Are there unique challenges when building rammed earth in desert areas?

Moisture Sensitive Soil Mix

In desert areas, it’s crucial to select a soil mix that is less prone to moisture absorption and desiccation. A mix with a high percentage of sand and gravel (typically 20-30% sand and 10-20% gravel) can help reduce the risk of water absorption and cracking. However, the mix cannot be too dry, as it may compromise the structural integrity of the walls. A good starting point is a mix with 5-10% organic matter (such as compost or humus) and 1-2% cement.

Extreme Temperature Considerations

Rammed earth walls in desert areas are exposed to extreme temperature fluctuations, which can cause thermal expansion and contraction. To mitigate this, it’s essential to use a well-designed formwork system that allows for thermal movement. A 1-inch (2.5 cm) gap between the formwork and the finished wall surface can help accommodate thermal expansion. Additionally, the use of insulation and shading devices can help reduce the temperature difference between the inside and outside of the walls.

Formwork and Wall Construction Techniques

In desert areas, it’s crucial to use a robust formwork system to prevent damage from high winds and extreme temperatures. A steel or aluminum formwork system can provide the necessary stability and durability. To ensure a smooth finish, the formwork should be tightly sealed, and the soil mix should be compacted in 2-inch (5 cm) layers, with a minimum of 12 hours of compaction time between each layer. This will help minimize the risk of cracking and ensure a strong, durable wall.