following procedure is used to obtain coreshaving a
40、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 moisture to evaporate. When surfaces ap-pear dry, but not later than 1 h after drilling, place cores inseparate pla
41、stic 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 the testing laboratory as soon as practicable. Keepcores in the sealed plastic bags or nonabsorbent containers atall
42、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 soon as practicable, but nolater than 2 days after drilling of cores. After completing endpreparation, use a dry cl
43、oth 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 preparation.8.3.3 Allow cores aged 28 days or more to remain in thesealed plastic bags or nonabsorbent containers for a
44、t 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 tests.NOTE 5The waiting period of at least 5 days is intended to reducemoisture gradients introduced when the core is
45、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. Report the alternative moisture condition-ing procedure.8.4 Sawing of EndsThe ends of core specimens to betested in co
46、mpression 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, 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
47、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 thicknesses thatexceed the requirements of Practice C 617.8.5 CappingIf the ends of the cores do not conform to theperp
48、endicularity and planeness requirements of Test MethodC 39/C 39M, they shall be sawn or ground to meet thoserequirements or capped in accordance with Practice C 617.Ifcores are capped in accordance with Practice C 617, thecapping device shall accommodate actual core diameters andproduce caps that ar
49、e concentric with the core ends. Measurecore lengths to the nearest 0.1 in. 2 mm before capping.Unbonded caps in accordance with Practice C 1231 are notpermitted.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 this length to compute the length-diameter (L/D) ratio.Determine the average diameter by averaging two measure-ments t
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