Question

In marshall mix design the specific gravities and weights of the aggregates used is given below. The weight of the bitumen is 100 gm. The weight and volume of one marshall specimen is 1080 gm and 450 cc. The percent volume of bitumen if the volume of air voids is 5% is
$\begin{array}{ccc}\text{Particular}& \text{Weight(gm)}& \text{Specific Gravity}\\ \text{Aggregate}& 2000& 2.6\\ \text{Filler}& 300& 2.4\end{array}$

• A. 5.505%
• B. 8.505%
• C. 6.505%
• D. 10.505%

Answer 1

The correct option is A 5.505%

Actual specific gravity,
$=1080/450=2.4$
$VMA=V_v\%+V_b\%$
$VMA=100-$percent volume of aggregates and filler

$=100-\left[\frac{\frac{W_{agg+Filler}}{G_{agg+Filler}}}{\frac{W_{total}}{G_{actual}}}\right]\times 100$
Specific gravity of aggregates + filler:
$\frac{2000+300}{G_{agg+Filler}}=\frac{2000}{2.6}+\frac{300}{2.4}$
$G_{agg+filler}=2.57$
$VMA=100-\left[\frac{\frac{2000+300}{2.57}}{\frac{2000+300+100}{2.4}}\right]\times 100$
$=10.505\%$
Percent volume of bitumen
$=10.505-5=5.505\%$