AASHTO T90-14 pdf free download

AASHTO T90-14 pdf free download.Determining the Plastic Limit and Plasticity Index of Soils.
3.5. Balance—A class GI balance meeting the accuracy requirements of M 231.
3.6. Oven—Thermostatically controlled and capable of maintaining temperatures of 110 ± 5°C for drying samples.
4. CALIBRATIONS, STANDARDIZATIONS, AND CHECKS
4.1. (Jnless otherwise specified, follow the requirements and intervals for equipment calibrations. standardizations, and checks in R 18.
4.2. Follow the procedures for performing equipment calibrations, standardizations, and checks found in R61.
5. SAMPLE
5.1. If on/v the plastic limit is to he determined—Take a quantity of soil with a mass of about 20 g from the thoroughly mixed portion of the material passing the 0.425-mm (No. 40) sieve, obtained in accordance with R 58 or T 146. Place the air-dried soil in a mixing dish and thoroughly mix with distilled or demineralized water until the mass becomes plastic enough to be easily shaped into a ball (Notes 2 and 3). Take a portion of this ball with a mass of about 8 g for the test sample. Note 2—Tap water may be used for routine testing if comparative tests indicate no differences in results between using tap water and distilled or demineralized water. however, use distilled or demineralized water for referee or disputed tests.
Note 3—The objective is to add enough moisture to a plastic soil sample so that the 3-mm thread described in Section 6 does not crumble on the first roll. For a nonplastic soil, this will not be possible.
5.2. If the plasticity index (both liquid and plastic limit) is to be determined—Take a test sample with a mass of about 8 g from the thoroughly wet and mixed portion of the soil prepared in accordance with T X9. Take the sample at any stage of the mixing process at which the mass becomes plastic enough to be easily shaped into a ball without sticking to the fingers excessively when squeezed. Tf the sample is taken before completion of the liquid limit test, set it aside and allow to season in air until the liquid limit test has been completed. lithe sample taken during the liquid limit test is too dry to permit rolling to a 3-mm thread as described in Section 6, add more water and remix (Note 3).
6. PROCEDURE
6.1. Deermine and record the mass of the moisture content container.
6.2. Select a 1.5- to 2.0-g portion from the 8-g mass of soil prepared in accordance with Section 5. Form the selected portion into an ellipsoidal mass.
6.3. (Jse one of the following methods to roll the soil mass into a 3-mm-diameter thread at a rate of
80 to 90 strokes per minute, counting a stroke as one complete motion of the hand forward and back to the starting position again.
6.3.1. land Rolling Method—Roll the mass between the palm or lingers and the ground-glass plate or unglazed paper with just sufficient pressure to roll the mass into a thread of uniform diameter throughout its length. Deform the thread further on each stroke until its diameter reaches 3 mm. Take no more than 2 mm to roll the soil mass to the 3-mm diameter.
Note 4 The amount of hand or finger pressure required will vary greatly, according to the soil. Fragile soils of low plasticity are best rolled under the outer edge of the palm or at the base of the thumb.AASHTO T90-14 pdf download.