You are on page 1of 3 Search inside document Standard Test Method for Flexural Strength of Concrete Using Simple Beam with Third-Point Loading 1 This standard is issued under the xed designation C 78; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon e indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense.
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You are on page 1of 3 Search inside document Standard Test Method for Flexural Strength of Concrete Using Simple Beam with Third-Point Loading 1 This standard is issued under the xed designation C 78; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision.
A number in parentheses indicates the year of last reapproval. A superscript epsilon e indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense. Scope 1. The SI equivalent of inch-pound units has been rounded where necessary for practical application.
It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Referenced Documents 2.
Signicance and Use 3. Results are calculated and reported as the modulus of rupture. The strength determined will vary where there are differences in specimen size, preparation, moisture condition, curing, or where the 1 This test method is under the jurisdiction of ASTM Committee C09 on Concrete and Concrete Aggregatesand is the direct responsibility of Subcommittee C Current edition approved Jan. Published March Originally published as C 78 30T.
Last previous edition C 78 It is used in testing concrete for the construction of slabs and pavements Note 1. Apparatus 4. Hand operated testing machines having 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 replenishment are permitted and shall be capable of applying loads at a uniform rate without shock or interruption.
A diagram of an apparatus that accomplishes this purpose is shown in Fig. Each case-hardened bearing surface in contact with the specimen shall not depart from a plane by more than 0. The angle subtended by the curved surface of each block should be at least 45 0. If the testing machine applies force through a spherically seated head, the center pivot may be omitted, provided one load-applying block pivots on a rod and the other on a ball.
NOTE 21 in. The uppermost bearing plate and center point ball in Fig. Testing 5. The sides of the specimen shall be at right angles with the top and bottom. All surfaces shall be smooth and free of scars, indentations, holes, or inscribed identication marks. Grind, cap, or use leather shims on the specimen contact surface to eliminate any gap in excess of 0.
Leather shims shall be of uniform 14 in. Gaps in excess of 0. Grinding of lateral surfaces should be minimized inasmuch as grinding may change the physical characteristics of the specimens. Capping shall be in accordance with the applicable sections of Practice C The load shall be applied at a constant rate to the breaking point.
Procedure 6. Surface drying of the specimen results in a reduction in the measured exural strength. When using sawed specimens, position the specimen so that the tension face corresponds to the top or bottom of the specimen as cut from the parent material. Center the loading system in relation to the applied force. Using 0. Measurement of Specimens After Test 7. For each dimension, take one measurement at each edge and one at the center of the cross section.
Use the three measurements for each direction to determine the average width and the average depth. Take all measurements to the nearest 0. If C 78 the fracture occurs at a capped section, include the cap thickness in the measurement. Calculation 8. NOTE 2The weight of the beam is not included in the above calculation. Precision and Bias The multilaboratory coefficient of variation has been found to be 7.
Keywords NOTE 3The weight of the beam is not included in the above calculation. Report 9. Carrasquillo and R. ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility.
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ASTM C78 PDF
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 asttm size. Email addresses can only contain letters, numbers and the following special characters: Concrete, Asphalt and Rock. The desired results are that modulus of rupture is calculated and the specimen fails within the middle third of the span length in the aztm area or underside of the specimen. Work Item s — proposed revisions of this standard. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. We find that operators prefer this style of system over manually controlled f78 because of the more consistent control of the loading rate and the asttm risk of shock to the specimen.