1、Designation: C903 10Standard Practice forPreparing Refractory Castable Specimens by Cold Gunning1This standard is issued under the fixed designation C903; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、 number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers a procedure for preparing refractorycastable specimens usually containing calcium aluminate ce-ment with or witho
3、ut metal fibers by cold nozzle-mix gunning.Specimens prepared in accordance with this practice areintended for use in standard ASTM test methods required forevaluating gunned materials.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathem
4、aticalconversions to SI units that are provided for information onlyand are not considered standard.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 heal
5、th practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C401 Classification of Alumina and Alumina-SilicateCastable RefractoriesC865 Practice for Firing Refractory Concrete Specimens3. Significance and Use3.1 The properties of r
6、efractory castables can be affected bytheir method of installation. This practice attempts to minimizethe variables encountered during installation by pneumaticgunning.3.2 This practice provides parameters to produce gunnedspecimens for use in other ASTM test methods.3.3 This practice may be used to
7、 produce specimens foracceptance testing, service evaluation, manufacturing control,and research and development.3.4 Differences between various kinds of equipment and thedifferences in procedures and operator techniques may result insignificant variations in the physical properties of the gunnedspe
8、cimens. It is recommended that the same operator use thesame equipment to produce specimens for referee testingagreed to by the involved testing parties. The specific operatingparameters should be shown in the report.3.5 Although this practice is specifically designed for re-fractory castables conta
9、ining calcium aluminate cement, it maybe used with minor modifications for gun mixes containingother bond systems.4. Apparatus4.1 Gun, pneumatic nozzle-mix.3At least 50 ft (15.2 m) ofhose should be available. Acceptable nozzle diameters rangefrom 1 to 2 in. (25 to 51 mm).4.2 Air Compressor, capable
10、of delivering sufficient pres-sure and volume to adequately move castable to the gun. Thecompressor should be able to supply at least 250 ft3(7 m3)/min.4.3 Forms, suitable nonabsorbent type, which will vary insize in accordance with the number and size of samples beingprepared, but are at minimum 12
11、 by 12 by 4 in. (305 by 305 by100 mm). Forms should be sized to prevent rebound entrap-ment. The use of12 inch hardware cloth as sidewalls of theform allows most of the rebound to pass through.4.4 Suitable eye and hand protection must be worn capableof protection against high velocity refractory par
12、ticles and steelfibers.5. Procedure5.1 Store the castable to be gunned at 70 to 85F (20 to27C) for 24 h prior to gunning.5.2 Oil the forms lightly. Typically 10W-30 oil is used.Place the form against a rigid surface at an angle of 80 to 90to the horizontal.5.3 If recommended by the supplier, predamp
13、en the castableby mixing with potable water in a paddle mixer for 1 to 5 minor follow manufacturers specific instructions. In general,regular (dense) castables require 2 to 4 % of predampeningwater and lightweight (insulating) castables require 5 to 8 %.NOTE 1Castables that contain a high-purity cem
14、ent may benefit byaging for 5 to 10 min after dampening before gunning. This “aging1This practice is under the jurisdiction ofASTM Committee C08 on Refractoriesand is the direct responsibility of Subcommittee C08.09 on Monolithics.Current edition approved Jan. 1, 2010. Published February 2010. Origi
15、nallyapproved in 1979. Last previous edition approved in 2008 as C903 08. DOI:10.1520/C0903-10.2For 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 Documen
16、t Summary page onthe ASTM website.3Equipment available from Allentown Equipment Co., 421 Schantz Road,Allentown, PA 18104, http:/, has been found suit-able for this purpose (Model N-3 or N-2).1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United
17、States.procedure should be used if gunning without it produces excessiverebound, dusting, or slumping.NOTE 2Treat castables containing metal fibers in a normal manner. Ifmetal fibers are to be added to the gunning material, add them to thepaddle mixer before any water is introduced. The amount of fi
18、ber to beadded and the methods of reporting this amount shall be agreed upon bythe parties involved. To prevent clumping of the fibers they should beadded slowly through a suitable screen of12 in. mesh. Fibers larger than1 in. may require larger openings. If any predampening water is to beadded, dry
19、 mix for two to three min before adding water.5.4 Gun the castable into the form at a distance of 3 to 4 ft(0.91 to 1.2 m) from gun nozzle. Hold the gun nozzle at 90 tothe form. Gunning pressures are suggested to be approximately40 psi (276 kPa) for regular-weight castables and approxi-mately 20 psi
20、 (138 kPa) for insulating refractory castables. Ifmore than 50 ft (15 m) of hose is used, it may be necessary toadd 5 psi (34 kPa) for each additional 50 ft. These conditionsand the amount of potable water used must be adjusted by thenozzleman for acceptable rebound. The gunning pattern in-volves mo
21、ving the nozzle in a circular motion, back and forthacross the form, beginning at the bottom. Report any unusualdusting, slumping, or other unique characteristics of therefractory castable. The water, material, and environmenttemperature shall also be reported.NOTE 3For referee tests all participati
22、ng laboratories should agree ona specific gun pressure and other test parameters to obtain reproducibleresults. Excessive air pressures and hose lengths may cause changes inproperties of the gunned castable especially in properties of gunnedinsulating castables.5.5 Trim the gunned surface approximat
23、ely parallel to theback of the form. See Practice C865 for procedures concerningthe measurement of specimens.5.6 Cover the castable surface with a curing medium, forexample a curing compound or polyethylene plastic sheet. Forcalcium aluminate bonds, optimum curing temperature is 90 to95F (32 to 35C)
24、 for 24 + 0.5 h.5.7 Cut suitably sized lamination-free specimens from thecentral section. Cut specimen to exclude the portion nearest thebackboard to eliminate trapped rebound. Identify the gunnedface or gunning direction on each specimen since it mayinfluence the results of subsequent tests.5.8 Spe
25、cimens prepared according to section 5.7 that will beused for further testing shall be placed in a 150F oven; holduntil all specimens have been inserted. Increase temperature ata rate of 50F/h (28C/h) maximum from 150F to between220 to 230F (105 to 100C) and hold for at least 15 h priorto testing or
26、 firing in a prescribed manner.5.9 Determine specific properties by selected test proce-dures.6. Report6.1 Report the following information:6.1.1 Specific predampening water content and type ofmixer,6.1.2 Premix time,6.1.3 Temperature of the water, castable, and environment,6.1.4 Aging time (if any)
27、,6.1.5 Type of gun, length and diameter of hose,6.1.6 Gunning pressure employed,6.1.7 Nozzle size and type,6.1.8 Size and type of form used,6.1.9 Type and amount (by weight or volume) of any metalfibers added prior to gunning, and6.1.10 Curing time, temperature and environment.6.2 The report may als
28、o specify the amount of rebound andany unusual gunning characteristics observed.6.3 The report may include any other parameters agreed toby the parties involved.7. Keywords7.1 gunning; rebound; predampening; refractory castable;specimensASTM International takes no position respecting the validity of
29、 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 rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to
30、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 revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Y
31、our 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 you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is co
32、pyrighted 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 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/).C903 102
