concrete water rill 1

[coxy84]

a client has requested a water rill constructed from concrete, not very large around 500mm wide 200mm deep, construction wise i was thinking few inches of compact stone then dpm and 100mm slab of concrete with steel mesh in
bottom and along side walls, allow that to set then make ply former for side walls and pour 100mm wide walls, the rill is quite long around 8-10m would expansion joints be needed? any comments much appreciated

 

[dicksewerrat]

Please explain more about what this will do.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[cntw1953]

If this water rill (open flow channel, or ditch) is for water conveying, then joint is not desirable, moderate steel reinforcing may suffice. But, as pointed out above, more information is required to evaluate this problem, and provide appropriate comments.

 

[Ron]

8 to 10m long is not long for a concrete structure, even one as small in cross-section as this one. I would not anticipate the need for an expansion joint except an isolation joint if it adjoins another rigid structure.

With the cross-section you described, I would anticipate shrinkage cracks at 2 to 3m. With reinforcing, the cracks should remain tightly closed, but you might consider a coating anyway.

If the rill has intermittent dry periods, cracking will be worse, as wetting/drying causes cracking in concrete.

As cntw1953 noted, it is not desirable to have joints in a water conveyance.

 

[bimr]

You do not need any expansion joints. However, you should use a liner. You will never be able to keep water in it unless it is lined.

There are some simple directions to build a rill on eHow:

http://www.ehow.com/how_5698493_build-rill-water-garden.html

 

[bimr]

Here is an example of a rill that was constructed from prefabricated sections joined by expansion joints:

http://www.asla.org/meetings/am2008/docs/T18TarpFarm.pdf

A major concern in the construction of the one hundred and sixty foot long water rill was the problem of
frost-heave. The rill is made up of ten-foot sections that can rack or twist but not leak, linked by expanding
leak-proof joint material.

 

[coxy84]

the water rill is for aesthetic purposes a water feature it bubbles up at the top end and runs down to fall into a pool,
bimr when you say it needs to be lined can this be done under concrete as concrete is the finish they want what liner would you recommend, thanks for all comments

 

[Ron]

coxy84...I would use a white, 40 to 60 mil PVC or Terpolymer roof membrane. Since the rill is not that long and certainly not very wide, you could get this in one piece so that you have no joints in the membrane.

 

[coxy84]

cheers ron

 

[bimr]

PVC and Butyl liners are the two most commonly used liners.

PVC Liners
PVC liners are also called plastic liners. They are the most flexible and widely used because they are easy to install and maintain. These liners are also considered safe for aquatic plants and animals.

Butyl Liners
Butyl offer a good competition to the PVC liners in terms of usage. These liners are extremely durable since they have a life span of at least 20 years. These liners are also resistant to damage caused by extreme heat from the sun or UV rays. They are also ozone resistant. The butyl liners are easy to install and maintain too.

Butyl liners are at least 45mm thick as compared to PVC liners which are just 30mm thick. Butyl liners, unlike PVC liners are available in pre-cut, custom-cut and rolls option.

http://www.butylproducts.co.uk/Products-Services/Ponds-Lakes/