1、Designation: C 952 02 (Reapproved 2009)Standard Test Method forBond Strength of Mortar to Masonry Units1This standard is issued under the fixed designation C 952; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev
2、ision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method provides two procedures for
3、measuringbond strength of mortar to masonry units: a crossed brickcouplet tensile test for evaluating mortar-brick bond strengthand a stacked-bond, flexural test for evaluating mortar-concreteblock bond strength.1.2 The values stated in inch-pound units are to be regardedas standard. The values give
4、n 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 the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropri
5、ate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C67 Test Methods for Sampling and Testing Brick andStructural Clay TileC90 Specification for Loadbearing Concrete MasonryUnitsC 129 Specification for Nonloa
6、dbearing Concrete MasonryUnitsC 140 Test Methods for Sampling and Testing ConcreteMasonry Units and Related UnitsC 270 Specification for Mortar for Unit MasonryC 780 Test Method for Preconstruction and ConstructionEvaluation of Mortars for Plain and Reinforced UnitMasonryC 1072 Test Method for Measu
7、rement of Masonry FlexuralBond StrengthC 1357 Test Methods for Evaluating Masonry BondStrengthC 1437 Test Method for Flow of Hydraulic Cement MortarE 518 Test Methods for Flexural Bond Strength of Masonry3. Significance and Use3.1 These procedures are useful for research into bondstrength of masonry
8、. They are not intended to predict the bondstrength of commercial masonry construction. The bondstrength in commercially built structures is determined bymany factors beyond the characteristics of mortar, masonryunits, and the procedures of this test method.NOTE 1The crossed-brick couplets method me
9、asures a direct tensilestrength of the bond between the mortar and masonry unit. It does notdetermine the flexural strength of the unit mortar assembly. Other testmethods may be more appropriate for determining the flexural bondstrength between mortar and masonry units. These include Test MethodC 10
10、72, Test Methods C 1357, and Test Methods E 518.PREPARATION AND TESTING OF FRESH MORTAR4. Preparation of Mortar4.1 Proportion mortar materials by weights equivalent tovolume proportions to be used in prism construction. Use unitweights for individual materials as given in SpecificationC 270. Sand sh
11、all be permitted to be used in a damp loosecondition, provided that moisture content of sand is determinedwith reference to the oven-dried condition and batch propor-tions are adjusted accordingly. Record weight of ingredients(including water) added to the batch of mortar.4.2 Mix mortar in a mechani
12、cal paddle-type mortar mixer.Time periods referenced below are measured from when waterand cementitious materials are combined.4.2.1 Add an estimated amount of water to the mortar toachieve the desired consistency (Note 2). Mix mortar for threeminutes and determine consistency. If the desired consis
13、tencyis specified by flow determine it in accordance with TestMethod C 1437. If the desired consistency is specified as initialcone penetration, determine it in accordance with Test MethodC 780. Once consistency is recorded, return the material usedto measure the consistency to the mixer. If the con
14、sistency iswithin the desired range, continue mixing the batch for anadditional two minutes. If the consistency is less than the1This test method is under the jurisdiction of ASTM Committee C15 onManufactured Masonry Units and is the direct responsibility of SubcommitteeC15.04 on Research. Committee
15、 E-6 maintains a continued interest in thesepractices and will make use of them in the future.Current edition approved June 1, 2009. Published July 2009. Originally approvedin 1959. Last previous edition approved in 2002 as C 952 021.2For referenced ASTM standards, visit the ASTM website, www.astm.o
16、rg, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.desired rang
17、e, add water to the batch and mix for one minuteand determine consistency. Once consistency is recorded,return the material used to measure consistency to the mixer. Ifthe consistency is within the desired range, continue mixing thebatch for one minute.NOTE 2Workable consistency of mortar for concre
18、te masonry con-struction generally requires an initial cone penetration reading of 55 6 5mm or a flow of 125 6 5 %. Workable consistency of mortar for claymasonry construction generally requires an initial cone penetrationreading of 65 6 5 mm or a flow of 135 6 5 %. Optimum consistency fora specific
19、 mortar-unit combination may differ from these values.4.2.2 If after the one-time addition of water the consistencyis not in the desired range, discard the batch.4.2.3 If the measured consistency exceeds the desired rangeat any time, discard the batch.4.3 Immediately after mixing the mortar, determi
20、ne itsinitial cone penetration in accordance with Test Method C 780.Determine the cone penetration of the mortar every 15 6 5minutes. If the cone penetration is less than 80 % of its initialvalue, discard the remaining portion of the mortar withoutconstructing additional mortar joints.PREPARATION AN
21、D TESTING OF BOND STRENGTHTEST SPECIMENS5. Apparatus5.1 MiscellaneousBrass-covered mortar board 18 in. (457mm) square, an 11-in. (279-mm) long masons trowel, labora-tory trowel with straight edges, short handled spoon or scoopof14-cup (0.5-dm3) capacity, steel straightedge 10 in. (254mm) long, metal
22、 mold12 in. (13 mm) deep with 358-in.(92-mm) square opening beveled to slope of 0.08 (total 0.04),splash board (Fig. 1) with handle 20 in. (508 mm) long and 3in. (76 mm) wide.5.2 Drop Hammer for crossed-brick couplets (Fig. 2, Table1).5.3 Drop Hammer for block assemblies (Fig. 3).5.4 Loading Jigs fo
23、r crossed-brick couplets (Fig. 4).5.5 Frames (Fig. 5) for testing block assemblies: upperframe fitted with ball bearing mounted 10 in. (254 mm) fromvertical axis of specimen for eccentric application of verticalload. .5.6 Torque Wrench.6. Crossed-Brick Couplets6.1 BrickTest specimens consisting of c
24、rossed-brick cou-plets may be used to determine:6.1.1 Bond between specified brick and a specified mortar,6.1.2 Relative bond between different brick and a specifiedmortar, or6.1.3 Relative bond between a specified brick and differentmortars.6.1.4 In each case, the initial rate of absorption of the
25、brickshall be determined in accordance with Test Methods C67. Thebrick used for couplets shall include the full range of absorp-tion rates acceptable under the specifications.6.2 Construction of Test Specimens:6.2.1 Center the mold on the lower brick of the couplet andlightly mix a small quantity of
26、 mortar on the board by turningover with the spoon.6.2.2 Half-fill the mold by sharply dashing into each cornerand the center of the mold a small quantity of mortar from thehalf-filled spoon. Note the time at start of a 1-min interval.Apply additional mortar by heaping loosely with the spoonabove th
27、e top of the mold. Strike off excess mortar with thestraightedge, starting on a diagonal across the mold andworking first to one corner and then to the opposite corner ofthe mold. Remove the mold from the mortar bed.6.2.3 At the end of the 1-min time interval, place the upperbrick on the mortar bed
28、in a crosswise direction to the lowerbrick. Place the frame of the hammer on the top brick with theweight of the hammer held in the other hand. Drop the hammerin a frame a distance of 112 in. (38 mm).6.2.4 Measure and record the extrusion of the mortar on thetop surface of the lower brick. Cut away
29、extruded mortar fromall four edges of the mortar bed.6.3 CuringPromptly enclose the test specimen within anairtight covering. Keep covered for 7 days. Remove the coverand store until tested. Unless otherwise specified, the specimenshall be stored in laboratory air at a relative humidity of at least5
30、0 %.6.4 TestingCenter the specimen between the upper andlower tripods and place in the testing machine as shown in Fig.6. Load the specimen at the rate of 600 lb (2.7 kN)/min or ata rate sufficient to cause failure in 1 to 2 min. Note and recordmaximum load and type of failure.NOTE 3The method of ma
31、king the specimens typically produces afailure of the joint at the top of the mortar bed.NOTE 4Reproducibility of test results may be improved by theinsertion of strips of high-density insulation board interlayers between thetest specimen and test apparatus.6.5 CalculationCalculate the maximum tensi
32、le bondstrength as follows:FIG. 1 Splash BoardC 952 02 (2009)2Tensile bond strength, T, psi or N/m2! 5 A/B (1)where:A = total applied load, lbf (or N), andB = cross-sectional area in bond, in.2(or m2).7. Concrete Masonry Unit Assemblies7.1 Concrete Masonry UnitsConcrete masonry units usedin test spe
33、cimens shall conform to Specification C90or C 129.The moisture content of the concrete masonry units shall be asspecified. In the absence of any other specified moisturecontent, the concrete masonry units shall be conditioned tohave a moisture content of between 25 % and 35 % of totalabsorption, as
34、determined in accordance with Test MethodsC 140.7.2 Construction of Test Specimens:7.2.1 Position the bottom concrete masonry unit of theassembly on a metal pallet with the thickest part of the faceshells upwards. Lightly turn over and remix the mortar on theboard with a masons trowel.7.2.2 With a m
35、asons trowel and technique, apply mortar tothe top of the face shell that will be in the compressive face ofthe specimen, when tested. The amount of mortar applied shallFIG. 2 Drop Hammer for Cross-Brick CoupletsTABLE 1 Metric Equivalents for Figs. 2, 3, 4, 5, and 6Inch-Pound Metric Inch-Pound Metri
36、c Inch-Pound Metric1/16 in. 1.6 mm 134 in. 44 mm 5 in. 127 mm18 in. 3 mm 178 in. 48 mm 514 in. 133 mm3/16 in. 4.7 mm 2 in. 51 mm 534 in. 146 mm14 in. 6.4 mm 218 in. 54 mm 6 in. 152 mm38 in. 9.5 mm 214 in. 57 mm 614 159 mm7/16 in. 11 mm 238 in. 61 mm 712 in. 190 mm12 in. 12.7 mm 212 in. 64 mm 8 in. 2
37、03 mm58 in. 15.8 mm 258 in. 67 mm 812 in. 216 mm34 in. 19 mm 3 in. 76 mm 934 in. 248 mm7/8 in. 22 mm 318 in. 79 mm 1034 in. 273 mm1 in. 25 mm 314 in. 82 mm 16 in. 406 mm118 in. 28 mm 312 in. 89 mm 1612 in. 419 mm1316 in. 30 mm 358 in. 92 mm 1834 in. 476 mm114 in. 32 mm 334 in. 95mm 28in. 711mm138 in
38、. 35 mm 4 in. 102 mm 2 lb 0.9 kg112 in. 38 mm 434 in. 121 mm 3.5 lb 1.6 kgC 952 02 (2009)3FIG. 3 Drop Hammer for Concrete Block AssembliesFIG. 4 Loading Jigs for Crossed-Brick CoupletsC 952 02 (2009)4be sufficient to produce a bed joint of the desired thickness inthe finished specimen (Note 5). In t
39、he absence of any specifiedthickness, the bed joints in the finished specimen shall be of anominal38-in. (9.5-mm) thickness.FIG. 5 Frames for Testing Concrete Block AssembliesFIG. 5 Frames for Testing Concrete Block Assemblies (continued)C 952 02 (2009)5NOTE 5The consistency of the mortar, when made
40、, and the amount ofwater used in the mortar shall have been adjusted to meet the requirementsfor the proper joint thickness of concrete masonry unit assemblies.7.2.3 Hold the splash board along the top of the oppositeface shell (the shell that will be in the tensile face of thespecimen) and with the
41、 masons trowel lightly loaded, sharplydash a thin bed of mortar on the top of this shell as shown inFig. 7. Remove the splash board. Note the time for the start ofa 1-min interval. Load the trowel and build up the mortar bedby gently rolling or dropping a sufficient amount of additionalmortar.7.2.4
42、At the end of the 1-min time interval, pick up and levelthe upper concrete masonry unit of the assembly on the mortarbeds by bringing the concrete masonry unit downward andforward to one end of the lower masonry unit. The upperconcrete masonry unit shall be placed with the thin edge of theface shell
43、s in the mortar.7.2.5 Immediately position the drop hammer frame at thecenter of the upper masonry unit, holding the weight of thehammer in the other hand. Drop the hammer in the tubularFIG. 6 Crossed-Brick Test Assembly Positioned in Testing MachineFIG. 7 Preparing Concrete Block Test AssemblyC 952
44、 02 (2009)6frame a distance of 4 in. (102 mm). Remove the drop hammer.No further adjustment of the top masonry unit on its bed shallbe made.7.2.6 Measure and record the extrusion of mortar from thefaces of the specimen. Cut extruded mortar away with themasons trowel. Tool the joints with a rounded i
45、ron.7.3 CuringPromptly enclose the specimen in an airtightcovering. Keep covered for 7 days. Remove the cover and storeuntil tested. Unless otherwise specified, the specimen shall bestored in laboratory air at a relative humidity of at least 50 %.7.4 TestingClamp the specimen in the lower and uppert
46、est frames by tightening the screws of the test frames with atorque wrench (see Fig. 8). Center the ball bearing on the uppertest frame in the testing machine. Apply a vertical load to thespecimen at the rate of 600 lbf (2.7 kN)/min or at a ratesufficient to cause failure in 1 to 2 min.7.5 Calculati
47、onCalculate the maximum flexural bondstrength of the section for the gross and the net section of thespecimen, taken normal to the face shells, as follows:fg5 xPc/Ig! 2 P/Ag! (2)fn5 xPc/In! 2 P/An!where:fg= flexural bond stress on gross area, psi (or N/m2)fn= flexural bond stress on net area, psi (o
48、r N/m2),x = lever arm of load about vertical axis of specimen, in.(or m),P = applied load, lbf (or N),c = distance from neutral axis to face of specimen, in. (orm),Ig= moment of inertia of gross section, in.4(or m4),In= moment of inertia of net section, in.4(or m4),b = length of masonry unit, in. (o
49、r m),d = width of masonry unit, in. (or m),t = minimum thickness of face shell, in. (or m),Ag= gross area of section = bd, in.2(or m2), andAn= net area of section = 2bt, in.2(or m2).8. Precision and Bias8.1 Variability is a characteristic of tensile and flexural bondstresses. Round robin testing has not been performed on thesemethods. Coefficients of variation of 15 to 35 % are common-place in published investigations using the methods of thisstandard.9. Keywords9.1 bond; concrete masonry unit; crossed brick coup
