Page 50 - Lecture Notes DCC3113

Figure 3-18: Aggregate Mixing Specimen
Density determination

Compacted specimens have cooled to room
temperature, the bulk specific gravity of each test
specimen shall be determined in accordance with
ASTM D 2726

Marshall Stability and Flow test

i. The stability and flow value of each test
specimens shall then be determined in
accordance with ASTM D 1559.
ii. The stability portion of the test measures the
maximum load supported by the test
specimen at a loading rate of 50.8
mm/minute (2 inches/minute).
iii. The maximum load achieved, after correction
to allow for variation in specimen size, is
reported in kN as the Stability of the mix.
iv. The differential movement of the between
initial and maximum loading is recorded as
the Flow (mm)
Figure 3-18: Marshall Stability and Flow Test
Using Dial Gauge

Plotting test results and determination of optimum bitumen content (OBC)

i. After the completion of the stability and flow test, specific gravity and voids analysis shall be
carried out for each test specimen to determine the percentage air voids in the compacted
aggregate filled with bitumen (VFB) and that percentage air voids in the compacted mix
(VIM).
ii. The average values of bulk specific gravity, stability, flow, VFB and VIM obtained above shall
be plotted separately against the bitumen content and smooth curve drawn through the
plotted value.

Figure 3-20: Five different types of graphs in Marshall Design

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