Sikalastic® Rapid-721
Sikalastic® Rapid-721 is a seamless, crack-bridging and joint-bridging waterproofing membrane that is able to withstand mechanical stresses. It
contains a highly flexible and fleece-reinforced waterproofing layer as well as abrasion-resistant system layers for foot traffic. The waterproofing system's liquid application and high bonding strength on almost any substrate also allow breakthroughs and upstands to be integrated securely and seamlessly.
- Cold applied
- Fast-curing
- Highly flexible and crack--bridging even at extreme sub-zero temperatures
- Permanently weather--resistant (UV, hydrolysis and alkali resistant)
- Fully bonded to the substrate, therefore no flow paths for water under the membrane
- Easy and fast application
- Can also be applied at sub-zero temperatures
- Solvent-free
- Seamless membrane
- Minimal disruption and low maintenance
- Elastic properties – tolerant of thermal movement
- Flexible, impact resistant membrane
Usage
- Water-proofing of communal walkways, flat roof structures, podium decks and terrace roofs
- For new construction and refurbishment projects
- Applicable to existing concrete, asphalt, roofing felt, brickwork (subject to condition and priming requirements)
Advantages
- Cold applied
- Fast-curing
- Highly flexible and crack--bridging even at extreme sub-zero temperatures
- Permanently weather--resistant (UV, hydrolysis and alkali resistant)
- Fully bonded to the substrate, therefore no flow paths for water under the membrane
- Easy and fast application
- Can also be applied at sub-zero temperatures
- Solvent-free
- Seamless membrane
- Minimal disruption and low maintenance
- Elastic properties – tolerant of thermal movement
- Flexible, impact resistant membrane
Packaging
| Sikalastic® Rapid-721 | 10 Kg |
| Sikalastic® Rapid Catalyst | 0.2 Kg |
| Total | 10.20 Kg |
Colour
Pigmented liquid
RAL 7043 (Dark Grey)
Product Details
APPROVALS / STANDARDS
- BBA Accreditation (Cert No: 16/5925)
- External fire performance: BRoof (t4) in accordance with BS EN 13501-5:2005
Chemical Base
Two-component Polymethylmethacrylate (PMMA) Resin and catalyst
Shelf Life
6 months
Storage Conditions
Store products sealed in their original airtight container and in a cool, dry and frost-free place. Direct sunlight on the containers should be avoided, including on site. After removing some of the contents, reseal the containers so they are airtight.
Reference should also be made to the storage recommendations of the material safety datasheet.
Density
| 1.22 g/cm³ | (EN ISO 2811-1) |
System Structure
Communal Walkways - Durability dependent on condition of the substrate Sikalastic Rapid Trafficable (Wearing system)
| Preparation | Prior to priming all substrates must be clean dry and sound free from any oxidisation, mould and any other deleterious materials. For further information please contact technical services | |
| Waterproofing Layer (Upstands) | Sikalastic® Rapid -721 Thixo (Wet on wet application) Sikalastic® Rapid Fleece 110 (0.26m width) | 2.5kg/m² |
| Protective Layer | Sikalastic®-Rapid Levelling Mortar | 4.0kg/m² |
| Wearing Layer | Sikalastic®-Rapid Aggregate Sikalastic®-Rapid Pigmented Sealer | 3.0kg/m² 0.6kg/m² |
Communal Walkways - Durability dependent on condition of the substrate Sikalastic Rapid Trafficable (Waterproofing & wearing system)
| Preparation | Prior to priming all substrates must be clean dry and sound free from any oxidisation, mould and any other deleterious materials. For further information please contact technical services | |
| Waterproofing Layer (Upstands) | Sikalastic® Rapid -721 Thixo (Wet on wet application) Sikalastic® Rapid Fleece 110 (0.26m width) | 2.5kg/m² |
| Waterproofing Layer (Field Areas) | Sikalastic® Rapid-721 (Wet on wet application) Sikalastic® Rapid Fleece 110 (1.05m width) | 2.5kg/m² |
| Protective Layer | Sikalastic®-Rapid Levelling Mortar | 4.0kg/m² |
| Wearing Layer | Sikalastic®-Rapid Aggregate Sikalastic®-Rapid Pigmented Sealer | 3.0kg/m² 0.6kg/m² |
Communal Walkways - Durability dependent on condition of the substrate Sikalastic Rapid Trafficable (Buried system)
| Preparation | Prior to priming all substrates must be clean dry and sound free from any oxidisation, mould and any other deleterious materials. For further information please contact technical services | |
| Waterproofing Layer (Upstands) | Sikalastic® Rapid -721 Thixo (Wet on wet application) Sikalastic® Rapid Fleece 110 (0.26m width) | 2.5kg/m² |
| Waterproofing Layer (Field Areas) | Sikalastic® Rapid-721 (Wet on wet application) Sikalastic® Rapid Fleece 110 (1.05m width) | 2.5kg/m² |
| Protective Layer | Sikalastic® Rapid-721 Sikalastic®-Rapid Aggregate | 0.6kg/m² 3.0kg/m² |
| Wearing Layer | Tiles or Pavers |
Waterproofing for Roofs (infrequently trafficked)
| Preparation | Prior to priming all substrates must be clean dry and sound free from any oxidisation, mould and any other deleterious materials. For further information please contact technical services | |
| Waterproofing Layer (Upstands) | Sikalastic® Rapid -721 Thixo (Wet on wet application) Sikalastic® Rapid Fleece 110 (0.26m width) | 2.5kg/m² |
| Waterproofing Layer (Field Areas) | Sikalastic® Rapid-721 (Wet on wet application) Sikalastic® Rapid Fleece 110 (1.05m width) | 2.5kg/m² |
Application
Ambient Air Temperature
-5 °C min. / +35 °C max.
Relative Air Humidity
The relative humidity must be ≤90%
Substrate Temperature
+3 °C min. / +50 °C max.
Dew Point
Beware of condensation. Surface temperature during application and cure must be a minimum of 3°C above dew point.
The substrate temperature must not be less than +3°C if a topping is applied to the surface. Reaction problems can occur at lower temperatures.
Substrate Moisture Content
The surface to be coated must be dry and ice-free
The surface must be protected from moisture until the coating has hardened
Substrate Pre-Treatment
| Substrate Priming | |
| Substrate | Primer |
| Cementitious Substrates | Sikalastic® Rapid Cementitious Primer |
| Brick and Stone | Sikalastic® Rapid Cementitious Primer |
| Tiles | Sikalastic® Rapid Cementitious Primer - Adhesion test required |
| Asphalt | Sikalastic® Rapid Asphalt Primer |
| Bituminous Felt | Not required |
| Single Ply | Adhesion to single ply may vary depending on type, age, etc. Consult Sika Liquid Plastics for further advice on priming requirements. |
| Bituminous Coatings | Sikalastic® Rapid Asphalt Primer |
| Metals | Sikalastic® Metal Primer or Sika® Primer 204N |
| Timber Substrates | Timber based roof decks require a layer of S-Vap 7000E DP. For small areas of exposed timber (i.e. upstands) use Sikalastic® Rapid Cementitious Primer, (exposed timber should be Marine ply to BS 1088 or equivalent). |
| Paints | Always remove coats of paint completely. |
| Polyurethane Coating | Not required |
Pot Life
The material in opened containers should be applied immediately
At 20°C, 2% catalyst the pot life is approximately 15 minutes
Applied Product Ready for Use
| Temperature | Catalyst | Rain resistant | Can be | Full cure |
| 20°C | 2% | 30 minutes | 1 hour | 3 hours |
Note: Times are approximate and will be affected by changing ambient conditions.
Higher temperatures or greater proportions of Sikalastic Rapid Catalyst will reduce reaction times, while lower temperatures and smaller proportions of Catalyst will increase reaction times.
The following table indicates the recommended amount of Sikalastic Rapid Catalyst required to adjust the curing reaction to the temperature.
Substrate temperature in °C; required amounts of Sikalastic Rapid Catalyst in % w/w (guide)
| +3 | 5 | 10 | 15 | 20 |
| 4% | 4% | 4% | 2% | 2% |
| 25 | 30 | 35 | 40 | 50 |
| 2% | 2% | 2% | 1% | 1% |
Return-to-service times are provided as a guide only and may vary as a result of conditions. Newly installed balconies should be protected from exposure to heavy traffic by overlaying with an appropriate protective covering. This is particularly critical where early access is needed by other construction related traffic. Sika Liquid Plastics will not be held responsible for damage to balcony surfaces that results from failures to adequately protect newly laid areas.
For further advice, consult Sika Liquid Plastics Technical Customer Services
SUBSTRATE PREPARATION
Substrate preparation is crucial to ensure durability. Please refer to the Sikalastic Rapid Method Statement or Sika Liquid Plastics specification for more information.MIXING
Use a twin-paddle stirrer to mix the product First stir the tub contents thoroughly.
Then add the Sikalastic® Rapid Catalyst while stirring the resin at the slow speed setting and mix for 2 minutes. Make sure that the product on the base and sides of the container is mixed in. At product temperatures <10°C the product should be stirred for 5 minutes,as the catalyst will take longer to dissolve.
APPLICATION
Apply Sikalastic® Rapid-721 & Sikalastic® Rapid -721 Thixo using a sheepskin roller or brush for areas that are not accessible with a roller.
Sikalastic® Rapid-721 is applied together with Sikalastic® Rapid Fleece 110 reinforcement for waterproofing large areas and details on roofs as well as for waterproofing water-impermeable concrete joints.
Sikalastic® Rapid -721 Thixo is a variant of Sikalastic® Rapid-721 that is more viscous / thixotropic to reduce run-off when applied to sloping and vertical surfaces.
Use Sikalastic® Rapid-721 for waterproofing horizontal areas. Sikalastic® Rapid -721 thixo is used for vertical surfaces (e.g. upstands on details)..
Refer to Sikalastic® Rapid Method Statement for more information
CLEANING OF TOOLS
If work is interrupted or when it is completed, clean the tools thoroughly with Sikalastic® Rapid Cleaner within the pot life of the material (approx. 10 minutes). This can be done with a brush. Do not use the tools again until the cleaner has evaporated fully.
Simply immersing the tools in the cleaner will not prevent the material hardening.