Question

In the Marshall method of mix design, the coarse aggregates, fine aggregates, filler and bitumen, having respective specific gravities of 2.62, 2.72, 2.70 and 1.02 are mixed in the ratio of 55, 34.6, 4.8 and 5.6%, respectively. The theoretical specific gravity of the mix would be

• A. 2.40
• B. 2.50
• C. 2.36
• D. 2.44

Answer 1

The correct option is D 2.44

Theoretical specific gravity of mix,
$G_t=\frac{100}{\frac{W_{CA}}{G_{CA}}+\frac{W_{FA}}{G_{FA}}+\frac{W_F}{G_F}+\frac{W_b}{G_b}}$

$W\to$% by weight
$G\to$ specific gravity

$G_t=\frac{100}{\frac{55}{2.62}+\frac{34.6}{2.72}+\frac{4.8}{2.70}+\frac{5.6}{1.02}}$

$=2.44$