10000 L Brick Water Storage Tank


  #1  
Old 04-14-05, 03:33 PM
MG13124
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10000 L Brick Water Storage Tank

Hello All,

I am an engineering student designing a 10000 liter water tank for a community in Rwanda, East Africa. The tank will be made of standard red bricks. The internal dimentions will be 2.8m square, by 1.5 m high. The walls will be three bricks deep on the bottom, with the standard orientation: thinest dimention vertical, longest dimention along the face of the wall. The walls will be steped on the outside, with 3 tiers, each 1/3 of the total hight. The first tier being three bricks, the second, 2 bricks, and the third, 1 brick thick.

When filled, the tank should weigh in at about 27000 Kg

The roof will be composed of 12 minislabs of reinforced concrete of dimentions 1.5m * 0.5m * 0.08m. There will be an internal wall two bricks thick to support the minislabs.

The tank will sit on a slab of reinforced concrete.

Some questions:

How thick should the foundation slab be? Is 6" with #4 rebar going both ways, spaced 1' on center enough?

Will the roof minislabs, with the given dimentions, be thick enough to support their own weight as well as the the live loads of a few people on top of the tank?

I am thinking of using steel grid mesh to reinforce these minislabs, does A98, 5mm mesh with 200 mm spacing sound reasonable? Is that too much or too little?

I am thinking that the bricks should be layed such that there is interlocking at the corners of the two adjoining walls. I figure that will help strenthen the corners to resist the overturning moment of the water pressure. Does this sound reasonable?

As far as the bricklaying pattern goes for the 2 multibrick tiers, should there be some bricks that are rotated 90 degrees from the standard orientation to join the layers together?

I have zero actual masonry construction expierence so I am building a small prototype here in the states to make sure that my team knows what we're doing when we get to Rwanda. Can somone explain the basic procedure of bricklaying to me? I assume that I would mix up some mortar and lay the first course all around the perimeter, then ensure that it's level and then continue with the higher courses. How much mortar do I put between the bricks, and how do I apply it?

Any help would be appreciated.

-Max
 
  #2  
Old 04-14-05, 05:53 PM
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10000 L Brick Water Storage Tank

This is just a comment -

If this will actually be built rather that just be a design project you should do some research on the size and properties of the most common material.

In international construction, there is no such thing as a common or standard red brick. You probably will not find any red brick in Rowanda or other parts of Africa, but you probably will find light tan or yellow brick with different properties. I do not think the brick will be anything like what people are familiar with in the U.S. They will probably be much softer, weaker and more absorbant. Rather than clay brick, you may find that concrete brick is the local standard and will probably be stronger and may have lower absorption.

The locally available size will determine the laying pattern. If clay, it could be anything. If concrete, it would probably one of the "standard" German or other Euriopean sizes, which are larger than U.S. brick. In any case, you will need a running bond and may want to lay some brick cross-ways in the wall for additional strength.

All of these type of tanks I have seen have been plastered because the locally available clay brick are not really kiln fired and are softer and much more absorptive.

In India, these type of tanks are plastered or parged with up to 6 cm of plaster inside and out to prevent the clay brick from "dissolving". For below grade tanks, they only use the thick plaster or parge on the inside.

An E-mail to the South African Concrete Masonry Association may be a start for some information if you do not have a local contact. They are aware of the masonry construction practices generaly used in much of Africa.

Good luck!

Dick
 
  #3  
Old 04-16-05, 01:23 AM
MG13124
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Any thoughts on the slabs?
 
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Old 04-16-05, 06:54 AM
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10000 L Brick Water Storage Tank

The slabs sound like they should work, depending on what load they have to carry. You did not mention if the tank was above ground or below ground. If the top is at ground level you could get heavy, unintended loads like a truck.

If you are above ground level, I would take a hard look at the structural design of the walls of the tank. The tensile forces due to the water pressure must be resisted, no matter what the strength of the brick is. The amount of reinforcement in the walls is less than a quick design would give you because of the aspect ratio.

The most common construction of these tanks I have seen internationally is 150 x 190 x 390 mm masonry units (6" block) with reinforcement depending on size and shape of the tank. A typical "quick and dirty" American design would be to use 8" block or even more, which is overkill. There is nothing wrong to use 8" block if that is the only size available. The cores of the block are filled as needed or desired. Conventional masonry joints are 10 mm or 3/8" everywhere in the world. Parging or waterproofing wuld depend on local materials and practices.

You should be able to find 150mm (6") block in Africa. This is the basic unit for housing in many countries.

Good luck.

Dick
 
  #5  
Old 04-17-05, 07:10 PM
MG13124
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Do you think the brick walls should be reinforced with masonry ties? In the current design, there are header bricks that span across the layers every foot or so, is this enough?

How about using barbed wire as ties by putting pieces of barbed wire in the mortar between bricks? Maybe even long loops of barbed wire between courses?

Would that cause problems?

-Max



*edit: The tank is completly above ground.
 
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Old 04-18-05, 08:13 PM
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10000 L Brick Water Storage Tank

Forget about masonry ties if you are thinking about the corrugated type used to hold brick on to wood frame construction. The will be of little help for your situation.

I have seen barbed wire used as joint reinforcement and it works well if you are careful. It never flew in the U.S. because of the obvious problems. What you want is long stands of wire paralle to the face of the wall. Put the wire close to the tensile side of the wall and try to keep about 3/4 to 1 inch of cover. Horizontal will be the easiest, but vertical would be a nice addition too, if possible. The important thing is to tie everything together using the wire for continuity.

You don't need high strengths of mortar, but use proportion similar to a Type N or Type S. Fortunately, you will probably be using a portland and lime mixture. Mortar cement or masonry cement will work but is a second choice for your application.

I talked to a friend from Kenya who is familiar with Rwanda. He said be willing to make some changes to use the best materials available locally. Always good advice that is often overlooked by many designers.

Dick
 
 

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