1、Designation: C 1552 08aStandard 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 () 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, r
3、elated 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 stan
4、dard. The values given in parentheses are mathematicalconversions 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 st
5、andard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 140 Test Methods for Sampling and Testing ConcreteMasonry Units and Related UnitsC 617 Practice for Capping Cylindrical Co
6、ncrete Speci-mensC 1093 Practice for Accreditation of Testing Agencies forMasonryC 1209 Terminology of Concrete Masonry Units and Re-lated UnitsC 1232 Terminology of MasonryC 1314 Test Method for Compressive Strength of MasonryPrisms3. Terminology3.1 Terminology defined in Terminology C 1209 and Ter
7、-minology C 1232 shall 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
8、 compressiontesting. The procedures are based on those contained (orpreviously contained) in Test Methods C 140, Practice C 617,and Test Method C 1314.NOTE 2Specimens capped using this practice will vary significantlyin size and weight. Appropriate care and handling may differ based onspecimen size
9、and weight. Provide care and handling as needed to providefor proper capping based on the physical characteristics of the specimenbeing capped.5. Apparatus5.1 Capping PlateIf used, the capping plate shall be madeof steel having a thickness of not less than 1 in. (25.4 mm), ora polished plate of gran
10、ite or diabase at least 3 in. (76 mm)thick. The capping surface shall be plane within 0.003 in. in 16in. (0.075 mm in 400 mm) and shall be free of gouges, grooves,and indentations greater than 0.010 in. (0.25 mm) deep orgreater than 0.05 in.2(32 mm2) in surface area. At the time ofcapping, the cappi
11、ng surface shall be level within116 in. (1.6mm) over the length of the plate.5.1.1 Capping Wear PlateIf used, the capping wear plateshall be placed directly on top of the capping plate and shallmeet the requirements of 5.2. At the time of capping, the wearplate surface shall be level within116 in. (
12、1.6 mm) over thelength of the plate. Do not use a capping wear plate with sulfurcapping materials.NOTE 3A capping wear plate has been found to reduce the potentialof damage to the capping plate. The capping wear plate is typically moreresistant to scratches and can be replaced at less cost than that
13、 required toresurface the capping plate. See Fig. 1 for a schematic of capping setupwhen using gypsum cement materials.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.(
14、0.075 mm in 400 mm).6. Materials6.1 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 Nov. 1,
15、2008. Published November 2008. Originallyapproved in 2002. Last previous edition approved in 2008 as C 1552 08.2For 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 s
16、tandards Document Summary 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
17、6.2, qualification tests shall 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-g
18、ypsum cement ratio should 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 filler
19、s or extenders to the high 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: Hydrostone (trademarked) an
20、d Hydrocal (trade-marked) white gypsum cement. Both are available from U.S. GypsumCompany.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
21、 No.100 (150-m) sieve with or without a plasticizer.6.1.3 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, pl
22、aster of paris, mixtures of plaster of paris and portland 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 t
23、he cubes shall be in accordance withPractice C 617. The 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 tha
24、n 15 min prior to testing. Test cubes atan age of 2 h 6 10 min after completing the filling of themolds.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 s
25、trength requirements, the package from whichthe 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, ra
26、ndomly obtain and test three addi-tional samples 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-
27、sive stone to remove loose protrusions from the surfaces of thespecimens to be capped. Refer to the appropriate compressiontest method (Test Methods C 140 or Test Method C 1314) forother specimen preparation requirements.7.2 Capping Test SpecimensCap top and bottom bearingsurfaces of specimens by on
28、e of the methods in 7.2.1 or 7.2.2.Use alignment devices as needed to 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 th
29、e capping plate correctlyin the first motion. For capping with gypsum 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 MaterialsSeeFig. 1 for capping setup. Spread the gy
30、psum cement cappingFIG. 1 Gypsum Capping SchematicC 1552 08a2material evenly on the capping plate or capping wear plate thathas been lightly coated with oil or sprayed with a TFE-fluorocarbon coating (Note 9). Bring the surface of the speci-men to be capped into contact with the capping material; fi
31、rmlypress down the specimen with a single motion, holding it sothat its axis is at right angles to the capping surface to complywith the requirements of 7.4. Do not disturb the specimen untilthe capping material has solidified.7.2.1.1 Alternative Capping Method Using Gypsum CementMaterialsSee Fig. 1
32、 for capping setup. Spread the gypsumcement capping material evenly on the top surface of thespecimen. Bring the casting plate, which has been lightlycoated with oil or sprayed with TFE-fluorocarbon coating(Note 9), into contact with the capping paste; firmly pressdown the plate with a single motion
33、 holding it so it is at rightangles to the specimen. Within 30 s, lightly adjust the plate toachieve a resulting cap that will comply with the requirementsof 7.4. Do not further disturb the specimen or casting plate untilthe capping material has solidified.NOTE 9The use of oil or TFE-fluorocarbon co
34、atings 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 be removed from capping orcasting plates after 30 min without damaging the cap. However, the lengthof time to assure setting of the
35、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 the tempera-ture of the mix water.7.2.2 Capping Using Sulfur Capping Materials:7.2.2.1 (WarningHydrogen sulfide gas is often produceddu
36、ring 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 eggs;however, the odor is not a reliable warning sign, since thesensitivity to the odor disappears rapidly on exposure. Highconcentrat
37、ions are lethal and less concentrated dosages mayproduce nausea, stomach distress, dizziness, headache, orirritation of the eyes. For this and other safety reasons, locatethe capping station in a well-ventilated area and the melting potunder a hood with an exhaust fan.)7.2.2.2 (WarningSulfur capping
38、 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 mixture in a thermostatically con-trolled heating pot to a temperature of 265 to 290F (129 to143C) to maintain fluidity after contact wit
39、h the cappingsurface. Verify sulfur capping material temperature using anall-metal thermometer placed at the center of the mass. Verifytemperature at hourly intervals during capping operations.7.2.2.4 Empty the pot and recharge with fresh materialsperiodically to ensure that the oldest material in t
40、he 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. 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
41、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 sulfur cappingmaterial immediately prior to pouring each cap.7.2.2.6 Form a rectangular mold on the capping plate whosedimensions are approximately
42、12 in. (13 mm) greater than theoverall dimensions of the specimen. The mold must besufficiently rigid to not move or deflect during the cappingoperation, and large enough to accommodate the specimen tobe capped and the sulfur capping material without overflow.(See Note 11.) Fill the mold to a depth
43、of14 in. (6 mm) withthe hot sulfur compound. Bring the surface of the specimen tobe capped quickly into contact with the liquid, holding thespecimen so that its axis is at right angles to the surface of thecapping liquid to achieve a resulting cap that will comply withthe requirements of 7.4.NOTE 11
44、The use of four 1-in. square steel bars has been found to beadequate for forming this capping mold.7.2.2.7 Do not disturb 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 fro
45、m thecapping or casting plates in such manner as to prevent damageto the caps and specimens.7.4 Caps shall be perpendicular 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 ave
46、rage thickness of the cap shall not exceed18 in.(3 mm).7.6 Do not patch caps. Remove imperfect caps and replacewith new ones. 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; cappi
47、ng materials; capping plate; castingplate; compressive strength; gypsum cement; sulfurC 1552 08a3SUMMARY OF CHANGESCommittee C15 has identified the location of selected changes to this standard since the last issue(C 1552 08) that may impact the use of this standard. (Approved Nov. 1, 2008.)(1) Adde
48、d a requirement to 5.1.1 that the capping wear platebe level at the time of capping.(2) Added Fig. 1 to clarify configuration when capping andwhen casting.Committee C15 has identified the location of selected changes to this standard since the last issue(C 1552 07) that may impact the use of this st
49、andard. (Approved June 1, 2008.)(1) Revised 5.1 to allow the use of granite or diabase as acapping plate material.(2) Revised 7.2.2.6 in regards to sulfur capping molds.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 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
