How to Seal Water Tanks That are Flexing Stop Tanks Leaking Externally

Specification to Seal Water Tanks That are Flexing and Leaking Externally

How to Seal Water Tanks That are Flexing Stop Tanks Leaking externally this the method to seal those water tanks that are flexing. This type of concrete tank is usually 20 – 30 years old.  The original strength of the concrete is often close to total collapse. For the tank to continue to hold water it must be strengthened. External Strengthening is temporary at best! The internal of the tank is still exposed to chemical attack by the water (carbonation).

The walls of the tank will be showing efflorescence, mould, and leaking or dampness

Products required

Membranes

Maxseal Foundation | Maxseal Flex  | Maxmesh | Drizoro Brush

Quick Set Mortars

Maxplug – stops running water
Drizoro Maxrite 700  and Maxrest are used where you don’t have running water.|
Maxjoint Elastic Express – for expanding/flexing joints (no running water)

Method for External Repair of Flexing Concrete Tanks Leaking Water

1. Remove all render, paint or other material from the substrate. Pressure clean to remove any growth on the surface.

2. Any cracks or voids (wider than 1 mm) should be repaired with either MAXREST or MAXPLUG if there is flowing water. MAXRITE 700 can be used to replace Maxrest when the tank is empty.

The crack should be ground at least 3.5 mm wide and 20mm deep with a dovetail or square shoulders before filling as per MAXPLUG.
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DRIZORO MAXJOINT ELASTIC may also be used for crack & joint repairs.

3. For joints;

a. Joints. Coat with MAXSEAL FLEX using MAXMESH to reinforce & strengthen the product.

b. Expansion joints.

Use MAXFLEX XJS bandage and MAXSEAL FLEX. This will flex to absorb excessive movement in the substrate

4. Strengthen the area where the cracking has occurred.

Build a post inside the tank. Building a tank with a post externally is more difficult. Especially if you expect such a repaired tank to last another 20 years. The amount of Maxrest/Maxrite will depend on the strength required. Consult an engineer for a recommendation.  If you use steel reinforcing to add further strength you will need at least 25-50mm (See Australian Standards). Keep the repair mortar damp during curing.

5. Apply the first coat of Maxseal (1-1.5Kg/m²). Leave to cure overnight.

6. Curing

14 hours minimum between coats on the remainder of the surface area with MAXSEAL FLEX. High humidity will affect the curing of the Drizoro products. It is recommended that the area be well ventilated or curing time will be longer

7. A tank surface requires approximately 2.5 Kg of product per square meter. Coating is not thick enough, then add a third coat. ( ca.1.25 mm per coat)

8. After the final coating wait for a minimum of 14 days before filling the tank with water

To make your tank last longer. Bracing tanks with steel is expensive. Cargo straps definitely will be cheaper. Here the tank is supported using a loadbearing strap/s. The two steel, posts reduce movement up and down the tank. Add more as required. This just stops the the degraded tank from flex. It is not a permanent solution

Personally, the new transport straps used by heavy vehicles would seem to be the way to go. They are much more cost efficient that steel straps.

Best Method for Internal Repair & Waterproofing Concrete Tanks Leaking Water

Warning:- IT’S YOUR LIFE TAKE HEED
You are entering a confined space. For your safety before entering a water tank open all external drains and ventilate the tank to ensure the air is breathable!!

Remember Carbon Dioxide displaces Oxygen.
Note: Oxygen required for life function

1. Remove any loose material from the substrate. Pressure clean to remove any organic growth from the surface.

2. Cracks and voids (wider than 1 mm) should be ground or chiselled open. Recommended 20-25 mm wide and 20 mm deep with dovetail or square shoulders (see diagram below) and repaired with MAXREST or MAXRITE.

Strongly recommended that if the crack is also apparent on both sides of the water tank it be repaired as per Method Repair for External Cracks

 

NOTE:- On old tanks reduction of the structural strength of the tank may be the reason for the crack formation and to AVOID the crack reforming. We strongly recommended that the area surrounding the crack be built up using MAXREST or MAXRITE. This restores some structural integrity and creates extra support (like a pillar/post) and spreads the pressure created by the water, across a greater area, when full.

 

3. For joints;
a. Joints. Embed first coat of MAXSEAL FLEX with MAXMESH to reinforce & strengthen the product.

b. Expansion joints. Use MAXFLEX XJS bandage and MAXSEAL FLEX. This will flex to absorb excessive movement in the substrate

4. Coat the total area inside the tank. Leave to cure overnight.

5. 14 hours minimum between coats on the remainder of the surface area with MAXSEAL FLEX. High humidity will affect the curing of the Drizoro products. It is

Keep the completed application in the tank well ventilated or longer curing times will result.

6. A tank surface requires approximately 2.5 Kg of product per square meter. If the coating is not thick enough, then add a third coat. ( ca.1.25 mm per coat)

7. After the final coating wait for a minimum of 14 days before filling the tank with water

8. Support your tank against movement

Commonly Used Products In Tank Repairs

Go here for External Waterproofing Method where your tank is structurally sound