1、Designation: C1074 17Standard Practice forEstimating Concrete Strength by the Maturity Method1This standard is issued under the fixed designation C1074; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A n
2、umber 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 provides a procedure for estimating con-crete strength by means of the maturity method. The maturityindex is expressed ei
3、ther in terms of the temperature-timefactor or in terms of the equivalent age at a specified tempera-ture.1.2 This practice requires establishing the strength-maturityrelationship of the concrete mixture in the laboratory andrecording the temperature history of the concrete for whichstrength is to b
4、e estimated.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 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 es
5、tablish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.(WarningFresh hydraulic cementitious mixtures are causticand may cause chemical burns to skin and tissue uponprolonged exposure.2)1.5 This international standard w
6、as developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referen
7、ced Documents2.1 ASTM Standards:3C31/C31M Practice for Making and Curing Concrete TestSpecimens in the FieldC39/C39M Test Method for Compressive Strength of Cylin-drical Concrete SpecimensC78/C78M Test Method for Flexural Strength of Concrete(Using Simple Beam with Third-Point Loading)C109/C109M Tes
8、t Method for Compressive Strength ofHydraulic Cement Mortars (Using 2-in. or 50-mm CubeSpecimens)C125 Terminology Relating to Concrete and Concrete Ag-gregatesC192/C192M Practice for Making and Curing Concrete TestSpecimens in the LaboratoryC511 Specification for Mixing Rooms, Moist Cabinets,Moist R
9、ooms, and Water Storage Tanks Used in theTesting of Hydraulic Cements and ConcretesC803/C803M Test Method for Penetration Resistance ofHardened ConcreteC873/C873M Test Method for Compressive Strength ofConcrete Cylinders Cast in Place in Cylindrical MoldsC900 Test Method for Pullout Strength of Hard
10、ened Con-creteC918/C918M Test Method for Measuring Early-Age Com-pressive Strength and Projecting Later-Age StrengthC1768/C1768M Practice forAccelerated Curing of ConcreteCylinders3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this practice, refer toTerminology C125.3.2 Definit
11、ions of Terms Specific to This Standard:3.2.1 maturity methoda technique for estimating concretestrength that is based on the assumption that samples of a givenconcrete mixture attain equal strengths if they attain equalvalues of the maturity index (1, 2, 3).43.2.2 strength-maturity relationshipan e
12、mpirical relation-ship between concrete strength and maturity index that isobtained by testing specimens whose temperature history up tothe time of test has been recorded.1This practice is under the jurisdiction of ASTM Committee C09 on Concreteand ConcreteAggregates and is the direct responsibility
13、 of Subcommittee C09.64 onNondestructive and In-Place Testing.Current edition approved Dec. 15, 2017. Published June 2018. Originallyapproved in 1987. Last previous edition approved in 2011 as C1074 11. DOI:10.1520/C1074-17.2Section on Safety Precautions, Manual of Aggregate and Concrete Testing,Ann
14、ual Book of ASTM Standards, Vol 04.02.3For 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.4The boldface numbers i
15、n parentheses refer to the list of references at the end ofthis standard.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in acco
16、rdance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.14. Summary of Practice4.1 A str
17、ength-maturity relationship is developed by labo-ratory tests on the concrete mixture to be used.4.2 The temperature history of the field concrete, for whichstrength is to be estimated, is recorded from the time ofconcrete placement to the time when the strength estimation isdesired.4.3 The recorded
18、 temperature history is used to calculate thematurity index of the field concrete.4.4 Using the calculated maturity index and the strength-maturity relationship, the strength of the field concrete isestimated.5. Significance and Use5.1 This practice can be used to estimate the in-placestrength of co
19、ncrete to allow the start of critical constructionactivities such as: (1) removal of formwork and reshoring; (2)post-tensioning of tendons; (3) termination of cold weatherprotection; and (4) opening of roadways to traffic.5.2 This practice can be used to estimate strength oflaboratory specimens cure
20、d under non-standard temperatureconditions.5.3 The major limitations of the maturity method are: (1) theconcrete must be maintained in a condition that permits cementhydration; (2) the method does not take into account the effectsof early-age concrete temperature on the long-term strength (3,4); and
21、 (3) the method needs to be supplemented by otherindications of the potential strength of the field concrete.5.4 The accuracy of the estimated strength depends, in part,on using the appropriate parameters (datum temperature orvalue of Q) for the maturity functions described in Section 6.NOTE 1Approx
22、imate values of the datum temperature, To, and theQ-value for use in Eq 1 or Eq 2, respectively, are given in Appendix X2.If maximum accuracy of strength estimation is desired, the appropriatevalues of Toor Q for a specific concrete mixture may be determined usingthe procedures given in Appendix X1.
23、6. Maturity Functions6.1 There are two alternative functions for computing thematurity index from the measured temperature history of theconcrete. Refer to Note 1.6.2 One maturity function is used to compute thetemperature-time factor as follows:Mt! 5(Ta2 To! t (1)where:M(t) = the temperature-time f
24、actor at age t, degree-days ordegree-hours,t = a time interval, days or hours,Ta= average concrete temperature during time interval,t, C, andTo= datum temperature, C.6.3 The other maturity function is used to compute equiva-lent age at a specified temperature as follows (5):te5(e2QS1Ta21TsD t (2)whe
25、re:te= equivalent age at a specified temperature Ts, days or h,Q = activation energy divided by the gas constant, K,Ta= average temperature of concrete during time intervalt,K,Ts= specified temperature, K, andt = time interval, days or h.NOTE 2Temperature used in Eq 2 is expressed using the absolute
26、temperature scale. Temperature in kelvin (K) equals approximatelytemperature C + 273 C.7. Apparatus7.1 A device is required to monitor and record the concretetemperature as a function of time and compute the maturityindex in accordance with Eq 1 or Eq 2.NOTE 3Acceptable devices include commercial ma
27、turity instrumentsthat monitor temperature and compute and display either temperature-timefactor or equivalent age. Some commercial maturity instruments use fixedvalues of datum temperature or activation energy in evaluating thematurity index; thus the displayed maturity index may not be indicative
28、ofthe true value for the concrete mixture being used. Refer to Appendix X2for information on correcting displayed time-temperature values foranother value of datum temperature. Equivalent-age values displayed by amaturity instrument cannot be adjusted for another activation energyvalue.7.2 Alternati
29、ve devices include temperature sensors con-nected to data-loggers, or embedded digital devices thatmeasure, record, and store temperature data as a function oftime. The temperature data are used to calculate the maturityindex according to Eq 1 or Eq 2.7.3 The time interval between temperature measur
30、ementsshall be12 h or less for the first 48 h and1horless thereafter.The temperature recording device shall be accurate to within61 C.8. Procedure to Develop Strength-Maturity Relationship8.1 Prepare at least 15 cylindrical specimens according toPractice C192/C192M. The mixture proportions and const
31、itu-ents of the concrete shall be similar to those of the concretewhose strength will be estimated using this practice. If twobatches are needed to prepare the required number of cylinders,cast an equal number of cylinders from each batch, and test onecylinder from each batch at the test ages given
32、in 8.4.8.2 After the specimens are molded, embed temperaturesensors to within 615 mm of the centers of at least twospecimens (Note 4). After inserting the sensor, tap the side ofthe cylinder mold with a rubber mallet or the tamping rod sothat the fresh concrete comes into contact with the sensor.Aft
33、ertapping is completed, connect the sensors to a maturityinstrument or to a temperature-recording device.NOTE 4A method to assist in the proper positioning of the sensor is toinsert a small diameter rigid rod into the center of the freshly madecylinder. The rod will push aside any interfering aggreg
34、ate particles. Therod is removed and the sensor is inserted into the cylinder.8.3 Moist cure the specimens in a water bath or in a moistroom meeting the requirements of Specification C511.NOTE 5Curing under water will aid in reducing temperature differ-ences among test specimens.8.4 Unless specified
35、 otherwise, perform compression testsat ages of 1, 3, 7, 14, and 28 days in accordance with TestC1074 172Method C39/C39M. Test two specimens at each age andcompute the average strength. If the range of compressivestrength of the two specimens exceeds 10 % of their averagestrength, test another cylin
36、der and compute the average of thethree tests. If a low test result is due to an obviously defectivespecimen, discard the low test result.NOTE 6For concrete mixtures with rapid strength development, orwhen strength estimates are to be made at low values of maturity index,tests should begin as soon a
37、s practicable. Subsequent tests should bescheduled to result in approximately equal increments of strength gainbetween test ages. At least five test ages should be used.8.5 At each test age, record the average maturity index forthe instrumented specimens.8.5.1 If maturity instruments are used, recor
38、d the average ofthe displayed values.8.5.2 If temperature recorders are used, evaluate the matu-rity index according to Eq 1 or Eq 2. Unless specifiedotherwise, use a time interval (t)of12 h or less for the first 48h of the temperature record. Longer time intervals are permit-ted for the relatively
39、constant portion of the subsequenttemperature record.NOTE 7Judgement should be used in selecting the initial timeintervals to record temperature in mixtures that result in rapid changes inearly-age temperature due to rapid hydration. Appendix X3 gives anexample of how to evaluate the temperature-tim
40、e factor or equivalent agefrom the recorded temperature history of the concrete.8.6 Plot the average compressive strength as a function ofthe average value of the maturity index. Draw or calculate abest-fit curve to the data (Note 8). The resulting curve is thestrength-maturity relationship to be us
41、ed for estimating thestrength of the concrete mixture cured under other temperatureconditions. Fig. 1 is an example of a relationship betweencompressive strength and temperature-time factor, and Fig. 2 isan example of a relationship between compressive strength andequivalent age at 20 C.NOTE 8The st
42、rength-maturity relationship can be established by usingregression analysis to determine a best-fit equation to the data. Possibleequations that have been found to be suitable for this purpose may befound in Ref. (3). A popular equation is to express strength as a linearfunction of the logarithm of
43、the maturity index (see Fig. 3).8.7 If specified, a flexural strength versus maturity indexrelationship is permitted. Prepare at least 15 beam specimens inaccordance with Practice C192/C192M. If two batches areneeded to prepare the required number of specimens, cast anequal number of beams from each
44、 batch, and test one beamfrom each batch at the test ages given in 8.4. Embed tempera-ture sensors in two specimens, one from each batch if twobatches are made. Connect the sensors to maturity instrumentsor temperature recording devices, and moist cure the speci-mens in a water bath or in a moist ro
45、om meeting therequirements of Specification C511 (see Note 5). Measureflexural strength in accordance with Test Method C78/C78M attime intervals of 1, 3, 7, 14 and 28 days, or as specifiedotherwise (see Note 6). Test two specimens at each age andcompute the average strength. If the range of flexural
46、 strengthof the two specimens exceeds 15 % of their average strength,test another beam and compute the average of the three tests. Ifa low test result is due to an obviously defective specimen,discard the low test result. Use the same procedures as in 8.5and 8.6 to develop the flexural strength-matu
47、rity relationship.FIG. 1 Example of a Relationship Between CompressiveStrength and Temperature-Time FactorFIG. 2 Example of a Relationship Between CompressiveStrength and Equivalent Age at 20 CFIG. 3 Example of Compressive Strength as a Function of Loga-rithm of Equivalent AgeC1074 1738.8 It is also
48、 permitted to develop a relationship betweencube strength of concrete and the maturity index. Follow theprocedure as given for cylinders except that the cubes are to beprepared and tested in accordance with the applicable testmethod. Insert temperature sensors at the centers of at least twocubes. Te
49、st two cubes at each test age. In deciding whether todiscard a low cube strength result, use the precision statementof the standard test method for cube strength as guidance.9. Procedure to Estimate In-Place Strength9.1 Secure temperature sensors within the section to be castbefore concrete placement, or embed temperature sensors intothe fresh concrete as soon as is practicable after concreteplacement (see Note 9). Place temperature sensing elements sothat they will be surrounded by concrete and not be in directcontact with metallic embedments or oth
