Description Sikaflex®-428 Precast:
This is a 1-component, moisture-curing, elastic joint sealant. Suitable for use in hot and tropical climatic conditions. USES Sikaflex®-428 Precast is designed for movement and connection joints between concrete precast elements, GRC, and GRP parts. It is also suitable for masonry, concrete and blockwork joints, roof joints, and terminations.
Application Instruction Substrate Preparation:
Sikaflex®-428 Precast generally has strong adhesion without primers or activators to most clean, dry, and sound precast concrete substrates. The substrate must be clean, dry, sound, and homogeneous, free from oils, grease, dust, and loose or friable particles. Sikaflex®-428 Precast adheres without primers and/or activators. However, for optimum adhesion and critical, high-performance applications, such as on multi-story buildings, highly stressed joints, and/or extreme weather exposure, the following priming and/or pre-treatment procedures shall be followed: porous substrates Concrete, aerated concrete, and cement-based renders, mortars, and bricks shall be primed using Sika® Primer-3 N applied with a brush. Before sealing, allow a flash-off time of > 30 minutes (< 4 hours). For more detailed advice and instructions please contact our Technical Department. Note: Primers are adhesion promoters. They are neither a substitute for the correct cleaning of a surface nor do they improve the strength of the surface significantly
Application Method / Tools:
Sikaflex®-428 Precast is supplied ready to use. After the necessary substrate preparation, insert a suitable backing rod to the required depth and apply any primer if necessary. Insert a foil pack or cartridge into the sealant gun and extrude Sikaflex®-428 Precast into the joint making sure that it comes into full contact with the sides of the joint and avoiding any air entrapment. Sikaflex®-428 Precast sealant must be firmly tooled against the joint sides to ensure adequate adhesion. It is recommended to use masking tape where exact joint lines or neat lines are required. Remove the tape within the skin time. If Sikaflex® Precast is dry-tooled it shows a slightly structured, concrete-like surface. If it is wet-tooled (using a compatible tooling agent, for example Sika® Tooling Agent N) it shows a smooth surface. Do not use tooling products containing solvents. CLEANING OF EQUIPMENT Clean all tools and application equipment immediately after use with Sika® Remover-208 and/or Sika® Top Clean T. Once cured, residual material can only be removed mechanically. FURTHER INFORMATION ▪ Safety Data Sheet ▪ Pre-treatment Chart Sealing and Bonding ▪ Method Statement Joint Sealing Method Statement Joint Maintenance, Cleaning, and Renovation ▪ ▪ Technical Manual Facade Sealing
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