Quick Answer
Optimal moisture levels for curing rammed earth walls are generally considered to be between 15% and 25% relative humidity (RH) or between 15% and 20% moisture content by weight. This allows for a controlled rate of drying to minimize shrinkage cracks.
Key Considerations for Curing Rammed Earth Walls
When it comes to curing rammed earth walls, moisture control is crucial to prevent excessive shrinkage and cracking. Aiming for a relative humidity of 15% to 25% is ideal, and this can be achieved through various methods such as using a misting system or covering the walls with a breathable membrane. It’s essential to avoid over-saturating the walls, as this can lead to water seepage and erosion.
Formwork and Soil Mix Considerations
To achieve optimal moisture levels, the formwork used for rammed earth construction should be designed to allow for air circulation and moisture evaporation. The formwork should be removed after 24 to 48 hours, and the walls should be allowed to dry slowly. The soil mix itself should also be formulated to have a moisture content between 10% and 15% when compacted. This can be achieved by using a combination of sandy and clay soils, with adequate sand content to prevent excessive shrinkage.
Thermal Mass and Desert Climates
In desert and arid climates, rammed earth walls can be particularly prone to moisture loss due to high evaporation rates. To mitigate this, it’s essential to incorporate thermal mass into the design, such as through the use of thick walls or internal massing elements. This helps to regulate the indoor temperature and reduce the need for mechanical cooling. Additionally, using a mixture of local soil types can help to improve the wall’s durability and resistance to moisture fluctuations.
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