1、Standard Method of Test for One-Point Method for Determining Maximum Dry Density and Optimum Moisture AASHTO Designation: T 272-18 Technical Section: 1b, Geotechnical Exploration, Instrumentation, Stabilization, and Field Testing Release: Group 3 (August) American Association of State Highway and Tr
2、ansportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-1b T 272-1 AASHTO Standard Method of Test for One-Point Method for Determining Maximum Dry Density and Optimum Moisture AASHTO Designation: T 272-18 Technical Section: 1b, Geotechnical Exploration, Instrumentat
3、ion, Stabilization, and Field Testing Release: Group 3 (August) 1. SCOPE 1.1. This method is for the rapid determination of the maximum dry density and optimum moisture content of a soil sample using a one-point determination and an individual moisture/density curve or a family of curves. 1.2. The f
4、ollowing applies to all specified limits in this standard: For the purposes of determining conformance with these specifications, an observed value or a calculated value shall be rounded off “to the nearest unit” in the last right-hand place of figures used in expressing the limiting value, in accor
5、dance with the rounding-off method of ASTM E29. 1.3. The values stated in SI units are to be regarded as the standard. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: R 75, Developing a Family of Curves T 99, MoistureDensity Relations of Soils Using a 2.5-kg (5.5-lb) Rammer and a 305-mm (12-in.) Drop
6、 T 180, MoistureDensity Relations of Soils Using a 4.54-kg (10-lb) Rammer and a 457-mm (18-in.) Drop T 217, Determination of Moisture in Soils by Means of a Calcium Carbide Gas Pressure Moisture Tester T 255, Total Evaporable Moisture Content of Aggregate by Drying T 265, Laboratory Determination of
7、 Moisture Content of Soils 2.2. ASTM Standard: E29, Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications 3. SIGNIFICANCE AND USE 3.1. The method described herein corresponds to the methods in either T 99 or T 180 and must be chosen accordingly; for
8、 example, when moisturedensity relationships as determined by 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-1b T 272-2 AASHTO Method C of T 99 are used to form the family of curves, then Method C d
9、escribed in T 99 must be used for the one-point determination. 3.2. A family of curves is a group of typical soil moisturedensity relationships determined using T 99 or T 180, which reveal certain similarities and trends characteristic of the soil type and source. Soils sampled from one source will
10、have many different moisturedensity curves, but if a group of these curves are plotted together, certain relationships usually become apparent. In general, it will be found that higher unit mass soils assume steeper slopes with maximum dry densities at lower optimum moisture contents, while the lowe
11、r unit mass soils assume flatter, more gently sloped curves with higher optimum moisture contents. 4. METHOD SELECTION 4.1. See T 99 or T 180. 4.2. One-point determinations are made by compacting soil using T 99 or T 180 and one of the procedural methods described therein: Method AA 101.6-mm (4-in.)
12、 mold; soil material passing a 4.75-mm (No. 4) sieve. Method BA 152.4-mm (6-in.) mold; soil material passing a 4.75-mm (No. 4) sieve. Method CA 101.6-mm (4-in.) mold; soil material passing a 19.0-mm (3/4in.) sieve. Method DA 152.4-mm (6-in.) mold; soil material passing a 19.0-mm (3/4in.) sieve. 4.3.
13、 The method used to compact the sample shall be the same method and procedure used to develop the moisture/density curve or family of curves used for the reference curve(s). 5. APPARATUS 5.1. See T 99 or T 180 for the selected method. 6. SAMPLE 6.1. Refer to T 99 or T 180. 6.1.1. Follow the initial
14、drying step in Sample section of T 99 or T 180 or; 6.1.2. Sieve sample over the appropriate sieve. 7. PROCEDURE 7.1. The representative sample needs to be between 80 to 100 percent of the optimum moisture. Adjust the moisture content, if necessary. The maximum density determination will be more accu
15、rate the closer the moisture content is to the optimum moisture content. 7.2. Compact the prepared soil using the selected procedural method. 7.3. Determine the wet density of the compacted sample according to T 99 or T 180. 7.4. Determine the moisture content using one of the following methods: T 2
16、17, T 255, or T 265. 7.5. Determine the dry density using the wet density determined in Section 7.3 and moisture content determined in Section 7.4 according to the Calculation section in T 99 or T 180. 2018 by the American Association of State Highway and Transportation Officials. All rights reserve
17、d. Duplication is a violation of applicable law.TS-1b T 272-3 AASHTO 8. MAXIMUM DENSITY AND OPTIMUM MOISTURE CONTENT DETERMINATION 8.1. An individual moisture/density curve as determined by T 99 or T 180 or a family of curves as developed by R 75 may be used for the reference curve(s). 8.2. Individu
18、al Moisture/Density Curve: 8.2.1. Moisture content must be within 80 to 100 percent of optimum moisture of the reference curve. Compact another specimen, using the same material, at an adjusted moisture content if the one-point does not fall in the 80 to 100 percent of optimum moisture range. 8.2.2.
19、 Plot the one-point moisture content as the abscissa and the corresponding dry density (unit mass) of the soil as ordinate to define the one-point on the reference curve. 8.2.3. Use the maximum dry density and optimum moisture content defined by the curve when the one-point falls on the curve or wit
20、hin 2.0 lb/ft3of the curve at the one-point moisture content (Figure 1). 8.2.3.1. When oversized particles have been removed, it is necessary to use the annex from T 99 or T 180 to determine the corrected maximum dry density and optimum moisture content. 8.2.4. Perform a full moisture/density relati
21、onship if the one-point determination cannot meet these requirements. 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-1b T 272-4 AASHTO Figure 1Determining Maximum Dry Density and Optimum Moisture Co
22、ntent Using Individual Moisture/Density Curve 8.3. Family of Curves: 8.3.1. Plot the one-point moisture content as the abscissa and the corresponding dry density (unit mass) of the soil as ordinate to define the one-point on the reference family of curves. 8.3.2. If the one-point falls on one of the
23、 curves in the family of curves, use the maximum dry density and optimum moisture content defined by that curve. 8.3.3. Draw a new curve through the plotted one-point parallel and in character with the nearest existing curve in the family of curves when the one-point falls within the family but not
24、on a curve. 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-1b T 272-5 AASHTO 8.3.4. Determine the maximum dry density and optimum moisture content as defined by the new curve. The moisture content m
25、ust be within 80 to 100 percent of the determined optimum moisture content (Figure 2). 8.3.4.1. When oversized particles have been removed, it is necessary to use the annex from T 99 or T 180 to determine the corrected maximum dry density and optimum moisture content. 8.3.5. Perform a full moisture/
26、density relationship if the one-point determination does not fall within the family or cannot meet the 80 to 100 percent range. Figure 2Determining Maximum Dry Density and Optimum Moisture Content Using Family of Curves 2018 by the American Association of State Highway and Transportation Officials.
27、All rights reserved. Duplication is a violation of applicable law.TS-1b T 272-6 AASHTO 9. REPORT 9.1. The report shall include the following: 9.1.1. The standard (T 99 or T 180) and method used (A, B, C, or D). 9.1.2. The optimum moisture content to the nearest 0.1 percent. 9.1.2.1. The corrected op
28、timum moisture, if applicable. 9.1.3. The maximum dry density to the nearest 1 kg/m3(0.1 lb/ft3). 9.1.3.1. The corrected maximum density, if applicable. 10. KEYWORDS 10.1. Individual moisture/density curve; maximum dry density; one-point determination; optimum moisture content. 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.
