AASHTO T97-14 pdf free download

AASHTO T97-14 pdf free download.Flexural Strength of Concrete (Using Simple Beam with Third- Point Loading).
4.2.2. The ratio of the horizontal distance between the point of application of the load and the point of application of the nearest reaction to the depth of the beam shall be 1 .0 ± 0.03.
4.2.3. I[aii apparatus similar to that illustrated in Figure 1 is used:
4.2.3.1. The load-applying and support blocks should not be more than 64 mm (2’/2 in.) high, measured from the center or the axis of pivot, and should extend entirely across or beyond the full width of the specimen. Each case-hardened bearing surface in contact with the specimen shall not depart from a plane by more than 0.05 mm (0.002 in.) and should be a portion of a cylinder, the axis of which is coincidental with either the axis of the rod or center of the ball, whichever the block is pivoted upon. The angle subtended by the curved surface of each block should be at least 45 degrees (0.79 rad).
4.2.3.2. The load-applying and support blocks should be maintained in a vertical position and in contact with the rod or ball by means of spring-loaded screws that hold them in contact with the pivot rod or ball.
4.2.3.3. The uppermost bearing plate and centerpoint ball in Figure 1 may be omitted when a spherically seated bearing block is used, provided one rod and one ball are used as pivots for the upper load- applying blocks.
5. TESTING
5.1. The test specimen shall conform to all requirements of T 23, T 24M1T 24, and R 39. The specimen shall have a test span within 2 percent of being three times its depth as tested. 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 identification marks.
6. PROCEDURE
6.1. Flexural tests of moist-cured specimens shall be made as soon as practical after removal from moist storage. Surface drying of the specimen results in a reduction in the measured flexural strength.
6.2. When using molded specimens, turn the test specimen on its side with respect to its position as molded and ccnter it on the support blocks. 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.
6.3. (‘enter the loading system in relation to the applied force. Bring the load-applying blocks in contact with the surface of the specimen at the third points and apply a load of between 3 and 6 percent of the estimated ultimate load.
6.4. Using 0.10-mm (0.004-in.) and 0.38-mm (0.015-in.) leaf-type feeler gauges, determine whether any gap between the specimen and the load-applying or support blocks is greater or lesser than each of the gauges over a length of 25 mm (1 in.) or more. Grind, cap, or use leather shims on the specimen contact surface to eliminate any gap in excess of 0.10 mm (0.004 in.) in width. Leather shims shall be of uniform 6.4mm (0.25 in.) thickness, 25 to 50mm (1 to 2 in.) width, and shall extend across the full width of the specimen. Gaps in excess of 0.38 mm (0.015 in.) shall be eliminated only by capping or grinding. Grinding of lateral surfaces should be minimized in as much as grinding may change the physical characteristics of the specimens. Capping shall be in accordance with T 231.AASHTO T97-14 pdf download.