1、Designation: C903 10C903 15Standard 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 revi
2、sion. A 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 refractory castable specimens usually containing calcium aluminate cementwith or
3、 without metal fibers by cold nozzle-mix gunning. Specimens prepared in accordance with this practice are intended for usein standard ASTM test methods required for evaluating gunned materials.1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses a
4、re mathematicalconversions to SI units that are provided for information only and are not considered standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safet
5、y and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C401 Classification of Alumina and Alumina-Silicate Castable RefractoriesC865 Practice for Firing Refractory Concrete Specimens3. Significance and Use3.1 The proper
6、ties of refractory castables refractories can be affected by their method of installation. This practice attempts tominimize the variables encountered during installation by pneumatic gunning.3.2 This practice provides parameters to produce gunned specimens for use in other ASTM test methods.3.3 Thi
7、s practice may be used to produce specimens for acceptance testing, service evaluation, manufacturing control, andresearch and development.3.4 Differences between various kinds of equipment and the differences in procedures and operator techniques may result insignificant variations in the physical
8、properties of the gunned specimens. It is recommended that the same operator use the sameequipment to produce specimens for referee testing agreed to by the involved testing parties. The specific operating parametersshould be shown in the report.3.5 Although this practice is specifically designed fo
9、r refractory castables refractories containing calcium aluminate cement, itmay be used with minor modifications for gun mixes containing other bond systems.4. Apparatus4.1 Gun, pneumatic nozzle-mix. At least 50 ft (15.2 m) of hose should be available. Acceptable nozzle diameters range from1 to 2 in.
10、 (25 to 51 mm).4.2 Air Compressor, capable of delivering sufficient pressure 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 in size in accordance with the number and size of
11、samples beingprepared, but are at minimum 12 by 12 by 4 in. (305 by 305 by 100 mm). Forms should be sized to prevent rebound entrapment.The use of 12 inch hardware cloth as sidewalls of the form allows most of the rebound to pass through.1 This practice is under the jurisdiction of ASTM Committee C0
12、8 on Refractories and is the direct responsibility of Subcommittee C08.09 on Monolithics.Current edition approved Jan. 1, 2010Oct. 1, 2015. Published February 2010December 2015. Originally approved in 1979. Last previous edition approved in 20082010as C903 08.C903 10. DOI: 10.1520/C0903-10.10.1520/C
13、0903-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended
14、 only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current v
15、ersionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.4 Suitable eye and hand protection must be worn capable of protection against high velocity refract
16、ory particles and steelfibers.5. Procedure5.1 Store the castable to be gunned at 70 to 85F (20 to 27C) 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 90 to thehorizontal.5.3 If recommended by the supplier
17、, predampen the castablerefractory by mixing with potable water in a paddle mixer for 1 to5 min or follow manufacturers specific instructions. In general, regular (dense) castables require 2 to 4 % of predampening waterand lightweight (insulating) castables require 5 to 8 %.NOTE 1CastablesRefractori
18、es that contain a high-purity cement may benefit by aging for 5 to 10 min after dampening before gunning. This “agingprocedure should be used if gunning without it produces excessive rebound, dusting, or slumping.NOTE 2Treat castablesrefractories containing metal fibers in a normal manner. If metal
19、fibers are to be added to the gunning material, add them tothe paddle mixer before any water is introduced. The amount of fiber to be added and the methods of reporting this amount shall be agreed upon by theparties involved. To prevent clumping of the fibers they should be added slowly through a su
20、itable screen of 12 in. mesh. Fibers larger than 1 in. mayrequire larger openings. If any predampening water is to be added, dry mix for two to three min before adding water.5.4 Gun the castablerefractory into the form at a distance of 3 to 4 ft (0.91 to 1.2 m) from gun nozzle. Hold the gun nozzle a
21、t90 to the form. Gunning pressures are suggested to be approximately 40 psi (276 kPa) for regular-weight castablesrefractories andapproximately 20 psi (138 kPa) for insulating refractory castables. refractories. If more than 50 ft (15 m) of hose is used, it maybe necessary to add 5 psi (34 kPa) for
22、each additional 50 ft. These conditions and the amount of potable water used must beadjusted by the nozzleman for acceptable rebound. The gunning pattern involves moving the nozzle in a circular motion, back andforth across the form, beginning at the bottom. Report any unusual dusting, slumping, or
23、other unique characteristics of therefractory castable. refractory. The water, material, and environment temperature shall also be reported.NOTE 3For referee tests all participating laboratories should agree on a specific gun pressure and other test parameters to obtain reproducible results.Excessiv
24、e air pressures and hose lengths may cause changes in properties of the gunned castable especially in properties of gunned insulating castables.5.5 Trim the gunned surface approximately parallel to the back of the form. See Practice C865 for procedures concerning themeasurement of specimens.5.6 Cove
25、r the castable surface with a curing medium, for example a curing compound or polyethylene plastic sheet. Follow therecommended manufacturers curing instructions. For calcium aluminate bonds, optimum curing temperature is 90 to 95F (32 to35C) for 24 + 0.5 h.5.7 Cut suitably sized lamination-free spe
26、cimens from the central section. If excessive tearout of refractory grain occurs whilecutting, it may be necessary to dry the panel first before cutting (ex. Low Cement Gun Mix) and then re-drying. Cut specimen toexclude the portion nearest the backboard to eliminate trapped rebound. Identify the gu
27、nned face or gunning direction on eachspecimen since it may influence the results of subsequent tests.5.8 Specimens prepared according to section 5.7 that will be used for further testing shall be placed in a 150F oven; hold untilall specimens have been inserted. Increase temperature at a rate of 50
28、F/h (28C/h) maximum from 150F to between 220 to230F (105 to 100C) and hold for at least 15 h prior to testing or firing in a prescribed manner.5.9 Determine specific properties by selected test procedures.6. Report6.1 Report the following information:6.1.1 Specific predampening water content and typ
29、e of mixer,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,6.1.7 Nozzle size and type,6.1.8 Size and type of form used,6.1.9 Type and amount (by weight or volume) of a
30、ny metal fibers added prior to gunning, and6.1.10 Curing time, temperature and environment.6.2 The report may also specify the amount of rebound and any unusual gunning characteristics observed.6.3 The report may include any other parameters agreed to by the parties involved.C903 1527. Keywords7.1 g
31、unning;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. Users of this standard are expressly advised that determination of the validity of an
32、y 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 withdrawn.Your comments are in
33、vited 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 comments have not receive
34、d 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 t
35、his 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 Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ Equipment available from Allentown Equipment Co., 421 Schantz Road, Allentown, PA 18104, http:/, has been found suitable for thispurpose (Model N-3 or N-2).C903 153
