1、Designation: C1552 15C1552 16Standard 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 case
2、 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 unit
3、s, 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 as
4、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 t
5、his 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 Cylindrical
6、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 practice
7、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 containe
8、d) 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 th
9、e 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 within
10、 0.002 in. in 12 in.(0.05 mm in 300 mm) and shall be free of gouges, grooves, and indentations greater than 0.010 in. (0.25 mm) deep or greater than0.05 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 lengthof the plate.5.1.1
11、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 wear plate with sulfur
12、 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, 2015Dec. 1, 2016. Published January 2016December 2016. Originally approved in 2002. La
13、st previous edition approved in 20142015as C1552 14a.C1552 15. DOI: 10.1520/C1552-15.10.1520/C1552-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards D
14、ocument 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 changes accurately, AST
15、M 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 Barr Harbor Drive, PO
16、Box C700, West Conshohocken, PA 19428-2959. United States1NOTE 3Acapping 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 resurface the capping plate
17、. 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 0.002 in. in 12 in. (0.05 mm in 300 mm).6. Materials6.1 C
18、apping 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. Procedures used for preparing the high streng
19、th 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 willusually permit development of 3500 ps
20、i (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 effects on required water-cement ratio sh
21、ould 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 % sulfur by weight, the remainder being gr
22、oundfire 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 be unsuitable for capping purposes inclu
23、de, 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 at least 3500 psi(24.1 MPa) at an age o
24、f 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 after solidification is complete and remove
25、 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 intervals not exceeding threemonths. If a
26、 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 conform to the strength requirements. If th
27、e 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 requirements, no part of the lot shall be used.FI
28、G. 1 Gypsum Capping SchematicC1552 1627. 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 Test Method C1314) for otherspecimen prep
29、aration 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 demonstrated to be effective. For cappi
30、ng 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. Bullseye levels work particularly well wit
31、h 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 coating (Note 9). Bring the surface of the s
32、pecimen 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 capping material hassolidified.7.2.1.1 A
33、lternative 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-fluorocarbon coating (Note 9), into contact with
34、 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 specimen or casting plate until the cappi
35、ng 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 or casting plates after 30 min without
36、 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 mix water.7.2.2 Capping Using Sulfur Cap
37、ping 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 odor isnot a reliable warning sign, since
38、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 station in a well-ventilated area and the
39、 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 thermostatically controlled heating pot to a t
40、emperature 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 operations.7.2.2.4 Empty the pot and re
41、charge 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 molten sulfur capping material for the s
42、ame 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 materialimmediately prior to pouring each cap.7.
43、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 accommodate the specimen to be capped a
44、nd 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 at right angles to the surface of the ca
45、pping 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 solidified and cooled.7.3 Once the caps ha
46、ve 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) or 0.5 of the vertical axis of the speci
47、men. Forspecimens up to 12 in. in length, the surfaces of the caps shall be plane within 0.002 in. in 12 in. (0.05 mm in 300 mm). Forspecimens greater than 12 in. in length, the surfaces of the caps shall be in plane within 0.002 in. in any 12 in. (0.05 mm in300 mm) span.C1552 1637.5 The average thi
48、ckness 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 at least two hours.7.7 Capping Verifications:7.7.1 During
49、 each day of capping operations, verify the planeness of both caps prior to compression testing on at least onerandomly selected specimen. Verify by making a minimum of four measurements in two different orientations on each cap toensure that the surface of the caps do not depart from a plane by more than 0.002 in. in 12 in. (0.05 mm in 300 mm).7.7.2 During each day of capping operations, verify the perpendicularity of both caps prior to compression testing on at leastone randomly selected specimen. Verify by making a minimum of one check against
