Sealing Around Tank Bottom

Obviously a steel tank. Holding what? How big? What is it sitting on, other that the "Shalitex" board, i.e., what sort of foundation are we talking about? Any photos available of the installation?

I have found it useful to provide a strong base before laying any protective layer. It may help laying a chicken mesh uniformly on the surface to be protected and gun-nite concrete and after the concrete is set the protective layer can be laid.

This will help seepage of water.

Radha

You might want to try Type S Mortar and Diamond mesh. It can be applied like a plaster repair and both the bottom and top joints sealed with an epoxy caulk. It should only have to be a half to 3/4 inch thick with the diamond mesh overlapped 3 inches. The normal mix is 3 buckets sand to 1 bag Type S mortar but to prevent cracking go with 4 buckets sand to 1 bag. Diamond mesh comes in 2' by 8' sheets.

Thank you for comments, further these tanks are of a capacity of 1.50 lacs Kilolitres filled with water or Fuel. The basic requirement is that due to expansion/contraction the tank is liable for movement thus if any fixed material like mortar or gunniting will crack itself.

After talking about the solution I gave yesterday, I did consider and think about the expansion and cracking problem. The solution I thought about was to have vertical caulk joints maybe every 10 to 12 ft. Good Luck.

I usually don't attemp to install a moisture barrier to seal seal underneath a tank as I provide a way to keep the water evacuated from the areda by draining it away with gravel and French style drains. Most of the time I first pour a 8-16" wide concrete curb with a footer on center with the tank wallI sized to adequately support the tank.

After I get the footer and curb in I then finish removing the saturated dirt from inside the curb and replace it with 2-3 feet of gravel inside the curb as well as backfill with 2-3 foot gravel on the outside of the curb with perforated drainage pipe to remove moisture to the closest sewer and/or cap this with 10-18" of well packed sand on most up to 40 ft OD atmospheric tanks. In a really saturated areas you can drive pilings and/or pour a concrete slab with a 1" re-bar mat to help support the tank. After we get the base support completed we would then do the same as above but I have at times removed several more feet of earth and replace it with flow-able mix before I put down the gravel sand and concrete.

You can also coat the concrete slab with an epoxy based material that will prevent moisture from seeping in though the concrete. I have used Belazona brand products for this purpose a on a few tanks in the past. I find the gravel , sand and drainage system to be far less expensive I think works just as good as the concrete epoxy coated concrete slab does.

I also use epoxy grout to seal around the annular ring of our tanks to prevent corrosion from moisture seeping in under the tank floor. There are several brands of products for sealing around th base of tanks, some are mixable grout products and some are made as a flexible rod made from rubber material that is pounded under the tank annular ring and then pour concrete to in case the area including the annular ring. I can't remember the name of this product right now but if I find it I will send it on to you. Be careful to use non shrinking or expanding grout for chinking the annular ring for obvious reasons.

We had two 50% caustic tanks start sinking into the ground awhile back. These were in a concret containment area and the whole mees started to sink which caused the tanks to lean to one side pretty bad. The young engineer that was asiigned the repair chose to use an expanding concrete grout product to pick these tanks up and level them. This stuff is pumped in underneathe the tank and as it cures it will lift thetank very well. What the engieer did not think about was that he only needed to raise the low side of the tank but he instead pumped the concrete underneath the entire ftank floor which lifted the tanks to high in the area that was not sinking and the they are still leaning today, allthough they lean to the other side now.