Question

In an aggregate mix, the proportions of coarse aggregate, fine aggregate and mineral filler are 55%, 40% and 5%, respectively. The values of bulk specific gravity of the coarse aggregate, fine aggregate and mineral filler are 2.55, 2.65 and 2.70, respectively. The bulk specific gravity of the aggregate mix (round off to two decimal places) is \(\underline{\hspace{2cm}}\).

Hint:

The bulk specific gravity of the aggregate mix is calculated using the weighted average of the specific gravities of the components.

Answer 1

Correct Answer: 2.58

The bulk specific gravity of the aggregate mix can be calculated using the weighted average method: \[ G_b = (G_{b1} \times V_1 + G_{b2} \times V_2 + G_{b3} \times V_3) / (V_1 + V_2 + V_3), \] where \( G_b \) is the bulk specific gravity of the aggregate mix, \( G_{b1} \), \( G_{b2} \), and \( G_{b3} \) are the bulk specific gravities of the coarse aggregate, fine aggregate, and mineral filler, and \( V_1 \), \( V_2 \), and \( V_3 \) are the volumes of coarse aggregate, fine aggregate, and mineral filler, respectively. Given that the proportions are 55%, 40%, and 5%, we calculate the weighted bulk specific gravity: \[ G_b = (2.55 \times 0.55 + 2.65 \times 0.40 + 2.70 \times 0.05) = 2.58. \] Thus, the bulk specific gravity of the aggregate mix is \( \boxed{2.58} \).