1、Standard Method of Test for Family of Curves One-Point Method AASHTO Designation: T 272-15 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-1b T 272-1 AASHTO Standard Method of Test for Family of CurvesOne-Point Met
2、hod AASHTO Designation: T 272-15 1. SCOPE 1.1. These methods of tests are for the rapid determination of the maximum density and optimum moisture content of a soil sample utilizing a family of curves and a one-point determination. 1.2. One-point determinations are made by compacting the soil in a mo
3、ld of a given size with a 2.5-kg (5.5-lb) rammer dropped from a height of 305 mm (12 in.). Four alternate procedures are provided as follows: Method AA 101.6-mm (4-in.) mold; soil material passing a 4.75-mm (No. 4) sieve. Sections 5 and 6. Method BA 152.4-mm (6-in.) mold; soil material passing a 4.7
4、5-mm (No. 4) sieve. Sections 7 and 8. Method CA 101.6-mm (4-in.) mold; soil material passing a 19.0-mm (3/4in.) sieve. Sections 9 and 10. Method DA 152.4-mm (6-in.) mold; soil material passing a 19.0-mm (3/4in.) sieve. Sections 11 and 12. 1.3. The methods described herein correspond to the methods i
5、n T 99 and must be chosen accordingly; that is, when moisture-density relationships as determined by Method C of T 99 are used to form the family of curves, then Method C described in this procedure must be used for the one-point determination (Note 1). Note 1Direct reference to T 99 is made through
6、out these test methods, and most terminology, apparatus, and procedures are the same. 1.4. In addition, the concepts described herein are applicable to one-point determinations and moisture-density relationships as specified in T 180, with appropriate apparatus and method used as required. 1.5. The
7、following 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 acco
8、rdance with the rounding-off method of ASTM E29. 1.6. The values stated in SI units are to be regarded as the standard. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: T 99, Moisture-Density Relations of Soils Using a 2.5-kg (5.5-lb) Rammer and a 305-mm (12-in.) Drop T 180, Moisture-Density Relations
9、 of Soils Using a 4.54-kg (10-lb) Rammer and a 457-mm (18-in.) Drop T 248, Reducing Samples of Aggregate to Testing Size 2015 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 T 265, Labora
10、tory Determination of Moisture Content of Soils 2.2. ASTM Standard: E29, Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications 3. TERMINOLOGY 3.1. Definition: 3.1.1. A family of curves is a group of typical soil moisture-density relationships determ
11、ined using T 99, which reveal certain similarities and trends characteristic of the soil type and source. Soils sampled from one source will have many different moisture-density curves, but if a group of these curves are plotted together, certain relationships usually become apparent. In general, it
12、 will be found that higher unit mass soils assume steeper slopes with maximum dry densities at lower optimum moisture contents, while the lower unit mass soils assume flatter, more gently sloped curves with higher optimum moisture contents (Figure 1). Figure 1Example of Curves 2015 by the American A
13、ssociation of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1b T 272-3 AASHTO 4. APPARATUS 4.1. See T 99, Section 3. METHOD A 5. SAMPLE 5.1. Obtain a representative sample. This sample must be large enough that when the oversized (ret
14、ained on the 4.75-mm (No. 4) sieve) particles are removed 3 kg (7 lb) or more of the sample remains. 5.2. Dry the sample until it becomes friable under a trowel. Drying may be in air or by use of a drying apparatus that is maintained at a temperature not exceeding 60C (140F). Thoroughly break up the
15、 aggregations in such a manner as to avoid reducing the natural size of individual particles. 5.3. Sieve the soil over the 4.75-mm (No. 4) sieve. When the sample has oversized particles, particles retained on the 4.75-mm (No. 4) sieve, refer to T 99. 5.4. Reduce the sample, to a mass of 3 kg (7 lb)
16、or more in accordance with T 248. 6. PROCEDURE 6.1. Determine the mass of the mold and base plate. 6.2. Thoroughly mix the selected representative sample with sufficient water to dampen approximately 4 percentage points below optimum moisture content. Greater accuracy in the determination of the max
17、imum density will result as the moisture content used approaches optimum moisture content. Moisture content of the sample should never exceed the optimum water content. 6.3. Form a specimen by compacting the prepared soil in the 101.6-mm (4-in.) mold assembly in three approximately equal layers to g
18、ive a total compacted depth of about 125 mm (5 in.). Compact each layer by 25 uniformly distributed blows from the rammer dropping free from a height of 305 mm (12 in.) above the elevation of the soil when a sleeve-type rammer is used, or from 305 mm (12 in.) above the approximate elevation of compa
19、cted soil when a stationary mounted type of rammer is used. During compaction, the mold assembly shall rest firmly on a dense, uniform, rigid, and stable foundation (Note 2). Note 2Each of the following has been found to be a satisfactory base on which to rest the mold during compaction of the soil:
20、 a block of concrete, with a mass not less than 91 kg (200 lb) supported by a relatively stable foundation; a sound concrete floor; and for field application, such surfaces as are found in concrete box culverts, bridges, and pavements. 6.3.1. Following compaction, remove the collar and carefully tri
21、m the compacted soil even with the top of the mold by means of the straightedge. Determine the mass of the mold, base plate, and moist soil in kilograms to the nearest 1 g (0.002 lb). Calculate the wet density, W1, as described in Section 13. 6.4. Detach the base plate and remove the material from t
22、he mold and slice vertically through the center. Take a representative sample of the material from one of the cut faces, determine the mass immediately. Determine the moisture content in accordance with T 265, and record the results. 2015 by the American Association of State Highway and Transportati
23、on Officials.All rights reserved. Duplication is a violation of applicable law.TS-1b T 272-4 AASHTO METHOD B 7. SAMPLE 7.1. Obtain a representative sample in accordance with Section 5, except that the sample shall have a mass of approximately 7 kg (16 lb). 8. PROCEDURE 8.1. Follow the same procedure
24、 as described for Method A in Section 6, except for the following: Form a specimen by compacting the prepared soil in the 152.4-mm (6-in.) mold assembly in three approximately equal layers to give a total compacted depth of about 125 mm (5-in.), each layer being compacted by 56 uniformly distributed
25、 blows from the rammer. Calculate the wet density, W1, as described in Section 13. METHOD C 9. SAMPLE 9.1. Obtain a representative sample. This sample must be large enough that when the oversized retained on the 19.0-mm (3/4-in.) sieve) particles are removed 5 kg (11 lb) or more of the sample remain
26、s. 9.2. Dry the sample until it becomes friable under a trowel. Drying may be in air or by use of a drying apparatus such that the temperature does not exceed 60C (140F). Then thoroughly break up the aggregations in such a manner as to avoid reducing the natural size of individual particles. 9.3. Si
27、eve an adequate quantity of the representative pulverized soil over the 19.0-mm (3/4-in.) sieve. When the sample has oversized particles, refer to T 99. 9.4. Reduce the sample to a mass of 5 kg (11 lb) or more in accordance with T 248. 10. PROCEDURE 10.1. Determine the mass of the mold and base plat
28、e. 10.2. Thoroughly mix the selected representative sample with sufficient water to dampen it to approximately 4 percentage points below optimum moisture content. Greater accuracy in the determination of the maximum density will result as the moisture content used approaches the optimum moisture con
29、tent. 10.3. Form a specimen by compacting the prepared soil in the 101.6-mm (4-in.) mold assembly in three approximately equal layers to give total compacted depth of about 125 mm (5 in.). Compact each layer by 25 uniformly distributed blows from the rammer dropping free from a height of 305 mm (12
30、in.) above the elevation of the soil when a sleeve-type rammer is used or from 305 mm (12 in.) above the approximate elevation of each finely compacted layer when a stationary mounted type rammer is used. During compaction, the mold assembly shall rest firmly on a dense, uniform, rigid, and stable f
31、oundation (Note 2). 2015 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 10.3.1. Following compaction, remove the collar and carefully trim the compacted soil even with the top of the mol
32、d by means of the straightedge. Holes developed in the surface by removal of coarse material shall be patched with smaller-size material. Determine the mass of the mold, base plate, and moist soil in kilograms to the nearest 1 g (0.002 lb). Calculate the wet density, W1, as described in Section 13.
33、10.4. Detach the base plate and remove the material from the mold and slice vertically through the center. Take a representative sample of the material from one of the cut faces, determine the mass immediately. Determine the moisture content in accordance with T 265 and record the results. METHOD D
34、11. SAMPLE 11.1. Obtain a representative sample in accordance with Section 9 except that it shall have a mass of approximately 11 kg (25 lb). 12. PROCEDURE 12.1. Follow the same procedure as described for Method C in Section 10, except for the following: Form a specimen by compacting the prepared so
35、il in the 152.4-mm (6-in.) mold assembly in three approximately equal layers to give a total compacted depth of about 125 mm (5 in.), each layer being compacted by 56 uniformly distributed blows from the rammer. Calculate the wet density, W1, as described in Section 13. CALCULATIONS AND REPORT 13. C
36、ALCULATIONS 13.1. Wet density (W1) shall be determined using the mold volume. For masses recorded in kilograms, the unit of wet density is kilograms per cubic meter of compacted soil. For masses recorded in pounds, the unit of wet density is pounds per cubic foot of compacted soil. W1= (A B )/V (1)
37、where: W1= wet density in kg/m3(lb/ft3) of compacted soil, A = mass of the mold, base plate, and wet soil, B = mass of the mold, base plate, V = mold volume as determined in T 99. 13.2. The dry density is related to the wet density as follows: 1100100WWw= +(2) where: W = dry density, in kg/m3(lb/ft3
38、) of compacted soil, W1= wet density in kg/m3(lb/ft3) of compacted soil, w = moisture content (percent) of the specimen. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1b T 272-6 AASHTO 14. MAXIMUM D
39、ENSITY AND OPTIMUM MOISTURE CONTENT DETERMINATION 14.1. The calculations in Section 13 shall be made to determine the moisture content and corresponding oven-dry mass (density) in kilograms per cubic meter (pounds per cubic foot) of the compacted specimen. The dry density (unit mass) of the soil sha
40、ll be plotted as ordinate and the corresponding moisture content as the abscissa to define one-point within or on the family of curves (Figure 1). 14.2. If the one-point falls on one of the curves in the family of curves, the maximum dry density and optimum moisture content defined by that curve sha
41、ll be used (Note 4). 14.3. If the one-point falls within the family but not on a curve, a new curve shall be drawn through the plotted one-point parallel and in character with the nearest existing curve in the family of curves. The maximum dry density and optimum moisture content as defined by the n
42、ew curve shall be used (Note 4). Note 3If the one-point plotted within or on the family of curves does not fall in the 80 to 100 percent of optimum moisture range, compact another specimen, using the same material, at an adjusted moisture content that will place the one-point within this range. 14.3
43、.1. If the family of curves is such that the profile of a new curve to be drawn through a one-point is not well defined or in any way questionable, then a full moisture-density relationship shall be made for the soil in question to correctly define the new curve and verify the applicability of the f
44、amily of curves (Note 5). Note 4New curves drawn through plotted one-point determinations shall not become a permanent part of the family of curves until verified by a full moisture-density relationship. 15. REPORT 15.1. The report shall include the following: 15.1.1. The method used (Method A, B, C
45、, or D). 15.1.2. The optimum moisture content as a percentage to the nearest whole number. 15.1.3. The maximum density to the nearest 1 kg/m3(0.1lb/ft3). 15.1.4. In Methods C and D, indicate if the material retained on the 19.0-mm (0.75 in.) sieve was removed or replaced. 15.1.5. Type of face if oth
46、er than 50.8-mm (2 in.) circular. Note 5Inherent variability of soils places limitations on this method of test. The person using this test method must realize this and become thoroughly familiar with the material being tested. Knowledge of the AASHTO Soil Classification System and ability to recogn
47、ize the gradation of soils are requirements for this work. 16. KEYWORDS 16.1. Compaction; family of curves; moisture content; one-point method; sieve; soil density; soil moisture. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a vio
48、lation of applicable law.TS-1b T 272-7 AASHTO APPENDIX (Nonmandatory Information) X1. DEVELOPING A MOISTURE-DENSITY FAMILY OF CURVES X1.1. The purpose of the family of curves is to represent the average moisture-density characteristics of the material. The family must, therefore, be based on moistur
49、e-density relationships that adequately represent the entire mass range and all types of material for which the family is to be used. It may be that particular soil types have moisture-density relationships that differ considerably and cannot be represented on one general family of curves; in this case, a separate family may be developed. Also, moisture-density relationships for material of widely varying geologic origins should be carefully examined to determine if separate families are required. X1.2. When a small number of moisture-densit
