AASHTO T 140-20 pdf free download

AASHTO T 140-20 pdf free download.Compressive Strength of Concrete Using Portions of Beams Broken in Flexure.
4. APPARATUS
4.1. The testing 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 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 spherical 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 0.00 1 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 0.00 1 in. (0.025 mm) in the diameter of any smaller block. New blocks shall be manufactured within one half of this tolerance.
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 free 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) tolerance. 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).
5.2.2. 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 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 plates 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 Loading—A pply the load continuously and without shock. The moving head of the screw type of testing machine shall travel at the rate of approximately 0.05 in./min (1.3 mm/mm) 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 kPals).
6.4. Test specimens to failure, Record the total load 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 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).
AASHTO T 140-20 pdf download.