Is it preferable to compact bedding for concrete pipes?

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In the middle third of the base of precast concrete pipes, the bedding layers are recommended to be left uncompacted because it helps to reduce the reaction force at the invert of the pipes and intensifies the effect of shear forces. Moreover, the bending moment at pipe invert is increased by the compaction of bedding layer. The general rule for this region of bedding layer is that it should be firm enough for the pipes to rest on.

The sides of haunch and bedding directly under the haunch should be compacted because this will reduce the bending moment at the invert which is the critical failure location for pipes. The compacted haunch helps to resist the pipe load and maintain level and alignment.


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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  • Ted Cronk August 14, 2011 at 3:14 pm


    Have you any information on pipe laying that relates to establishing trench elevation to start the excavating and establishing a grade for trench over distance?

    I am also looking for information relating to maintaining pipe installation grade and alignment using batter board system and lasers.

    Finally, I am looking for a book that will provide the above and contain blueprint symbols and pipe laying terminology relevent to civil works in Canada that I can use as a reference.

    Thank you for your consideration to my query,


    Ted Cronk
    British Columbia

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