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TESTS ON AGGREGATE - 14070_311
Figure 13-35.Data sheet for specific gravity of bituminous mix components (DD Form 1216). - 14070_313

Engineering Aid 1 - Advanced Structural engineering guide book
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Figure 13-34.-Dunagan apparatus for specific gravity test. Test for Mineral Dust In bituminous paving, particles finer than the No. 200 sieve are referred to a mineral dust. To measure the amount  of  mineral  dust  in  a  selected  sample,  you perform a washed sieve analysis (discussed in the EA3 TRAMAN), using the No. 40 and No. 200 sieves. After all the material possible has passed the No. 200 sieve and has been discarded, the materials remaining on the sieve  are  returned  to  the  original  washed  sample, oven-dried,  and  weighed  The  amount  of  mineral  dust  is then calculated, using the following formula: Tests for Specific Gravity The  specific  gravities  of  aggregates  used  in bituminous   paving   mixtures   are   required   in   the computation  of  the  percent  of  air  voids  and  percent  of voids filled with bitumens. Apparent specific gravity used  with  aggregate  blends  showing  water  absorption of less than 2 1/2 percent is based upon the apparent volume of the material, which does not include those pore spaces in the aggregate that are permeable to water. Bulk-impregnated  specific  gravity  is  used  for  aggregate blends  with  2  1/2  percent  or  greater  water  absorption The  methods  for  determining  absorption  were  discussed earlier in this chapter in the discussion of concrete aggregates. The apparent specific gravity can be determined using  the  methods  described  in  NAVFAC  MO-330  for apparent  and  bulk  specific  gravity.  It  may  also  be determined using the Dunagan apparatus shown in figure 13-34. The procedures are as follows: 1. Select approximately 5,000 grams of aggregate from the sample, not including particles smaller than the 3/8-inch  sieve. 2. Wash the aggregate to remove any dust or other coating and dry it to constant weight in the oven. Record the total weight of ovendry aggregate on the data sheet, as shown in figure 13-35. 3. Immerse the aggregate in water at 15°C to 25°C for a period of 24 hours. 13-46







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