Advantages of using Exposed Aggregate Retarder
Exposed aggregate retarders are widely used in today's construction to make surfaces durable and smooth. The aggregate retarders are highly resistant to weather change and thus prevent damage on the surfaces where it is used. For these reasons, aggregate retarders are widely used in sidewalks, driveways, plazas, and similar areas to make them durable and long-lasting. The exposed aggregate retarders are also used in sound barriers and decorative retaining walls.
Advantages of Using the Exposed Aggregate Retarder
There are various benefits of using exposed aggregate retarders. It is primarily used to make the flooring strong so that it can withstand extremes of exposure. Following are the many advantages of using exposed aggregate retarders.
- Strength
One of the prime reasons to use exposed aggregate retarder is that it gives strength and sturdiness to the concrete so that it becomes durable and long-lasting. It will be able to withstand extremes of temperature.
- Long-lasting
One of the prime reasons to use exposed aggregate retarder is because it slows down the speed of the reaction between cement and water by affecting the growth of the hydration products. Thereby, it helps to cut down water penetration inside the cement. It thus acts like a plastic covering that protects the concrete, increasing the shelf-life.
- Bleeding
Since the retarding mixtures delay the process of the setting, the retarded concretes are most likely to bleed more which provides time for the workers to work freely.
- Cost-effective
One of the benefits of using exposed aggregate retarder is that it is cost-effective. Once you use it, it stays for a long time unaffected because of its resistance qualities.
- Reduce Slump Loss
Aggregate retarder boosts workability as it decreases slump loss. Hence, you can use it without worrying about overhead expenses.
- Retain heat output
Concrete retarder does not decrease the heat output of the concrete where the work is in progress. Hence, it makes the concrete more robust and more durable.
The Best Time to Apply Exposed Aggregate Retarder
If you want the best results out of a concrete surface, it is advisable to use the exposed aggregate retarder after the entire process of concreting is over and the bleed water has dissipated. After completing the entire concrete work, you must apply the surface retarder evenly over the surface using a sprayer or roller. Most of the retarders you apply on the concrete act like a protective covering to ensure that extremes of temperature and rain do not damage the surface. It would be best not to seal the concrete as it will prevent the retarder from performing its functions.
The Process Of Retardation
Once you apply the retarder, it works in four steps. They are-
- Adsorption
When you use the retarder, the mixture is adsorbed. It then creates a protective covering around the cement particles, so they are not exposed to extremes of temperature, including rain, high heat and cold, and thunder. It is because the covering water is unable to reach the cement particles. Hence, the cement particles remain un-hydrated, thus helping to slow down the entire process. It is a great way to ensure the concrete remains strong and durable for years.
- Nucleation
When water is added to the cement, the mixture releases calcium, and hydroxyl ions on the surface, forming crystals. Therefore, when you add the retarding mixture, it is absorbed by the calcium hydroxide nuclei and hence decreases the growth of the nuclei till it reaches a level of supersaturation.
- Complexation
As soon as you apply the retarder, it leads to the formation of calcium ions that are released from the cement grains. However, during hydration, due to the presence of the retarding mixture, there is a formation of iron and other elements. It thus prevents the precipitation of the ions from forming calcium hydroxide. Thus, the process of hydration eventually slows down.
- Precipitation
When water is added to cement, the pH of the solution rises, eventually giving rise to insoluble derivatives that are highly alkaline.
Conclusion
Retarders are a great way of making concrete durable, especially in the hot summer months. It is also effective as the retarder can withstand all temperatures, including rain and storm, and prevent the surface to get exposed to the weather components. The retarders are durable and hence cost-effective. For these reasons, the retarders are used in modern complexes, including walkways and driveways.
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