8 November 2017

Marshall stability and flow test of bituminous mix

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:
Bitumen content (%)
Corrected Stability(kN)
Flow(mm)
4.0
10.71
2.28
4.5
11.76
2.31
5.0
13.33
2.97
5.5
13.78
2.30
6.0
13.52
2.95
6.5
12.13
3.62
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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