1、Designation: D7792/D7792M 15Standard Practice forFreeze/Thaw Conditioning of Pultruded Fiber ReinforcedPolymer (FRP) Composites Used in Structural Designs1This standard is issued under the fixed designation D7792/D7792M; the number immediately following the designation indicates theyear of original
2、adoption or, in the case of revision, 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 In general, it is feasible that the mechanical properties ofFRP comp
3、osites will be affected by environmental conditionssuch as freeze/thaw cycling. In order to make reliable com-parisons between different materials under freeze/thaw envi-ronmental conditions, it is necessary to standardize the freeze/thaw conditions to which specimens of these materials aresubjected
4、 prior to and during testing. This practice definesprocedures for freeze/thaw conditioning of pultruded FRPcomposites intended for use in structural design applications.1.2 UnitsThe values stated in either SI units or inch-pound units are to be regarded separately as standard. Thevalues stated in ea
5、ch system may not be exact equivalents;therefore, each system shall be used independently of the other.Combining values from the two systems may result in noncon-formance with the standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is
6、 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.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD3918 Terminology Relating to Re
7、inforced Plastic Pul-truded ProductsD6641/D6641M Test Method for Compressive Properties ofPolymer Matrix Composite Materials Using a CombinedLoading Compression (CLC) Test FixtureD7290 Practice for Evaluating Material Property Character-istic Values for Polymeric Composites for Civil Engineer-ing St
8、ructural ApplicationsD7745 Practice for Testing Pultruded Composites3. Terminology3.1 Definitions:3.1.1 standard laboratory temperaturea temperature of23 6 2C 73.4 6 3.6F.3.1.2 standard laboratory atmospherean atmosphere hav-ing a temperature of 23 6 2C 73.4 6 3.6F and a relativehumidity of 50 6 10
9、%.3.1.3 freeze/thaw resistancethe ability of a thermosetpultruded composite to withstand repeated water exposure andsubsequent freeze cycling for 100 freeze/thaw cycles. Thisability will be quantified in terms of the % retention of themechanical property of interest as compared to samples ex-posed t
10、o water for a comparable time without subsequentfreeze/thaw cycling.3.2 Terminology relating to pultruded composites is foundin Terminology D3918.4. Significance and Use4.1 The freeze/thaw conditioning procedures prescribed inthis practice are designed to provide a standard procedure to beused to ev
11、aluate and compare the effect of 100 freeze/thawcycles under controlled laboratory conditions on pultrudedFRP composites to be used in structural design applications.The conditioning procedures prescribed in this practice aredesigned to obtain reproducible results to compare and evalu-ate these mate
12、rials but are not intended to produce equilibriumconditions or actual service conditions for these materials.5. Sampling5.1 Sampling shall be in accordance with the locations fromwhich test specimens shall be taken from the reinforcedpultruded composites as defined in Practice D7745.1This test metho
13、d is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.18 on Reinforced Thermoset-ting Plastics.Current edition approved Sept. 1, 2015. Published October 2015. DOI: 10.1520/D7792_D7792M-15.2For referenced ASTM standards, visit the ASTM websi
14、te, 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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
15、15.2 Sampling shall be in accordance with the ASTM testmethods for the specific mechanical properties to be deter-mined.36. Test Specimens6.1 The numbers and types of test specimens shall be inaccordance with the ASTM test methods for the specificmechanical properties to be determined. If Practice D
16、7290 is tobe used to determine characteristic values, at least ten samplesare needed for the control and ten samples are needed for thefreeze/thaw exposure for a total of at least 20 samples.6.2 Test specimens shall be machined or otherwise fabri-cated to the test coupon geometry specified by the AS
17、TM testmethod for the properties to be determined prior to theirexposure to the environmental conditioning.6.3 The thickness of the test specimens shall be the originalproduct thickness without any machining of the surface. Thespecimen thickness needs to be compatible with the thicknessrequirements
18、of the mechanical property test method that willbe used to evaluate the samples.6.4 All test specimens shall be conditioned in the standardlaboratory atmosphere in accordance with Practice D618,Procedure A, prior to initiating the freeze/thaw conditioningprocedures described here.6.5 Use test specim
19、ens up to 25 mm 1.0 in. in thicknesswith this freeze/thaw standard practice. Experimental data hasshown that for pultruded composite samples up to 25 mm 1.0in. the interior center of the test specimen is freezing andthawing as desired during the cycle time and temperaturesdescribed in this practice.
20、 If the interior center is not freezingand thawing during this cycle for the specimen, property dataobtained from samples exposed to conditioning as described inthis freeze/thaw practice shall not be reported as being obtainedusing this freeze/thaw standard practice.7. Apparatus7.1 Cold ChamberCapab
21、le of maintaining a constanttemperature of -20 6 2C -4 6 3.6F.7.2 Water TankA chamber capable of maintaining a con-stant water temperature corresponding to a standard laboratorytemperature of 23 6 2C 73.4 6 3.6F and equipped with adevice or mechanism for separating test specimens from eachother such
22、 that the faces of the specimens do not rest againstone another.8. Procedure8.1 Prior to the start of the freeze/thaw cycling, the testspecimens to be exposed to the freeze/thaw cycling and anequal number of control test specimens shall be placed in awater tank at standard laboratory temperature of
23、23 6 2C73.4 6 3.6F for 30 days. Samples removed from the watertank after this initial 30 day moisture exposure period shall beconsidered to be control test specimens at 0 freeze/thaw cycles.8.1.1 Distilled water shall be used for all conditioning.Distilled water is to be used to serve as a standard
24、medium forthe conditioning procedure; however, distilled water is notintended to mimic field conditions.8.1.2 The presence of any residue in the water bath duringthe exposure time shall be noted in the report as the presenceof residue indicates a material loss of the test specimens.8.2 Perform tests
25、 for desired mechanical properties on the 0freeze/thaw cycle test specimens at the conclusion of the 30day water immersion to establish the baseline properties priorto the freeze/thaw cycling.8.2.1 When conducting tests on specimens removed fromthe water immersion, wipe the specimens with a dry clot
26、h andtest them at standard laboratory temperature. Specimens shouldonly be removed from the water as the tests are ready to beconducted. Start the mechanical property tests immediately atthe conclusion of the exposure period, and complete them assoon as possible. Record the testing time period in th
27、e report.8.3 Freeze/Thaw CyclingEach freeze/thaw cycle shallconsist of at least 3 hours of exposure in air at -20 6 2C -46 3.6F in the cold chamber followed by 3 hours (610minutes) of immersion in distilled water at standard laboratorytemperature of 23 6 2C 73.4 6 3.6F. The faces of thesamples shall
28、 not rest on each other as the samples are held inthe water tank for thawing. This process shall be repeated until100 cycles of freeze/thaw cycling are reached.8.3.1 When the sequence of freeze/thaw cycling must beinterrupted, such as in an overnight period during a manualcycling operation, the spec
29、imens are to be left in the frozencondition. The cold exposure time of longer than three hours isnot an issue, but the extra exposure time shall still beconsidered as only one cycle and a record of this extended timein the freezing condition shall be maintained.8.3.2 The specimens shall be visually
30、examined for anyvisual defects such as delamination after every freeze/thawcycle, and a record shall be maintained of the results of thisexamination.8.4 Perform tests for the desired mechanical properties onthe 100 freeze/thaw cycle test specimens at the conclusion ofthe freeze/thaw cycling followin
31、g the last thaw cycle accordingto the applicable ASTM test method.8.4.1 When conducting tests on specimens removed fromthe water immersion of the last thaw cycle, wipe the specimenswith a dry cloth and test them at standard laboratory tempera-ture. Specimens should only be removed from the water as
32、thetests are ready to be conducted. Start the tests immediately atthe conclusion of the exposure period and complete them assoon as possible. Record the testing time period in the report.9. Report9.1 The report of any test referencing this practice shallstate:9.1.1 The specific identification of the
33、 pultruded composite.9.1.2 The location on the pultruded composite from whichthe specimens were machined.3To evaluate the effect of freeze/thaw cycling on the matrix and fiber/matrixinterface of a pultruded composite material, the use of Test Method D6641/D6641Mfor mechanical property determination
34、is suggested. If other property effects are tobe examined, appropriate test methods for the desired property should be selected.D7792/D7792M 1529.1.3 The geometry of the test specimens used and themechanical testing procedure for which they were prepared.9.1.4 Any deviation from the specified condit
35、ioning proce-dures and any extended freezing cycle times beyond thespecified three hours.9.1.5 The time period of testing of each specimen.9.1.6 Any visual observations made during the conditioningor subsequent testing.9.1.7 Freeze/thaw resistance quantified in terms of the %retention of the mechani
36、cal property of interest as compared tosamples exposed to water for a comparable time withoutsubsequent freeze/thaw cycling.10. Precision and Bias10.1 No statements of precision and bias are applicable tothis practice; these are dependent upon the ASTM test methodsfor the specific properties to be d
37、etermined.11. Keywords11.1 freeze; pultrusion; thawASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent righ
38、ts, and the riskof 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 andif not revised, either reapproved or withdrawn. Your comments are invited either for
39、revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing
40、you shouldmake 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. Individual reprints (single or multiple copies) of this standard may
41、be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 153
