1、Designation: C862 02 (Reapproved 2008)C862 16Standard Practice forPreparing Refractory Concrete Specimens by Casting1This standard is issued under the fixed designation C862; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、 of last revision. A number in parentheses 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 U.S. Department of Defense.1. Scope1.1 This practice covers the mix
3、ing, casting and curing of monolithic refractory concrete specimens under laboratory conditionsfor use in further testing. It does not apply to monolithic castable refractories intended primarily for gunning applications.1.2 The values givenstated in inch-pound units are to be regarded as the standa
4、rd. The values given in parentheses are forinformation only.mathematical conversions to SI units that are provided for information only and are not considered standard.1.3 Various specimen sizes are required for specific test methods. Refer to these test methods to determine the size and numberof sp
5、ecimens, which will be required from the sample.1.4 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 safety and health practices and determine the applicability of regu
6、latorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C133 Test Methods for Cold Crushing Strength and Modulus of Rupture of RefractoriesC192/C192M Practice for Making and Curing Concrete Test Specimens in the Laboratory3. Significance and Use3.1 This practice is used to standard
7、ize mixing, mold conditions, placement and curing of refractory concrete specimens to beused for testing and evaluation under other test methods.3.2 This practice standardizes laboratory conditions for producing refractory concrete specimens to minimize laboratory-to-laboratory variation and does no
8、t attempt to duplicate the conditions of field installations.3.3 This practice can be used for the preparation of specimens used in referee testing.4. Apparatus and Conditions4.1 Laboratory ConditionsThe laboratory ambient should be controlled between 70 and 80F (20 and 27C) (Note 1) andfrom 40 to 6
9、0 % relative humidity for preconditioning materials and equipment, batching and mixing casting test specimens,stripping molds, and testing specimens. Report laboratory temperature and relative humidity with physical test results if other thanspecified.NOTE 1A 5 to 6F temperature difference can drast
10、ically change the set time of a mix. It is a good practice to always record ambient temperatureconditions for each cast.4.2 BalancesAppropriately sized scales having a sensitivity of 0.2 % of the related batch size.4.3 Castable MixersAn electrically operated mechanical mixer (Fig. 1) may be used for
11、 preparing castable batches for castingspecimens.A2-ft3 (56.6-dm(0.057-m3) mixing bowl or a 212-ft3 (70.8-dm(0.071-m3) concrete mixer has sufficient capacity to mixabout 1 ft3 (0.0285 m3) of refractory castable. The smallest batches required for casting 1-in. (25-mm) square bars can be mixedin a 0.1
12、0-ft3 (2.83-dm(0.0028-m3) bowl available with bench mixers. Size mixing bowl to contain from 50 to 75 % volume loading1 This practice is under the jurisdiction of ASTM Committee C08 on Refractories and is the direct responsibility of Subcommittee C08.09 on Monolithics.Current edition approved March
13、1, 2008Nov. 1, 2016. Published March 2008November 2016. Originally approved in 1977. Last previous edition approved in 20022008as C862 02.C862 02 (2008). DOI: 10.1520/C0862-02R08.10.1520/C0862-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at
14、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 only to provide the user of an ASTM standard an indication of what changes have been made to the previous versi
15、on. 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 versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM Internationa
16、l, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1with the dry batch. Castable water requirement variation becomes more significant as dry volume loadings drop below 40 %because the water required to wet the bowl surfaces changes more rapidly with decreasing volu
17、me loadings.NOTE 1Castable water requirement variation becomes more significant as dry volume loadings drop below 40 % because the water required to wetthe bowl surfaces changes more rapidly with decreasing volume loadings.4.4 Gang MoldsMetal, two or more sets, as shown inTypical molds are 9 by 2 by
18、 2 in. and 2 by 2 by 2 in. made from metal,plastic or rubber and are watertight, rigid, Figs. 2 and 3, for casting specimens to the size required for specific physical propertytesting (seeand removable. There are commercially available molds from concrete testing suppliers and other sources. Molds m
19、aybe reusable or for single use. Although brick-sized shapes may be cut with a diamond saw to obtain a specific size, it is preferableNote 8). The front plate of the mold illustrated is held in placeto fabricate the desired shape. The smallest mold dimension shouldbe a minimum of three times the lar
20、gest aggregate diameter, as specified in Practice C192/C192Mby quick-release clamps (50-lbf(222-N) pull exerted by each clamp) that permit emptying the mold by releasing the clamps and tapping the left end of the frontplate, thereby parting all of the separator. In some cases, when smaller specimens
21、 are required and grain sizing does not allow forsmaller castings, cut specimens may be used. See Table 1plates and loosening the cast-test specimens4.4.1 As an alternative design for 1 in. (25-mm) square bars, individual molds may be constructed out of 16-gage (1.588-mm)stainless-steel sheet and ga
22、nged in groups of five with a large rubber band on a glass base-plate.4.4.2 There are commercially available molds from concrete testing suppliers and other sources. Molds may be reusable or forsingle use. Molds must be water tight, rigid, and removable.4.5 CalipersSuitable for measuring internal lo
23、ngitudinal mold dimensions and subsequent specimen length size to the nearest0.01 in. (0.25 mm).4.6 Mold LubricantEither paraffin or silicone-based oils can be used as a release or parting agent for coating molds. Othermold lubricants such as vegetable oils and petroleum-based oils can be used.4.7 S
24、trike-Off Bar20-in. (510-mm) length of steel bar stock, 1Straight edge tool (trowel, bar, or other) at12 by 316 in. (38 by5 mm).least 2 in. wider than mold width.4.8 ThermometerDigital or dial-type, metal, with a range from 0 to 180F (18 to 80C).4.9 TimerSignal-type, for periods up to 5 min. Signal-
25、type. (A stop watch may be used.)FIG. 1 Five Quart Hobart MixerTABLE 1 Metric Mold EquivalentsMetric Equivalentsin.mm1320.818353243165146516838101213916145816111617in.mm7822131630112382126525867331681410241211492301434375NOTE 1Sizes other than 9-in. straights commonly used for physical testing are:
26、212 by 412 by 412 in. (65 by 114 by 114 mm); 2 by 2 by 7 or 9 in.(51 by 51 by 178 or 230 mm); 112 by 112 by 412 in. (38 by 38 by 114 mm); or 1 by 1 by 6 or 7 in. (25 by 25 by 152 or 178 mm). Dimensions are ininches.FIG. 3 Detail Drawing for Gang MoldC862 1624.10 Trowels6 in. pointing and 2 by 6 in.
27、(51 by 152 mm) square, and a 10-in. (254-mm) stainless-steel spatula.4.11 OvenFor curing and drying, preferably forced draft rather than natural convection, with a capacity to hold a minimumof one sample group of specimens (12 by 12 by 12 in.) (30 by 30 by 30-mm).30 cm).4.12 Heavy Rubber GlovesFor c
28、astables containing metal fibers.4.13 ScoopFor transferring the castable from the mixer to the mold more easily.4.14 Vibration TableFor use in 6.4.2.4.15 Sample SplittersThe sample splitter opening shall be a minimum of 3 times the maximum grain size.4.16 Mixing BoxBox of suitable size and strength
29、to hand mix lightweight castable. Inside surface of box should not be waterabsorbent. Fig. 4 is a possible solution.4.16 HoeHand-held hoe for mixing lightweight castable.4.17 Humidity CabinetA cabinet capable of maintaining a relative humidity of greater then 95 % within 90-95F (32-35C)90 to 95F (32
30、 to 35C) is optional.5. Sampling5.1 A sufficient amount of dry castable should be batched to overfill the gang molds by at least a 10 %. This should eliminatethe use of both trailings and scrapings of wet castable.5.2 At the time of use, the dry sample should be between 70 and 80F (20 and 27C). Meas
31、ure the temperature (Note 2) byinserting the full length of the thermometer stem into the material until the reading is constant. Record and report with physicaltest results.NOTE 2It is recommended that in referee tests involving more than one laboratory, the temperature of the dry refractory concre
32、te mix and mixingwater be within the specified range, in all laboratories.5.3 The contents of the container should be thoroughly mixed dry prior to water addition. When less than a full bag is required,reduce the contents of the sample container with a sample splitter to obtain a representative samp
33、le of the desired size. When thesample consists of more than one bag or container, the contents should be combined and mixed thoroughly before being sentthrough the sample splitter. Take precautions to prevent segregation.NOTE 3When the castable mix consists of more than one bag or container, the co
34、ntents should be combined and mixed thoroughly before beingquartered.6. Molding Test Specimens6.1 Water AdditionDetermine the amount of water to be used in the mix for casting test specimens in accordance with themanufacturersmanufacturers or referees recommendations. Use potable water (Note 43) hav
35、ing temperature between 70 and 80F(20 and 27C). Report the temperature with any physical test results. Measure the water addition to the nearest 0.1 % by weight.NOTE 3Potable water is used only if soluble constituents do not affect castable properties significantly. However, filtered, deionized, or
36、distilled wateris preferred and should be sufficient and used in referee tests.6.2 Mechanical MixingAdd the weighed batch to an appropriately sized drum or paddle castable mixer (4.3). If dry batch hasnot been pre-mixed, dry mix for 1 min at slow speed. Operate the mixer at slow speed and add the re
37、quired water to the mix within1 min. Part of the water may be added to the mixer first, if the mix is already homogenous and dry mixing is not necessary.Continue to mix at slow speed for a total time of 3 to 5 min after water addition (Notes 54 and 65) or according to manufacturersrecommendations.NO
38、TE 4For drum mixers, select the speed of rotation and drum angle to provide a cascading effect. For paddle type, a paddle speed should be selectedto provide good mix agitation without throwing the batch out of the mixing zone.NOTE 5Batches should be homogeneous after mixing. Fast-setting mixes are n
39、ormally mixed within 3 min. to provide adequate time for casting soundspecimens. Lightweight castables and others may require the full 5 min. to reach homogeneity.NOTE 7Although brick sized shapes may be cut with a diamond saw to obtain a specific size, it is preferable to fabricate the desired shap
40、e. Thesmallest mold dimension should be a minimum of three times the largest aggregate diameter, as specified in Practice C192/C192M. In some cases, whensmaller specimens are required and grain sizing does not allow for smaller castings, cut specimens may be used.6.3 Manual MixingManual mixing may b
41、e necessary for lightweight mixes having friable aggregate which may be broken bymechanical mixing. Place the weighed dry batch in the a watertight mixing box and all of the required water. Mix by cutting intothe material with the hoe, pulling it upward and forward, and continue until all the batch
42、is piled at the end of the box. Then,standing at the opposite end, work the batch forward in the same manner, but by hoeing slices 2 to 3 in. (51 to 76 mm) thick,frequently pressing the mix with the back of the hoe. Continue the mixing in a rapid and intensive manner until the batch ishomogeneous in
43、 appearance, but for a period not exceeding 3 to 5 min.6.4 Molding Test SpecimensSpecimens:C862 1636.4.1 Obtain Initial Cast LengthLength, if requiredPrior to filling each mold, use the calipers to obtain a measurement ofthe internal length to the nearest 0.01 in. (0.3 mm). Record this value to prov
44、ide the basis for determining linear change of cured,dried, and fired specimens.6.4.2 Fill MoldsAfter the 3 to 5 min. mixing has been accomplished, start the timer and begin filling the molds. Use ascoopscoop/hand for cutting into the batch to get a good section and half fill the mold cavity. Consol
45、idate the material in the moldsby spading at close intervals with a square trowel or spatula held vertically, and with the blade turned to form an angle of 45 withthe side of the mold. Spade along the length and then reverse the 45 angle for the next pass along the mold. trowel, spatula, orfinger ta
46、mping to ensure consolidation of the material into the mold corners. Self-flowing castables will not require spading, butwill simply be poured into place. Fill the molds with an excess of the mix and repeat the trowel spading. spading/tamping. Usethe strike-off bar with a sawing motion to remove the
47、 excess mix, then smooth the exposed surface with a minimum amount oftroweling (troweling. Note 8). Complete the operation of filling the molds within 5 min. or at a rate of 1 min. per test specimen.Mechanical vibration should not be used unless specified by the manufacturer. Vibrate at a consistent
48、 amplitude and frequency.NOTE 8The cited procedure is applicable when filling deep molds, that is, brick molds as shown in Fig. 2 or larger. Hand placement of the castablecan be used to fill and consolidate the material in shallow molds (normally 2 in. (50 mm) deep or less). Appropriate spading with
49、 the spatula should beused with the finger tamping to ensure consolidation of the material into the mold comers. Self flowing castables will not require spading, but will simplybe poured into place.6.4.2.1 When filling deep molds, that is, brick molds 4 in. (100 mm) deep or larger, fill the mold cavity halfway and consolidatethe material in the molds by spading at close intervals with a square trowel or spatula held vertically, and with the blade turnedto form an angle of 45 with the side of the
