1、Designation: C 903 08Standard Practice forPreparing Refractory Castable Specimens by Cold Gunning1This standard is issued under the fixed designation C 903; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、 A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 wi
3、thout 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 the standard. The values given in parentheses are
4、 providedfor information 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 practices and determine the applica-bility of regulatory limitation
5、s prior to use.2. Referenced Documents2.1 ASTM Standards:2C 401 Classification of Alumina and Alumina-SilicateCastable RefractoriesC 865 Practice for Firing Refractory Concrete Specimens3. Significance and Use3.1 The properties of refractory castables can be affected bytheir method of installation.
6、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 produce specimens foracceptance testing, service evaluation, manufa
7、cturing 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 gunnedspecimens. It is recommended that the same operator use thesame equipme
8、nt 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 containing calcium aluminate cement, it maybe used with minor modificatio
9、ns 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 of delivering sufficient pres-sure and volume to adequately move cas
10、table 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 of samples being prepared,but are typically 36 by 36 by 512 in. (915 by 915 by 140 mm).Forms should be sized to prevent rebo
11、und entrapment. The useof12 inch hardware cloth as sidewalls of the form allows mostof the rebound to pass through. This reduces the size of theform required to achieve the desired standard sized centralportion of 24 by 24 in. (610 by 610 mm).4.4 Suitable eye and hand protection must be worn capable
12、of protection against high velocity refractory particles 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 hori
13、zontal.5.3 If recommended by the supplier, predampen 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
14、8 %.NOTE 1Castables that contain a high-purity cement 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 app
15、roved March 1, 2008. Published April 2008. Originallyapproved in 1979. Last previous edition approved in 2004 as C 903 98 (2004).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informati
16、on, refer to the standards Document 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 Co
17、nshohocken, PA 19428-2959, United 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 wat
18、er is introduced. The amount of fiber 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 pre
19、dampening water is to beadded, dry 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 c
20、astables and approxi-mately 20 psi (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
21、. The gunning pattern in-volves moving 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
22、3For referee tests all participating 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
23、Trim the gunned surface approximately parallel to theback of the form. As soon as possible after gunning, score thepanel as deep as possible in from all sides to provide a standardsized central portion of 24 by 24 in. (610 mm by 610 mm) freefrom rebound. See Practice C 865 for procedures concerningt
24、he 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) for 24 + 0.5 h.5.7 Cut suitably sized lamination-free specimens from thecentral
25、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 Specimens prepared according to section 5.7 that will beused for further testing sha
26、ll 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 firing in a prescribed manner.5.9 Determine specific properties by selected test
27、 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),6.1.5 Type of gun, length and diameter of hose,6.1.6 Gunning pressure employed,6
28、.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 also specify the amount of rebound andany unusual gunning characteristics observed.6
29、.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 any patent rights asserted in connection with any item mentionedin this standard
30、. 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 revision at any time by the responsible technical committee and must be reviewed
31、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. Your comments will receive careful consideration at a meeting of theresponsible te
32、chnical 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 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 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).C903082
