Effective use of curing compounds
Curing compounds are essential for preventing the evaporation of water from freshly poured concrete, in specific applications.
The primary goal is to maintain optimal temperature and moisture conditions, thereby enhancing the strength, impermeability and durability of the final product.
This curing process is fundamental for the surface and near-surface zones of the concrete.
The importance of curing
Water loss in concrete is primarily caused by environmental factors such as sunlight, wind and humidity. Without proper curing, these elements can cause the concrete to lose moisture too quickly, leading to shrinkage stresses and potential cracking.
Curing protects the concrete from these factors until it reaches the adequate strength to resist shrinkage. If the rate of evaporation surpasses the rate of bleeding, plastic shrinkage cracks may develop. Therefore, it is important to retain moisture within the concrete, ensuring that the hydration process continues, and allowing the concrete to achieve its ultimate strength, typically at 28 days.
Curing compounds are membrane-forming liquids sprayed onto the surface of the concrete to prevent water evaporation.
Phases of curing
Curing methods can be divided into two key phases:
- Curing before the initial set: This involves continuous curing during the bleeding process of the concrete. The objective is to prevent premature water loss and ensure that the concrete maintains sufficient moisture levels.
- Curing after the initial set and final surface finishing: This phase begins after the initial set, ideally before the final set. Once the concrete’s surface transitions from a shiny to a matte appearance, it indicates that bleeding has ceased, and surface finishing can commence. Following the surface finishing, curing compounds can be applied to maintain moisture.
It is essential to recognise that bleeding occurs up to a point before the initial set. Once this point is reached and the surface loses its shine, curing compounds should be applied to prevent further evaporation of water.
Application and selection
Without proper curing, concrete can lose moisture too quickly, leading to shrinkage stresses and potential cracking.
Curing compounds are membrane-forming liquids sprayed onto the surface of the concrete to prevent water evaporation. These compounds should be applied as soon as the bleeding process stops and the bleed water evaporates, or immediately after the removal of formwork.
The choice of curing compound is vital. If further surface treatments, such as painting, plastering, sealing or rendering, are anticipated, some curing compounds may interfere with these subsequent treatments.
Special considerations
In hot weather conditions, concrete is especially vulnerable to rapid moisture loss due to the sun and wind. To mitigate this, it is important to protect the concrete surface with curing compounds. This protection ensures that the concrete retains its moisture, allowing the hydration process to continue uninterrupted, and achieve the desired strength and durability.
Proper application and selection of curing compounds enhance the long-term performance of concrete, particularly when additional surface treatments are planned.
For more information, contact a.b.e.®Saint-Gobain:
Tel: +27 860 223 773
Email: talk2us@saint-gobain.com
Website: www.abe.co.za