17-01-2014, 03:12 PM
MARSHALL STABILITY
AIM
To determine the Marshall stability of bituminous mixture as per
ASTM D 1559.
PRINCIPLE
Marshall stability is the resistance to plastic flow of cylindrical
specimens of a bituminous mixture loaded on the lateral surface.
o
It is the load carrying capacity of the mix at 60 C and is
measured in kg.
SAMPLE
From Marshall stability graph, select proportions of coarse
aggregates, fine aggregates and filler in such a way, so as to fulfill
the required specification. The total weight of the mix should be
1200g.
PROCEDURE
i) Heat the weighed aggregates and the bitumen separately
o
o
upto 170 C and 163 C respectively.
ii) Mix them thoroughly, transfer the mixed material to the
compaction mould arranged on the compaction pedestal.
iii) Give 75 blows on the top side of the specimen mix with a
standard hammer (45cm, 4.86kg). Reverse the specimen
and give 75 blows again. Take the mould with the specimen
and cool it for a few minutes.
iv) Remove the specimen from the mould by gentle pushing.
Mark the specimen and cure it at room temperature,
overnight.
v) A series of specimens are prepared by a similar method
with varying quantities of bitumen content, with an increment
of 0.5% (3 specimens) or 1 bitumen content.
vi) Before testing of the mould, keep the mould in the water
o
bath having a temperature of 60 C for half an hour.
REPORTING OF RESULTS
Plot % of bitumen content on the X-axis and stability in kg on
the Y-axis to get maximum Marshall stability of the bitumen mix.
A sample plot is given in Annexure-X.