1、Designation: C1552 09a C1552 12Standard Practice forCapping Concrete Masonry Units, Related Units andMasonry Prisms for Compression Testing1This standard is issued under the fixed designation C1552; the number immediately following the designation indicates the year oforiginal adoption or, in the ca
2、se of revision, 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 procedures for capping concrete masonry un
3、its, related units, includingcoupons or other specimens obtained from such units, and masonry prisms for compression testing.NOTE 1The testing laboratory performing these test methods should be evaluated in accordance with Practice C1093.1.2 The values stated in inch-pound units are to be regarded a
4、s standard. The values given in parentheses are 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
5、 this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C140 Test Methods for Sampling and Testing Concrete Masonry Units and Related UnitsC617 Practice for Capping Cylindrica
6、l Concrete SpecimensC1093 Practice for Accreditation of Testing Agencies for MasonryC1232 Terminology of MasonryC1314 Test Method for Compressive Strength of Masonry Prisms3. Terminology3.1 Terminology defined in Terminology C1232 shall apply for this practice.4. Significance and Use4.1 This practic
7、e describes procedures for providing plane surfaces on the two bearing surfaces of units and prisms. The purposeof this standard is to provide consistent and standardized procedures for capping units and prisms for compression testing. Theprocedures are based on those contained (or previously contai
8、ned) in Test Methods C140, Practice C617, and Test Method C1314.NOTE 2Specimens capped using this practice will vary significantly in size and weight. Appropriate care and handling may differ based on specimensize and weight. Provide care and handling as needed to provide for proper capping based on
9、 the physical characteristics of the specimen being capped.5. Apparatus5.1 Capping PlateIf used, the capping plate shall be made of steel having a thickness of not less than 1 in. (25.4 mm), or apolished plate of granite or diabase at least 3 in. (76 mm) thick. The capping surface shall be plane wit
10、hin 0.0030.002 in. in 1612in. (0.075(0.05 mm in 400300 mm) and shall be free of gouges, grooves, and indentations greater than 0.010 in. (0.25 mm) deepor greater than 0.05 in.2 (32 mm2) in surface area. At the time of capping, the capping surface shall be level within 116 in. (1.6 mm)over the length
11、 of the plate.5.1.1 Capping Wear PlateIf used, the capping wear plate shall be placed directly on top of the capping plate and shall meetthe requirements of 5.2. At the time of capping, the wear plate surface shall be level within 116 in. (1.6 mm) over the length ofthe plate. Do not use a capping we
12、ar plate with sulfur capping materials.1 This practice is under the jurisdiction of ASTM Committee C15 on Manufactured Masonry Units and is the direct responsibility of Subcommittee C15.04 on Research.Current edition approved Dec. 1, 2009Dec. 1, 2012. Published December 2009 December 2012. Originall
13、y approved in 2002. Last previous edition approved in 2009 asC1552 09.C1552 09a. DOI: 10.1520/C1552-09A.10.1520/C1552-12.2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, re
14、fer 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 version. Becauseit may not be technically possible to adequately depict all c
15、hanges 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100
16、Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1NOTE 3A capping wear plate has been found to reduce the potential of damage to the capping plate. The capping wear plate is typically more resistantto scratches and can be replaced at less cost than that required to resu
17、rface the capping plate. See Fig. 1 for a schematic of capping setup when usinggypsum cement materials.5.2 Casting PlateIf used, the casting plate shall be of transparent glass with a thickness of not less than 12 in. (13 mm). Thecasting plate shall be plane within 0.0030.002 in. in 1612 in. (0.075(
18、0.05 mm in 400300 mm).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 required in 6.2, qualification tests shall be made to determine the effectsof water-cement ratio and age on compressive strength. Proced
19、ures used for preparing the high strength gypsum cement cappingmaterials shall ensure that water-cement ratios used for each batch provide the required strength.NOTE 4The water-gypsum cement ratio should typically be between 0.26 and 0.30. Use of low water-gypsum cement ratios and vigorous mixing wi
20、llusually permit development of 3500 psi (24.1 MPa) at ages of one or two hours. Higher water-gypsum cement ratios extend working time, but reducestrength.6.1.1.2 Do not add fillers or extenders to the high strength gypsum cement.NOTE 5Retarders extend working time for capping materials but their ef
21、fects on required water-cement ratio should be determined prior to use.NOTE 6See Appendix X1 for more information on high-strength gypsum capping materials and product recommendations.6.1.2 Sulfur Capping Materials:6.1.2.1 Proprietary or laboratory prepared sulfur mixtures shall contain 40 to 60 % s
22、ulfur by weight, the remainder being groundfire 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 and 6.1.2. Do not use other capping materials.NOTE 7Examples of materials that have been found to b
23、e unsuitable for capping purposes include, but are not limited to: low-strength molding plaster,plaster of paris, mixtures of plaster of paris and portland cement, and other cement-based materials.6.2 Compressive Strength of Capping MaterialsThe compressive strength of the capping material shall be
24、at least 3500 psi(24.1 MPa) at an age of 2 h. The cube molds and methods of preparing and testing the cubes shall be in accordance with PracticeC617. The capping material shall be placed in the cube at capping consistency. Store the filled molds in laboratory air. Removecubes of sulfur material afte
25、r solidification is complete and remove cubes of gypsum cement material from the molds not morethan 15 min prior to testing. Test cubes at an age of 2 h 6 10 min after completing the filling of the molds.6.2.1 The strength of the capping material shall be determined on receipt of a new lot and at in
26、tervals not exceeding threemonths. If a given test of the capping material fails to conform to the strength requirements, the package from which the materialwas sampled shall not be used unless two additional subsequent samples are taken from the same package and both of thesesubsequent samples conf
27、orm to the strength requirements. If the strength tests from an individual package are inadequate,randomly obtain and test three additional samples from the lot. These additional samples shall be taken from separate packages,if available. Unless these three samples conform to the strength requiremen
28、ts, no part of the lot shall be used.FIG. 1 Gypsum Capping SchematicC1552 1227. Procedure7.1 Preparation of Specimens for CappingUse an abrasive stone to remove loose protrusions from the surfaces of thespecimens to be capped. Refer to the appropriate compression test method (Test Methods C140 or Te
29、st Method C1314) for otherspecimen preparation requirements.7.2 Capping Test SpecimensCap top and bottom bearing surfaces of specimens by one of the methods in 7.2.1 or 7.2.2. Usealignment devices as needed to make sure the caps meet the requirements of 7.4.NOTE 8Various alignment devices have been
30、demonstrated to be effective. For capping with sulfur materials, which sets quickly, alignment jigs makesure that the specimen is placed on the capping plate correctly in the first motion. For capping with gypsum cement materials, levels placed across thetop of specimen have proven to work well. Bul
31、lseye levels work particularly well with smaller specimens.7.2.1 Capping Using Gypsum Cement MaterialsSeeFig. 1 for capping setup. Spread the gypsum cement capping material evenly on the capping plate or capping wear plate that hasbeen lightly coated with oil or sprayed with a TFE-fluorocarbon coati
32、ng (Note 9). Bring the surface of the specimen to be cappedinto contact with the capping material; firmly press down the specimen with a single motion, holding it so that its axis is at rightangles to the capping surface to comply with the requirements of 7.4. Do not disturb the specimen until the c
33、apping material hassolidified.7.2.1.1 Alternative Capping Method Using Gypsum Cement MaterialsSee Fig. 1 for capping setup. Spread the gypsumcement capping material evenly on the top surface of the specimen. Bring the casting plate, which has been lightly coated withoil or sprayed with TFE-fluorocar
34、bon coating (Note 9), into contact with the capping paste; firmly press down the plate with asingle motion holding it so it is at right angles to the specimen. Within 30 s, lightly adjust the plate to achieve a resulting cap thatwill comply with the requirements of 7.4. Do not further disturb the sp
35、ecimen or casting plate until the capping material hassolidified.NOTE 9The use of oil or TFE-fluorocarbon coatings on capping or casting plates is not necessary if it is found that the plate and specimen can beseparated without damaging the cap.NOTE 10Generally, specimens can be removed from capping
36、 or casting plates after 30 min without damaging the cap. However, the length of timeto assure setting of the cap will vary depending on a variety of factors such as the water-gypsum cement ratio used, environmental conditions, theproperties of the specimen being capped, and the temperature of the m
37、ix water.7.2.2 Capping Using Sulfur Capping Materials:7.2.2.1 (WarningHydrogen sulfide gas is often produced during capping when sulfur capping material is contaminated withorganic materials such as paraffin or oil. The gas is colorless and has a notoriously bad odor of rotten eggs; however, the odo
38、r isnot a reliable warning sign, since the sensitivity to the odor disappears rapidly on exposure. High concentrations are lethal and lessconcentrated dosages may produce nausea, stomach distress, dizziness, headache, or irritation of the eyes. For this and other safetyreasons, locate the capping st
39、ation in a well-ventilated area and the melting pot under a hood with an exhaust fan.)7.2.2.2 (WarningSulfur capping materials are used in a hot, molten state. Adequate protection is required to prevent contactwith eyes, hands and other parts of the body.)7.2.2.3 Heat the sulfur mixture in a thermos
40、tatically controlled heating pot to a temperature of 265 to 290F (129 to 143C) tomaintain fluidity after contact with the capping surface. Verify sulfur capping material temperature using an all-metal thermometerplaced at the center of the mass. Verify temperature at hourly intervals during capping
41、operations.7.2.2.4 Empty the pot and recharge with fresh materials periodically to ensure that the oldest material in the pot has not beenused more than five times. Fresh sulfur capping material shall be dry at the time it is placed in the pot as dampness may causefoaming. Keep water away from the m
42、olten sulfur capping material for the same reason.7.2.2.5 Warm the capping plate before use to slow the rate of hardening of the molten sulfur capping material and to permit theproduction of thin caps. Lightly oil the surface of the capping plate (Note 9) and stir the molten sulfur capping materiali
43、mmediately prior to pouring each cap.7.2.2.6 Form a rectangular mold on the capping plate whose dimensions are approximately 12 in. (13 mm) greater than theoverall dimensions of the specimen. The mold must be sufficiently rigid to not move or deflect during the capping operation, andlarge enough to
44、accommodate the specimen to be capped and the sulfur capping material without overflow. (See Note 11.) Fill themold to a depth of 14 in. (6 mm) with the hot sulfur compound. Bring the surface of the specimen to be capped quickly into contactwith the liquid, holding the specimen so that its axis is a
45、t right angles to the surface of the capping liquid to achieve a resultingcap that will comply with the requirements of 7.4.NOTE 11The use of four 1-in. square steel bars has been found to be adequate for forming this capping mold.7.2.2.7 Do not disturb the specimen until the sulfur compound has sol
46、idified and cooled.7.3 Once the caps have solidified and, in the case of sulfur capping materials, cooled, separate the specimen from the cappingor casting plates in such manner as to prevent damage to the caps and specimens.7.4 Caps shall be perpendicular within 0.08 in. in 8 in. (2 mm in 200 mm) t
47、o the vertical axis of the specimen. The Forspecimens up to 12 in. in length, the surfaces of the caps shall be plane within 0.0030.002 in. in 1612 in. (0.075(0.05 mm in 400mm).300 mm). For specimens greater than 12 in. in length, the surfaces of the caps shall be in plane within 0.002 in. in any 12
48、in. (0.05 mm in 300 mm) span.C1552 1237.5 The average thickness of the cap shall not exceed 18 in. (3 mm).7.6 Do not patch caps. Remove imperfect caps and replace with new ones. Do not test the specimens until the cap has achievedthe desired strength based on qualification testing. Cap age shall be
49、at least two hours.8. Keywords8.1 cap; capping; capping materials; capping plate; casting plate; compressive strength; gypsum cement; sulfurAPPENDIX(Nonmandatory Information)X1. HIGH-STRENGTH GYPSUM CAPPING MATERIALSX1.1 High-strength gypsum capping materials have been successfully used for capping of many concrete products, especiallyconcrete masonry products. Currently, gypsum capping materials are required for capping of concrete paving units in accordancewith Test Methods C140.X1.2 An important factor in producing high-quality gypsum caps is t
