Question

In the laying of concrete, what paper is laid to make filter blanket effective?

(a) Filter Layer

(b) Filter Blanket

(c) Tar Paper

(d) Sandpaper

This question was addressed to me at a job interview.

The query is from Hard Surface or Rigid Linings in division Lining of Irrigation Canals and its Economics of Irrigation Engineering

Answer 1

The correct choice is (c) Tar Paper

Best explanation: Before laying the concrete the subgrade should be levelled dressed and moistened thoroughly so that the moisture is not taken from the concrete laid. To avoid this inverted filter blanket is laid over the subgrade before laying the concrete. And to make this blanket effective and to prevent the ingression of concrete being laid on the blanket a tar paper is placed over the filter blanket, before the placing of cement concrete.