AASHTO T 220-1966 Standard Method of Test for Determination of the Strength of Soil-Lime Mixtures《土壤-石灰混合物强度测定标准方法》.pdf

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1、Standard Method of Test for Determination of the Strength of Soil-Lime Mixtures AASHTO Designation: T 220-66 (2013) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-1a T 220-1 AASHTO Standard Method of Test for Dete

2、rmination of the Strength of Soil-Lime Mixtures AASHTO Designation: T 220-66 (2013) 1. SCOPE 1.1. This method provides for the determination of the unconfined compressive strength of soil-lime stabilization mixtures. Note 1Generally, an unconfined compressive strength of 690 kPa (100 psi) is satisfa

3、ctory for the final course of base construction, and it is desirable that materials for such courses contain a minimum of 50 percent plus 0.425-mm (No. 40) material before treatment. Various soil materials may be treated for subbase, and, in such cases, the minimum suggested unconfined compressive s

4、trength is 345 kPa (50 psi). 1.2. The values stated in SI units are to be regarded as the standard. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 92, Wire-Cloth Sieves for Testing Purposes M 216, Lime for Soil Stabilization T 146, Wet Preparation of Disturbed Soil Samples for Test 2.2. ASTM Stand

5、ards: D2216, Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass E4, Standard Practices for Force Verification of Testing Machines 3. APPARATUS 3.1. Automatic TamperA compaction device with base plate to hold 152 mm (6 in.) ID forming molds, equipp

6、ed with 4.54-kg (10-lb) ram and adjustable height of fall. Ram fall is 457 mm (18 in.). The striking face of the ram is a 40-degree segment of a circle of 76-mm (3-in.) radius. Automatic tamper shall be furnished an extra base plate to hold the forming mold during specimen top finishing. 3.2. Compac

7、tion Mold with Removable CollarMold is 152 mm (6 in.) ID and 215 mm (81/2in.) high. 3.3. Measuring Device for Specimen HeightA micrometer dial assembly with a standard set of spacer blocks. 3.4. Scale, rated 18.1-kg (40-lb) capacity, sensitive to 0.0005 kg (0.001 lb). 3.5. Press, hydraulic, to extru

8、de specimens from mold. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1a T 220-2 AASHTO 3.6. Drying Oven, controlled from 60 5C (140 9F) to 110 5C (230 9F). 3.7. A Supply of Metal Pans, wide and sha

9、llow, for mixing and drying materials, and a supply of rectangular stainless steel pans approximately 230 by 400 by 60 mm (9 by 16 by 21/4in.) deep, equipped with porous spacer plates. 3.8. Circular Porous Stones, slightly less than 152 mm (6 in.) in diameter and 51 mm (2 in.) high. 3.9. Axial Cells

10、, lightweight stainless steel cylinders, 171 mm (63/4in.) ID and 305 mm (12 in.) high, fitted with standard air valve and straight, tubular rubber membrane 152 mm (6 in.) in diameter. 3.10. Vacuum Pump, 20 to 35 L/min (0.70 to 1.25 cfm), or aspirator. 3.11. Air Compressor, 4.7 to 7.1 L/s (10 to 15 c

11、fm) with 230-L (60-gal) storage tank and controls, pressure regulators, gauges, and valves. 3.12. Moist Room, equipped with shelves and a constant pressure supply of air. 3.13. Micrometer Dial Gauge, calibrated to 0.02 mm (0.001 in.) with support to measure deflection of specimen. 3.14. A supply of

12、2.27- and 4.54-kg (5- and 10-lb) Lead Surcharge Weights. 3.15. Calibrated Proving Ring or Other Continuous Force Measuring Device, according to ASTM E4, except that an error of plus or minus 2 percent is allowed. 3.16. Circumference Measuring DeviceA specially made metal tape measure. 3.17. Screw Ja

13、ck Press and Assembly or other suitable testing press, with dial housing and two loading blocks. 3.18. Sieves with square openings of the following sizes conforming to M 92, Standard Specification for Sieves for Testing Purposes: 75-, 53-, 50-, 45-, 31.5-, 22.4-, 16.0-, 12.5-, 9.5-, 4.75-, 2.00-, 0.

14、850-, and 0.425-mm (3.0-, 2.12-, 2.00-, 1.75-, 1.25-, 7/8-, 5/8-, 1/2-, 3/8-in., No. 4, No. 10, No. 20, and No. 40) sieves. 3.19. Mechanical Pulverizer with adjustable clearance rotating plate. 3.20. Mechanical Sieve ShakerA laboratory size 0.014 m3(1/2ft3) sieve shaker, convenient but not absolutel

15、y necessary, used for separating material for recombining specimens. 3.21. A Supply of Small Tools and Accessories such as wedgewood mortar and pestle, rubber-covered pestle, rawhide hammer, spatulas, trowels, level, scoops, siphon tubes, sample containers, cardboard cartons, 510-by-510-mm (20-by-20

16、-in.) filter papers, etc. 4. MATERIALS 4.1. A supply of lime, preferably meeting the requirements of M 216 for either Type I or II lime. 4.2. Good quality tap water. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of appl

17、icable law.TS-1a T 220-3 AASHTO 5. SOIL PREPARATION 5.1. Select a 91-kg (200-lb) minimum representative sample for testing. 5.2. Spread the sample on a clean, dry floor to air-dry or use forced drafts of warm air. 5.3. The aggregations or hard lumps of clay in soils containing no appreciable amounts

18、 of coarse particles shall be crushed to pass the 2.00-mm (No. 10) sieve without breaking the coarse particles. The sample shall then be screened on the 0.850-mm (No. 20) sieve and the percentages retained and passing the 0.850-mm (No. 20) sieve determined. 5.4. Clays and other soils containing coar

19、se particles shall be broken up to pass the 4.75-mm (No. 4) sieve without breaking the coarse particles. This may be done by means of a plastic mallet, rubber covered tamper, or similar hand tools. The material shall then be separated as follows: 5.4.1. Coarse particle materials (crushed stone, grav

20、el, sand, and caliche) shall be dry-screened over the following suggested sieves: 45, 31.5, 22.4, 16, 9.5, 4.75, and 2.00 mm (1.75, 1.25, 7/8, 5/8, 3/8in., No. 4 and No. 10) to separate the various sizes of materials. Retain all material passing the 2.00-mm (No. 10) sieve. The material passing the 4

21、5-mm (1.75-in.) sieve is used in making specimens. Mix all minus 2.00-mm (No. 10) material on the floor until it is uniformly blended with respect to color, appearance, and moisture content. 5.5. Determine the mass of each size of material and compute the cumulative percentages retained on each siev

22、e and the percent passing the 2.00-mm (No. 10) sieve. These values are not to be used as true sieve analysis, but are used to recombine individual specimens to ensure uniform graduation within each specimen. 5.6. On the basis of the cumulative sieve size percentages obtained in Section 5.5 above, ca

23、lculate and weigh out a 4.54-kg (10-lb) representative sample for sieve analysis and soil constants (Atterberg Limits). This 4.54-kg (10-lb) sample is prepared for testing by the wet method, T 146. Rolls, tumblers, or mills that might alter the coarse particles should not be used in this preparation

24、. After preparation of the sample by the wet method, the following tests shall be performed in Table 1: Table 1Required Soils Tests Mechanical Analysis T 88 Liquid Limit, LL T 89 Plastic Limit (PL) and Plasticity Index (PI) T 90 6. SELECTION OF PERCENTAGE OF LIME 6.1. Enter plasticity index and perc

25、ent minus 0.425 mm (No. 40), determined as in Section 4, of untreated soil on Figure 1, and determine the percentage of lime to add to the soil. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1a T 22

26、0-4 AASHTO Figure 1Recommended Amounts of Lime for Stabilization of Subgrades and Bases (These percentages should be substantiated by approved testing methods on any particular soil material.) 7. PROCEDURE FOR DETERMINING OPTIMUM MOISTURE AND DENSITY 7.1. Determine the percent hygroscopic moisture i

27、n the soil using a representative sample of the soil according to ASTM D2216. Estimate the mass of air-dry material that will, when wetted and compacted, fill the 152-mm (6-in.) ID mold to a height of 200 mm (8 in.). Using this estimated mass and the air-dry screen analysis already obtained in prepa

28、ring the large sample, compute the cumulative masses of each size to combine to make the 152-mm (6-in.) diameter by 200-mm (8-in.) high specimen. The amount of lime to use is the percentage from Section 5 and is based on the dry density of the soil. 7.2. Weigh up the material as calculated in Sectio

29、n 6.1. Keep the coarse particle fraction separate from (1) the passing 2.00-mm (No. 10) sieve material for flexible base, and (2) the clay lumps and passing 0.850-mm (No. 20) sieve for fine soils. 7.3. Calculate the mass of water to add on the basis of the dry soil and weigh into a tared sprinkling

30、jar. 3 2010 30 40 50 603 2010 30 40 50 600201030405060708090100PercentSoilBinderWetMethodP.I.Wet MethodP.I.Wet MethodIncreasethispercentan amountanticipatedfrom Construction Operations.*Excluded Binder AreaSoils Section, Materials then mix until uniform. Take care not to lose any of the material and

31、 keep the mixing pan covered, when possible, to prevent loss of water by evaporation. In order to get uniform distribution of moisture in clay soils, pass the material through a 6.3-mm (1/4-in.) sieve. 7.6. Calculate and weigh out the material for one layer. This should be one fourth of the mass of

32、the wet mixture. Place this layer in the mold using putty knives, your hand, or convenient tools, keeping close watch in order to avoid segregation of rock sizes or fines. In base coarse materials or other coarse particle-type materials, place some excess fines, usually about 15 mm (0.5 in.) thick,

33、loosely on the bottom flat surface, and then begin with large particles and other sizes, ending up with some fines to ensure a dense layer. Successive layers do not require as much fines as the 15-mm (1/2-in.) loose thickness in the first layer. This procedure ensures a smooth, tight bottom for each

34、 layer. Level the layer by hand or spatula, then use the spatula around the insides of the mold, spading the layer to intermix fines and coarse particles for a denser, more uniform layer. Do not tamp the loose material either by hand or any other hand tool, but compact the layer using a compactive e

35、ffort of 50 accurately adjusted 457-mm (18-in.) drops of the 4.54-kg (10-lb) ram; determine the optimum moisture and maximum density for the soil-lime mixture. Keep the ram face clean of sticky or adhering material. Repeat this until all four layers are compacted. 7.7. After the last layer has been

36、compacted, fasten the mold containing the specimen upon the top of the extra base plate and finish the top by means of various hand tools, such as a putty knife, or a lead, rawhide, or plastic mallet, and a circular steel plate with a smooth surface. Use the small level to check the surface of the s

37、pecimen so that it will be plane and level with the top of the forming mold. Do not trim the specimen. 7.7.1. After the final layer has been compacted and while the hand finishing of the specimen is being done, the following type of blows (with hand hammers) shall be used after leveling, etc., to co

38、mplete the hand finishing. (See Table 2.) Table 2Type of Blows No. of 4.54-kg (10-lb), 457-mm (18-in.) Blows per Layer Type of Hammer No. of Blows and Description 15 to 20 0.45 to 0.90-kg (1 to 2-lb) hammer 2 to 4 light “pecking” blows 25 0.45 to 0.90-kg (1 to 2-lb) plastic 5 to 10 light and 1.80 to

39、 2.2-kg (4 to 5-lb) rawhide 2 medium firm 50 and above 0.45 to 0.90-kg (1 to 2-lb) plastic 5 to 10 light and 1.80 to 2.2-kg (4 to 5-lb) rawhide 5 firm 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1

40、a T 220-6 AASHTO 7.8. Remove the mold from the base plate, determine the mass of the specimen in the mold to the nearest 0.5 g (0.001 lb), and measure the height, by means of the measuring device, to the nearest 0.02 mm (0.001 in.). Record the data. 7.9. Carefully center the specimen over a porous s

41、tone and place in the press to extrude molded specimens. Push the material on the bottom stone upward out of the mold. 7.10. Place the specimen in a large tared pan, break up material by hand or using convenient hand tools, and oven dry to constant mass at 110 5C (230 9F). 7.11. If necessary, adjust

42、 the mass of the material to obtain a 200-mm (8-in.) height of specimen, vary the amount of molding water, and repeat the above operations using individual batches for each specimen to obtain several points for a good moisturedensity curve. 8. COMPACTION OF THE TEST SPECIMEN 8.1. Compact three speci

43、mens 152 mm (6 in.) in diameter and 200 mm (8 in.) in height at the optimum moisture and density found in Section 6. These lime-treated subgrade soil or flexible base specimens should be compacted as nearly identical as possible. The data for these specimens, as well as those obtained in the followi

44、ng test procedures, should be recorded on the test data sheet (Figure 2). Sample No. Date Molded Date Tested Percent Lime Percent Water Added Percent Hygro. Moist Total Percent Moist. In Spec. Kilograms Soil (Dry) Kilograms Lime Kilograms Soil (Dry) + Lime Kilograms soil + (Hygro. Moist.) Kilograms

45、Lime Kilograms Soil + Hygro. Moist. + Lime Mass Water Added Tare Mass Jar Mass Water + Jar Mass per Layer Mold No. Wet Mass Spec. + Mold Tare Mass Mold Wet Mass Specimen Dry Mass Specimen Height Specimen Vol. per Lin. M Volume of Spec. Dry Density Spec. Total LoadComp. Comp. Str. kPa (psi) Remarks:

46、Figure 2Compressive Strength Test Worksheet for Soil-Lime Mixes 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1a T 220-7 AASHTO 9. CURING TEST SPECIMENS 9.1. Immediately after extruding the test spe

47、cimens from the forming mold, with top and bottom porous stones in place, insert the specimens in a triaxial cell. Store the specimens at room temperature for a period of seven days. 9.2. After moist curing, remove the cells and place the specimens in an air dryer and dry at a temperature not to exc

48、eed 60C (140F) for about 6 h or until one third to one half of the molding moisture has been removed. All lime-treated soils are dried as given above even though a considerable amount of cracking may occur. Allow the specimen to cool for at least 8 h before continuing the test. 9.3. Determine the ma

49、ss and measure the specimens and subject them to capillarity for ten days by the method described in Section 10. 10. SUBJECTING TEST SPECIMENS TO CAPILLARITY 10.1. Specimens are subject to capillarity for ten days as follows: 10.1.1. Apply a vacuum to the axial cell and remove the cell from the specimen. Do not remove porous stones from specimens until after specimens have been tested. Cut a piece of filter paper, 250 by 510 mm (10 by 20 in.) in size,