Application Guide for Polyurethane Cement Industrial Flooring

Achieving a resilient, seamless, and chemical-resistant surface with polyurethane cement for industrial flooring requires meticulous attention to detail and adherence to precise procedures. This comprehensive guide incorporates moisture testing, shot blasting, and other critical steps, using metric measures:

Materials and Tools Required:

• Polyurethane Cement Kit: Resin base, hardener, graded aggregates.
• Primer: Epoxy or polyurethane primer, as recommended.
• Mixing Tools: Heavy-duty drill with a mixing paddle.
• Application Tools: Notched trowel, spiked roller, flat trowel, squeegee, gauge rake.

Surface Preparation Tools:

• Diamond grinder or shot blaster, industrial vacuum cleaner.
• Measuring Tools: Hygrometer, moisture meter, thermometer.
• Safety Gear: Nitrile gloves, safety goggles, respirator, protective clothing.

Step-by-Step Technical Guide:

1. Surface Preparation

Moisture Testing

Before proceeding with any application, it’s crucial to assess moisture levels in the concrete substrate. Different tests provide insights into the surface’s readiness:

• Calcium Chloride Test (ASTM F1869): Measures moisture vapor emission rate (MVER) to determine if the substrate is sufficiently dry. Acceptable limit: < 1.36 kg/92.9 sq. m./24 hours.
• Relative Humidity Test (ASTM F2170): Measures relative humidity within the concrete to evaluate moisture content. Acceptable limit: < 85%.
• Plastic Sheet Test (ASTM D4263): Determines moisture condensation under a sealed plastic sheet, indicating potential moisture issues.

Surface Preparation

Surface preparation is critical for promoting proper adhesion of the polyurethane cement and includes cleaning and roughening the concrete surface:

• Cleaning: Thoroughly remove all contaminants, including oil, grease, dirt, and previous coatings, using industrial cleaners and degreasers. Ensure the surface is completely dry.
• Mechanical Preparation: Achieve a Concrete Surface Profile (CSP) of 3-5 using either a diamond grinder or a shot blaster. CSP refers to the surface roughness measured on a scale from 1 to 9, with higher numbers indicating greater roughness. Vacuum the surface meticulously to remove any dust or debris.

Shot Blasting

Shot blasting, a surface preparation technique, is employed to propel steel shots at high velocity onto the concrete surface to achieve the desired profile:

• Steel Shots: Spherical grains made of high-carbon steel, available in various sizes and hardness levels.

• Shot Size Selection Criteria:

  • Fine Shots (S-70 to S-230): Suitable for light cleaning and smoothing the surface, achieving CSP 1-2.
  • Medium Shots (S-280 to S-390): Ideal for general-purpose cleaning and preparing the surface for coatings, achieving CSP 3-4.
  • Coarse Shots (S-460 to S-780): Best for heavy-duty cleaning and creating a rough surface profile, achieving CSP 5-6.

• Choosing Shot Size: Select based on the desired Concrete Surface Profile (CSP) required for the application.

2. Priming

• Primer Selection: Choose an appropriate epoxy or polyurethane primer that enhances adhesion and minimizes outgassing.\
• Application: Apply the primer uniformly using a roller or brush to prepare the substrate for the subsequent polyurethane cement layer. Aim for a target thickness of 0.2-0.3 mm.
• Curing: Allow the primer to cure for the recommended duration, typically between 4 to 24 hours, depending on environmental conditions.

3. Mixing Polyurethane Cement

• Proportioning: Precisely measure the resin base, hardener, and aggregates to achieve the desired properties and performance.
• Mixing Process: Utilize a heavy-duty drill with a mixing paddle to thoroughly blend the components until a homogenous mixture is obtained.
• Pot Life: Be mindful of the material’s pot life, typically ranging between 15 to 30 minutes, to ensure optimal workability and application.

4. Application

• Pouring: Carefully pour the mixed polyurethane cement onto the primed surface, ensuring even distribution.
• Spreading: Utilize a gauge rake or a notched trowel to spread the material uniformly to the specified thickness of 6-9 mm.
• Leveling and De-aerating: Use a spiked roller to level the surface and expel any entrapped air bubbles, ensuring consistent coverage and adhesion.
• Working Time: Complete the application within the material’s pot life to prevent premature curing and ensure proper bonding.

5. Finishing

• Detailing: Employ a flat trowel to smooth out edges and corners, enhancing the floor’s aesthetic appearance and durability.
• Edge Treatment: Apply masking tape to adjacent areas to achieve clean edges, removing it before the material sets to avoid adhesive residue.
• Expansion Joints: Ensure that existing expansion joints are mirrored in the new layer to accommodate structural movements and prevent cracking.

6. Curing

• Initial Cure: Allow the freshly applied floor to cure undisturbed for 12-24 hours, maintaining optimal environmental conditions for proper curing.
• Full Cure: Achieve full chemical and mechanical properties within 7 days, ensuring the floor’s long-term durability and performance.

7. Post-Application

• Inspection: Conduct a thorough inspection of the completed floor, addressing any imperfections such as air bubbles or uneven areas promptly.
• Cleaning: Clean all application tools and equipment with the recommended solvent immediately after use to prevent material hardening and ensure longevity.
• Safety: Prioritize safety by maintaining proper ventilation and using appropriate respiratory protection during the application process.