1. Purpose
The purpose of this method statement is to define the procedures and best practices for applying ready-mix cement and sand plaster on various surfaces, ensuring that the work is carried out efficiently, safely, and in accordance with project specifications and quality standards.
2. Scope of Work
This method statement covers the application of ready-mix cement and sand plaster on concrete, masonry, and other suitable surfaces for both internal and external applications.
3. Materials
- Ready-Mix Cement and Sand Plaster: Pre-mixed plaster conforming to relevant standards, containing a blend of cement, graded sand, and additives for improved workability and performance.
- Water: Clean and potable, free from any impurities.
- Bonding Agent: As required, for improved adhesion on smooth or dense surfaces.
- Plaster Mesh: Galvanized or fiberglass mesh for reinforcement at joints or areas prone to cracking (optional).
4. Tools & Equipment
- Trowels (steel and wooden floats)
- Hawk
- Plumb bob
- Spirit level
- Straight edge
- Buckets for mixing (if hand mixing)
- Mechanical mixer (if site mixing is required)
- Measuring tape
- Brushes and sponges
- Scaffolding or ladders (if required)
- Spray equipment (if plaster is applied using a machine)
5. Safety Precautions
- Ensure that all workers wear appropriate personal protective equipment (PPE) including safety helmets, gloves, goggles, and safety boots.
- Ensure scaffolding is secure and ladders are stable when working at heights.
- Maintain good ventilation in enclosed spaces to avoid inhaling dust.
- Handle ready-mix plaster with care, avoiding prolonged skin contact.
6. Preparation
- Surface Preparation:
- Inspect the surface to ensure it is clean, dry, and free from dust, oil, grease, and loose particles.
- Roughen smooth surfaces using a wire brush, chisel, or by applying a bonding agent, especially on concrete or precast surfaces.
- Repair any cracks or holes on the surface using a suitable filler before plaster application.
- Dampen the surface with clean water to ensure it is uniformly moist but not saturated, preventing rapid absorption of water from the plaster.
- Setting Out Levels:
- Establish and mark levels and reference lines using a plumb bob, spirit level, and chalk line to ensure that the plaster will be applied evenly.
- Install guide screeds to help maintain the desired plaster thickness across the surface.
7. Mixing
- Ready-Mix Preparation:
- Check the manufacturer’s instructions for any specific mixing requirements for the ready-mix plaster.
- If additional water is required, add it gradually to the ready-mix plaster and mix until a consistent, lump-free mixture is achieved.
- Use a mechanical mixer to ensure thorough and uniform mixing if necessary.
- Consistency:
- Ensure the mix has a smooth, workable consistency that can be easily applied to the surface. Avoid adding too much water, as this can weaken the plaster.
8. Application Procedure
- First Coat (Scratch Coat):
- Apply the first coat of ready-mix plaster to the surface using a trowel. The thickness is typically around 10 to 12 mm depending on the project specifications.
- Use a straight edge to level the plaster and remove any excess material, ensuring an even application.
- While the plaster is still fresh, create a rough texture on the surface using a notched trowel or a comb to provide a key for the subsequent coat.
- Allow the scratch coat to cure for at least 24 hours, keeping it moist to prevent premature drying and cracking.
- Second Coat (Finish Coat):
- Apply the second coat of ready-mix plaster, typically 6 to 8 mm thick, over the cured scratch coat.
- Use a straight edge and spirit level to ensure the surface is even and smooth.
- Smooth the surface using a wooden float for a medium finish or a steel trowel for a finer finish, depending on the desired texture.
- In areas prone to cracking or on large spans, consider embedding plaster mesh within the first coat to provide additional reinforcement.
- Machine Application (If Applicable):
- If using spray equipment, adjust the machine settings according to the manufacturer’s guidelines to achieve the desired thickness and finish.
- Spray the plaster evenly across the surface and immediately follow with a straight edge to level the material.
9. Finishing
- Final Smoothing:
- After the plaster has been applied and is partially set, use a steel trowel to achieve a smooth finish.
- For textured finishes, a sponge float or brush may be used while the plaster is still workable.
- Curing:
- Proper curing is essential to prevent cracks and ensure the plaster reaches its full strength. Begin curing after 24 hours by lightly spraying water on the plastered surface.
- Continue curing by keeping the plastered surface damp for 7 days. This is particularly important in hot or dry climates to prevent the plaster from drying too quickly.
10. Quality Control
- Thickness Verification: Ensure the plaster is applied to the specified thickness using a straight edge and spirit level.
- Surface Evenness: Check for flatness and uniformity of the plastered surface.
- Adhesion: Test for hollow spots by tapping the surface lightly; any hollow sounds indicate poor adhesion.
- Finish Inspection: Verify the finish quality, ensuring that the surface is free from cracks, voids, and other imperfections.
11. Clean-Up
- Clean tools and equipment immediately after use to prevent the plaster from hardening on them.
- Remove excess plaster from adjacent surfaces while it is still wet.
- Ensure that the work area is left clean and free from debris.
12. Completion & Handover
- Conduct a final inspection to ensure that the plastering work complies with project specifications and quality standards.
- Provide documentation confirming the completion of the plastering work, noting any deviations or corrective actions taken during the process.
- Hand over the plastered surfaces, ensuring they are ready for any subsequent treatments, such as painting or finishing.
Conclusion
This method statement provides a comprehensive guide for the application of ready-mix cement and sand plaster on various surfaces. By following these procedures, including proper surface preparation, mixing, application, and curing, the plastering work will meet the required quality standards, resulting in a durable and aesthetically pleasing finish that will perform well over time.
