1、Designation: C 1531 09Standard Test Methods forIn Situ Measurement Of Masonry Mortar Joint ShearStrength Index1This standard is issued under the fixed designation C 1531; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、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 These test methods cover procedures for the determina-tion of the average in situ mortar joint shear strength index i
3、nexisting unreinforced solid-unit and ungrouted hollow-unitmasonry built with clay or concrete units. Three methods areprovided:1.1.1 Method A (with Flatjacks Controlling Normal Com-pressive Stress)For determining mortar joint shear strengthindex when the state of normal compressive stress at the te
4、stsite is controlled during the test using the flatjack methoddescribed in Test Method C 1197. Horizontal displacement ofthe test unit is monitored throughout the test. The test setup forMethod A is shown in Fig. 1.1.1.2 Method B (without Flatjacks Controlling NormalCompressive Stress)For determinin
5、g mortar joint shearstrength index when using an estimate of the normal compres-sive stress at the location of the test site. Horizontal displace-ment of the test unit is not monitored during this procedure.The test set up for Method B is shown in Fig. 2.1.1.3 Method C (with Flatjack Applying Horizo
6、ntal Load)For determining mortar joint shear strength index using anestimate of the normal compressive stress at the location of thetest site, as shown in Fig. 3. Horizontal displacement of the testunit is generally not measured during this procedure.1.2 The values stated in inch-pound units are to
7、be regardedas standard. 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 t
8、he user of this standard 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 1180 Terminology of Mortar and Grout for Unit MasonryC 1196 Test Method for In Situ Compressive Stress W
9、ithinSolid Unit Masonry Estimated Using Flatjack Measure-mentsC 1197 Test Method for In Situ Measurement of MasonryDeformability Properties Using the Flatjack MethodC 1232 Terminology of MasonryE4 Practices for Force Verification of Testing Machines2.2 Other Document:Uniform Code for Building Conser
10、vation (Appendix Chap-ter 1, Earthquake Hazard Reduction in Existing Unrein-forced Masonry Buildings), International Conference ofBuilding Officials, Whittier, CA, 19973. Terminology3.1 Terminology defined in Terminologies C 1180 andC 1232 shall apply for these test methods.4. Summary of Test Method
11、4.1 The in-place shear test is used to provide an index of thein situ, horizontal shear resistance of mortar joints in unrein-forced masonry. For Method A, a single masonry unit isremoved from opposite ends of the chosen test unit as shownin Fig. 1. For Method B, a single masonry unit and a head joi
12、ntare removed from opposite ends of the chosen test unit, asshown in Fig. 2. For Method C, head joints on both ends of thetested unit are removed as shown in Fig. 3. Ensure that the bedjoints are not disturbed in the unit to be tested. The test unit isthen displaced horizontally relative to the surr
13、ounding masonryusing a hydraulic jack or specialized flatjacks. The horizontalforce required to cause first movement of the test unit providesa measured index of the mortar joint shear strength.1These test methods are under the jurisdiction of ASTM Committee C15 onManufactured Masonry Units and are
14、the direct responsibility of SubcommitteeC15.04 on Research.Current edition approved June 1, 2009. Published June 2009. Originallyapproved in 2002. Last previous edition approved in 2003 as C 1531 03.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Servic
15、e 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 C700, West Conshohocken, PA 19428-
16、2959, United States.FIG. 1 Test SetupMethod AFIG. 2 Test SetupMethod BFIG. 3 Test SetupMethod CC15310925. Significance and Use5.1 The masonry mortar joint shear strength index obtainedby this test method is related to the masonry wall shear strengthby a relationship contained within Appendix Chapter
17、 1 of theUniform Code for Building Conservation. The user of thisstandard is cautioned that the shear strength relationshipcontained within the Uniform Code for Building Conservationis an empirical relationship based on tests of early 20th-centuryunreinforced brick masonry. The relationship assumes
18、that wallshear strength is limited by shear of the mortar joints ratherthan shear through the units.5.2 For hollow ungrouted or solid unit masonry constructionthe shear strength index is measured only for the mortar bedjoints vertically adjacent to the unit being tested. When testinghollow ungrouted
19、 masonry construction, the shear strengthindex is based on the horizontal interface between the mortarand the test unit and the masonry above and below the test unit.In the case of multi-wythe construction, the measured mortarjoint shear strength index is applicable only to the wythe inwhich the tes
20、t unit is located; no headers shall exist immedi-ately above or below the test unit. The contribution of anyexisting collar joint mortar to the measured shear strengthindex is neglected, and this may lead to an overestimate of theshear strength index.5.3 The test procedure listed for Method A may be
21、 con-ducted as an extension of Test Method C 1197. The two-flatjack test, conducted in accordance with Test MethodC 1197, provides half of the required test setup for Method A.At the completion of the Method A test, one would know themeasured normal compressive stress, the deformability of themasonr
22、y at the test, and the relationship between the expectedjoint shear strength index and the normal compressive stress.6. Apparatus6.1 The following equipment is required for both Method Aand Method B:6.1.1 Equipment to measure load; two options exist: (1)Ahydraulic jack with an appropriate working pr
23、essure range toload the test unit. The force output of the jack throughout itsworking pressure range shall be known, to facilitate conversionbetween hydraulic pressure and force applied to the masonry;(2) For more precision, use a load cell to measure the forceapplied by the hydraulic jack. Verify l
24、oad in accordance withPractices E4. Place the load cell between the spherical seat andthe bearing plate nearest the test unit.6.1.2 Steel bearing plates shall be provided at each end ofthe test jack to distribute the load uniformly across the ends ofthe test unit and the reaction unit as shown in Fi
25、g. 1. Thebearing plates shall have a minimum thickness equal to18 thevertical dimension of the bearing plate. The bearing plates shallhave a vertical dimension that is18 in. (3.2 mm) less than theheight of the unit; the plate shall be centered vertically on theend of the unit. The bearing plate shal
26、l have a horizontaldimension that equals or exceeds the thickness of the unit. Thebearing plate surface in contact with the loaded unit shall befaced with a neoprene pad116 in. (1.6 mm) thick; the pad shallhave a durometer hardness in the range of 50 to 60.6.1.3 An electrically or manually operated
27、hydraulic pumpwith hydraulic hoses to pressurize the loading jack. Measurepressure using gauges calibrated to a traceable standard havingboth an accuracy of 1 % of full hydraulic scale and anappropriate operating range. The pressure gage shall have apeak hold feature to indicate the maximum hydrauli
28、c pressureattained during specimen loading. The hydraulic system shallbe capable of maintaining constant pressure within 1 % of fullscale for at least 5 min.6.2 The following additional apparatus is required forMethod A:6.2.1 Flatjacks and associated equipment to measure thestate of compressive stre
29、ss as described in Test Method C 1196.Test Method C 1197 describes apparatus necessary to apply aknown state of normal compressive stress to the masonry at thetest site using flatjacks.6.2.2 Use mechanical extensometers or electronic devices tomeasure horizontal displacement of the unit. The method
30、ordevice used to measure deformation shall be capable ofdeformation measurements up to14 in. (6 mm). Deformationmeasurements shall have an accuracy of at least 0.005 % ofgage length. Fasten brackets or other attachment devicessecurely to the surface of the masonry using a rigid adhesive.6.3 The foll
31、owing equipment is required for Method C:6.3.1 A small rectangular flatjack that is sized to fit in thehead joint on one side of the test unit. The flatjack dimensionsmust not exceed the dimensions of the end of the tested unit toprevent load application to the mortar joints.6.3.2 If load-deformatio
32、n data are required, use instrumen-tation as described in 6.2.2.7. State of Normal Compressive Stress7.1 The magnitude of normal compressive stress will have adirect effect on the measured joint shear strength index andmust be determined beforehand.7.2 Method A (with Flatjacks Controlling Normal Com
33、pres-sive Stress)Apply normal compressive stress using flatjacks.Place an upper flatjack two courses above and centered overthe test unit to within a tolerance of 618 in. (3 mm). Place alower flatjack five courses below the upper flatjack, centeredunder the test unit to within a tolerance of 618 in.
34、 (3 mm). Asingle masonry unit, located on the centerline midway betweenthe two flatjacks, is the unit to be tested for measurement ofjoint shear strength. The slots and flatjack installation shall bein accordance with Test Method C 1197.7.3 Method B (without Flatjacks Controlling Normal Com-pressive
35、 Stress)Estimate and record the average normalcompressive stress on the unit based upon the location of thetest unit in the structure and the estimated dead and acting liveloads.7.4 Method C (with Flatjack Applying Horizontal Load)Estimate the average normal compressive stress using themethod descri
36、bed in 7.3.8. Preparation of Test Site8.1 The location at which the joint shear strength index ismeasured is dictated by engineering objectives. Avoid areas inwhich the mortar joints appear to be nonparallel. The unit to betested must be in the stretcher orientation. Locate the test siteC1531093far
37、enough from wall openings or ends so that the loading jackbears against enough masonry to resist forces generated duringloading of the test unit. The basic arrangement is illustrated inFig. 1 for Method A, in Fig. 2 for Method B, and in Fig. 3 forMethod C. At the desired location the following steps
38、 must betaken to prepare the site for testing:8.1.1 For Method A or Method B, provide a space for theloading jack by removing a unit on one end of the test unit. Donot remove a unit for Method C.8.1.2 For Method A, if the joint shear strength index inopposite directions is to be determined, remove t
39、he unit at bothends of the test unit to isolate the joints being investigated.Otherwise, follow the procedure of 8.1.3. The mortar in thejoints above and below the test specimen shall not extendbeyond the vertical ends of the unit being tested.8.1.3 For Method B, remove a masonry unit on one side of
40、the test unit and the head joint on the opposite end of the testunit. The mortar in the joints above and below the testspecimen shall not extend beyond the vertical ends of the unitbeing tested.8.1.4 For Method C, remove the head joints on both ends ofthe test unit. The mortar in the joints above an
41、d below the testunit shall not extend beyond the vertical ends of the unit beingtested.8.2 For solid unit and solid grouted masonry construction,measure the width and length at the top and bottom of the testunit to an accuracy of132 in. (0.8 mm). For hollow ungroutedmasonry construction, measure the
42、 length at mid-height ofeach face to an accuracy of132 in. (0.8 mm) and measure theminimum thickness of each face shell at a point12 in. (12.7mm) above the mortar-bed plane to an accuracy of132 in. (0.8mm).9. Procedure9.1 Method A (with Flatjacks Controlling Normal Compres-sive Stress):9.1.1 Instrum
43、ent the test unit by attaching a dial gage orelectronic displacement transducer as shown in Fig. 1. Placethe loading jack, spherical seat, and bearing plates with bearingpads into the space next to the test unit. Shim the jack toprovide a centered horizontal force on the test unit.9.1.2 Set the pres
44、sure in the two flatjacks equal to 10 psi(0.07 MPa) or less and close the valve. Increase pressure in thehorizontal loading jack gradually, such that failure of the jointoccurs between 30 s and 2 min after initial loading, recordingdisplacement of the unit at small increments of horizontal load.Moni
45、tor the flatjack pressure during loading and adjust theinternal pressure, if necessary, to provide a constant normalcompressive stress. When the bond between the unit andmortar joints is broken, the unit will begin to displace continu-ously under constant horizontal load. This represents themaximum
46、horizontal load for this level of normal compressivestress.9.1.3 Increase the pressure in the flatjacks to induce the nextdesired level of normal compressive stress and repeat theprocess of horizontal loading until the maximum horizontalload for this level of normal compressive stress is reached.Rep
47、eat the sequence in this manner to determine the bed jointshear stress at various levels of normal compressive stress.9.1.4 To investigate the effect of shear force reversal on thein situ shear strength, if desired, the horizontal jack may betransferred to the opening on the opposite side of the tes
48、t unit,the displacement instrumentation reversed, and the test se-quence repeated in the opposite direction.9.1.5 Release pressure in the horizontal jack after the finaldisplacement measurement has been taken and remove theloading jack. Release pressure in the flatjacks and remove theflatjacks and d
49、isplacement measurement devices. Any voids orslots created during site preparation are permitted to be filledusing the original or similar units and a mortar or other suitablematerial of a color and strength similar to the original mortar.9.2 Method B (without Flatjacks Controlling Normal Com-pressive Stress):9.2.1 Place the loading jack, spherical seat ( if used), andbearing plates into the space next to the test unit. Shim the jackto provide a centered horizontal force on the test unit. Increasepressure in the hydraulic jack gradually until the test unitbegins t
