Humboldt H-3383L Humboldt Specific Gravity Flask (Phunque Flask) - Manual (Page 2)

Introduction
For fine aggregate— H-3383F
For coarse aggregate— H-3383L
The Phunque Flask is the key element in a newly developed method for
conducting specific gravity/absorption determinations for aggregate. This
method has been designed to eliminate the inherent guess work built into
ASTM C128 and AASHTO T-84— the current cone and tamper methods in
use today. The test is easy to perform, easy to understand and easily
reproduceable between technicians and labs; and is very easy to run reliably
in the field. The test can be especially helpful in asphalt operations where
specific gravities can make a big impact on pay factors. This test lets the
contractor check specific gravities on the material he is currently using, and
not rely on lab tests, which may not be current.
The test provides repeatable and consistent test results despite the use of
different labs or technicians. It also enables the contractor and DOTs to begin
to come to terms with the inherent problem of how much the aggregate from
a given pit or source varies, both by location within the pit, and from different
fundamental geological characteristics.
Additionally, the test allows specific gravities to be tracked, and a moving-
average chart maintained. If found to be appropriate, the contractor would
be able to calculate the volumetrics using a moving average approach for the
aggregate actually being used instead of the highly variable value determined
in a lab 6 months to a year earlier. This process, itself, could eliminate many
penalties and/or claims.
The H-3388F is for fine aggregate and has a neck approximately 1" in
diameter. The H-3388L is used for coarse aggregate and has a neck
approximately 2" in diameter. The scale on both items is readable to 0.1
grams; Both include an excel calculation sheet and a swabbing utensil to
keep the neck of the flask dry during loading.
Process
To begin, make sure personnel understand the terms used in the
measurements discussed here. Bulk specific gravity, as defined by members
of the American Association of State and Highway Transportation Officials
(AASHTO), is the characteristic generally used for calculations of the volume
occupied by the aggregate in various mixes containing aggregate that are
proportioned or analyzed on an absolute volume basis. In other words, it's
the measure of volume the aggregate takes up. Bulk specific gravity is also
used in the computation when the aggregate is assumed to be dry.
1