AASHTO T23-14 pdf free download
AASHTO T23-14 pdf free download.Making and Curing Concrete Test Specimens in the Field.
6. TEST SPECIMENS
6.1. compressive Strength Specimens—Compressive strength specimens shall be cylinders cast and allowed to set in an upright position. The length shall be twice the diameter. The cylinder diameter shall be at least three times the nominal maximum size of the coarse aggregate. When the nominal maximum size of the coarse aggregate exceeds 50 mm (2 in.), the concrete sample shall be treated by wet sieving through a 50-mm (2-in.) sieve as described in R 60. When the nominal maximum size of the coarse aggregate does not exceed 25.0mm (1 in.), the specimens may be 100 by 200 mm (4 by 8 in.) cylinders.
Note 2—When molds in SI units are required and not available, equivalent inch-pound unit size molds should be permitted.
6.2. Flexural Strength Specimens—Flexural strength specimens shall be beams of concrete cast and hardened with long axes horizontal. The length shall be at least 50 mm (2 in.) greater than three times the depth as tested. The ratio of width to depth as molded shall not exceed 1.5. The standard beam shall be 152 by 152 mm (6 by 6 in.) in cross section for concrete with a maximum-size coarse aggregate up to 50 mm (2 in.) or a beam 100 by 100 mm (4 by 4 in.) in cross section with a maximum-size coarse aggregate up to 38 mm (1.5 in.). When the nominal maximum size of the coarse aggregate exceeds 50 mm (2 in.), the smaller cross-sectional dimension of the beam shall be at least three times the nominal maximum size of the coarse aggregate.
7. SAMPLING CONCRETE
7.1. The samples used to fabricate test specimens under this standard shall be obtained in accordance with R 60 unless an alternative procedure has been approved.
7.2. Record the identification of the sample with respect to the location of the concrete represented and the time of casting.
8. SLUMP, AIR CONTENT, AND TEMPERATURE
8.1. Slump—Measure and record the slump of each batch of concrete, from which specimens are made, immediately after remixing in the receptacle as required in T 119.
8.2. Air Content—Determine and record the air content in accordance with either T 152 or T I 96M/T 196. The concrete used in performing the air content test shall not be used in fabricating test specimens.
8.3. Temperature—Determine and record the temperature in accordance with T 309M1T 309. Note 3—Some specifications may require the measurement of the unit weight of concrete. The volume of concrete produced per batch may be desired on some projects. Also, additional information on the air content measurements may be desired. Test Method T 121 MIT 121 is used to measure the unit weight, yield, and gravimetric air content of freshly mixed concrete.
9. MOLDING SPECIMENS
9.1. Place of Molding—Mold specimens promptly on a level, rigid, horizontal surface, free from vibration and other disturbances, at a place as near as practicable to the location where they are to be stored.
9.2. Casting tile concrete—Place the concrete in the molds using a scoop, blunted trowel, or shovel. Select each scoopful, trowelful, or shovelful of concrete from the mixing pan to ensure that it is representative of the batch. Remix the concrete in the mixing pan with a shovel or trowel to prevent segregation during the molding of specimens. Move the scoop, trowel, or shovel around the perimeter of the mold opening when adding concrete so the concrete is uniformly distributed within each layer with a minimum of segregation. In placing the final layer, the operator shall attempt to add an amount of concrete that will exactly fill the mold after compaction. Underfilled molds shall be adjusted with representative concrete during consolidation of the top layer. Overfilled molds shall have excess concrete removed.AASHTO T23-14 pdf download.
