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California Tact 301 1978 H. THE BATCHING OF BASE, SUBBASE AND BASE- 5. limisediately cover pan to prevc* ` less of mois- MENT SOILS CONTAINING PORTIONS OF BITUMI- lure before boo inning Part I1 of the test method. THOUS MIX 1. Break humps of bitll[ninnnS mix dawr,to pass the 1-inch sieve and remove all rocks over I inch.A sieve K. PRECAUTIONS analysis is not normally performed on samples such 1. Exercise c.ue in splitting and batching the pass- as these. ing No.4 sieve fractions to insure a minimum loss of 2. Quarter sample careful]), through a riffle split- dust from the sample.Tests have shown that differ- ter and then follow the procedure as outlined in Sec- enc•es in the amount of fines can have a profound tion F above. effect on the R-v!due test. 2. Complete and thorough mixing of the sample 1. INITIAL MOISTURE SAMPLE during the process of adding water is essential for For all materials to be tested,weigh out an extra uniformity of test results.The period of mixing given sample of 200 grans or more, having exactly the in Section F-6,of this procedure,must be observed same grading as the test samples,for the determirta- as the minimum requirement.However,to avoid ex- kion of initial moisture.Determine the moisture con- cess moisture loss due to evaporation,do not contin- tent by weighing accurately before and after drying ue mixing longer than two minutes after the addition to constant weight at a temperature between 221' of water has ceased. and 230'F. 3. At all times except during immediate process- J. MIXINGing,keep the samples in covered containers to pre- t 1. The R-value test requires the preparation of vent evaporative toss of moisture. four test briquettes at different moisture contents. The first briquette is used as a pilot specimen.After L. NOTES completing the pilot specimen, it can be used as a The determination of the proper soil weight-mois- gui_Se in the preparation of the other three stabilom- tune relationships of test specimens,which is needed eter specimens which shall,when possible,conform to meet the requirements of the 11-value test, re- to the following limitations: quires judgment and experience on the part of the Height = 2.5 ± 0.05 inches. operator.An estimation of the weight of material and - Exudation pressure:One sample should be above moisture must be made for the pilot or trial bri- and two below 309 psi or two above and one below quette,and its exudation pressure and height must 300 psi, conform to the above Section 1.Then, from the at- 2. All samples should exude moisture when the Cached chart (Figure 1) use the pilot specimen data pressure is between 100 and 800 psi, except when and determine the approximate weight of material very high expansion pressures are expected. In the For a 2'/.--inch high stabilometer specimen.From the latter case,wetter specimens are sometimes neces- exudation pressure of the pilot specimen,determine sary to'get expansion pressures low enough to pro- whether to use more or less moisture in the remain- vide an intersection with the R-value curve. ing samples to obtain the desired results.The deci- 3. On the day following the overnight curing peri- sion as to the amount of water to use still rests with od,add additional moisture,in the same manner as the operator. If the pilot specimen conforms to the described above in Section F-6, until the estimated requirements for a stabilometer specimen it may be saturation moisture is attained.If the optional proce- used as such,otherwise it should be discarded. dure for aggregate bases was used,add all the water ?Formally, three specimens are enough to deter. needed to attain saturation moisture. Mix well, in mine the R-value. However, in the case of critical either case,while adding water and continue mixing materials it is sometimes necessary to make addition- for one minute thereafter. al tests in order that the true shape of the exudation 4. Weigh out enough material to fabricate a com- pressure curve will be known at the"300 psi"exuda- pacted specimen 4 inches in diameter and 21/1 inches tion point. The exact number of tests needed is a high. matter of judgment. 1 i 4