Figure 13-36.-Data sheet for aggregate gradation of trial blends (DD Form 1217).primary roads. Seventy-five blows produce theequivalent of a tire pressure of 200 psi; 50 blowsproduce the equivalent of a tire pressure of 100 psi. Afterthe compaction process, place the mold in abearing-ratio jack and extract the compacted samplewith extraction equipment.Density and Voids DeterminationDensity of the specimens should be determined byweighing in air and in water. A direct weight in water ofopen-textured or porous specimens will give erroneousresults because of absorption of water, and other meansmust be used to determine the volume of the specimen.One means of measuring the volume of a porousspecimen is to coat the specimen with paraffin to seal.all the voids and then weigh the coated specimen in airand in water. A correction is made for the weight andvolume of the paraffin. The difference between thesetwo weights, in grams, gives the volume of the specimenin cubic centimeters. You can then determine the unitweight (density) of the mix in pounds per cubic foot foreach specimen by multiplying the specific gravity of thespecimen by 62.4 pounds (weight of 1 cubic foot ofwater). Before carrying out the calculations for percentof voids, you must know the specific gravity of theaggregate blend and the asphalt content used.Stability and Flow DeterminationA full discussion of the method used to test forstability and flow can be found in NAVFAC MO-330;13-49