AASHTO T209 沥青混合料理论最大密度试验方法.pdf

THEORETICAL MAXIMUM SPECIFIC GRAVITY and DENSITY of HOT MIX ASPHALT PAVING MIXTURES AASHTO T 209 GLOSSARY Specific gravity -- the ratio of the weight in air of a volume of material at 77° F (25° C) to the mass in air of an equal volume of water Residual pressure -- the pressure in a vacuum container when vacuum is applied SCOPE The volumetric properties of HMA are required to be controlled during design and production to produce durable pavements. A test to measure the volume of a mixture with all the air voids removed is needed to measure this durability. The maximum specific gravity (Gmm) of HMA is the ratio of the weight of the loose sample to the weight of an equal volume of water at the standard temperature of 77°F (25°C) Gmm is used along with the bulk specific gravity (Gmb) of the compacted mixture to determine air voids (P ). The G is often used also for determining the percent of compaction in laboratory a mm specimens or during roadway compaction. The procedure using a vacuum container for plant-produced mixture is the procedure that will be discussed herein. INDOT uses the weighing-in-water procedure with a vacuum container for determining the maximum specific gravity. Other procedures are covered in AASHTO T 209. SUMMARY OF TESTS Apparatus (Figure 1) Vacuum Container, capacity of at least 2000 mL, capable of withstanding the full vacuum applied and having a No. 200 (75 µm) wire mesh covering the hose opening Vacuum System, capable of subjecting contents to a partial vacuum of 27.5 ± 2.5 mm Hg (3.7 ± 0.3 kPa) Residual Pressure Manometer, capable of measuring the residual pressure down to 30 mm Hg (4.0 kPa) 1 Thermometer, con