NAME OF THE EXPERIMENT: Marshall stability and flow test
AIM OF THE EXPERIMENT:
To determine the resistance to plastic flow of cylindrical specimens of asphalt
paving mixture loaded in a direction perpendicular to the cylindrical axis by
means of the Marshall apparatus.
REFERRED STANDARDS:
Ø ASTM D6927-15
Standard Test Method for Marshall
Stability and Flow of Asphalt Mixtures.
Ø IRC:
111 – 2009 Specifications for Dense Graded Bituminous Mixes.
SUMMARY OF TEST METHOD:
(i) A
series of specimens were prepared with varying quantities of bitumen content,
with an increment of 0.5%, three specimens for one bitumen content.
(ii) Before
testing of the mould it was kept in the water bath having a temperature of 60˚C
for half an hour.
(iii)
Loaded the specimen in the Marshall testing head and brought the loading ram
into contact with testing head.
(iv)
Load-deformation were recorded simultaneously by
using a load cell and linear variable differential transducer (LVDT).
Significance
and use:
Ø Marshall
flow is a measure of deformation (elastic plus plastic) of the bituminous mix
determined during the stability test.
Ø Marshall
Stability and flow values along with density, air voids in the total mix, voids
in the mineral aggregate and voids filled with asphalt are used for laboratory
mix design and evaluation of asphalt mixtures.
Ø Marshall
Stability and flow may also be used to relatively evaluate different mixes and
the effects of conditioning such as with water.
OBSERVATIONS AND
CALCULATIONS:
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RESULTS:
The Marshall
Stability at the expected bitumen content of 5.0 % is found to be 13.33 kN and
the Marshall flow at that bitumen content is found to be 2.97mm.
Discussion:
Ø The
Marshall Stability and flow we got here in the test are satisfying the
specification given in IRC: 111 – 2009.
Ø Depending
on the composition and behaviour of the mixture, a less defined type of failure
can also be observed.
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