Cement-based waterproofing


Waterproof, transpiring and flexible coating with high mechanical resistance, featuring a cement base.
It is a two-component product, made of a component A, resin and a component B, cement and special inert. It is a coating that sticks to most of the constructions materials, like concrete, bricks, stones, little cement blocks, etc.

It protects and creates a waterproof barrier for water pools, drinking water tanks, underground structures subject to hydrostatic pressure, subways, car-parks, tunnels, canals, damns, containing walls, depuration plants, both inside than outside of new or existing structures.
It presents itself as a waterproof coating with flexible properties; it seals micro-fissures and shrinkage caused fissures.
It allows water vapour to go through and the transpiration of treated supports. It is resilient to abrasion, to the weather agents, to the corrosive effects of salty water and to the frosting and defrosting cycles.
It resists to the negative hydrostatic pressure, when applied inside underground structures. It presents an excellent adhesion, it is easy to apply and the maintenance costs are virtually non existent. It does not contain chloride and it is suitable for contact with drinking water.

Do not apply to frozen surfaces or at temperatures below 5 °C or when such temperature has been forecasted within the next two hours.
The application is advised at temperatures above 30 °C.


Component A appearance

milky liquid

Component B appearance grey powder
Density (A+B) 1,56 kg/dm3
Resistance under hydrostatic pressure over 4 bar
Resistance to frosting cycles and to the defrosting salts no deterioration nor alteration after more than 30 cycles
Concrete adhesion 2,0 N/mm2
Cracks absorption a 23° C 2mm a 0° C 2mm a -25° 0.7 mm
Non-toxicity the product is suitable for contact with drinking water
Set component B = 10 litres drum, component A = 25 kg bag
Colours  grey / smooth or rough
Details: the product is non-toxic. Use gloves during application; if the product should come in contact with the eyes rinse thoroughly with clean water.

The surface that needs to be treated has to be sound, clean, free of paint residues, blooms, grease, residues of release agent or any foreign material which might inhibit a proper adhesion. The imperfections of the concrete must be repaired with fast setting anti-shrinkage plaster, as KEYPLUG or KEYREPAR, and also the spacers and the reinforcing rods that surface have to be covered by at least 1 cm of thickness.
It is advised to wet the surface before starting the application. Add the powder (B) with the resin (A) and blend with a low speed drill until a homogeneous, clot free mix is obtained. Do not add water. The two components are supplied in a set ( 1 comp. A + 1 comp. B) with the correct dosage, ready to be mixed.
On a wet surface KEYSEAL FLEX can be applied with a brush, a roller, or a spray for wide surfaces. A plastering trowel can be used to apply the product on horizontal surfaces. The application requires two coats with a total incidence of 2,5-3Kg/m2 circa and with a time space of minimum 16 hrs and maximum 3 days between the two coats.
It is advised to apply the first coat with a brush to allow a proper impregnation of the surfaces. The application time varies depending on the temperature, from 30 min to 2 hrs. The complete drying process of KEYSEAL FLEX lasts 7 days, after which is possible to place the product in constant contact with water. The tools can be cleaned with water before the product dries up.
In presence of expansion joints, pools, tanks, and underground rooms, KEYSEAL FLEX can be used together with KEYSEAL FLEX JOINT. It is a rubber tape in TPE (EPDM), with two geo-textile side stripes, which is being placed with two or more layers of KEYSEAL FLEX over a movement and expansion joint, guaranteeing the waterproofing and the elasticity of the treated joint. Some of its main advantages:
• can be applied both with negative and positive hydrostatic pressure
• high joint elasticity, above 350%
• the application together with KEYSEAL FLEX allows its suitability on damp supports
• good chemical resistance
• total waterproofing and simplicity of application

By following the application instructions of KEYSEAL FLEX it will be possible to apply KEYSEAL FLEX JOINT on top of a fresh layer of KEYSEAL FLEX, which will have to be applied again, while the first layer is still fresh, over the geo-textile stripes until the stripes are completely covered. The thickness of the KEYSEAL FLEX layer to cover the stripes has to be of roughly 2-3 mm, with an indicative consumption, just to cover that specific area, of about 3-4 kg/m2. In case some tapes of KEYSEAL FLEX JOINT have to be joint together, welding or a reinforcing tape of the same material have to be used, the latter will have to be glued with a specific adhesive for EPDM rubber.

Rubber type: 
Thickness: 1 mm
Traction resistance: Longitudinal:11,0 N/mmq Transversal: 10,0 N/mm2
Lengthening at breaking point: 350% longitudinal; 325% transversal
Thermal behaviour: not liable to alteration until over -20 °C
Deformation at high temperatures: -0,35%
Steam penetration coefficient: 0.038 mg/m2 h Pa
Ozone resistance: Level O
Accelerated aging: over 5000 hrs
Behaviour in water immersion: mass lost: lower than 3,5% (tested after 8 months)
Maximum expansion referred to the EPDM tape: 15% equivalent to +9 mm for KEYSEAL FLEX JOINT


The products are produced with the best row materials available on the market in order to obtain a high quality product. Our guarantee covers the quality of the product but not its applications which cannot be under our control.


Mibo S.r.l. - Head and Operative offices: Via Chiavegoni, 11 - 36040 Brendola (VI) Italy
Tel/Fax: +39 0444 569182 - edilizia-meccanica@mibosrl.it - P.Iva: 01619760240 - Cookie Policy