Question

During design of Raft foundation according to IS code, the maximum settlement in sand and hard clay for reinforced concrete structures is:

1. 65 mm
2. 40 mm
3. 90 mm
4. 75 mm

Answer 1

Correct Answer - Option 4 : 75 mm

Explanation:

(i) For an isolated foundation on clayey soil, max allowable settlement is 75 mm as per IS 1904.For sands & hard clay it is only 50 mm.

(ii) For rafts founded on sands & hard clay it is limited to 75 mm whereas for soft clays it is allowed upto 100 mm.

For Differential Settlement:

(i) In Sand ⇒ 25 mm

(ii) In Clay ⇒ 40 mm