Introduction
Cracks in plastered walls can be one of the greatest frustrations in building construction. After the plaster has been applied, it may appear to be smooth and perfect, but cracks will begin to develop soon after the application of the plaster.
Depending on the application procedures, these minor cracks can develop into larger cracks in appearance and durability over time.
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Therefore, it is critical for contractors, builders and project owners to take Preventive Measures for Cracking in Ready Mix Plaster.
Although ready mix plasters are manufactured with a view to ensuring consistency and improved performance, cracking can still occur when proper application methods are not utilised.
At Sakshi Chem Sciences Pvt. Ltd., we strive to provide high-quality construction chemicals that will provide a durable and crack-resistant finish.
This blog addresses some of the primary causes of cracking in plaster, as well as means of preventing plaster cracking effectively.
What Ready Mix Plaster Is Intended To Do?
Ready Mix Plaster is an off-the-shelf, pre-mixed product that is ready for immediate use. It consists of Portland Cement, an aggregate (usually sand) and one or more types of performance enhancers.
The principles behind ready mix product development were developed to enable builders to accomplish their goals in an efficient manner while producing a high-quality product. The use of ready mix plaster has many advantages over traditional plaster, including:
- Consistency and uniformity in quality.
- Rapid application of plaster at job site.
- Reduces the need for manual mixing.
- Higher bond strengths than traditional plaster.
Despite these advantages, as with all types of plaster, preventing cracking in ready mix plaster has more to do with how a product is applied than with the actual product.
Common Causes of Cracks in Ready Mix Plaster
Cracks will not typically happen as a result of one issue; usually, they form for a multitude of reasons.
1. Shrinking Caused By Excessive Water
One common error made on the job site is the overuse of water in the plaster mix.
Why:
The water is used to enhance workability, extend working time, and make the application easier.
What It Does:
Adding too much water leads to an increase in drying shrinkage that produces hairline cracks and reduces the strength and durability of the plaster.
Even if you use the best ready mix plaster, it won’t perform as the manufacturer intended if you do not control the amount of water mixed in with it.
Best practices: Use the manufacturer’s recommended amount of water.
2. Excessive Application Thickness
Application thickness significantly contributes to how cracks form.
What Went Wrong: Trying to apply too much plaster in one coat, and not having a level surface built up correctly.
What This Caused:
The surface dried before the plaster on the inside and internal tension resulted in cracked plaster because of the unequal shrinkage rates.
Common areas where this occurs include:
- At joints between columns and beams.
- At electrical boxes that use both masonry and wood.
- At unequal masonry surfaces.
Best practices: Plaster should be applied in controlled layers, not one thick coat.
3. Poor Curing Methods
One of the most overlooked aspects of plastering is curing. Curing is a critical component in the development of strength.
Why curing matters:
- Maintains moisture for proper hydration.
- Reduces shrinkage.
- Improves bonding strength.
Common mistakes:
- No curing in hot weather.
- Delayed curing after application.
- Insufficient curing duration.
Without proper curing, even high-quality plaster can develop early cracks.
Best Practice: Start curing at the right time and maintain adequate moisture.
4. Improper Substrate Preparation
The application of plaster on different surfaces will affect the bonds of the plaster to those surfaces.
The application of plaster to the following types of surfaces may weaken the bond and increase the risk of cracking:
- Dirty
- Smooth or non-porous finishes
- Greasy
- Too dry or too thirsty
Best practices for applying ready mix plaster:
- Clean the surface of the wall thoroughly.
- Dampen the wall prior to plastering.
- Provide optimal roughness of the surface to promote bonding of plaster to the wall.
- Understanding the type of ready mix plaster will help you to prevent cracks in your plaster installation.
Types of Ready Mix Plaster:
Curable Ready Mix Plaster
- Requires appropriate curing after application.
- Suitability for exterior applications.
- Best suited for use in hot conditions.
- Provides superior long-term performance.
Non-Curable Ready Mix Plaster
- Requires very minimal curing after application.
- Suitability for interior applications.
- Best suited for use in fast-track projects.
- Performs well in controlled work environments.
Choosing the right type of ready mix plaster for the conditions you are working under is vital to help prevent cracking.
Practical Steps for Preventing Cracks in Ready Mix Plaster
Preventing cracks is very simple; it depends on following a disciplined approach and maintaining attention to detail.
This list will help you to effectively and efficiently prevent cracking in ready mix plaster:
- Use the proper water-to-plaster ratio.
- Apply plaster at a controlled thickness.
- Ensure that adequate curing is performed, particularly during hot weather.
- Always prepare the substrate prior to applying plaster.
- Select the appropriate type of plaster for the environment.
- Avoid drying plaster too quickly due to wind or heat.
By following these steps, it becomes relatively easy to prevent cracks with RMP (ready mix plaster).
Quality Materials Matter
The application practices for RMP are important but the quality of the materials also plays a significant role. Selecting a reputable manufacturer provides:
- Consistent formulation.
- Quality raw materials.
- Improved bond performance.
- Reduced risk of shrinkage.
At Sakshi Chem Sciences Pvt. Ltd., we manufacture construction chemicals that help create strong, durable, and crack-free finishes on your plaster. Our products have been formulated to perform consistently regardless of job-site conditions.
Summary
Cracks are not inevitable in ready-mix plaster; they are preventable. They typically occur because of too much water, improper thicknesses, inadequate curing, and/or inadequate preparation of the substrate. Consequently, by understanding these elements and implementing good practices, the contractor will be able to achieve smooth, durable finishes with their RMP.
Preventing Cracks in Ready Mix Plaster is ultimately about combining the right materials with the right techniques. With high-quality solutions from Sakshi Chem Sciences Pvt. Ltd., you can ensure better performance, durability, and peace of mind in every project.
FAQs
1. Why does ready mix plaster crack after drying?
Cracks usually occur due to shrinkage caused by excess water, poor curing, or thick application layers.
2. What is the ideal thickness for ready mix plaster?
Plaster should be applied in controlled layers as per project requirements. Avoid applying too thick in one coat.
3. Is curable ready mix plaster better for exterior walls?
Yes, curable plaster is generally preferred for exterior applications where durability and weather resistance are important.
4. How long should plaster be cured?
Curing duration depends on environmental conditions, but early and consistent curing is essential to prevent cracks.
5. How can cracks in plaster be prevented effectively?
By controlling water ratio, applying proper thickness, ensuring curing, preparing the substrate, and using quality materials.
Sagar Telrandhe is a Construction Engineer with a B.Tech in Construction Engineering & Management. Passionate about infrastructure development, project planning, and sustainable construction, he specializes in modern construction techniques, project execution, and quality management, contributing to efficient and innovative building.