Quick Answer
Enhancing cob durability involves using a combination of techniques such as adding a render coat, using a mixture of 5% sand to 95% clay, and incorporating stabilizing agents like lime or sawdust into the cob mixture.
Mixing the Perfect Cob Mixture
When it comes to creating a durable cob mixture, the ratio of ingredients is crucial. A mixture of 5% sand to 95% clay provides excellent strength and stability while also allowing for breathability and flexibility. The addition of a small amount of sawdust can also help to improve the mixture’s binding properties and reduce shrinkage.
Adding a Render Coat
Applying a render coat to the exterior of the cob building can help to protect it from the elements and increase its durability. A mixture of 1 part lime putty to 2 parts water can be applied to the wall surface and smoothed out to create a uniform finish. This render coat can be reapplied as needed to maintain the building’s integrity.
Compaction and Drying Techniques
Proper compaction and drying techniques are also essential for creating a durable cob building. The cob mixture should be compacted firmly into the formwork to remove any air pockets and prevent settling. A combination of natural drying and controlled drying methods, such as using a fogging system or a drying tunnel, can help to minimize shrinkage and promote even drying.
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