Question

Compaction of an embankment is carried out in 500mm thick layers. The rammer used for compaction has a foot area of 0.05$m^2$ and the energy imparted in every drop of rammer is 400 N-m. Assuming 50% more energy in each pass over the compacted area due to overlap, the number of passes required to develop compactive energy equivalent to Indian Standard light compaction for each layer would be

• A. 10
• B. 16
• C. 20
• D. 26

Answer 1

The correct option is D 26

As per Indian standard light compaction test a hammer of 2.6 kg is allowed to fall from a height of 310 mm and 3 layers are tamped 25 times in a mould of volume 1000 cc

$\therefore \text{Energy imparted,}$

= 2.6 $\times$ 25 $\times$ 3 $\times$ 9.81 $\times \frac{310}{1000}$

= 593.01 Nm

For embankment compaction, the volume os soil covered by rammer,

$=0.05\times {10}^4\times \frac{500}{10}=25000cc$


Energy imparted in each pass,

$=(1+50$% $)\times 400$

$=(1+\frac{50}{100})\times 400=600N.m$

If n number of passes are required to develop equivalent energy to Indian standard light standard light compaction test then,

$n\times \frac{600}{25000}=\frac{593.01}{1000}$

$\Rightarrow n=24.71$

= 25