Mapei Lamposilex 5KG
When youโve got water pushing through a crack or hole, you donโt need a โnormalโ repair mortar, you need something that grabs fast and stays put. Mapei Lamposilex is a pre-blended hydraulic binder made from high-strength cements and special admixtures, developed in Mapei research laboratories. It contains no chlorides and is designed specifically for blocking seeping water, including leaks under pressure.
Mixed with water, it becomes a plastic-thixotropic paste thatโs easy to apply on vertical faces, without the hassle of formwork. It has a very fast setting time (about one and a half minutes at +20ยฐC), and once cured it becomes waterproof and water-repellent.
Where To Use Mapei Lamposilex
Mapei Lamposilex is intended for urgent, practical waterproof sealing jobs where speed matters:
- Stopping water leaks in basements, subways and below-grade structures in general.
- Stopping water leaks in above-ground tanks.
- Waterproof sealing of rigid joints between walls and floor slabs.
- Waterproof sealing of cracks and holes.
Why Mapei Lamposilex Works Well On Active Leaks
Because it sets extremely quickly, Mapei Lamposilex can be moulded and pressed into the leak point while itโs starting to cure, then held in place until it locks off the water path. At +20ยฐC the pot life is approximately 1 minute, so itโs the kind of product you prep and apply immediately, not one you mix and โcome back to.โ
Preparing The Area Properly
For stopping water leaks, open the defect so the product has something to bite into. The datasheet recommends enlarging cracks or forming dovetail-shaped holes so the wider part is towards the inside, with minimum external sizes of around 2 cm wide and 2 cm deep, then remove any loose/incoherent material.
For rigid joints between wall and slab, remove degraded/loose material, clear dust (compressed air is suggested), then thoroughly wet the substrate. Before sealing, wait until excess water has evaporated, the ideal condition is a cavity saturated with water but with a dry surface.
Mixing Mapei Lamposilex
Lamposilex is mixed with water to a smooth, lump-free paste. The technical mix ratio is:
- By weight: 100 g Lamposilex : 28 g water (equivalent to 1 kg powder with 280 g water).
- By volume: 2.5 parts Lamposilex : 1 part water.
Because the setting is so fast, prepare only what you can use within about a minute.
Applying Mapei Lamposilex To Stop Leaks
For active leaks, mould the mixed Mapei Lamposilex by hand into a โcorkโ shape, wait a few seconds until it begins to cure, then force it into the crack or hole. Keep pressure on the material for 2-3 minutes until set. Once it has set, excess can be removed mechanically (for example with a sandpaper disc or abrasive wheel). If there are multiple leak points, start from the top and work down.
Sealing Rigid Joints Between Wall & Floor Slab
Work the freshly mixed Mapei Lamposilex straight into the prepared cavity using a trowel or float immediately after mixing. After application, keep the surface damp for the first 15-20 minutes.
Temperature & Site Conditions
Mapei Lamposilex is applied when both substrate and air temperature are between +5ยฐC and +35ยฐC. In warm weather, avoid exposing the material to sunlight and use very cold water for mixing. In low temperatures, use water around +20ยฐC and store the material in heated rooms, as the start of setting and curing is delayed at low temperatures.
Consumption & Clean-up
Typical consumption is 1.8 kg to fill a 1 dmยณ (1 litre) cavity. Tools can be cleaned with water before the material hardens; once set, residues need to be removed mechanically.


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