1、Standard Method of Test for Determination of Lime Content in Lime-Treated Soils by Titration AASHTO Designation: T 232-90 (2013)1American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-3a T 232-1 AASHTO Standard Method of
2、Test for Determination of Lime Content in Lime-Treated Soils by Titration AASHTO Designation: T 232-90 (2013)11. SCOPE 1.1. A method of test is described for determining the percentage of lime in soils or aggregates that have been treated with hydrated lime. It is based on the continuous neutralizat
3、ion of an aqueous solution from the lime-treated specimen for a specified time period. This is accomplished by adding sufficient acid to just neutralize the lime that is continuously being dissolved during the test. The amount of acid used is directly proportional to the lime content of the specimen
4、. 1.2. The following applies to all specified limits in this standard: For the purpose 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 valu
5、e, in accordance with ASTM E29, Using Significant Digits in Test Data to Determine Conformance with Specifications. (This test has a statement pertaining to significant figures.) (No statistical data are available.) 1.3. The values stated in SI units are to be regarded as the standard. 1.4. Refer to
6、 R 16 for regulatory information for chemicals. 1.5. This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of the standard to consult and establish a
7、ppropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 92, Wire-Cloth Sieves for Testing Purposes M 231, Weighing Devices Used in the Testing of Materials R 16, Regulatory Information for Chemica
8、ls Used in AASHTO Tests 2.2. ASTM Standard: E29, Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications 3. APPARATUS 3.1. A 100-mL titrating buret or other device permitting slow, easily controlled addition of acid, with stand and clamp. 2016 by the
9、American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3a T 232-2 AASHTO 3.2. Ten 1.9-L (2-qt) wide-mouth polyethylene containers (white). 3.3. Two 18.9-L (5-gal) plastic carboys, equipped with siphons, neoprene or tygo
10、n tubing, hose clamps, etc., for dispensing acid-working solution and water. 3.4. Glass (or plastic) dropping bottle. 3.5. Four Stirring RodsOf stainless steel or other suitable material. 3.6. Sieves37.5- and 9.5-mm sieves conforming to the requirements of the Specification for Wire-Cloth Sieves for
11、 Testing Purposes (M 92). (See Note 1.) Note 1Although sieves in 203-mm (8-in.) frames are satisfactory, a 9.5-mm sieve in 305-mm (12-in.) frame may be more suitable for separating the field samples (Sections 5.4 and 8.3). 3.7. BalancesThe balances shall conform to M 231, Class G 5 and Class G 2. 3.
12、8. Four Plastic BeakersHaving a minimum capacity of 500 mL. 3.9. A 200-mL glass beaker. 3.10. Four 50-mL graduates. 3.11. Fluorescent LightOne 915 mm (36 in.) long, or two 457 mm (18 in.) long. 4. REAGENTS 4.1. Hydrochloric Acid (HCl) (Approximately 3 Normal)Pour approximately 11.4 L (3 gal) of wate
13、r into an 18.9-L (5-gal) plastic carboy. Pour the contents of two full standard 2.7-kg (6-lb) bottles of concentrated reagent grade HCl in the carboy. Stir or mix the solution vigorously for about 1 min. Add tap water as necessary to bring the total volume of water and acid to 18.9 L (5 gal), and th
14、en stir or mix the solution vigorously for another minute. Allow the acid solution to stand overnight, and then remix it once again prior to using. Remix the acid solution once a week during use and also before using if the acid solution has been in storage for more than 1 week. 4.2. Phenolphthalein
15、 Indicator Solution (1 Percent Solution)Dissolve 5 g of phenolphthalein (U.S.P.) in 250 mL of 95 percent ethyl alcohol. Dilute with 250 mL of distilled water. 4.3. Polyacrylamide (Flocculating Agent) Stock SolutionMix 0.5 g of polyacrylamide (e.g., “separan” NP-10 by Dow Chemical Company) with 1000
16、mL of distilled water in a glass beaker. Stir frequently and allow to stand until no precipitates are visible. Prepare a fresh solution weekly. 5. MATERIALS FOR CALIBRATION TEST SPECIMENS 5.1. Two specimens with 1 percent less than the planned lime content and two specimens with 1 percent more than
17、the planned lime content for the project must be tested, and the data used in preparing a lime titration calibration curve. Aggregate, lime, and water to be used in the field project shall be used in preparing the calibration specimens. The moisture content of the specimens should be representative
18、of that to be used for the lime-treated material on the project. 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3a T 232-3 AASHTO 5.2. From Table 1, select the mass of aggregate corresponding to the
19、appropriate lime and moisture content. This is the mass of dry untreated aggregate required to prepare calibration test specimens of 300 g. If the sample of untreated aggregate initially contains moisture, adjust the mass of moist aggregate to yield the correct mass of dry material. A correction is
20、also made in the water measurement in Section 5.6 for the water contained in the moist aggregate. Table 1Quantities of Materials for Calibration Specimens Containing Various Percentages of Lime 1% Lime 2% Lime 3% Lime 4% Lime 5% Lime 6% Lime 7% Lime Dry Dry Dry Dry Dry Dry Dry Moisture Mass Mass Mas
21、s Mass Mass Mass Mass Content, Water, Agg, Lime, Agg, Lime, Agg, Lime, Agg, Lime, Agg, Lime, Agg, Lime, Agg, Lime, % mL g g g g g g g g g g g g g g 5 14 283 2.8 280 5.6 278 8.3 275 11.0 272 13.6 270 16.2 267 18.7 6 17 280 2.8 277 5.5 275 8.2 272 10.9 270 13.5 267 16.0 264 18.5 7 20 277 2.8 275 5.5 2
22、72 8.2 269 10.8 267 13.4 264 15.9 262 18.3 8 22 275 2.8 272 5.5 270 8.1 267 10.7 265 13.2 262 15.7 260 18.2 9 25 272 2.7 270 5.4 267 8.0 264 10.6 262 13.1 259 15.6 257 18.0 10 27 270 2.7 268 5.4 265 8.0 262 10.5 260 13.0 258 15.5 255 17.9 11 30 267 2.7 265 5.3 262 7.9 260 10.4 257 12.9 255 15.3 252
23、17.7 12 32 265 2.7 263 5.3 260 7.8 258 10.3 255 12.8 253 15.2 250 17.5 13 34 262 2.6 260 5.2 257 7.7 255 10.2 252 12.6 250 15.0 248 17.3 14 37 260 2.6 258 5.2 255 7.7 253 10.1 250 12.5 248 14.9 246 17.2 15 39 258 2.6 256 5.1 253 7.6 251 10.0 249 12.4 246 14.8 244 17.1 16 41 256 2.6 254 5.1 251 7.5 2
24、49 10.0 247 12.3 244 14.6 242 16.9 17 44 253 2.5 251 5.0 249 7.5 246 9.8 244 12.2 242 14.5 239 16.7 18 46 252 2.5 249 5.0 247 7.4 244 9.8 242 12.1 240 14.4 238 16.6 19 48 250 2.5 247 4.9 245 7.3 242 9.7 240 12.0 238 14.3 236 16.5 20 50 248 2.5 245 4.9 243 7.3 240 9.6 238 11.9 236 14.2 234 16.4 21 52
25、 246 2.5 243 4.9 241 7.2 238 9.5 236 11.8 234 14.0 232 16.2 22 54 244 2.4 241 4.8 239 7.2 236 9.4 234 11.7 232 13.9 230 16.1 23 56 242 2.4 239 4.8 237 7.1 235 9.4 232 11.6 230 13.8 228 16.0 24 58 240 2.4 237 4.7 235 7.1 233 9.3 230 11.5 228 13.7 226 15.8 25 60 238 2.4 235 4.7 234 7.0 231 9.2 229 11.
26、4 226 13.6 224 15.7 26 62 236 2.4 233 4.7 231 6.9 229 9.2 227 11.4 225 13.5 222 15.6 27 64 234 2.3 231 4.6 229 6.9 229 9.1 225 11.3 223 13.4 221 15.5 28 66 232 2.3 229 4.6 227 6.8 225 9.0 223 11.2 221 13.3 219 15.3 29 68 231 2.3 228 4.6 226 6.8 224 9.0 222 11.1 220 13.2 218 15.3 30 69 229 2.3 226 4.
27、5 224 6.7 222 8.9 220 11.0 218 13.1 216 15.1 31 71 227 2.3 225 4.5 222 6.7 220 8.8 218 10.9 216 13.0 214 15.0 32 73 225 2.3 223 4.5 220 6.6 218 8.7 216 10.8 214 12.8 212 14.8 33 75 224 2.2 222 4.4 219 6.6 217 8.7 215 10.8 213 12.8 211 14.8 34 76 222 2.2 220 4.4 217 6.5 215 8.6 213 10.7 211 12.7 209
28、14.6 35 78 220 2.2 218 4.4 216 6.5 213 8.5 211 10.6 209 12.5 207 14.5 5.3. From the project records, determine the average percentage of untreated aggregate passing the 37.5-mm sieve and retained on the 9.5-mm sieve. These percentages will be used for proportioning the calibration specimens. 5.4. Re
29、move and waste any aggregate in the sample of untreated material retained on the 37.5-mm sieve and separate the sample on the 9.5-mm sieve. Recombine for duplicate calibration test specimens with the aggregate mass found in Section 5.2 and the 9.5-mm sieve proportions found in Section 5.3. 2016 by t
30、he American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3a T 232-4 AASHTO 5.5. Select the required amount of lime from Table 1 and determine the mass to the nearest 0.1 g. 5.6. In a glass graduate, measure the require
31、d amount of water (corrected as in Section 5.2) in milliliters, given in Table 1. 6. CALIBRATION CURVE 6.1. Each test operator must establish two calibration curves at least once each day; one for a 4- or 5-h curing time, for use with field samples that are completely mixed and tested during the sam
32、e day, and one for a 24-h curing time, for use with field samples that are tested on the next day after mixing (see Note 2). If there is a change in acid, lime, aggregate, or water, new curves must be established after the change (see Note 3). Note 2Less correction will be needed and the results wil
33、l be more accurate if similar curing times are used for calibration test and field sample tests. Note 3A new calibration curve should be established when a fresh batch of diluted acid solution is prepared and when the source of the aggregate or water is changed. The calibration curve for each curing
34、 time should be checked when there is a suspected change in character of aggregate specimen or water from the same source. 6.2. For each specimen, pour the weighed aggregate and lime from Sections 5.4 and 5.5, respectively, into the 1.9-L (2-qt) plastic container and mix thoroughly with a stirring r
35、od. 6.3. Add the quantity of water measured in Section 5.6 and mix thoroughly. The time that the water is added is considered the start of the curing period. 6.4. Place the 1.9-L (2-qt) containers in a row on the table that is to be used for the testing, leave the samples uncovered, and allow to cur
36、e for the times given in Section 6.1. 6.5. Just prior to expiration of the curing time in Section 6.1, prepare the polyacrylamide solution as follows: Behind each testing specimen, place a plastic beaker into which has been measured 200 mL of tap water and 50 mL of the polyacrylamide stock solution
37、(prepared from Section 4.3); also for each test specimen, determine the mass of a glass graduate, add to it 50 mL of the polyacrylamide stock solution, and record the net mass to the nearest 0.1 g. 6.6. At the end of the curing period, the constant neutralization test is performed as follows: 6.6.1.
38、 Start the timer and add the mixed water and polyacrylamide stock solution to the first specimen. Add the liquid to successive specimens at intervals of 120 s. 6.6.2. Add two full droppers (approximately 40 drops) of phenolphthalein solution to each container. The water will normally turn red due to
39、 the presence of lime. 6.6.3. Determine the mass of each plastic container, including its contents, to the nearest 0.1 g. 6.6.4. Place the fluorescent light behind the plastic containers. 6.6.5. At 8 min after the addition of the mixed water and polyacrylamide stock solution to the first specimen (s
40、ee Section 6.6.1), start adding 3 Normal HCl to this specimen from a buret while stirring continuously. Only enough acid is added to cause the red color to just disappear. Similarly, add acid to successive specimens at 120-s intervals, that is, at timer readings of 10, 12, and 14 min for the second,
41、 third, and fourth specimens, respectively, or a series. 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3a T 232-5 AASHTO 6.6.6. When the red color starts to reappear after the initial introduction o
42、f acid, use the buret to make a second addition of acid in the amount (mL) necessary to cause the color to just disappear. Subsequent additions of acid are made as necessary to cause the color to just disappear. 6.6.7. In addition to the stirring accomplished during each introduction of acid, stir l
43、ightly for about 3 s of every minute and for about 6 s of every fifth minute, regardless of whether color is present (see Note 4). Perform the stirring in a circular and zigzag pattern across the bottom of the plastic container. Be careful to avoid the possibility of leaving any deposit of unneutral
44、ized lime in the center of the container. Note 4Caution: Stir lightly. Vigorous stirring at this time will cause the flocculated particles to disperse, making it difficult to see the end point. 6.6.8. At the end of 25 min after adding the initial amount of mixed water and polyacrylamide stock soluti
45、on to the first sample, stir the sample vigorously, add the additional 50 mL of polyacrylamide stock solution (see Section 6.5), and continue the test. Repeat this procedure with each of the specimens, allowing a 120-s interval between specimens. This will require timer readings of 27, 29, and 31 mi
46、n, respectively, for the second, third, and fourth specimens of a series. 6.6.9. Continue the procedure of adding acid and stirring until 38 min have elapsed since the initial addition (see Section 6.6.1) of mixed water and polyacrylamide stock solution to the first specimen. Then reweigh the plasti
47、c container contents to the nearest 0.1 g. Repeat this procedure with each of the specimens allowing 120-s intervals between specimens. This will require readings of 40, 42, and 44 min, respectively, for the second, third, and fourth specimens of a series. 6.6.10. Using the difference between the in
48、itial mass (determined in Section 6.6.3) plus the additional mass of polyacrylamide stock solution (determined in Section 6.5) and the final test specimen masses (determined in Section 6.6.9), calculate and record the total mass of hydrochloric acid (HCl) used to neutralize the solution, and then de
49、termine the average mass of HCl used for each pair of test specimens. 6.7. Plot the average mass of HCl used (see Section 6.6.10) against the percent lime used in the paired specimens. Draw a straight line between the two points. This is the calibration curve for determining the lime content of field-mixed, lime-treated specimens (see Figure 1). 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3a T 232-6 AASHTO 16-h Curing Time2.0-g Correction16-h Reading0 10 20 30
