When the job demands flexible waterproofing and robust concrete protection, the solution needs to be reliable. Sikalastic-1K is the single-component answer for structures that move, containing water, or resisting aggressive environments. It’s the fibre-reinforced, crack-bridging cementitious mortar that ensures concrete stays protected and waterproofed, even under challenging conditions.
Sikalastic-1K was developed to simplify flexible waterproofing and concrete protection. This one-component, fibre-reinforced, polymer-modified cementitious mortar delivers crack-bridging ability for various structures, including those designed to retain water. It stands as a reliable barrier against water ingress and environmental degradation, from basements facing negative water pressure to concrete tanks and under-tile wet areas.
Flexible waterproofing depends on the ability to handle movement. Sikalastic-1K provides a crack-bridging ability of greater than 0.50 mm (Class A3), or at least 0.75 mm under European standards (EN 14891). This means it maintains its integrity when minor substrate movement occurs, preventing water penetration through small cracks. Crucially for water-retaining structures, it demonstrates no water penetration after 72 hours at 5.0 bar of positive pressure and no penetration after 72 hours at 2.5 bar of negative pressure. This proves its capability to resist water from both sides, essential for basements and tanks. The product also boasts a strong tensile adhesion strength of at least 0.8 N/mm², even after exposure to water, heat, or freeze-thaw cycles. This ensures a durable bond to concrete, cement mortars, stone, and masonry, providing long-term protection.
Sikalastic-1K arrives as a single component, requiring only the addition of water. Its consistency is adjustable for brush or trowel application, offering good sag resistance even on vertical surfaces. Before mixing, ensure substrates are structurally sound, clean, and free from contaminants. Concrete should be repaired using SikaTop or Sika MonoTop materials if required, then adequately dampened to a saturated surface dry (SSD) condition. Mix with a low-speed drill (around 500 rpm), ensuring a homogeneous, lump-free mortar. Apply in multiple thin layers; a total dry film thickness of 2 mm is standard, with 3-4 mm recommended for negative pressure or immersed applications. Maximum thickness per layer is 2 mm by trowel or 1 mm by brush, with subsequent layers applied crosswise after the previous one is dry. Tools clean easily with water before the material sets.
Sikalastic-1K typically forms the primary waterproofing layer within a system. After necessary substrate preparation and repairs with SikaTop or Sika MonoTop mortars, Sikalastic-1K is applied in multiple layers. For critical movement joints or junctions with vertical surfaces, reinforcement with Sika Seal Tape S is recommended, embedded directly into the fresh first layer and then covered by subsequent layers of Sikalastic-1K. For immersed and tanking applications, or where high movement is expected in joints, the Sikadur Combiflex SG System provides a dedicated solution. Once Sikalastic-1K has fully hardened (typically 2-7 days depending on temperature and exposure), ceramic or vitreous tiles can be installed using a polymer modified cement-based tile adhesive from the Sika range, ensuring all joints are sealed.
Yes, Sikalastic-1K is certified to AS/NZS 4020:2005 for products in contact with drinking water. Ensure the product is fully hardened for 15 days before contact and wash thoroughly as per local regulations.
This fibre-reinforced mortar offers good crack-bridging ability, rated at ≥0.75 mm at both +23 °C and –5 °C. This helps maintain integrity against minor structural movement.
Yes, it can be applied to adequately dampened substrates. The surface should not be moist to the touch and must show a saturated surface dry appearance.
Yes, it is designed for inside waterproofing of walls and floors in basements under negative water pressure. It shows no penetration after 72 hours at 2.5 bar.
| Application | Key benefit | Primary trades |
|---|---|---|
| Flexible waterproofing for concrete structures (tanks, basins) | Certified to AS/NZS 4020:2005 for drinking water contact. Provides durable, crack-bridging protection. | Waterproofers, civil contractors, concreters |
| Waterproofing bathrooms, showers, terraces, and balconies under tiles | Complies with AS 4654.1:2012 for external above-ground membranes. Accepts polymer-modified tile adhesives. | Waterproofers, tilers, builders |
| Waterproofing external wall surfaces before backfilling | Offers good sag resistance for vertical application and protects against moisture ingress from surrounding soil. | Waterproofers, landscapers, builders |
| Interior waterproofing for basements with negative water pressure | Resists up to 2.5 bar of negative pressure for 72 hours, preventing moisture entry from hydrostatic pressure. | Waterproofers, basement specialists, builders |
| Flexible protection coating for reinforced concrete | Protects against freeze-thaw cycles and carbon dioxide attack, extending concrete durability with a permeable coating. | Concreters, remedial contractors, asset managers |
Danger: Causes serious eye damage. May cause an allergic skin reaction. May cause cancer by inhalation.
Wear protective gloves, protective clothing, eye protection, and a suitable face shield. If ventilation is inadequate, wear respiratory protection. Follow AS/NZS 1337.1 for eye protection and AS 2210:3 for protective clothing.
Provide appropriate exhaust ventilation in areas where dust is formed during handling or mixing.
Store locked up in original packaging, in cool, dry conditions, protected from water. Dispose of contents and container to an approved waste disposal plant in accordance with local regulations.
Proper substrate preparation is critical for Sikalastic-1K to achieve optimal adhesion and performance.
Surface prep: Substrates must be structurally sound, clean, and free from contaminants like dirt, oil, grease, or cement laitance. Clean by blast cleaning, high-pressure waterjetting (400 bar), wire-brushing, or grinding. Remove all previous coatings and adhesion-reducing materials. Vacuum away all dust from preparation.
Primer: Not required. The substrate must be adequately dampened before application. The surface should be saturated surface dry (SSD), not moist to the touch.
Surface prep: Ensure surfaces are clean, sound, and free of loose material or contaminants. Prepare as per concrete substrates to ensure a clean, stable bonding surface.
Primer: Not required. Dampen the substrate to an SSD condition before application to aid adhesion and prevent premature drying.
| Property | Value |
|---|---|
| Composition | Cement modified with alkali resistant polymers, selected aggregates, fine fillers, admixtures, and fibres |
| Packaging | 20 kg bags |
| Shelf Life | 6 months from date of production |
| Colour | Light grey |
| Maximum Grain Size | ~0.3 mm |
| Crack Bridging Ability | ≥0.75 mm (EN 14891 A.8.2/A.8.3 at +23°C and -5°C for 3.6 kg/m² in 2 layers) |
| Tensile Adhesion Strength | ≥0.8 N/mm² (initial, after water contact, heat aging, freeze-thaw cycles, lime water, chlorinated water) |
| Capillary Absorption | ~0.02 kg/m²·h0.5 (3 mm layer, 22% water) |
| Water Penetration (Positive Pressure) | No penetration after 72h at 5.0 bar (3 mm layer, 22% water); No penetration after 7 days at 1.5 bar (3.6 kg/m²) |
| Water Penetration (Negative Pressure) | No penetration after 72h at 2.5 bar (3 mm layer, 22% water) |
| Permeability to Water Vapour | Class I (permeable), SD < 5 m |
| Permeability to Carbon Dioxide | SD ≥ 50 m |
| Freeze-Thaw De-icing Salt Resistance | ≥0.8 N/mm² (3 mm layer, 22% water) |
| Reaction to Fire | Euroclass A2 |
| Fresh Mortar Density | ~1.5 kg/l |
| Pot Life | ~30 min at +20 °C |
| Consumption | ~1.2 kg/m²/mm |
| Minimum Layer Thickness (Standard) | 2 mm DFT (minimum 2 layers) |
| Minimum Layer Thickness (Negative Pressure/Immersed) | 3-4 mm DFT (minimum 2 layers) |
| Maximum Thickness per Layer (Trowel) | 2 mm |
| Maximum Thickness per Layer (Brush) | 1 mm |
| Ambient Air Temperature | 5 °C min. / 35 °C max. |
| Substrate Temperature | 5 °C min. / 35 °C max. |
| Waiting Time - Horizontal Tiling (20°C) | ~2 days |
| Waiting Time - Horizontal Tiling (10°C) | ~7 days |
| Waiting Time - Vertical Tiling (20°C) | ~2 days |
| Waiting Time - Vertical Tiling (10°C) | ~3 days |
| Waiting Time - Water Emulsion Coating (20°C) | ~2 days |
| Waiting Time - Water Emulsion Coating (10°C) | ~3 days |
| Waiting Time - Water Immersion (20°C) | ~2 days |
| Waiting Time - Water Immersion (10°C) | ~7 days |
| Waiting Time - Drinking Water Contact (20°C) | ~15 days |
| Waiting Time - Drinking Water Contact (10°C) | ~15 days |
| Water Dosage - Brush Application (per 20kg) | ~6.0 litres |
| Water Dosage - Trowel Application (per 20kg) | ~4.4 litres |
Here are some common examples on where Sikalastic®-1K Mortar used by our customers.
