Question

The _________ is suitable for caissons of Open Well type.

(a) Steel

(b) Timber

(c) Reinforced cement concrete

(d) Cast-iron

The question was posed to me by my school teacher while I was bunking the class.

This key question is from Classification of Caissons in division Deep Excavations, Pile Foundations and Caisson of Construction & Building Materials

Answer 1

Right option is (d) Cast-iron

To elaborate: New segments of cast iron are bolted as the caisson sinks. Cast iron is unsuitable for pneumatic caissons as there is risk of failures due to tension developed by the compressed air. The cost also works out to be more in relation to steel or RCC.