1、Designation: C 1552 03aStandard Practice forCapping Concrete Masonry Units, Related Units andMasonry Prisms for Compression Testing1This standard is issued under the fixed designation C 1552; the number immediately following the designation indicates the year oforiginal adoption or, in the case of r
2、evision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This practice covers apparatus, materials, and proce-dures for capping concrete masonry units,
3、related units, includ-ing coupons or other specimens obtained from such units, andmasonry prisms for compression testing.NOTE 1The testing laboratory performing these test methods shouldbe evaluated in accordance with Practice C 1093.1.2 The values stated in inch-pound units are to be regardedas the
4、 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 practices and determine the ap
5、plica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 140 Methods for Sampling and Testing Concrete Ma-sonry Units and Related UnitsC 472 Methods for Physical Testing of Gypsum, GypsumPlasters and Gypsum ConcreteC 617 Practice for Capping Cylindrical Concre
6、te Speci-mensC 1093 Practice for Accreditation of Testing Agencies forUnit MasonryC 1209 Terminology of Concrete Masonry Units and Re-lated UnitsC 1232 Terminology of MasonryC 1314 Method for Compressive Strength of MasonryPrisms3. Terminology3.1 Terminology defined in Terminology C 1209 andC 1232 s
7、hall apply for this practice.4. Significance and Use4.1 This practice describes procedures for providing planesurfaces on the two bearing surfaces of units and prisms. Thepurpose of this standard is to provide consistent and standard-ized procedures for capping units and prisms for compressiontestin
8、g. The procedures are based on those contained (orpreviously contained) in Methods C 140, C 617, and C 1314.NOTE 2Specimens capped using this practice will vary significantlyin size and weight. Appropriate care and handling may differ based onspecimen size and weight. Provide care and handling as ne
9、eded to providefor proper capping based on the physical characteristics of the specimenbeing capped.5. Apparatus5.1 Capping PlateIf used, the capping plate shall be ofsteel and have a thickness of not less than 1 in. (25.4 mm). Thecapping surface shall be plane within 0.003 in. in 16 in. (0.075mm in
10、 400 mm) and shall be free of gouges, grooves, andindentations greater than 0.010 in. (0.25 mm) deep or greaterthan 0.05 in.2(32 mm2) in surface area. At the time of capping,the capping surface shall be level within116 in. (1.6 mm) overthe length of the plate.NOTE 3When using gypsum cement capping m
11、aterials, the placementof a single glass plate directly on top of the capping plate has been foundto reduce the potential of damage to the capping plate. The glass plate istypically more resistant to scratches and can be replaced at less cost thanthat required to resurface the capping plate. The req
12、uirements for thecasting plate in 5.2 have demonstrated to be sufficient for this purpose.5.2 Casting PlateIf used, the casting plate shall be oftransparent glass with a thickness of not less than12 in. (13mm). The casting plate shall be plane within 0.003 in. in 16 in.(0.075 mm in 400 mm).6. Materi
13、als6.1 Capping Materials:6.1.1 High Strength Gypsum Cement Capping Materials:1This practice is under the jurisdiction of ASTM Committee C15 on Manufac-tured Masonry Units and is the direct responsibility of Subcommittee C15.04 onResearch.Current edition approved December 1, 2003. Published January 2
14、004. Originallyapproved in 2002. Last previous edition approved in 2003 as C 1552-03.2For 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
15、page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.1.1.1 In addition to the compressive strength testing re-quired in 6.2, qualification tests s
16、hall be made to determine theeffects of water-cement ratio and age on compressive strength.Procedures used for preparing the high strength gypsumcement capping materials shall ensure that water-cement ratiosused for each batch provide the required strength.NOTE 4The water-gypsum cement ratio should
17、typically be between0.26 and 0.30. Use of low water-gypsum cement ratios and vigorousmixing will usually permit development of 3500 psi (24.1 MPa) at ages ofone or two hours. Higher water-gypsum cement ratios extend workingtime, but reduce strength.6.1.1.2 Do not add fillers or extenders to the high
18、 strengthgypsum cement.NOTE 5Retarders extend working time for capping materials but theireffects on required water-cement ratio should be determined prior to use.NOTE 6The following two gypsum cements have successfully beenused for this purpose: Hydrostoney and Hydrocaly white gypsumcement. Both ar
19、e available from U.S. Gypsum Company.6.1.2 Sulfur Capping Materials:6.1.2.1 Proprietary or laboratory prepared sulfur mixturesshall contain 40 to 60 % sulfur by weight, the remainder beingground fire clay or other suitable inert material passing a No.100 (150-m) sieve with or without a plasticizer.6
20、.1.3 Use only capping materials identified in 6.1.1 and6.1.2. Do not use other capping materials.NOTE 7Examples of materials that have been found to be unsuitablefor capping purposes include, but are not limited to: low-strength moldingplaster, plaster of paris, mixtures of plaster of paris and port
21、land cement,and other cement-based materials.6.2 Compressive Strength of Capping MaterialsThe com-pressive strength of the capping material shall be at least 3500psi (24.1 MPa) at an age of 2 h. The cube molds and methodsof preparing and testing the cubes shall be in accordance withMethod C 617. The
22、 capping material shall be placed in thecube at capping consistency. Store the filled molds in labora-tory air. Remove cubes of sulfur material after solidification iscomplete and remove cubes of gypsum cement material fromthe molds not more than 15 minutes prior to testing. Test cubesat an age of 2
23、 hours 6 10 minutes after completing the fillingof the molds.6.2.1 The strength of the capping material shall be deter-mined on receipt of a new lot and at intervals not exceedingthree months. If a given test of the capping material fails toconform to the strength requirements, the package from whic
24、hthe material was sampled shall not be used unless twoadditional subsequent samples are taken from the same pack-age and both of these subsequent samples conform to thestrength requirements. If the strength tests from an individualpackage are inadequate, randomly obtain and test three addi-tional sa
25、mples from the lot. These additional samples shall betaken from separate packages, if available. Unless these threesamples conform to the strength requirements, no part of the lotshall be used.7. Procedure7.1 Preparation of Specimens for CappingUse an abra-sive stone to remove loose protrusions from
26、 the surfaces of thespecimens to be capped. Refer to the appropriate compressiontest method (C 140 or C 1314) for other specimen preparationrequirements.7.2 Capping Test SpecimensCap top and bottom bearingsurfaces of specimens by one of the methods in 7.2.1 or 7.2.2.Use alignment devices as needed t
27、o make sure the caps meetthe requirements of 7.4.NOTE 8Various alignment devices have been demonstrated to beeffective. For capping with sulfur materials, which sets quickly, alignmentjigs make sure that the specimen is placed on the capping plate correctlyin the first motion. For capping with gypsu
28、m cement materials, levelsplaced across the top of specimen have proven to work well. Bullseyelevels work particularly well with smaller specimens.7.2.1 Capping Using Gypsum Cement MaterialsSpreadthe gypsum cement capping material evenly on the cappingplate (or casting plate if used) that has been l
29、ightly coated withoil or sprayed with a TFE-fluorocarbon coating (Note 9). Bringthe surface of the specimen to be capped into contact with thecapping material; firmly press down the specimen with a singlemotion, holding it so that its axis is at right angles to thecapping surface to comply with the
30、requirements of 7.4. Do notdisturb the specimen until the capping material has solidified.7.2.1.1 Alternative Capping Method Using Gypsum CementMaterialsSpread the gypsum cement capping materialevenly on the top surface of the specimen. Bring the castingplate, which has been lightly coated with oil
31、or sprayed withTFE-fluorocarbon coating (Note 9), into contact with thecapping paste; firmly press down the plate with a single motionholding it so it is at right angles to the specimen. Within 30 s,lightly adjust the plate to achieve a resulting cap that willcomply with the requirements of 7.4. Do
32、not further disturb thespecimen or casting plate until the capping material hassolidified.NOTE 9The use of oil or TFE-fluorocarbon coatings on capping orcasting plates is not necessary if it is found that the plate and specimen canbe separated without damaging the cap.NOTE 10Generally, specimens can
33、 be removed from capping orcasting plates after 30 min without damaging the cap. However, the lengthof time to assure setting of the cap will vary depending on a variety offactors such as the water-gypsum cement ratio used, environmentalconditions, the properties of the specimen being capped, and th
34、e tempera-ture of the mix water.7.2.2 Capping Using Sulfur Capping Materials:7.2.2.1 (Warning Hydrogen sulfide gas is often producedduring capping when sulfur capping material is contaminatedwith organic materials such as paraffin or oil. The gas iscolorless and has a notoriously bad odor of rotten
35、eggs;however, the odor is not a reliable warning sign, since thesensitivity to the odor disappears rapidly on exposure. Highconcentrations are lethal and less concentrated dosages mayproduce nausea, stomach distress, dizziness, headache, orirritation of the eyes. For this and other safety reasons, l
36、ocatethe capping station in a well-ventilated area and the melting potunder a hood with an exhaust fan.)7.2.2.2 (Warning Sulfur capping materials are used in ahot, molten state. Adequate protection is required to preventcontact with eyes, hands and other parts of the body.)7.2.2.3 Heat the sulfur mi
37、xture in a thermostatically con-trolled heating pot to a temperature of 265 to 290F (129 toC 1552 03a2143C) to maintain fluidity after contact with the cappingsurface. Verify sulfur capping material temperature using anall-metal thermometer placed at the center of the mass. Verifytemperature at hour
38、ly intervals during capping operations.7.2.2.4 Empty the pot and recharge with fresh materialsperiodically to ensure that the oldest material in the pot has notbeen used more than five times. Fresh sulfur capping materialshall be dry at the time it is placed in the pot as dampness maycause foaming.
39、Keep water away from the molten sulfurcapping material for the same reason.7.2.2.5 Warm the capping plate before use to slow the rateof hardening of the molten sulfur capping material and topermit the production of thin caps. Lightly oil the surface of thecapping plate (Note 9) and stir the molten s
40、ulfur cappingmaterial immediately prior to pouring each cap.7.2.2.6 Place four 1-in. (25-mm) square steel bars on thecapping plate to form a rectangular mold whose dimensions areapproximately12 in. (13 mm) greater than the overall dimen-sions of the specimen. Fill the mold to a depth of14-in. (6 mm)
41、with the hot sulfur compound. Bring the surface of thespecimen to be capped quickly into contact with the liquid,holding the specimen so that its axis is at right angles to thesurface of the capping liquid to achieve a resulting cap that willcomply with the requirements of 7.4.7.2.2.7 Do not disturb
42、 the specimen until the sulfur com-pound has solidified and cooled.7.3 Once the caps have solidified and, in the case of sulfurcapping materials, cooled, separate the specimen from thecapping or casting plates in such manner as to prevent damageto the caps and specimens.7.4 Caps shall be perpendicul
43、ar within 0.08 in. in 8 in. (2mm in 200 mm) to the vertical axis of the specimen. Thesurfaces of the caps shall be plane within 0.003 in. in 16 in.(0.075 mm in 400 mm).7.5 The average thickness of the cap shall not exceed18 in.(3 mm).7.6 Do not patch caps. Remove imperfect caps and replacewith new o
44、nes. Do not test the specimens until the cap hasachieved the desired strength based on qualification testing.Cap age shall be at least two hours.8. Keywords8.1 cap; capping; capping materials; capping plate; castingplate; compressive strength; gypsum cement; sulfurSUMMARY OF CHANGESCommitee C15 has
45、identified the location of the following changes to this standard since C 155203 that mayimpact the use of this standard.(1) Paragraph 6.1.3 was revised and some of the informationfrom the previous version of this section was moved to Note 7.Subsequent notes were renumbered.Committee C15 has identif
46、ied the location of the following changes to this standard since C 155202 that may impact the useof this standard.(1) Requirements for verifying compliance of replacementcapping material in 5.2.1 were modified.(2) The end of 5.2 was revised to be more specific onpermitted time requirements for fulfi
47、lling the tasks of removingcubes from molds and testing them in compression.ASTM 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 validit
48、y 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 withdrawn. Your comment
49、s 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 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. Individ
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