AASHTO T 176-17 pdf free download
AASHTO T 176-17 pdf free download.Plastic Fines in Graded Aggregates and Soils by Use of the Sand Equivalent Test.
7.1.1. Alternate Method No. I—Air Dry.
7.1.1.1. Split or quarter enough material from the portion passing the 4.75-mm (No. 4) sieve to fill the
85-mL (3-oz) tin measure so it is slightly rounded above the brim. While filling the measure, tap the bottom edge of the tin on the work table or other hard surface to cause consolidation of the material and allow the maximum amount to be placed in the tin. Strike off the tin with the spatula or straightedge so the material is level with the top of the measuring tin.
7.1.2. Alternate Method No. 2—Pre-Wet.
7.1.2.1. The sample must be in the proper moisture condition to achieve reliable results. This condition is determined by tightly squeezing a small portion of the thoroughly mixed sample in the palm of the hand. If the cast that is formed permits careful handling without breaking, the correct moisture range has been obtained. If the material is too dry, the cast will crumble and it will be necessary to add water, rernix, and retest until the material forms a cast. If the material shows any free water it is too wet to test and must be drained and air dried, mixing it frequently to ensure uniformity. This overly wet material will form a good cast when checked initially, so the drying process should continue until a squeeze check on the drying material gives a cast that is more fragile and delicate to handle than the original. If the moisture content of the original sample prepared in Section 6.2 is within the limits described above, the test sample may be obtained immediately. If the moisture content is altered to meet these limits, the altered sample should be placed in a pan, covered with a lid or with a damp cloth that does not touch the material, and allowed to stand for a minimum of 15 minutes.
7.1 .2.2. After the minimum 15-minute tempering period, place the sample on the splitting cloth and mix by alternately lifting each corner of the cloth and pulling it over the sample toward the diagonally opposite corner, causing the material to be rolled. When the material appears homogeneous, finish the mixing with the sample in a pile near the center of the cloth.
7.1.2.3. Fill the 85-mL (3-oz) tin measure by pushing it through the base of the pile while exerting pressure with the hand against the pile on the side opposite the measure. As the tin is moved through the pile, hold enough pressure with the hand to cause the material to fill the tin to overflowing. Press firmly with the palm of the hand, compacting the material and allowing the maximum amount to be placed in the tin. Strike off the tin with the spatula or straightedge so the material is level with the top of the measuring tin.
Note 6 -Moist test specimens produce lower sand equivalent values than the corresponding over- dry specimens with almost no exceptions; therefore, if a dual specification encompassing both the wet and dry methods of sample preparation is utilized, it will be necessary to determine the appropriate correction for each material because a standard correction does not appear possible. Either method can be employed with equal confidence, however.
7.1.3. Reference Method (‘Mechanical Shaket)—Obtain the 85-mL (3-oz) tin measure of material by one of the alternate methods, Section 7.1.1 or 7.1.2, above; then dry the test sample to constant mass at 110 ± 5°C (230 ± 9°F) and cool to room temperature before testing.
8. PROCEDURE
8.1. Start the siphon by forcing air into the top of the solution bottle through the bent copper, glass, or stainless steel blow tube while the pinch clamp is open. The apparatus is now ready for use.
8.2. Siphon 101.6 ± 2.5 mm (4.0 ± 0.1 in.) of working calcium chloride solution into the plastic cylinder. Pour the prepared test sample from the measuring tin into the plastic cylinder using the funnel to avoid spillage (see Figure 3). Tap the bottom of the cylinder sharply on the heel of the hand several times to release air bubbles and to promote thorough wetting of the sample.AASHTO T 176-17 pdf download.
