What does the particle density of ASTM C128 represent?

[goldfish9776]

I was told that the bulk density of SP Gr of ASTM C128 for fine aggregate is (dry weight of aggragrate)/ ( weight of pycnometer filled with water + saturated surface dry of sample - weight of pycnometer filled with water and aggragrate )...What does the ( weight of pycnometer filled with water + saturated surface dry of sample - weight of pycnometer filled with water and aggragrate ) represent ?

 

[insightful]

What does the ( weight of pycnometer filled with water + weight of pycnometer with only saturated surface dry [] sample - weight of pycnometer filled with water and aggragrate ) represent ?

This represents the weight of the water displaced by the aggregate (plus the weight of the pycnometer). Notice my changes in red above. Note also that the numerator in your calculation should also be "weight of pycnometer with only saturated surface dry sample."

ASTM C128 actually gives the "particle density" of the aggregate.