Page 55 - Unit 2: Pavement Material

Civil Engineering Department | DCC3113 : Highway & Traffic Engineering

AC Mix Calculate the optimum bitumen content

Determination of optimum asphalt content using the test results pertaining to a Marshall trial
mix with different asphalt contents (i.e. evaluation of a trial mix), is illustrated in the following
Example:

Following are the test results pertaining to a Marshall trial mix with different bitumen
contents:

Bitumen Density Flow Air voids In VFB VMA

content (kg/m ) Stability (kN) (mm) Total Mix (%) (%)
3
(%)
(%)
4.5 2325 9.8 2.6 6.0 63.0 16.5
5.0 2380 9.9 3.1 4.0 75.0 16.0
5.5 2380 8.6 3.5 3.5 79.0 17.0

6.0 2345 7.6 3.7 3.0 83.0 18.0
6.5 2320 6.2 4.6 2.5 85.0 19.0

Plot the test results and find the optimum bitumen content to meet suggested requirements
for a surface course (12.5 mm or ½ inch aggregate) for a medium-traffic area.

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Prepared by : SITI ZURAIFA BINTI MD SAH, zuraifa@pmu.edu.my