How to repair concrete base of sewerage ventilation pipe?

[laesabolwell]

Recently a sewerage ventilation pipe fell down at our house. The old pipe was metal. The house dates to the early 1970’s. At the ground the old pipe was encased on concrete and at the top it was connected to another pipe fitting attached to the guttering. When the old metal pipe fell it broke the top surrounds of the concrete dome. It has since been replaced with a PVC pipe but we need to repair the concrete dome to encase and protect the base of the new pipe. Is there a product that we can use to do this repair?

[Jason]

Hi @laesabolwell,

Welcome to Bunnings Workshop. We're really pleased to have you join the community and look forward to reading all about your projects and plans for around the house and garden.

Sorry for the slow reply, but I'm sure our resident Bunnings D.I.Y. expert @EricL will be happy to share his thoughts with you about this repair as soon as possible. 

Let me also tag @JacobZ95 and @Dave-1 to see what they think.

Thanks,

Jason

[Dave-1]

Good Morning @laesabolwell 

Mmmm I was thinking along the lines thatit was a downpipe and was going to offer this suggestion Deks 100mm EW To PVC Rubber Joiner Adaptor 

Its a vent pipe so maybe you can use concrete only around it? 

Do you have a photo without the PVC pipe above it? Id be making sure any loose or high bits have been removed first before re-sealing around it to give the best possible connection tho.

Thinking about it I would still use that adaptor to give mechanical conenction to the pipe, since its standing on its own it would potentially happen again. Depending on the size of you pvc pipe it could also fit down into the existing terracotta pipe doing away with the need for that adaptor.

Dave

[laesabolwell]

Thankyou @Dave-1. Unfortunately I did not take a photograph before the new PVC pipe was put in. Yes the pipe is a vent pipe and not a down pipe. We would definitely remove the loose and broken bits of old concrete first and take care not to drop any down the hole. I was hoping there might be some type of bonding agent that can adhere to the remaining concrete base so we can rebuild the top of the broken concrete dome.

[Dave-1]

Morning @laesabolwell 

Maybe have a look at this Sika 20kg SikaQuick 2500 (au) Rapid Hardening Repair Mortar I have used concrete mate for a patio repair and that worked nicely (formwork was involved) But id make a drier mix of concrete and use that. Australian Builders 20kg High Strength Concrete Mix is What id try instead of the $60 version

I always forget to take pics of things that I look back and go mmm yeah that would have been an idea (And I take a LOT of pics)

Dave

[EricL]

Hello @laesabolwell 

It's great that you've received excellent advice from @Dave-1. 

Now that we know that it is just a ventilation pipe, I suggest slipping in a Holman 90mm PVC Stormwater Slip Coupling. This will reduce the gap between the PVC and the concrete base. 

To restore the conical shape of the dome, I suggest using Dingo 10kg Mortar Mix mixed to the consistency of peanut butter or toothpaste. With this consistency the mortar will behave like soft playdough for a limited time. This is the best opportunity to shape the mortar back to the concretes original form.

Once the mortar cures, you can then paint it back to its original colour.

If you have any other questions we can help with, please let us know.

Eric    

[laesabolwell]

Thankyou @Dave-1 @EricL @Jason . The advice you all shared is very helpful. Best regards

[EricL]

Hi @laesabolwell 

Don't forget to post a photo update, I'm sure our members will be keen to see the results of the repair. If you run into any other repair issues, please don't hesitate to post a question.

Eric