Leavin Train

Water Tower

Water tanks wateproofing with cement based products

 

PREFACE

When it comes to the waterproofing of water tanks, constant hydrostatic pressure combined with rigid and porous structure of concrete pose serious challenges for an effective and lasting job.

All water containing and water retaining structures should meet the strictest specifications from the conception to the design and finally the materialization of the project.

THE CONCRETE

Cracks number and width is controlled from sufficient and properly placed steel reinforcement.

Aim for a water/cement ratio W/C? 0,45. Try PCE superplasticizers.

Concrete synthesis, placement as well as curing practices should conform to the local regulations of concrete technology for water resisting concrete.

WATER RESISTING ADMIXTURES

The first successful movement is to use a PCE superplasticizer. This should reduce size, number and continuity of pores.

We in MACON, usually use pore blockers as silica fume. We also use  hydrophobic materials based on esters of fatty acids to line the concrete pores and thus reduce capillary absorption by altering the intermolecular forces in the system concrete – air – water.

LEVELING MORTAR

Depending on the smoothness of concrete substrate a leveling mortar layer should be used.

Usually these leveling mortars are quite thin (less than 6mm thick). To reinforce them and increase their adhesion we use  an SBR LATEX 
The formula we use:

Portland cement: 1 part

Moist, sharp sand: 3 parts

SBR Latex: 0,2-0,25 parts

Clean water: as required to achieve desirable consistency.

CONSTRUCTION JOINTS

All not movable joints e.g. new to aged concrete, floor to wall joints, casting interruption joints should be preventively sealed with QUELLMAX bentonite waterstops. The same is valid for all through-wall penetrations.

SURFACE PREPARATION

Please refer to “WATERPROOFING WITH CRYSTALLINE COATINGS”.

WATERPROOFING OPTIONS

All cementitious materials used in water tanks should better be certified for contact with potable water.

(1) Rigid, one-component cementitious waterproofing products.

These products are suitable only for below ground concrete water tanks. We are strongly in favor of crystalline cementitious waterproofing. Products like these actually offer a double defense line against water ingress. The first line is the waterproof layer on the surface and the second is the in depth pore blocking.

Products like these work with the crystallization process. Proprietary active salts of the product penetrate deeply in concrete mass using substrate humidity as a carrier. That’s why the substrate should be fully saturated with water.

When the active salts meet free lime, complex chemical reactions take place and new salts are produced to totally block the pores!

This is a real structural modification of the concrete! No comparison could be made with conventional one-component cementitious products!!

In order to avoid the most usual errors related to these products use:

Please check: “CEMENTITIOUS WATERPROOFING: 6 FATAL MISTAKES”.

(2) Flexible, two-component cementitious waterproofing products.

For above ground water tanks, mixed type water tanks or water towers the choice is one-way: Flexible cementitious waterproofing.

These products have impressive crack bridging capabilities further enhanced by suitable reinforcements.

These products are two-component, easy to mix and use! Just avoid the 6 FATAL MISTAKES!!!

Chris Strogilis

About the Author

Civil engineer with postgraduate studies in MBA and Marketing.
christos@macon.gr
http://maconwaterproofing.blogspot.com/
http://totalfitness-christos.blogspot.com

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This entry was posted on Tuesday, February 6th, 2007 at 3:28 pm and is filed under Trains. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.