ASTM C496/C496M:11 pdf free download – Standard Test Method for Spltting Tensile Strength of Cylindrical Concrete Specimens.
The surfaces of the bar or plate shall he machined to within ± 0.025 mm I ± 0.(X)l in.I of planeness. as measured on any line of contact of the hearing area. It shall have a width of at least 50 mm 12 in.]. and a thickness not less than the distance from the edge of the spherical or rectangular bearing block to the end of the cylinder. The bar or plate shall be used in such manner that the load will be applied over the entire length of the specimen.
5.3 Bearing Sirips—Two bearing strips of nominal 3.0 mm (Vs in. J thick plywood. free of imperfections, approximately 25 mm in. wide, and of a length equal to. or slightly longer than, that of the specimen shall be provided for each specimen. The bearing strips shall he placed between the specimen and both the upper and lower bearing blocks of the testing machine or between the specimen and supplemental bars or plates. when used (sec 5.2). Bearing strips shall not be reused.
6. Test Specimens
6.1 The test specimens shall conform to the size, molding, and curing requirements set forth in either Practice C31/C3 1M (field specimens) or Practice C192/C192M (laboratory specimens). Drilled cores shall contirrn to the size and moisture- conditioning requirements set forth in Test Method C42/C42M. Moist-cured specimens. during the period between their removal from the curing environment and testing. shall be kept moist by a wet burlap or blanket covering, and shall be tested in a moist condition as soon as practicable.
6.2 The following curing procedure shall be used for evaluations of light-weight concrete: specimens tested at 28 days shall he in an air-dry condition after 7 days moist curing followed by 21 days drying at 23.0 ± 2.0°C (73.5 ± 3.5°FJ and 50 ± 5 % relative humidity.
7. Procedure
7.1 Marking—Draw diametral lines Ofl each end of the specimen using a suitable device that will ensure that they are in the same axial plane (see Fig. I, Fig. 2 and Note I). or as an alternative, use the aligning jig shown in Fig. 3 (Note 2).
Note I —Figs, I and 2 show a suitablc dcvicc for drawing diamctral lincs on each cnd of a 150mm X 300 mm 16 in. X 12 in.l cylinder in the same axial plane. The device consists of three parts as follows:
Ib A length of 100-mm [4-in.] steel channel, the flanges of which hise been machined flat.
(2) A section, part a. that is grooved to it smoothly over the flanges of the channel and that includes cap screws for positioning the vertical member of the assembly, and
(3) A vcrtical bar, part b. for guiding a pencil or marker,
The assembly (part a and pan b is not fastened to the channel and is positioned at either end of (he cylinder without disturbing the position of the specimen when marking the diametral lines.
Now 2—Fig. 4 is a detailed drawing of the aligning jig shown in Fig. 3 for achieving the same purpose as marking the diametral lines. The device consists of:
(1) A base for holding the lower bearing strip and cylinder.
(2) A supplementary bearing bar confonning to the requirements in Section 5 as to critical dimensions and planeness. and
(3) Two uprights to serve for positioning the test cylinder, bearing strips, and supplementary bearing bar.
7.2 Measurements—Determine the diameter of the test specimen to the nearest 0.25 mm 10.01 in.1 by averaging three diameters measured near the ends and the middle of the specimen and lying in the plane containing the lines marked on the two ends. Determine the length of the specimen to the nearest 2 mm 10.1 in.J by averaging at least two length measurements taken in the plaiie containing the lines marked on the two ends.