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What is the function of waterproof or separation membrane for concrete carriageway?

A layer of waterproof (or separation) membrane is normally placed between sub-base and concrete slab for the following reasons:

(i) It prevents the loss of water from cement paste which affects the strength of concrete slab.

(ii) It enhances the movement of concrete slab relative to sub-base layer and reduces the frictional forces developed at their interface.

(iii) It avoids the possibility of active aggressive agents from soil water being attached to the concrete slab.


(iv) It prevents the intermixing of freshly placed concrete with loose materials on the surface of sub-base.

location of separation membrane

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.

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Kanwarjot Singh

Kanwarjot Singh is the founder of Civil Engineering Portal, a leading civil engineering website which has been awarded as the best online publication by CIDC. He did his BE civil from Thapar University, Patiala and has been working on this website with his team of Civil Engineers.

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One comment on "What is the function of waterproof or separation membrane for concrete carriageway?"

Bhusal T.L. says:

very very informative and increase knowledge.

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