1、Designation: C 1552 09Standard 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 re
2、vision, 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, re
3、lated 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 stand
4、ard. 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 sta
5、ndard 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 Con
6、crete Speci-mensC 1093 Practice for Accreditation of Testing Agencies forMasonryC 1232 Terminology of MasonryC 1314 Test Method for Compressive Strength of MasonryPrisms3. Terminology3.1 Terminology defined in Terminology C 1232 shall applyfor this practice.4. Significance and Use4.1 This practice d
7、escribes 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 compressiontesting. The procedures are based on those contained (orpreviously contained)
8、 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 and weight. Provide care and handling as needed to providefor proper capping based on the
9、 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 granite or diabase at least 3 in. (76 mm)thick. The capping surface shall be plane within 0.0
10、03 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 capping surface shall be level within116 in. (1.6mm) over the length of the plate.5.1.1 Cappin
11、g 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. (1.6 mm) over thelength of the plate. Do not use a capping wear plate with sulfurcapping m
12、aterials.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 required toresurface the capping plate. See Fig. 1 for a schematic of capping setupwhen
13、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.(0.075 mm in 400 mm).1This practice is under the jurisdiction of ASTM Committee C15 on Man
14、ufac-tured Masonry Units and is the direct responsibility of Subcommittee C15.04 onResearch.Current edition approved June 1, 2009. Published June 2009. Originallyapproved in 2002. Last previous edition approved in 2008 as C 1552 08a.2For referenced ASTM standards, visit the ASTM website, www.astm.or
15、g, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards 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 C
16、700, West Conshohocken, PA 19428-2959, United States.6. Materials6.1 Capping Materials:6.1.1 High Strength Gypsum Cement Capping Materials:6.1.1.1 In addition to the compressive strength testing re-quired in 6.2, qualification tests shall be made to determine theeffects of water-cement ratio and age
17、 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 typically be between0.26 and 0.30. Use of low water-gypsum cement
18、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 strengthgypsum cement.NOTE 5Retarders extend working time for cap
19、ping materials but theireffects on required water-cement ratio should be determined prior to use.NOTE 6Hydrostone (trademarked) gypsum cement has been success-fully used for this purpose. It is available from U.S. Gypsum Company.6.1.2 Sulfur Capping Materials:6.1.2.1 Proprietary or laboratory prepar
20、ed 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.6.1.3 Use only capping materials identified in 6.1.1 and6.1.2. Do not use other capping materials.NOTE 7Examp
21、les 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 portland cement,and other cement-based materials.6.2 Compressive Strength of Capping MaterialsThe com-pressive s
22、trength 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 withPractice C 617. The capping material shall be placed in thecube at capping consistency. Store the filled molds in labora-tory
23、 air. Remove cubes of sulfur material after solidification iscomplete and remove cubes of gypsum cement material fromthe molds not more than 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
24、-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 whichthe material was sampled shall not be used unless twoadditional subsequent samples are taken from the same pack-age a
25、nd 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 samples from the lot. These additional samples shall betaken from separate packages, if available. Unless these threesam
26、ples 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 the surfaces of thespecimens to be capped. Refer to the appropriate compressiontest method (Test Methods C 140 or Tes
27、t Method C 1314) forother specimen preparation requirements.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 to make sure the caps meetthe requirements of 7.4.NOTE 8Various alignment devices have been de
28、monstrated 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 gypsum cement materials, levelsplaced across the top of specimen have proven to work well. Bullsey
29、elevels work particularly well with smaller specimens.FIG. 1 Gypsum Capping SchematicC15520927.2.1 Capping Using Gypsum Cement MaterialsSeeFig. 1 for capping setup. Spread the gypsum cement cappingmaterial evenly on the capping plate or capping wear plate thathas been lightly coated with oil or spra
30、yed with a TFE-fluorocarbon coating (Note 9). Bring the surface of the speci-men to be capped into contact with the capping material; firmlypress 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
31、 disturb the specimen untilthe capping material has solidified.7.2.1.1 Alternative Capping Method Using Gypsum CementMaterialsSee Fig. 1 for capping setup. Spread the gypsumcement capping material evenly on the top surface of thespecimen. Bring the casting plate, which has been lightlycoated with oi
32、l or sprayed with TFE-fluorocarbon coating(Note 9), into contact with the capping paste; firmly pressdown the plate with a single motion 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. D
33、o not further disturb the specimen or casting plate untilthe capping material has solidified.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
34、can 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
35、 the tempera-ture of the mix water.7.2.2 Capping Using Sulfur Capping Materials:7.2.2.1 (WarningHydrogen 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 rotte
36、n 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,
37、 locatethe capping station in a well-ventilated area and the melting potunder a hood with an exhaust fan.)7.2.2.2 (WarningSulfur 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 m
38、ixture in a thermostatically con-trolled heating pot to a temperature of 265 to 290F (129 to143C) 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 hourly interva
39、ls 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. Keep water
40、 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 sulfur capp
41、ingmaterial immediately prior to pouring each cap.7.2.2.6 Form a rectangular mold on the capping plate whosedimensions are approximately12 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
42、enough to accommodate the specimen tobe capped and the sulfur capping material without overflow.(See Note 11.) Fill the mold to a depth 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 axi
43、s is at right angles to the surface of thecapping liquid to achieve a resulting cap that will comply withthe requirements of 7.4.NOTE 11The 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 ha
44、s 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 perpendicular within 0.08 in. in 8 in. (2mm in 200 mm)
45、 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 ones. Do not test the specimens until the ca
46、p 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; sulfurC1552093SUMMARY OF CHANGESCommittee C15 has identified the location of selecte
47、d changes to this standard since the last issue(C 1552 08a) that may impact the use of this standard. (Approved June 1, 2009.)(1) Revised Note 6.Committee 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. (A
48、pproved Nov. 1, 2008.)(1) Added 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.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any i
49、tem 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 by the responsible technical committee and must be reviewed 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 com
