1、Designation: C865 13Standard Practice forFiring Refractory Concrete Specimens1This standard is issued under the fixed designation C865; 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 parenthe
2、ses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This practice covers the firing of specimens made fromrefractory concret
3、es (castable refractories) in accordance withPractice C862 for cast specimens. The procedure is alsorecommended for heating rates to be used for high-temperaturetest methods such as Methods C16, C583, etc., when thesemethods are used to test refractory concretes.1.2 The values stated in inch-pound u
4、nits are to be regardedas the standard. The values given in parentheses are forinformation only.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health p
5、ractices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C16 Test Method for Load Testing Refractory Shapes atHigh TemperaturesC583 Test Method for Modulus of Rupture of RefractoryMaterials at Elevated TemperaturesC862 Practice for P
6、reparing Refractory Concrete Specimensby CastingE230 Specification and Temperature-Electromotive Force(EMF) Tables for Standardized Thermocouples3. Significance and Use3.1 This practice is used to standardize the firing conditionsof refractory concrete specimens prepared in accordance withPractice C
7、862. The standards are set down to minimizelaboratory-to-laboratory variation and do not attempt to dupli-cate any particular field applications.4. Apparatus4.1 Kiln, equipped with instruments capable of controllingthe heating rate of the kiln at 100 to 700F (55 to 380C)/h (see6.5) and holding the s
8、oak temperature to 610F (5.5C) of thenominal soak temperature. For temperatures up to 2500F(1370C) an electrically heated kiln is preferred, but gas- oroil-fired kilns can be used for all temperatures, provided theheating rates specified can be maintained, the flame of theburners does not impinge di
9、rectly on any specimen, and thefurnace atmosphere contains a minimum of 0.5 % oxygen with0 % combustibles.5. Preparation of Samples5.1 Samples are prepared by casting in accordance withMethods C862. If the sample size of the cast specimen is thesame as that specified for the test, it can be used dir
10、ectly.However, cutting samples of the required size from larger castblocks will often be necessary (Note 1). In this case, it isrecommended that the samples be cut with a diamond saw.After cutting, the samples should be dried at 230F (110C) fora minimum of 18 h. All cut samples should have sharp edg
11、esand corners and should not show pull-out of grains on the cutsurfaces. For some low-strength castables, drying prior tocutting may be needed to increase their strength and resistanceto pull-outs.NOTE 1Specimens cut from the interior of large cement bondedcastables shapes may be stronger than speci
12、mens cut from small castshapes because the interior of large cast shapes are exposed to highpressure steam during dryout which causes more complete hydration ofthe cement.5.2 Some types of castables, especially those containingaggregates of a relatively low hardness (such as lightweightcastables), m
13、ay be cut on a dry saw. This procedure isacceptable provided that specimens with sharp corners andedges, which show no signs of grain pull-out at the cutsurfaces, are obtained.6. Procedure6.1 Label all specimens with ceramic ink or ceramic cray-ons.6.2 Place the specimens in the kiln so that each sp
14、ecimenwill rest on the surface formed by its longest and smallest1This practice is under the jurisdiction ofASTM Committee C08 on Refractoriesand is the direct responsibility of Subcommittee C08.09 on Monolithics.Current edition approved Sept. 1, 2013. Published October 2013. Originallyapproved in 1
15、977. Last previous edition approved in 2007 as C865 02 (2007).DOI: 10.1520/C0865-13.2For 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 p
16、age onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1dimension (that is, the 9 by 212-in. (230 by 65-mm) surface for9-in. straight, or the 6 by 1-in. (152 by 25-mm) surface for 6 by1 by 1 in. samples). Support each s
17、pecimen on a flat supportingbrick, which does not soften or shrink at the intended soaktemperature. Place between the test specimens and the support-ing brick a layer of suitable refractory material that is nonre-active under the test conditions and passes a No. 16 (1.18-mm)sieve and is retained on
18、a No. 40 (425-m) sieve.6.3 The following maximum heating rates at temperaturesbelow 1500F (815C) are recommended:Cross Section of SpecimenMaximum HeatingRatein. mm F/h C/h412 by 3 114 by 76 100 55412 by 212 114 by 65 100 552 by 2 228 by 64 300 1701 by 1 25 by 25 700 380At temperatures over 1500F a h
19、eating rate up to 700F(390C)/h is permissible. Generally, a slower heating rate doesnot affect the properties of the specimens adversely. Thus,when smaller and larger specimens are fired together, theheating rate applicable to the larger specimens should be used.NOTE 2Different heating rates are spe
20、cified for various samples toensure that the difference in temperature between the center and thesurface of the specimen does not exceed 45F (25C). Experimentalevidence indicates that cracking may occur when a castable sample isheated too rapidly. The safe heat-up rate increases with decreasing samp
21、lesize.6.4 Hold the specimens at the specified temperature for 5 h.During the holding period a furnace atmosphere containing aminimum of 0.5 % oxygen with 0 % combustibles should bemaintained. For special high-temperature tests, a longer orshorter holding time may be required. Please refer to theapp
22、ropriate test method for details.6.5 Measure the temperature within the kiln by means of anappropriate calibrated thermocouple. Refer to E230, tables 1and 2, for tolerances and upper temperature limits for use ofvarious thermocouples. An alternative method is the use of acalibrated optical pyrometer
23、 where applicable. Make tempera-ture readings at intervals of 15 min or less when the tempera-ture is not recorded and controlled automatically. The use ofcone plaques is advised as a guide to temperature uniformitywithin the kiln.6.6 After completion of the firing, cool the specimens in aclosed kil
24、n at a cooling rate not exceeding 500F (280C)/h.7. Keywords7.1 castables; refractory concreteASTM 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 determinati
25、on of the validity of any such patent rights, 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 withdr
26、awn. Your comments are invited either for 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
27、comments have not received a fair hearing 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
28、 or multiple copies) of this standard may 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 ASTM website (www.astm.org/COPYRIGHT/).C865 132
