Civil Engineering - Highway Engineering - Discussion

Sub-base materials comprise natural sand, gravel, laterite, brick metal, crushed stone or combinations thereof meeting the prescribed grading and physical requirements. The sub-base material should have a minimum CBR of 20 % and 30 % for traffic upto 2 msa and traffic exceeding 2 msa respectively. Sub-base usually consist of granular or WBM and the thickness should not be less than 150 mm for design traffic less than 10 msa and 200 mm for design traffic of 1:0 msa and above. Base The recommended designs are for unbounded granular bases which comprise conventional water bound macadam (WBM) or wet mix macadam (WMM) or equivalent confirming to MOST specifications. The materials should be of good quality with minimum thickness of 225 mm for traffic up to 2 msa an 150 mm for traffic exceeding 2 msa. Bituminous surfacing The surfacing consists of a wearing course or a binder course plus wearing course.

The most commonly used wearing courses are surface dressing, open graded premix carpet, mix seal surfacing, semi-dense bituminous concrete and bituminous concrete. For binder course, MOST specifies, it is desirable to use bituminous macadam (BM) for traffic upto o 5 msa and dense bituminous macadam (DBM) for traffic more than 5 msa.

It should be 15 cm.

As per IRC 37.

Minimum thickness of base course for traffic up to 2 msa is 225mm.

Minimum thickness of base course for traffic greater than 2 msa is 250 mm.

Wearing course 10 cm.

Base course 30 cm.

Can you explain why it should be 15cm? @Sanjay.

It should be 25 cm.

I think it is 25.

What is the right answer? please tell.