ASTM C78C78M-2018 pdf free download

ASTM C78C78M-2018 pdf free download.Standard Test Method for Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading)
1. Scope
1.1 This test method covers the determination ofthe flexural strength of concrete by the use of a simple beam with third-point loading. 1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.4 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
3. Terminology
3.1 Definitions: 3.1.1 For definitions of terms used in this test method, refer to Terminology C125 and Terminology E6. 3.2 Definitions ofTerms Specific to This Standard: 3.2.1 flexural strength—maximum resistance of a speci- men subjected to bending. 3.2.1.1 Discussion—In this test method, flexural strength is reported as the modulus ofrupture. 3.2.2 flexural testing apparatus—fixture used to apply force to the beam specimen and consists of loading and support blocks. 3.2.3 loading block—component of the testing apparatus in the shape of a portion of a cylinder that is used to apply a force to the beam specimen. 3.2.4 modulus of rupture—calculated stress, assuming linear-elastic behavior, in the tensile face of a beam specimen at the maximum bending moment during a standard test method. 3.2.5 span length—distance between lines of support, or reaction, for the beam specimen, and it is equal to three times the nominal depth of the beam. 3.2.5.1 Discussion—For example, for a 100 mm [4 in.] nominal depth beam, the span length is 300 mm [12 in.] and for a 150 mm [6 in.] nominal depth beam, the span length is 450 mm [18 in.]. See 3.2.6.1, for discussion of reaction block.
4. Significance and Use
4.1 This test method is used to determine the flexural strength of specimens prepared and cured in accordance with Test Methods C42/C42M or Practices C31/C31M or C192/ C192M. Results are calculated and reported as the modulus of rupture. For the same specimen size, the strength determined will vary if there are differences in specimen preparation, curing procedure, moisture condition at time of testing, and whether the beam was molded or sawed to size. 4.2 The measured modulus ofrupture generally increases as the specimen size decreases. 3,4,5 4.3 The results ofthis test method may be used to determine compliance with specifications or as a basis for mixture proportioning, evaluating uniformity of mixing, and checking placement operations by using sawed beams. It is used primar- ily in testing concrete for the construction of slabs and pavements. 4.4 For identical test specimens, the modulus of rupture obtained by this test method will, on average, be lower than that obtained by Test Method C293/C293M.
5. Apparatus
5.1 Testing Machine—Hand operated testing machines hav- ing pumps that do not provide a continuous loading in one stroke are not permitted. Motorized pumps or hand operated positive displacement pumps having sufficient volume in one continuous stroke to complete a test without requiring replen- ishment are permitted and shall be capable of applying loads at a uniform rate without shock or interruption. The testing machine shall be equipped with a means of recording or holding the peak value that will indicate the maximum load, to within 1 % accuracy, applied to the specimen during a test. 5.1.1 Verification:5.1.1.1 The testing machine shall conform to the require- ments of the sections on Basis ofVerification, Corrections, and Time Interval Between Verifications of Practice E4.