1、Designation: C 780 08aStandard Test Method forPreconstruction and Construction Evaluation of Mortars forPlain and Reinforced Unit Masonry1This standard is issued under the fixed designation C 780; 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.This standard has been approved for use by agencies of the Department of Defense.INTRODUCTIONThis test m
3、ethod provides a standard procedure for sampling and testing mortars for compositionand plastic and hardened properties, either before or during actual construction. The proceduresoutlined in the Annexes are considered applicable for evaluating various combinations of portlandcement, lime, and mason
4、ry cement for mortars common to plain and reinforced unit masonryconstruction.The test procedures describe methods for the measurement of mortar composition and mortarproperties. No attempt is made to claim or substantiate specific correlations between the measuredproperties and mortar performance i
5、n the masonry. However, data from these test methods can becombined with other information to formulate judgments about the quality of the masonry.Testing using these procedures is limited to the preconstruction evaluation of masonry mortarswithin the laboratory, to the evaluation of masonry mortars
6、 at the construction site, and in establishingthe degree of quality control exercised during mortar production at the construction site.1. Scope*1.1 This test method covers procedures for the sampling andtesting of mortars for composition and for their plastic andhardened properties, either before o
7、r during their actual use inconstruction.NOTE 1Guide C 1586 provides guidance on evaluating mortar andclarifies the purpose of both this test method and Specification C 270.NOTE 2The testing agency performing this test method should beevaluated in accordance with Practice C 1093.1.2 Preconstruction
8、EvaluationThis test method permitscomparisons of mortars made from different materials undersimulated field conditions. It is also used to establish baselinevalues for comparative evaluation of field mortars.1.3 Construction EvaluationUse of this method in thefield provides a means for quality assur
9、ance of field-mixedmortar. It includes methods for verifying the mortar mixproportions, comparing test results for field mortars to precon-struction testing, and determining batch-to-batch uniformity ofthe mortar.1.4 The test results obtained under this test method are notrequired to meet the minimu
10、m compressive values in accor-dance with the property specifications in Specification C 270.1.5 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered st
11、andard.1.6 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 standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For spe
12、cific hazardsstatements, see Section 8.2. Referenced Documents2.1 ASTM Standards:2C 39/C 39M Test Method for Compressive Strength of Cy-lindrical Concrete SpecimensC 109/C 109M Test Method for Compressive Strength ofHydraulic Cement Mortars (Using 2-in. or 50-mm CubeSpecimens)1This test method is un
13、der the jurisdiction ofASTM Committee C12 on Mortarsand Grouts for Unit Masonry and is the direct responsibility of SubcommitteeC12.02 on Research and Methods of Test.Current edition approved Dec. 15, 2008. Published January 2009. Originallyapproved in 1974. Last previous edition approved in 2008 as
14、 C 780 08.2For referenced ASTM standards, visit the ASTM website, www.astm.org, 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 o
15、f this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.C 128 Test Method for Density, Relative Density (SpecificGravity), and Absorption of Fine AggregateC 173/C 173M Test Method for Air Content of FreshlyMixed Concrete by th
16、e Volumetric MethodC 187 Test Method for Normal Consistency of HydraulicCementC 231 Test Method for Air Content of Freshly MixedConcrete by the Pressure MethodC 270 Specification for Mortar for Unit MasonryC 470/C 470M Specification for Molds for Forming Con-crete Test Cylinders VerticallyC 496/C 49
17、6M Test Method for Splitting Tensile Strengthof Cylindrical Concrete SpecimensC511 Specification for Mixing Rooms, Moist Cabinets,Moist Rooms, and Water Storage Tanks Used in theTesting of Hydraulic Cements and ConcretesC 1093 Practice for Accreditation of Testing Agencies forMasonryC 1586 Guide for
18、 Quality Assurance of MortarsE11 Specification for Wire Cloth and Sieves for TestingPurposes3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 Terms peculiar to testing masonry mortar are indicatedand defined below:3.1.2 disturbed sampleany plastic mortar test samplewhich is take
19、n at some time after mixing and bulk sampling,that is further remixed or molded immediately prior to test, orboth.3.1.3 undisturbed sampleany plastic mortar test samplemolded immediately after mixing and sampling that sits on avibration-free surface until tested.3.2 During sampling, the following de
20、scriptions will iden-tify sample locations:3.2.1 Batch mixer samples are those obtained during orimmediately after the discharge of the mortar from the batchmixer.3.2.2 Mortar board samples are those obtained from themortar board after some established time period from the endof mixing, and before r
21、etempering. Retempered mortar boardsamples are those obtained from the mortar board afterretempering. Since mortar on a masons mortar board isdisturbed by the activity of the mason, samples from a masonsmortar board shall be so identified to differentiate them fromsamples taken from a mortar board u
22、sed exclusively for testpurposes.4. Summary of Test Method4.1 Preconstruction evaluation of mortar systems involvesthe preparation of one or more trial batches which are mixed inthe laboratory using mechanical batch mixers. These trialbatches are sampled and used in establishing the plastic andharde
23、ned properties of the mixtures. Because all the trialmixtures are prebatched by weight, additional characteristics ofthe mortars may be calculated and used in an analysis of mortarperformance.4.2 During actual construction, evaluation of masonry mor-tars is possible by sampling the mortar at various
24、 stages ofconstruction, and performing tests on both its plastic andhardened properties. The test results permit further verificationof preconstruction testing, and reflect batch-to-batch variationsintroduced during mortar production and use at the construc-tion site. More immediate corrective actio
25、n for the mixingprocedure is thereby attainable.4.3 The following test methods may be singly or collec-tively incorporated into the testing to establish mortar compo-sition, and mortar plastic and hardened properties:4.3.1 Annex A1Consistency by Cone Penetration TestMethod,4.3.2 Annex A2Consistency
26、Retention of Mortars forUnit Masonry,4.3.3 Annex A3Initial Consistency and Consistency Re-tention or Board Life of Masonry Mortars Using a ModifiedConcrete Pentrometer,4.3.4 Annex A4Mortar Aggregate Ratio Test Method,4.3.5 Annex A5Mortar Air Content Test Method,4.3.6 Annex A6Compressive Strength of
27、Molded Ma-sonry Mortar Cylinders and Cubes, and4.3.7 Annex A7Splitting Tensile Strength of MoldedMasonry Mortar Cylinders.5. Significance and Use5.1 During preconstruction and construction evaluations,use of these test methods establishes specific and overallperformance characteristics for the morta
28、r system.5.2 Preconstruction testing of mortars prebatched by weightprovides information for the selection of the individual mortarsystem best suited for the masonry to be constructed. Therecommended tests and their significance are as follows:5.2.1 Consistency determinations by cone penetration all
29、owgaging the water additions for all mortars included in thepreconstruction test series. Even if the mortar consistency asmeasured at the construction site is at a different penetrationvalue than those measured during the preconstruction tests, thecone preparation test serves to standardize water ad
30、ditions formortars being considered as alternatives before construction.Additional testing of mortar water content-consistency rela-tionships (Annex A4) will allow relating these two factors tobatch-to-batch variations at the construction site.5.2.2 Consistency retention by cone penetration using di
31、s-turbed or undisturbed mortar samples provides a means ofestablishing the early-age setting and stiffening characteristicsof the mortars. Because laboratory testing is conducted understatic climatic conditions, consistency retention test resultsreflect the relative performance of the mortar systems
32、 undertest. The same general relationships are expected to holdduring testing at the construction project, except as they areinfluenced by jobsite weather conditions.5.2.3 Mortar water-content determinations (Annex A4) al-low measurement of the water content of the mortar mixture.Mortars prebatched
33、using moist masonry sand may be math-ematically analyzed for mortar water content; however, thistest, when used for preconstruction evaluation, establishes theeffectiveness of the test method and serves as the control orbase for tests performed at the construction site.5.2.4 Mortar aggregate ratio t
34、esting provides a method fordetermining the ratio of aggregate-to-cementitious materials.C 780 08a2The sieving operation employed during this test is incapable ofseparating an individual cementitious material when more thanone such material is used, but can accurately establish theaggregate-to-cemen
35、titious materials ratio of the mixture.5.2.5 Mortar air-content testing is useful in establishing thevalue of this component of the mortar. This test is of particularimportance in evaluating mortars that contain air-entrainingportland cement, air-entraining lime, masonry cement or anycombination the
36、reof.5.2.6 Compressive strength testing of molded mortar cylin-ders and cubes establishes one of the characteristics of hard-ened mortar. Mortar compressive strength test values are notrepresentative of the actual compressive strength of mortar inthe assembly and are not appropriate for use in predi
37、cting thecompressive strength that would be attained by the mortar inthe masonry assembly. The measured compressive strength ofa molded mortar specimen is almost always lower than thestrength of the same mortar in the wall, primarily as a result ofdifferences in mortar water content and specimen sha
38、pe.Mortar compressive strength is influenced by mortar watercontent at the time of set. Because molded mortar specimensare not in contact with absorptive masonry units and are notsubjected to other mechanisms of water loss, they have higherwater contents than mortar in the wall. Higher water content
39、salmost always result in lower strengths. Specimen size andshape also affect compressive strength. Cylinders and cubesexhibit different strengths even when made from the samemortar mix. Both of these specimen configurations yield lowerstrengths than what would be attained if a specimen having thesam
40、e size and configuration of a typical mortar joint could bereliably tested.NOTE 3When cube and cylinder test specimens from like mixturesare to be compared, the cylinder compressive strength is approximately85 % of the cube compressive strength.5.2.7 Splitting tensile strength of molded mortar cylin
41、dersprovides a method for determining the splitting tensile strengthdeveloping characteristics of the mortar. The measuredstrength is dependent upon the mortar water content at the timeof set, along with other factors, and reflects the general strengthattainable by the mortar in the masonry. The mea
42、sured value,however, is not representative of the actual strength of themortar in the masonry.5.3 Testing during the actual construction may employ oneor more of the test methods described in 4.2. Repetitive testingusing these test methods on consecutive or intermittent batchesprovides a method for
43、measurement of batch-to-batch varia-tions in the mortar production. Testing during actual construc-tion may be referenced to laboratory testing and used to predictlater age mortar characteristics. In addition to the comments in5.2, the following test meanings may be obtained fromconstruction project
44、 testing:5.3.1 Consistency by cone penetration is used as a quickreference for indicating batch-to-batch variations in mix ingre-dients and mixing time. Erratic consistency readings indicatepoor control during batching and mixing, but they do notindicate if cement, sand, or water additions are impro
45、per. Othertest methods must be used to isolate and identify the unsatis-factory proportioning or mixing procedure, for example, ce-ment to aggregate, mortar water, or air content tests.5.3.2 Consistency retention by cone penetration tests estab-lishes the early-age setting and stiffening characteris
46、tics of themortar. These properties are influenced by mix proportions andingredients, weather conditions, effects of chemical additives,and mixing time.5.3.3 Individual and repeated evaluations of mortar watercontent (Annex A4) show the ability of the mixer operator toproperly and consistently add w
47、ater to the mixer.5.3.4 Individual and repeated tests for mortar aggregateratio show the ability of the mixer operator to properly andconsistently add the cementitious material and sand to themixer, and will establish batch-to-batch variations in thecomposition of the mortar.5.3.5 Individual and rep
48、etitive tests for mortar air contentshow the changes caused by variations in mixing time, mixingefficiency and other factors.5.3.6 Comparison of compressive strength tests of fieldbatched mortars to preconstruction mortar compression tests,each conducted in accordance with this test method, can beus
49、ed to identify variations in mortar mix constituents and/orproportions. Variations in compressive strength values typi-cally indicate changes in mix water content, mixing proce-dures, mix materials, material proportions, and environmentalconditions.NOTE 4Variations in the measured compressive strengths of field-sampled mortar and between the measured compressive strengths ofconstruction and pre-construction mortar samples should be expected.Many of these variations result from sampling mortar from the mixer ormortarboard and do not necessarily translate into signi
