Lining/Coating Concrete Structure for Brine Application

[stanier]

I would appreciate any experience that others may have in lining or coating a concrete structure that will be subjected to brine concentrate from a desalination plant.

Challenge is that it is below ground and when emptied the ground water may provide an external pressure and disbond any coating from the concrete.

 

[Ron]

You could consider a coating for the lining (bituminous mastic for instance), an epoxy, a urethane or you could increase the cover and make sure the concrete density is high. Use a corrosion inhibiting admixture (lithium or similar).

Don't worry about hydrostatic pressure debonding a coating. The head loss through concrete is so high that there will be little actual pressure against the back of the coating. The hydrostatic pressure moreso affects the entire structure.

 

[dik]

We do a fair number of these and just use 35MPa concrete, 3" cover and HDG rebar and they hold up quite well.

Dik

 

[Zambo]

"quite well" is that OK?

There are some construction chemicals which could help such as Xypex

http://www.xypex.com/products/products.php

this can either be as an admixture or as a coating.

The first aim is to provide a dense concrete. Standard 35MPA might not be sufficient in this case (why not use 40MPA?) and I would aim to increase the resistance to water penetration by adding either waterproofing admixtures or silca fume.

dik recommends 3" concrete cover this is a good recomendation on the earth side, to avoid cracks I would prefer 50mm cover on the brine side.

The rebar design must be for a water retaining structure to minimise crack widths.

 

[bimr]

If you want a high quality lining system, I recommend the anchor-lok system,

http://209.235.237.139/products/corrosion_resistant/linings_membranes.asp

ANCHOR-LOK thermoplastic sheets are manufactured with anchor studs on one side of the sheet. The unique engineered anchoring and connecting system of H-Zip strips provide a smooth lining system that is an integral part of the concrete structure. The anchor studs become embedded in
the concrete thus locking the lining in place. The
ANCHOR-LOK lining will not loosen if moisture penetrates through the concrete from the exterior as can occur when coatings or linings are installed on concrete that is below grade or in areas with a high water table.

http://www.atlasmin.com/products/corrosion_resistant/pdf/4-5000ps--7-05.pdf

 

[dik]

I've use 2" cover for numerous parkades... but the 3" is a client requirement as is the HDG, and they seem to hold up against corrosion well...

Dik

 

[stanier]

Xypex has been pretty well ruled out as not meeting its claimed performance by the durability experts.

The brine is highly oxegenated and levels vary with tides and flows. The design life is 100 years. TDS 72,000 mg/L.

Bare concrete would appear to be a courageous choice. What desalination plants around the globe have employed this technical solution?

 

[dik]

We just had a fellow in the office yesterday floggin' a material called BGM Environap. This is a bitumastic material that is reinforced with geotextile... installed cost is $2 to $3 a sq ft... it can be torched on for adhesion, and sticks to concrete or steel...

It appears to be a pretty good product and will consider lining an HCl containment with the product (the containment is tertiary, so not overly critical) and will be in contact with their product chemmie teks...

Dik