Constructing strong and durable concrete columns and walls requires careful attention to detail. In this guide, we’ll delve into the essential steps and precautions to ensure the desired strength and longevity of your concrete structures. Let’s explore each step in a detailed manner.
If the height of your wall or column form is not significantly tall, the recommended approach is to pour concrete from the top of the forms. This method ensures a more controlled and uniform distribution of concrete.
Place the concrete either directly at its final position or as close to it as possible. This helps minimize the chances of displacement during the pouring process, ensuring the integrity of the structure.
When dealing with taller reinforced concrete columns, adopt a layered pouring strategy with each layer having a thickness ranging from 30cm to 50cm. This approach facilitates proper consolidation and adherence to steel bars.
For concrete walls, limit each layer to a maximum thickness of 60cm in one pass. This prevents segregation issues and ensures a more uniform composition throughout the structure.
Maintain a reasonable time gap between successive concrete layers. In normal conditions, this gap should not exceed half an hour, while in hot weather, it’s advisable to limit it to 20 minutes to prevent complications.
For walls deeper than 1.2m, employ vertical trunks or chutes spaced at 2.4m intervals. This method prevents segregation during the concrete’s freefall.
Utilize vibrations to consolidate fresh concrete. However, exercise caution to avoid over-vibration, as it can lead to segregation. Lift the vibrator only after complete compaction of each layer, extending it into the previous layer by 10-15cm.
If concrete supply is interrupted during pouring, take measures to prevent the formation of cold joints in the wall or column. This ensures a seamless and robust structure.
In some cases, set retarder materials like sugar can be applied to delay concrete setting, allowing a good bond with the next batch. Adjust the thickness of subsequent layers accordingly, and extend vibration into the previous layers.
To avoid concrete separation leading to honeycomb formation, be cautious about concrete strikes against formwork walls during pouring.
In RC columns and narrow walls, initiate concrete pouring with a 5 to 10cm grout layer to prevent the accumulation of loose stones at the bottom, which may lead to honeycomb formation.
In case concreting stops for a day, roughen concrete surfaces with a brush after the initial set to enhance bonding with the next concrete layer.
Watch out for sloping layer lines and honeycombs, which are indicators of improper concrete pouring in walls.
To avoid issues arising from improper concreting practices, adhere to guidelines such as preventing full-depth placement of concrete at one point, maintaining a lower slump for upper layers, restricting lateral movement of vibrators, and ensuring thorough vibration of concrete layers. By following these steps, you’ll contribute to the creation of robust and enduring concrete structures.