1、Standard Method of Test for Compressive Strength of Concrete Using Portions of Beams Broken in Flexure AASHTO Designation: T 140-97 (2016) Release: Group 1 (April 2016) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001
2、TS-3c T 140-1 AASHTO Standard Method of Test for Compressive Strength of Concrete Using Portions of Beams Broken in Flexure AASHTO Designation: T 140-97 (2016) Release: Group 1 (April 2016) 1. SCOPE 1.1. This method covers the determination of compressive strength of concrete, using portions of beam
3、s broken in flexure for test specimens. Note 1This method was originally developed to cover testing portions of beams having a square cross section as “modified cubes” and former versions of this procedure were subtitled “Modified Cube Method.” This terminology no longer applies because beams of rec
4、tangular cross section may be tested as provided under Section 6.1. Note 2For methods of making flexural test specimens from which the specimens for this test method may be obtained, refer to R 39, T 23, and T 24M/T 24. Note 3For methods of making the flexural strength test, refer to T 97 and T 177.
5、 1.2. The values stated in inch-pound units are to be regarded as the standard. 1.3. This standard does not purport to address the safety concerns associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the app
6、licability of regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: R 39, Making and Curing Concrete Test Specimens in the Laboratory T 22, Compressive Strength of Cylindrical Concrete Specimens T 23, Making and Curing Concrete Test Specimens in the Field T 24M/T 24, Ob
7、taining and Testing Drilled Cores and Sawed Beams of Concrete T 97, Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading) T 177, Flexural Strength of Concrete (Using Simple Beam with Center-Point Loading) T 231, Capping Cylindrical Concrete Specimens 2.2. ASTM Standard: E4, Stan
8、dard Practices for Force Verification of Testing Machines 3. SIGNIFICANCE AND USE 3.1. This test method is intended for use in the laboratory and as a research tool for determining relative compressive strength values for various concrete mixtures. It is not intended as an 2016 by the American Assoc
9、iation of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 140-2 AASHTO alternative for T 22, and the test values obtained by these two test methods are not interchangeable and not necessarily comparable. 4. APPARATUS 4.1. The testi
10、ng machine may be of any type of sufficient capacity that will provide the rate of loading prescribed in Section 6.3. It shall conform to the requirements of the sections on Basis of Verification, Corrections, and Time Interval between Verifications of ASTM E4. The testing machine shall be equipped
11、with two steel bearing blocks with hardened faces (Note 4), one of which is a spherically seated block that will bear on the top bearing plate described in Section 4.2, and the other a plain rigid block that will support the bottom bearing plate described in Section 4.2. The diameter of the spherica
12、l bearing block shall be at least 75 percent of the width (B in Figure 1) of the specimen. The bearing faces shall not depart from a plane by more than 0.001 in. (0.025 mm) in any 6 in. (152 mm) for a block 6 in. (152 mm) in diameter or larger or by more than 0.001 in. (0.025 mm) in the diameter of
13、any smaller block. New blocks shall be manufactured within one half of this tolerance. Figure 1Device Suitable for Aligning Bearing Plates Note 4It is desirable that the bearing faces of blocks used for compression testing of concrete have a Rockwell hardness of not less than HRC 60. 4.2. Machined o
14、r ground metal bearing plates not less than 3/4in. (19 mm) in thickness, that meet the planeness requirements for the bearing faces of specimens specified in Section 5.2.1 and the hardness requirements for bearing blocks specified in Section 4.1, shall be mounted on the bearing surfaces of the speci
15、men. The bearing plates shall be of such dimensions that the contact faces shall be substantially square and shall have the same dimensions as the nominal width of the beam tested. The upper bearing plate shall be placed directly over the lower plate. A drawing of a satisfactory device designed to e
16、nsure the proper location of the upper plate with reference to the lower plate is shown in Figure 1. The bearing faces shall not depart from a plane by more than 0.001 in. (0.025 mm) in 6 in. (152 mm), and new bearing plates shall be manufactured within one-half of this tolerance. Boss Welded in Bea
17、ring Plateto keep Plate in AlignmentBBDD ( B)Top Bearing PlateTestSpecimenAbout1/2-in.(12-mm) clearanceGuide Support is weldedto Bottom Bearing PlateBottom Bearing Platewidth equals B plusapprox.1/2-in. (12-mm)clearance on each side 2016 by the American Association of State Highway and Transportatio
18、n Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 140-3 AASHTO 5. TEST SPECIMENS 5.1. The length of broken portions of beams selected for the compression test shall be at least 2 in. (50 mm) greater than the width. The selected compression test section shall be fr
19、ee from cracks, chipped surfaces, and other obvious defects. 5.2. Preparation of Test Specimens: 5.2.1. The bearing faces of the specimen shall not depart from a plane by more than 0.002 in. (0.05 mm); bearing faces that are not plane shall be ground or capped to meet the 0.002 in. (0.05 mm) toleran
20、ce. Capping procedures shall follow the applicable provisions of T 231. Caps shall cover the full width of the beam and shall be of such length as to permit the adjustment of the bearing plates for the test so that the upper bearing plate may be aligned directly above the lower plate (Figure 1). 5.2
21、.2. During the interval between testing of specimens in flexure, or after capping and testing the broken portions in compression, the specimens shall be kept in the same condition as prescribed under the method for making and curing flexural test specimens from which the specimens for this test were
22、 obtained. 6. PROCEDURE 6.1. Orientation of the specimen shall be such that the width (B in Figure 1) shall be equal to or less than the height (D in Figure 1). If the beam has a square cross section, the bearing surfaces may be the sides of the beam as originally cast. 6.2. Center the bearing plate
23、s in the testing machine so that the thrust of the spherically seated block of the test machine is aligned with the center of the bearing plates. Apply the load to the bearing plates by means of an adjustable head. 6.3. Rate of LoadingApply the load continuously and without shock. The moving head of
24、 the screw type of testing machine shall travel at the rate of approximately 0.05 in./min (1.3 mm/min) when the machine is running idle. In hydraulic machines, adjust the loading to a constant rate within the limits of 35 15 psi/s (241 103 kPa/s). 6.4. Test specimens to failure. Record the total loa
25、d indicated by the testing machine at failure of the test specimen. 7. CALCULATION 7.1. Calculate the unit compressive strength calculated to the nearest 10 psi (69 kPa). The cross-sectional area of the specimen shall be taken as the average of at least two measurements of the “B” dimensions (Figure
26、 1) of both the top and bottom bearing plates multiplied by the average of at least two measurements of the “B” dimension of both the top and bottom bearing surfaces of the specimen determined to the nearest 0.01 in. (0.25 mm). 8. REPORT 8.1. Report the following information: 8.1.1. That the determi
27、nation was made using this test method; 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 140-4 AASHTO 8.1.2. Specimen identification number; 8.1.3. “B” and “D” dimensions in inches (or millimeters
28、); 8.1.4. Cross-sectional area, in square inches (or square millimeters); 8.1.5. Maximum load, in pound-force (newtons); 8.1.6. Compressive strength calculated to the nearest 10 psi (69 kPa); 8.1.7. Method of obtaining specimen; 8.1.8. Age of specimen and details of curing; 8.1.9. Orientation of spe
29、cimen with respect to the top of the beam as cast; 8.1.10. Type of failure and appearance of concrete; and 8.1.11. Conditions of curing the specimens and moisture condition at time of test. 9. PRECISION AND BIAS 9.1. The precision of this test has not been determined, but data are being collected an
30、d a precision statement will be included when it is developed. 9.2. No statement concerning bias is being made at this time. 10. KEYWORDS 10.1. Compressive strength; concrete; flexural beams; strength testing. 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
